Pressure Vessel Design Asme Guide 6f541s
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Overview of Pressure Vessel Design
Instructor’s Guide
1
INFORMATION ASME Headquarters 1-800-THE-ASME ASME Professional Development 1-800-THE-ASME
Eastern Regional Office 8996 Burke Lake Road – Suite L102 Burke, VA 22015-1607 703-978-5000 800-221-5536 703-978-1157 (FAX)
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International Regional Office 1-800-THE-ASME You Youcan canalso alsofind findinformation informationon onthese these courses and all of ASME, including courses and all of ASME, includingASME ASME Professional ProfessionalDevelopment, Development,the theVice Vice President Presidentof ofProfessional ProfessionalDevelopment, Development, and other s and other sat atthe theASME ASMEWeb Web site...... site...... http://www.asme.org http://www.asme.org
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Overview of Pressure Vessel Design By: Vincent A. Carucci Carmagen Engineering, Inc.
Copyright © 1999 by
All Rights Reserved
3
TABLE OF CONTENTS
Abstract………………………………………………………………… 5 Introduction…………………………..…………………………………6 Organizing Unit Responsibilities……………………………………..7 Instructor Guidelines and Responsibilities………………………….9 Overview of Pressure Vessel Design Outline/ Teaching Plan…………………………………………………………11 Instructor Notes……………………………………………………….13 Appendix A: Reproducible Overheads Appendix B: Course and Instructor Evaluation Form Appendix C: Continuing Education Unit (CEU) Submittal Form Course Improvement Form Instructor’s Biography Form
4
ABSTRACT
Pressure vessels are typically designed, fabricated, installed, inspected, and tested in accordance with the ASME Code Section VIII. Section VIII is divided into three separate divisions. This course outlines the main differences a mong the divisions. It then concentrates on and presents an overview of Division I. This course also discusses several relevant items that are not included in Division I.
5
INTRODUCTION
This Overview of Pressure Vessel Design course is part of the ASME International Career Development Series – an educational tool to help engineers and managers succeed in today’s business/engineering world. Each course in this series is a 4hour (or half-day) self-contained professional development seminar. The course material consists of a participant manual and an instructor’s guide. The participant manual is a self-contained text for students/participants, while the guide (this booklet) provides the instructional material designed to be presented by a local knowledgeable instructor with a minimum of preparation time. The balance of this instructor’s guide focuses on: 1. 2. 3.
Organizing Unit Responsibilities Instructor Guidelines and Responsibilities Comprehensive teaching materials which may be used “as is” or adapted to incorporate experiences and perspective of the instructor.
Welcome to the ASME International Career Development Series! We wish you all the best in your presentation, operation and delivery of this course.
6
7
8
9
10
Suggested Outline/Teaching Plan Time, min.
Major Interval 10
Class Segment Introduction
Sub-Segment Interval 5 5
25
General
10 10
5 20
Materials of Construction
15
5 10
Exercise
10
10 55
Break Design
10 10
25
20
Sub-Segment Introduction/Logistics Outline Module Module based primarily on the ASME Code Section VIII, Division 1. Divisions 2 and 3 will be briefly described Main Pressure Vessel Components Scope of ASME Code Section VIII • Division 1 • Division 2 • Division 3 Structure of Section VIII, Division 1 Material Selection Factors • Strength • Corrosion Resistance • Resistance to Hydrogen Attack • Fracture Toughness • Fabricability Maximum Allowable Stress Material Selection Based On Fracture Toughness Design Conditions and Loadings • Pressure • Temperature • Other Loadings Design for Internal Pressure • Weld ts • Cylindrical Shells • Heads • Conical Sections Sample Problem Design for External Pressure and Compressive Stresses • Cylindrical Shells • Other Components • Sample Problem
Overheads/ Participant Pages OV – 1 Part. – 65 OV – 2 Part. – 65
OV – 3-9 Part. – 67 OV – 10-13 Part. – 75
OV – 14 Part. –78 OV – 15-31 Part. – 79
OV – 32-34 Part. – 87 OV – 35-38 Part. – 91 OV – 39-43 Part. – 92
OV – 44-55 Part. - 98
OV – 56-65 Part. – 109
11
Suggested Outline/Teaching Plan, continued Time, min.
Major Interval 10 - 50
Class Segment
Sub-Segment Interval
Major Break
Sub-Segment
Overheads/ Participant Pages
Lunch or Major Break
15
Exercise
15
Required Thickness for Internal Pressure
OV – 66-68 Part. - 118
50
Design (Cont’d.)
20
Reinforcement of Openings (Include Sample Problem) Flange Rating (Including Sample Problem) Flange Design
OV – 69-84 Part. – 119 OV – 85-90 Part. – 127 OV – 91-97 Part. – 131 OV – 98 Part. – 138
10 15
10 20
20
15
10
Break Other Design Considerations
Fabrication
Inspection and Testing
Closure
5
Maximum Allowable Working Pressure (MAWP)
10
Local Loads
10
Vessel Internals
10
Acceptable Welding Details
10
Postweld Heat Treatment (PWHT)Requirements
10
Inspection
5
Pressure Testing
10
Summary Questionnaire (fill in and collect) CEU Form (hand out – individual responsibility to return)
OV – 99 Part. – 139 OV – 100-102 Part. – 141 OV – 103-106 Part. – 143 OV – 107 Part. – 146 OV – 108-113 Part. – 148 OV – 114-115 Part. – 152 OV – 116 Part. - 155
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Overview of Pressure Vessel Design Instructor’s Personal Notes
OVERVIEW OF PRESSURE VESSEL DESIGN By: Vincent A. Carucci Carmagen Engineering, Inc .
1
Instructor’s Outline 1. Course discusses pressure vessel design and is introductory in nature.
Major Learning Points Course Introduction
2. Based on ASME Code Section VIII. 3. Preliminary emphasis is on Division 1 but Divisions 2 and 3 are highlighted. 4. Introduces several items that are not covered in the ASME Code.
13
Overview of Pressure Vessel Design Instructor’s Personal Notes Course Overview • General • Materials of Construction • Design • Other Design Considerations • Fabrication • Inspection and Testing 2
Instructor’s Outline 1. The objective: Provide a general knowledge of design requirements for pressure vessels.
Major Learning Points •
Establish course objectives.
•
Outline course content, a road map.
2. This is not a comprehensive course. It provides sufficient information for management personnel to have an overall understanding of this subject. Individuals having more detailed responsibility will receive a solid starting point to proceed further. 3. Review outline. 4. Establish schedule. 5. Participation is key: •
Questions
•
Discussion/interaction
14
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pressure Vessels • Containers for fluids under pressure • Used in variety of industries – Petroleum refining – Chemical – Power – Pulp and paper – Food 3
Instructor’s Outline
Major Learning Points
1. Describe what a pressure vessel is.
•
Define pressure vessels.
2. Note that pressure vessels are used in a wide variety of industries. They can be designed for a wide variety of conditions and in a broad range of sizes.
•
Identify wide variety of industrial applications.
15
Overview of Pressure Vessel Design Instructor’s Personal Notes Horizontal Drum on Saddle s Nozzle
A
Shell
Head
Head
Saddle (Sliding)
Saddle (Fixed) A
SectionA-A
Figure 2.1 4
Instructor’s Outline
Major Learning Points
1. Use this and following overheads to describe main pressure vessel components and shapes.
Main pressure vessel components and configurations.
2. Shell is primary component that contains pressure. Curved shape. 3. Vessel always closed by heads. 4. Components typically welded together. 5. Vessel shell may be cylindrical, spherical, or conical. 6. Multiple diameters, thicknesses or materials are possible. 7. Saddle s used for horizontal drums. •
Spreads load over shell.
•
One fixed, other slides.
16
Overview of Pressure Vessel Design Instructor’s Personal Notes Vertical Drum on Leg s Head
Shell
Nozzle
Head
Leg
5
Instructor’s Outline 1. Most heads are curved shape for strength, thinness, economy.
Figure 2.2
Major Learning Points Main pressure vessel components and shapes.
2. Semi-elliptical shape is most common head shape. 3. Small vertical drums typically ed by legs. •
Typically maximum 2:1 ratio of leg length to diameter.
•
Number, size, and attachment details depend on loads.
17
Overview of Pressure Vessel Design Instructor’s Personal Notes
Tall Vertical Tower Nozzle Head
Trays
Shell
Nozzle
Cone
Nozzle Shell
Nozzle
6
Instructor’s Outline 1. Nozzles used for: •
Piping systems
•
Instrument connections
•
Manways
•
Attaching other equipment
Head Skirt
Figure 2.3
Major Learning Points Main pressure vessel components and shapes.
2. Ends typically flanged, may be welded. 3. Sometimes extend into vessel.
18
Overview of Pressure Vessel Design Instructor’s Personal Notes
Vertical Reactor Inlet Nozzle Head
Upper Catalyst Bed
Shell
Catalyst Bed Grid
Lower Catalyst Bed Outlet Collector Head Outlet Nozzle Skirt
7
Figure 2.4
Instructor’s Outline
Major Learning Points
1. Skirt s typically used for tall vertical vessels:
Main pressure vessel components and shapes.
•
Cylindrical shell
•
Typically ed from grade
2. General design (not just for skirts) •
Design for weight, wind, earthquake.
•
Pressure not a factor.
•
Temperature also a consideration for material selection and thermal expansion.
19
Overview of Pressure Vessel Design Instructor’s Personal Notes
Spherical Pressurized Storage Vessel Shell
Leg
Cross Bracing
Figure 2.5 8
Instructor’s Outline 1. Spherical storage vessels typically ed on legs.
Major Learning Points Main pressure vessel components and shapes.
2. Cross-bracing typically used to absorb wind and earthquake loads.
20
Overview of Pressure Vessel Design Instructor’s Personal Notes Vertical Vessel on Lug s
9
Instructor’s Outline 1. Vessel size limits for lug s: •
1 – 10 ft diameter
•
2:1 to 5:1 height/diameter ratio
Figure 2.6
Major Learning Points Main pressure vessel components and configurations.
2. Vessel located above grade. 3. Lugs bolted to horizontal structure.
21
Overview of Pressure Vessel Design Instructor’s Personal Notes Scope of ASME Code Section VIII • Section VIII used worldwide • Objective: Minimum requirements for safe construction and operation • Division 1, 2, and 3
10
Instructor’s Outline 1. Section VIII is most widely used Code.
Major Learning Points Define scope of ASME Code Section VIII.
2. Assures safe design. 3. Three divisions have different emphasis.
22
Overview of Pressure Vessel Design Instructor’s Personal Notes Section VIII Division 1 • 15 psig < P ≤ 3000 psig • Applies through first connection to pipe • Other exclusions – Internals (except for attachment weld to vessel) – Fired process heaters – Pressure containers integral with machinery – Piping systems
11
Instructor’s Outline
Major Learning Points
1. Review scope of Division 1.
•
Scope of Division 1
2. Division 1 not applicable below 15 psig.
•
Exclusions from scope
3. Additional rules required above 3000 psig. 4. Items that are connected to pressure vessels not covered by Division 1, except for: •
Their effect on pressure part.
•
Welded attachment to pressure part.
23
Overview of Pressure Vessel Design Instructor’s Personal Notes
Section VIII, Division 2, Alternative Rules • Scope identical to Division 1 but requirements differ – Allowable stress – Stress calculations – Design – Quality control – Fabrication and inspection
• Choice between Divisions 1 and 2 based on economics
12
Instructor’s Outline 1. Review differences between Divisions 1 and 2.
Major Learning Points Differences between Division 1 and 2.
2. Division 2 allowable membrane stress is higher. 3. Division 2 requires more complex calculations. 4. Division 2 does not permit some design details that are permitted in Division 1. 5. Division 2 requires more stringent material quality control, fabrication, and testing requirements.
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Overview of Pressure Vessel Design Instructor’s Personal Notes Division 3, Alternative Rules High Pressure Vessels • Applications over 10,000 psi • Pressure from external source, process reaction, application of heat, combination of these • Does not establish maximum pressure limits of Division 1 or 2 or minimum limits for Division 3. 13
Instructor’s Outline 1. Review application of Division 3.
Major Learning Points Scope of Division 3
2. Newest Division of Section VIII and has least applicability. 3. After this point, this course only addresses Division 1 requirements when code-specific items are discussed.
25
Overview of Pressure Vessel Design Instructor’s Personal Notes
Structure of Section VIII, Division 1
• Subsection A
– Part UG applies to all vessels
• Subsection B – Requirements based on fabrication method – Parts UW, UF, UB
• Subsection C – Requirements based on material class – Parts UCS, UNF, UHA, UCI, UCL, UCD, UHT, ULW, ULT
• Mandatory and Nonmandatory Appendices
14
Instructor’s Outline 1. Review Division 1 organization 2. Fabrication methods: •
Welded
•
Forged
•
Brazed
Major Learning Points Basic organizational structure of Division 1.
3. Material classes •
Carbon and low-alloy steel
•
Non-ferrous metals
•
High alloy steel
•
Cast iron
•
Clad and lined material
•
Ductile iron
•
Heat treated steels
•
Layered construction
•
Low-temperature material
4. Highlight several mandatory and nonmandatory appendices.
26
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Selection Factors • • • • •
Strength Corrosion Resistance Resistance to Hydrogen Attack Fracture Toughness Fabricability
15
Instructor’s Outline 1. ASME Code does not specify particular materials to use in each application. Owner must do this.
Major Learning Points Primary factors that influence pressure vessel material selection.
2. ASME Code specifies permitted materials and the requirements that these must meet.
27
Overview of Pressure Vessel Design Instructor’s Personal Notes
Strength • Determines required component thickness • Overall strength determined by: – Yield Strength – Ultimate Tensile Strength – Creep Strength – Rupture Strength
16
Instructor’s Outline 1. Strength: Material’s ability to withstand imposed loading.
Major Learning Points Material strength and pressure vessel design.
2. Higher strength material → thinner component. 3. Describe properties that are used to define strength.
28
Overview of Pressure Vessel Design Instructor’s Personal Notes
Corrosion Resistance • Deterioration of metal by chemical action • Most important factor to consider • Corrosion allowance supplies additional thickness • Alloying elements provide additional resistance to corrosion
17
Instructor’s Outline 1. Corrosion is thinning of metal. 2. Adding extra component thickness (i.e., corrosion allowance) is most common method to address corrosion.
Major Learning Points Importance of corrosion resistance in materials selection.
3. Alloy materials are used in services where corrosion allowance would be unreasonably high if carbon steel were used.
29
Overview of Pressure Vessel Design Instructor’s Personal Notes
Resistance to Hydrogen Attack • At 300 - 400°F, monatomic hydrogen forms molecular hydrogen in voids • Pressure buildup can cause steel to crack • Above 600°F, hydrogen attack causes irreparable damage through component thickness 18
Instructor’s Outline 1. Low-temperature H 2 attack can cause cracking.
Major Learning Points Hydrogen attack can damage carbon and low-alloy steel.
2. Higher temperature H 2 attack causes through-thickness strength loss and is irreversible. 3. H2 attack is a function of H 2 partial pressure and design temperature. •
Increased alloy content (i.e., Cr) increases H 2 attack resistance.
•
Reference API-941 for “Nelson Curves.”
30
Overview of Pressure Vessel Design Instructor’s Personal Notes Brittle Fracture and Fracture Toughness • Fracture toughness: Ability of material to withstand conditions that could cause brittle fracture • Brittle fracture – Typically at “low” temperature – Can occur below design pressure – No yielding before complete failure 19
Instructor’s Outline 1. Describe brittle fracture as equivalent to dropping a piece of glass.
Major Learning Points Brittle fracture and its consequences.
2. Material selection must ensure that brittle fracture will not occur.
31
Overview of Pressure Vessel Design Instructor’s Personal Notes Brittle Fracture and Fracture Toughness, cont’d • Conditions required for brittle fracture – High enough stress for crack initiation and growth – Low enough material fracture toughness at temperature – Critical size defect to act as stress concentration 20
Instructor’s Outline 1. A brittle fracture will occur the first time the appropriate conditions occur.
Major Learning Points Three conditions that are required for a brittle fracture to occur.
2. Brittle fracture occurs without warning and is catastrophic.
32
Overview of Pressure Vessel Design Instructor’s Personal Notes Factors That Influence Fracture Toughness • Fracture toughness varies with: - Temperature - Type and chemistry of steel - Manufacturing and fabrication processes
• Other factors that influence fracture toughness:
21
Instructor’s Outline 1. Describe influence of material and temperature factors on fracture toughness.
- Arc strikes, especially if over repaired area - Stress raisers or scratches in cold formed thick plate
Major Learning Points Primary factors that influence material fracture toughness.
2. Other factors increase brittle fracture risk.
33
Overview of Pressure Vessel Design Instructor’s Personal Notes
Charpy V-Notch Test Setup
Scale Starting Position Hammer
Pointer
h'
End of swing Specimen h' Anvil
22
Instructor’s Outline 1. Charpy V-Notch test is most widely used measure of material fracture toughness.
Major Learning Points Charpy V-Notch testing.
2. Describe test set-up.
34
Overview of Pressure Vessel Design Instructor’s Personal Notes ASME Code and Brittle Fracture Evaluation • Components to consider – Shells – Manways – Heads – Reinforcing pads – Backing strips that remain in place
– Nozzles – Tubesheets – Flanges – Flat cover plates – Attachments essential to structural integrity that are welded to pressure parts
23
Instructor’s Outline
Major Learning Points
1. ASME Code contains brittle fracture evaluation procedure.
Components to consider is ASME Code brittle fracture evaluation.
2. Review components to be included only items that relate to structural integrity of pressure-containing shell.
35
Overview of Pressure Vessel Design Instructor’s Personal Notes
Temperatures to Consider • Minimum Design Metal Temperature (MDMT) – Lowest temperature at which component has adequate fracture toughness
• Critical Exposure Temperature (CET) – Minimum temperature at which significant membrane stress will occur
24
Instructor’s Outline 1. Describe the distinction between MDMT and CET. •
MDMT is a material property.
•
CET is an environmental factor.
Major Learning Points Two temperatures to be considered in brittle fracture evaluation.
2. Important to understand this distinction.
36
Overview of Pressure Vessel Design Instructor’s Personal Notes Simplified ASME Evaluation Approach • Material specifications classified into Material Groups A through D • Impact test exemption curves – For each Material Group – Acceptable MDMT vs. thickness where impact testing not required
• If combination of Material Group and thickness not exempt, then must impact test at CET 25
Instructor’s Outline 1. Outline ASME procedure. 2. Details described in following overheads.
Major Learning Points Simplified ASME brittle fracture evaluation procedure.
37
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Groups MATERIAL GROUP Curve A
APPLICABLE MATERIALS • All carbon and low alloy steel plates, structural shapes, and bars not listed in Curves B, C & D • SA-216 Gr. WCB & WCC, SA-217 Gr. WC6, if normalized and tempered or water-quenched and tempered
Curve B
• SA-216 Gr. WCA, if normalized and tempered or water-quenched and tempered • SA-216 Gr. WCB & WCC for maximum thickness of 2 in., if produced to fine grain practice and water-quenched and tempered • SA-285 Gr. A & B • • • •
SA-414 Gr. A SA-515 Gr. 60 SA-516 Gr. 65 & 70, if not normalized Except for cast steels, all materials of Curve A if produced to fine grain practice and normalized which are not included in Curves C & D
• All pipe, fittings, forging, and tubing which are not included in Curves C & D
Table 3.1 (Excerpt) 26
Instructor’s Outline 1. Materials are grouped based on common fracture toughness properties.
Major Learning Points Material group classifications for brittle fracture evaluations.
2. Groups A through D move from worst to best fracture toughness. 3. Point out several common materials. •
SA-516 Gr. 65 and 70 are Curve B if not normalized.
•
Most pipe, fittings and forgings are Curve B.
38
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Groups, cont’d MATERIAL GROUP Curve C
Curve D
Bolting and Nuts
APPLICABLE MATERIALS • •
SA-182 Gr. 21 & 22, if normalized and tempered SA-302 Gr. C & D
•
SA-336 Gr. F21 & F22, if normalized and tempered
•
SA-387 Gr. 21 & 22, if normalized and tempered
• •
SA-516 Gr. 55 & 60, if not normalized SA-533 Gr. B & C
•
SA-662 Gr. A
•
All material of Curve B if produced to fine grain practice and normalized which are not included in Curve D
•
SA-203
•
SA-537 Cl. 1, 2 & 3
•
SA-508 Cl. 1
•
SA-612, if normalized
•
SA-516, if normalized
•
SA-662, if normalized
•
SA-524 Cl. 1 & 2
•
SA-738 Gr. A
•
See Figure UCS-66 of the ASME Code Section VIII, Div. 1, for impact test exemption temperatures for specified material specifications
Table 3.1 (Excerpt) 27
Instructor’s Outline 1. Identify other common materials. •
SA-516 Gr. 55 and 60 are Curve C if not normalized.
•
SA-516 (all grades) is Curve D if normalized.
Major Learning Points Material group classifications for brittle fracture evaluations.
2. Highlight points. •
Lower strength grades of same specification have better fracture toughness.
•
Normalization improves fracture toughness.
39
Overview of Pressure Vessel Design Instructor’s Personal Notes
Impact Test Exemption Curves for Carbon and Low-Alloy Steel 140 120
Minimum Design Metal Temperature, F
100 B
A
80 60
C 40 D
20 0 -20 -40 -55 -60
Impact testing required
-80 0.394
1
2
3
4
5
Nominal Thickness, in. (Limited to 4 in. for Welded Construction)
Figure 3.1 28
Instructor’s Outline 1. Describe relationship between Material Group, component thickness, and MDMT.
Major Learning Points Impact test exemption curves.
2. Impact testing not required if point is at or below curve (i.e., OK if MDMT ≤ CET). 3. Example: 1.5 in. thick Group B material does not require impact testing if CET ≥ 50°F. 4. If not exempt, must impact test material at CET. 5. “Exemption” means there is enough experience that material has adequate fracture toughness without need for further testing.
40
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional ASME Code Impact Test Requirements • Required for welded construction over 4 in. thick, or nonwelded construction over 6 in. thick, if MDMT < 120°F • Not required for flanges if temperature ≥ -20°F • Required if SMYS > 65 ksi unless specifically exempt
29
Instructor’s Outline 1. Review additional requirements.
Major Learning Points Additional impact test requirements.
2. Note that most flanges will not require impact testing.
41
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional ASME Code Impact Test Requirements, cont’d • Not required for impact tested low temperature steel specifications – May use at impact test temperature
• 30°F MDMT reduction if PWHT P-1 steel and not required by code • MDMT reduction if calculated stress < allowable stress 30
Instructor’s Outline 1. Review additional requirements.
Major Learning Points Additional impact test requirements.
2. PWHT reduces MDMT by 30°F provided PWHT not required by Code and resulting MDMT ≥ -55°F. 3. Can take MDMT credit if component thickness greater than needed (i.e., calculated stress < allowable stress).
42
Overview of Pressure Vessel Design Instructor’s Personal Notes
Fabricability • Ease of construction • Any required special fabrication practices • Material must be weldable
31
Instructor’s Outline Describe fabricability.
Major Learning Points Definition of fabricability.
43
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Stress • Stress: Force per unit area that resists loads induced by external forces • Pressure vessel components designed to keep stress within safe operational limits • Maximum allowable stress: – Includes safety margin – Varies with temperature and material
• ASME maximum allowable stress tables for permitted material specifications 32
Instructor’s Outline 1. Discuss the use of allowable stress in determining vessel component design.
Major Learning Points •
Description of allowable stress.
•
ASME Code allowable stress tables
2. Section II, Part D, Appendix I contains allowable stress criteria for materials other than bolting. 3. Section II, Part D contains allowable stress tables.
44
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Stress, cont’d ALLOWABLE STRESS IN TENSION FOR CARBON AND LOW-ALLOY STEEL Nominal P-No. Group No. Min. Yield Min. Tensile Composition (ksi) (ksi) Carbon Steel Plates and Sheets SA-515 55 C-Si 1 1 30 55 60 C-Si 1 1 32 60 65 C-Si 1 1 35 65 70 C-Si 1 2 38 70 Spec No.
SA-516
Grade
55 60 65 70
C-Si C-Mn-Si C-Mn-Si C-Mn-Si
Plate - Low Alloy Steels SA-387 2 Cl.1 1/2Cr-1/2Mo 2 Cl.2 1/2Cr-1/2Mo 12 Cl.1 1Cr-1/2Mo 12 Cl.2 1Cr-1/2Mo 11 Cl.1 1 1/4Cr-1/2Mo-Si 11 Cl.2 1 1/4Cr-1/2Mo-Si 22 Cl.1 2 1/4Cr-1Mo 22 Cl.2 2 1/4Cr-1Mo
1 1 1 1
1 1 1 2
30 32 35 38
55 60 65 70
3 3 4 4 4 4 5 5
1 2 1 1 1 1 1 1
33 45 33 40 35 45 30 45
55 70 55 65 60 75 60 75
ASME Maximum Allowable Stress (Table 1A Excerpt) Figure 3.2 33
Instructor’s Outline 1. Describe information contained in first section of table.
Major Learning Points ASME Code allowable stress tables.
2. Information is grouped by material chemistry and material form.
45
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Stress, cont’d ALLOWABLE STRESS IN TENSION FOR CARBON AND LOW ALLOY STEEL Max Allowable Stress, ksi (Multiply by 1,000 to Obtain psi) for Metal Temperature, °F, Not Exceeding 650
700
750
800
13.8 15.0 16.3 17.5
13.3 14.4 15.5 16.6
12.1 13.0 13.9 14.8
10.2 10.8 11.4 12.0
8.4 8.7 9.0 9.3
6.5 6.5 6.5 6.5
4.5 4.5 4.5 4.5
2.5 2.5 2.5 2.5
Spec No. 1050 1100 1150 1200 Carbon Steel Plates and Sheets ----SA-515 ----SA-515 ----SA-515 ----SA-515
13.8 15.0 16.3 17.5
13.3 14.4 15.5 16.6
12.1 13.0 13.9 14.8
10.2 10.8 11.4 12.0
8.4 8.7 9.0 9.3
6.5 6.5 6.5 6.5
4.5 4.5 4.5 4.5
2.5 2.5 2.5 2.5
-----
13.8 17.5 13.8 16.3 15.0 18.8 15.0 17.7
13.8 17.5 13.8 16.3 15.0 18.8 15.0 17.2
13.8 17.5 13.8 16.3 15.0 18.8 15.0 17.2
13.8 17.5 13.8 16.3 15.0 18.8 15.0 16.9
13.8 17.5 13.4 15.8 14.6 18.3 14.4 16.4
13.3 16.9 12.9 15.2 13.7 13.7 13.6 15.8
9.2 9.2 11.3 11.3 9.3 9.3 10.8 11.4
5.9 5.9 7.2 7.2 6.3 6.3 8.0 7.8
Plate-Low Alloy Steels (Cont'd) ----SA-387 ----SA-387 4.5 2.8 1.8 1.1 SA-387 4.5 2.8 1.8 1.1 SA-387 4.2 2.8 1.9 1.2 SA-387 4.2 2.8 1.9 1.2 SA-387 5.7 3.8 2.4 1.4 SA-387 5.1 3.2 2.0 1.2 SA-387
850
900
950
1000
-----
-----
-----
SA-516 SA-516 SA-516 SA-516
ASME Maximum Allowable Stress (Excerpt), cont'd Figure 3.2, cont'd 34
Instructor’s Outline 1. Review allowable stress vs. design temperature.
Major Learning Points ASME Code allowable stress tables.
2. Most ferritic materials have a constant allowable stress at temperatures through 650°F.
46
Overview of Pressure Vessel Design Instructor’s Personal Notes Material Selection Based on Fracture Toughness Exercise 1 • • • • • • • •
New horizontal vessel CET = - 2°F Shell and heads: SA-516 Gr. 70 Heads hemispherical: ½ in. thick Cylindrical shell: 1.0 in. thick No impact testing specified Is this correct? If not correct, what should be done?
35
Instructor’s Outline
Major Learning Points
1. This independent Exercise gives the Participants practice in material selection based on fracture toughness.
Participant Exercise 1 covering fracture toughness.
2. Review the given information together. 3. Allow approximately 10 minutes for the Participants to solve the problem. Then review the solution with them.
47
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 1 - Solution • Must assume SA-516 Gr. 70 not normalized. Therefore, Curve B material (Ref. Table 3.1). • Refer to Curve B in Figure 3.1. – ½ in. thick plate for heads: MDMT = -7°F – ½ in. thick plate exempt from impact testing since MDMT < CET
• 1 in. shell plate: MDMT = +31°F – Not exempt from impact testing
36
Instructor’s Outline 1. Review difference between normalized and non-normalized material with respect to fracture toughness.
Major Learning Points Solution to Participant Exercise.
2. Review MDMT determination in each case. 3. Note difference between MDMT and CET in each case.
48
Overview of Pressure Vessel Design Instructor’s Personal Notes Exercise 1 - Solution, cont’d • One approach to correct: Impact test 1 in. plate at -2°F. If es, material acceptable. • Another approach: Order 1 in. plate normalized – Table 3.1: normalized SA-516 is Curve D material – Figure 3.1: 1 in. thick Curve D, MDMT = -30°F – Normalized 1 in. thick plate exempt from impact testing
37
Instructor’s Outline 1. Review possible solutions for the 1 in. plate.
Major Learning Points Solution to Participant Exercise.
49
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 1 - Solution, cont’d • Choice of option based on cost, material availability, whether likely that 1 in. thick nonnormalized plate would impact testing
38
Instructor’s Outline 1. Review rationale for which option to select.
Major Learning Points Solution to Participant Exercise 1.
50
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design Conditions and Loadings • Determine vessel mechanical design • Design pressure and temperature, other loadings • Possibly multiple operating scenarios to consider • Consider startup, normal operation, anticipated deviations, shutdown 39
Instructor’s Outline 1. Review conditions to be considered. 2. Worst case operating scenario determines mechanical design.
Major Learning Points Design conditions and loadings to be considered in pressure vessel mechanical design.
51
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design Pressure PT = Design Pressure at Top of Vessel
γ = Weight Density of Liquid in Vessel
H = Height of Liquid
PBH = Design Pressure of Bottom Head
Figure 4.1 40
Instructor’s Outline 1. May have internal of external pressure, or both at different times.
Major Learning Points Design pressure as a mechanical design condition.
2. Must have margin between maximum operating pressure at top of vessel and design pressure. 3. Hydrostatic pressure of operating liquid (if present) must be considered at corresponding vessel elevation.
52
Overview of Pressure Vessel Design Instructor’s Personal Notes Temperature Zones in Tall Vessels Section 4 (T-Z)
Section 3 (T-Y)
Section 2 (T-X)
Section 1 (T) F Skirt Grade
Figure 4.2 41
Instructor’s Outline 1. Margin required between operating temperature and design temperature.
Major Learning Points Design temperature as a mechanical design condition.
2. Maximum design temperature needed to determine allowable stress and thermal expansion considerations. 3. CET needed for material selection considering brittle fracture. 4. There may be a wide temperature variation between the bottom and top of a tall tower.
53
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional Loadings • Weight of vessel and normal contents under operating or test conditions • Superimposed static reactions from weight of attached items (e.g., motors, machinery, other vessels, piping, linings, insulation) • Loads at attached internal components or vessel s • Wind, snow, seismic reactions 42
Instructor’s Outline 1. Highlight other loads that must be considered in the mechanical design.
Major Learning Points Loadings other than pressure and temperature must also be considered.
2. These other loads may govern the mechanical design in local areas.
54
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional Loadings, cont’d • Cyclic and dynamic reactions caused by pressure or thermal variations, equipment mounted on vessel, and mechanical loadings • Test pressure combined with hydrostatic weight • Impact reactions (e.g., from fluid shock) • Temperature gradients within vessel component and differential thermal expansion between vessel components 43
Instructor’s Outline 1. Review these additional other loads.
Major Learning Points Additional other loadings to consider.
55
Overview of Pressure Vessel Design Instructor’s Personal Notes
Weld t Categories C
C
C A
A A D
B
D B
A
C
B
C
D
A
D
B
B
D
A C
Figure 4.3 44
Instructor’s Outline 1. Review the ASME Code Weld t Categories.
Major Learning Points ASME Code defines welded ts by category.
2. Only specific weld types may be used in each category.
56
Overview of Pressure Vessel Design Instructor’s Personal Notes
Weld Types Butttsasattainedbydouble-weldingorbyother means which will obtain the same quality of deposited weld metal on the inside and outside weld surface.
1
Backing strip, if used, shall be removed after completionofweld. Single-welded butt t with backing strip which remainsinplaceafterwelding.
2
For circumferential t only
3
Single-welded butt t without backing strip.
4
Double-fullfilletlapt.
5
Single-full fillet lap t with plug welds.
6
Single-full fillet lap t without plug welds.
Figure 4.4 45
Instructor’s Outline 1. Review the different weld types. 2. Limited applications for Types 3 through 6.
Major Learning Points ASME Code defines specific weld types that may be used.
57
Overview of Pressure Vessel Design Instructor’s Personal Notes Weld t Efficiencies t Type
Acceptable t Categories
Degree of Radiographic Examination Full
Spot
None
1
A, B, C, D
1.00
0.85
0.70
2
A, B, C, D (See ASME Code for limitations)
0.90
0.80
0.65
3
A, B, C
NA
NA
0.60
4
A, B, C (See ASME Code for limitations)
NA
NA
0.55
5
B, C (See ASME Code for limitations)
NA
NA
0.50
6
A, B, (See ASME Code for limitations)
NA
NA
0.45
Figure 4.5 46
Instructor’s Outline 1. Weld t efficiency, E, is a measure of weld quality and s for stress concentrations.
Major Learning Points Weld t efficiency vs. t Type, Category, Radiographic Examination.
2. E is needed in component thickness calculations. 3. Review information in table. 4. Note that corrosion allowance was previously discussed.
58
Overview of Pressure Vessel Design Instructor’s Personal Notes
Summary Of ASME Code Equations Part
Thickness, tp , in.
Cylindrical shell
Pr SE1 − 0.6P
SE 1t r + 0.6t
P(r + 0.6t) tE1
Spherical shell
Pr 2SE1 − 0.2P
2SEt r + 0.2t
P(r + 0.2t ) 2tE
PD 2SE − 0.2P
2SEt D + 0.2t
P(D + 0.2t ) 2tE
0.885PL SE − 0.1P
SEt 0.885L + 0.1t
P (0.885L + 0.1t ) tE
PD 2 cos α (SE − 0.6P)
2SEt cos α D + 1.2t cos α
P(D + 1.2t cos α) 2tE cos α
2:1 Semi - Elliptical head Torispherical head with 6% knuckle Conical Section ( α = 30°)
Pressure, P, psi
Stress, S, psi
Figure 4.6 47
Instructor’s Outline 1. Circumferential stress governs minimum required component thickness in most cases.
Major Learning Points ASME Code equations for various components under internal pressure.
2. Longitudinal stress may govern local thickness in some cases (e.g., under wind or earthquake loads). 3. Review ASME Code equations for internal pressure design. •
May calculate required thickness, permitted pressure, component stress.
•
Must for corrosion allowance.
59
Overview of Pressure Vessel Design Instructor’s Personal Notes Typical Formed Closure Heads t
t R sf sf ID
ID
Flanged
Hemispherical t t
h sf
h
Elliptical
α
sf Flanged and Dished (torispherical)
α
t
t
sf r ID Toriconical
ID Conical
48
Instructor’s Outline 1. Review the different head types. 2. The 2:l semi-elliptical head is the most common.
Figure 4.7
Major Learning Points Different types of closure heads may be used.
60
Overview of Pressure Vessel Design Instructor’s Personal Notes
Hemispherical Head to Shell Transition th
l ≥ 3y
Thinner Part
Thinner Part
th
l ≥ 3y Tangent Line
y
Length of required taper, l, may include the width of the weld ts
y
ts
Figure 4.8 49
Instructor’s Outline
Major Learning Points
1. Required thickness of a hemispherical head is about half that of the connected cylindrical shell.
Thickness transition at a hemispherical head.
2. Must have a tapered thickness transition in the head to end up matching the shell thickness.
61
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Hemispherical
4' - 0" 60' - 0"
DESIGN INFORMATION Design Pressure = 250 psig Design Temperature = 700° F Shell and Head Material is SA-515 Gr. 60 Corrosion Allowance = 0.125" Both Heads are Seamless Shell and Cone Welds are Double Welded and will be Spot Radiographed The Vessel is in All Vapor Service Cylinder Dimensions Shown are Inside Diameters
10' - 0"
6' - 0" 30' - 0"
2:1 Semi-Elliptical
Figure 4.9 50
Instructor’s Outline 1. Sample Problem 1 illustrates calculation of required shell and head thicknesses for internal pressure.
Major Learning Points Sample Problem to illustrate calculation of required thickness for internal pressure.
2. Review the given information. 3. Review the problem solution with the Participants.
62
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 1 - Solution • Required thickness for internal pressure of cylindrical shell (Figure 4.6):
tp =
Pr SE1 − 0. 6P
• Welds spot radiographed, E = 0.85 (Figure 4.5) • S = 14,400 psi for SA- 515/Gr. 60 at 700°F (Figure 3.2) • P = 250 psig 51
Instructor’s Outline 1. Review the relevant equation for a cylindrical shell.
Major Learning Points Sample Problem 1 solution.
2. Note the sources used for the various parameters.
63
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Solution, cont’d • For 6 ft. - 0 in. shell r = 0.5D + C = 0.5 × 72 + 0.125 = 36.125 in. Pr 250 × 36.125 tp = = S E1 − 0.6P 14,400 × 0.85 − 0.6 × 250 = 0.747 in. t = tp + c = 0.747 + 0.125 t = 0.872 in., including corrosion allowance 52
Instructor’s Outline 1. The corrosion allowance must be added to obtain the inside radius.
Major Learning Points Sample Problem 1 solution.
2. The corrosion allowance must be added to the calculated thickness.
64
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 1 Solution, cont’d • For 4 ft. - 0 in. shell r = 0.5 × 48 + 0.125 = 24.125 in. tp =
250 × 24.125 14,400 × 0. 85 − 0. 6 × 250
= 0.499 in.
t = 0.499 + 0.125 t = 0.624 in., including corrosion allowance 53
Instructor’s Outline 1. The calculation is repeated for the other cylindrical shell section.
Major Learning Points Sample Problem 1 solution.
65
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Solution, cont’d Both heads are seamless, E = 1.0. Top Head - Hemispherical (Figure 4.6) r = 24 + 0.125 = 24.125 in.
tp =
Pr 250 × 24.125 = 0.21 in. = 2SE1 − 0.2P 2 × 14,400 × 1 − 0.2 × 250 t = tp + c = 0.21 + 0.125 t = 0.335 in., including corrosion allowance
54
Instructor’s Outline 1. Review the relevant equation for a hemispherical head.
Major Learning Points Sample Problem 1 solution.
2. Note the sources for the relevant parameters and how corrosion allowance is ed for.
66
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Solution, cont’d • Bottom Head - 2:1 Semi-Elliptical (Figure 4.6) D = 72 + 2 × 0.125 = 72.25 in.
tp =
PD 250 × 72 .25 = = 0.628 in. 2SE − 0.2P 2 × 14,400 × 1 − 0.2 × 250 t = 0.628 + 0.125 t = 0.753 in., including corrosion allowance
55
Instructor’s Outline 1. Review the relevant equation for a semi-elliptical head.
Major Learning Points Sample Problem 1 solution.
2. Note the sources for the relevant parameters and how corrosion allowance is ed for.
67
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design For External Pressure and Compressive Stresses • Compressive forces caused by dead weight, wind, earthquake, internal vacuum • Can cause elastic instability (buckling) • Vessel must have adequate stiffness – Extra thickness – Circumferential stiffening rings
56
Instructor’s Outline
Major Learning Points
1. Buckling of a shell under external pressure or compressive forces is analogous to column buckling under a compressive force.
Different procedures are used to design for external pressure or compressive loads.
2. Addition of stiffener rings reduces effective buckling length.
68
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design For External Pressure and Compressive Stresses, cont’d • ASME procedures for cylindrical shells, heads, conical sections. Function of: – Material – Diameter – Unstiffened length
– Temperature – Thickness
57
Instructor’s Outline 1. Highlight the main parameters that affect buckling strength.
Major Learning Points Parameters that affect compressive strength.
2. ASME Code has design procedure for each type of shell or head.
69
Overview of Pressure Vessel Design Instructor’s Personal Notes
Stiffener Rings Moment Axis of Ring h/3
L
L
L
L
L
L
L
L
L
L
h/3 h = Depth of Head
Figure 4.10 58
Instructor’s Outline 1. Stiffener rings reduce the buckling length of a shell and may be either inside or outside.
Major Learning Points Use and location of stiffener rings.
2. Stiffener rings are not used for heads.
70
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 DESIGN INFORMATION Design Pressure = Full Vacuum Design Temperature = 500° F Shell and Head Material is SA-285 Gr. B, Yield Stress = 27 ksi Corrosion Allowance = 0.0625" Cylinder Dimension Shown is Inside Diameter
4' - 0"
150' - 0"
2:1 Semi-Elliptical (Typical)
Figure 4.11 59
Instructor’s Outline
Major Learning Points
1. Sample Problem 2 illustrates procedure for calculation of required cylindrical shell thickness for external pressure.
Sample Problem to illustrate calculation of required cylindrical shell thickness for external pressure.
2. The problem does not cover all aspects of the general procedure since it is geometry-specific. 3. Review the given information. 4. Review the problem solution with the participants.
71
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 - Solution • Calculate L and Do of cylindrical shell. L = Tangent Length + 2 × 1/3 (Head Depth) L = 150 × 12 + 2/3 × (48/4) = 1,808 in. Do = 48 + 2 × 7/16 = 48.875 in. • Determine L/Do and Do/t for corrosion allowance: t = 7/16 – 1/16 = 6/16 = 0.375 in. Do/t = 48.875 / 0.375 = 130 L/Do = 1808 / 48.875 = 37 60
Instructor’s Outline 1. Corroded shell diameter and thickness are used in the calculations.
Major Learning Points Sample Problem 2 solution.
2. The unstiffened length of the shell must include part of the head depth.
72
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d • Determine A. • Use Figure 4.12, Do /t, and L/Do. Note:
If L/Do > 50, use L/Do = 50. For L/Do < 0.05, use L/Do = 0.05
61
Instructor’s Outline 1. Factor A is determined based only on geometry.
Major Learning Points Sample Problem 2 solution.
2. Note the source of Factor A.
73
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d
4 5 6 789
Do/t = 100 D o/t = 125 D o/t = 150 D /t = 200
2 1.6 1.4
2.0 1.8
2.5
3.5 3.0
6.0
4.0
7.0
5.0
8.0
10.0 9.0
14.0
20.0 18.0
16.0
25.0
30.0
35.0
40.0
50.0
12.0
0 00 ,00 00 00 800 = 4 t=5 t = 6 =1 /t / / /t = /t Do Do Do Do Do
D o/t = 300
.00001
3
o
D o/t = 250
1.2
Do /t = 130
.0001
A = 0.000065
Length + Outside Diameter = L/Do
L/Do = 37
Factor A Figure 4.12 62
Instructor’s Outline 1. Note how Factor A is determined from these curves.
Major Learning Points Sample Problem 2 solution.
2. After determine Factor A, go to applicable material chart.
74
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d up to 300°F 500°F
14,000
700°F
12,000
800°F
10,000
900°F
9,000 8,000 7,000
E=29.0 x 106
6,000
E=27.0 x 106
5,000
E=24.5 x 106 E=22.8 x 106
4,000
E=20.8 x 106
3,500 3,000 2,500 2,000
2 .00001
3 4 5 6 789 .0001
A=0.000065
63
Instructor’s Outline 1. Different material charts are used for different material types. This is chart used for most carbon and lowalloy steels.
2
3
4 5 6 789
2
3 4 5 6789
.001
2
3
4 5 6 789
.01
.1
FACTOR A
Factor B Figure 4.13
Major Learning Points Sample Problem 2 solution.
2. If A is under curves: •
Move up to intersect with temperature line.
•
Move right to get B.
•
B is then used to calculate allowable external pressure.
3. Since A is to left of curves in our case, must use alternate procedure.
75
FACTOR B
20,000 18,000 16,000
GENERAL NOTE: See Table CS-1 for tabular values
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d • Calculate maximum allowable external pressure
Pa =
2AE 3(Do / t )
Where: E = Young's modulus of elasticity E = 27 × 106 psi (Figure 4.13) at T = 500°F P a = 9 psi 64
Instructor’s Outline 1. Pa is calculated using indicated equation because A is not under curves.
Major Learning Points Sample Problem 2 solution.
2. Must use E from curves at design temperature.
76
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d Since Pa < 15 psi, 7/16 in. thickness not sufficient • Assume new thickness = 9/16 in., corroded thickness L = 1/2 in.
Do 48. 875 = = 97.75 t 0. 5
A = 0.000114
Pa =
L = 3 7 (as before) Do
2 × 0.000114 × 27 × 10 6 = 15. 7 psi 3 × 130. 33
65
Instructor’s Outline 1. Since P a < 15 psi, must either increase shell thickness or add stiffeners to decrease L.
Major Learning Points Sample Problem 2 solution.
2. Problem illustrates results if increase thickness. 3. Choice of whether to increase thickness or add stiffeners depends on cost.
77
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 2 - Required Thickness for Internal Pressure • • • • • • • •
Inside Diameter - 10’ - 6” Design Pressure - 650 psig Design Temperature - 750°F Shell & Head Material - SA-516 Gr. 70 Corrosion Allowance - 0.125 in. 2:1 Semi-Elliptical heads, seamless 100% radiography Vessel in vapor service
66
Instructor’s Outline
Major Learning Points
1. This independent Exercise gives the Participants practice in determining required vessel thicknesses for internal pressure.
Participant Exercise 2 covering required thickness for internal pressure.
2. Review the given information together. 3. Allow approximately 15 minutes for the Participants to solve the problem. Then review the solution with them. 4. Note that this Exercise may be skipped and assigned as homework if available class time is an issue.
78
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 2 - Solution • For shell
tp =
Pr SE 1 − 0 .6P
P = 650 psig r = 0.5 × D + CA = (0.5 × 126) + 0.125 = 63.125 in. • S = 16,600 psi, Figure 3.3 for SA-516 Gr. 70 • E = 1.0, Figure 4.8 for 100% radiography
tp =
650 × 63. 125 = 2. 53 in. (16,600 ×1 .0 ) − (0 .6 × 650)
67
Instructor’s Outline 1. Note the relevant equation for the cylindrical shell and the appropriate parameters.
Major Learning Points Exercise 2 solution.
2. Note how corrosion allowance is ed for.
79
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 2 - Solution, cont’d Add corrosion allowance tp = 2.53 + 0.125 = 2.655 in. • For the heads tp =
PD 2 SE − 0. 2P
tp =
650 (126 × 0 . 9) + 0 . 250 = 2 . 23 in. (2 × 16, 600) − (0 . 2 × 650 )
Add corrosion allowance 68
Instructor’s Outline 1. Note the relevant equation for the heads and the appropriate parameters.
tp = 2.23 + 0.125 = 2.355 in.
Major Learning Points Exercise 2 solution.
2. Note how corrosion allowance is ed for.
80
Overview of Pressure Vessel Design Instructor’s Personal Notes
Reinforcement of Openings • Simplified ASME rules - Area replacement • Metal used to replace that removed: -
Must be equivalent in metal area Must be adjacent to opening
69
Instructor’s Outline 1. Simplified ASME rules do not require stress calculations. Use “area replacement” approach.
Major Learning Points Openings must be reinforced to for metal removed.
2. Metal removed must be replaced by equivalent metal.
81
Overview of Pressure Vessel Design Instructor’s Personal Notes
Cross Sectional View of Nozzle Opening Dp tn
te
2.5t or 2.5t n + te Use smaller value
t
2.5t or 2.5t n Use smaller value
Rn
t rn
tr
c
h
d
d or R n + tn + t
d or R n + tn + t
Use larger value
Use larger value
For nozzle wall inserted through the vessel wall
For nozzle wall abutting the vessel wall
Figure 4.14 70
Instructor’s Outline 1. Review cross-sectional view of region and associated nomenclature. 2. Note the different areas involved in the calculations and the “reinforcement zone” in the nozzle and shell.
Major Learning Points Region near opening and nomenclature.
82
Overview of Pressure Vessel Design Instructor’s Personal Notes
Nozzle Design Configurations (a) Full Penetration Weld With Integral Reinforcement
(a-1)
(a-2)
(a-3)
Separate Reinforcement Plates Added
(b)
(c)
(d)
(e)
Full Penetration Welds to Which Separate Reinforcement Plates May be Added
(f-1)
(f-3)
(f-2) (f-4)
(g)
Self - Reinforced Nozzles
71
Instructor’s Outline 1. Note the different nozzle design details that may be used.
Figure 4.15
Major Learning Points Typical nozzle configurations.
2. The actual detail used in each case depends on the design conditions and the needed reinforcement.
83
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional Reinforcement • Necessary if insufficient excess thickness • Must be located within reinforcement zone • Allowable stress of reinforcement pad should be ≥ that of shell or head • Additional reinforcement sources – Pad – Additional thickness in shell or lower part of nozzle 72
Instructor’s Outline 1. The method used to provide additional reinforcement depends on the particular situation.
Major Learning Points Requirements for additional reinforcement.
2. The ASME Code specifies circumstances where nozzle reinforcement evaluation is not needed. The opening is considered to be “inherently” reinforced in these cases.
84
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 DESIGN INFORMATION Design Pressure = 300 psig Design Temperature = 200° F Shell Material is SA-516 Gr. 60 Nozzle Material is SA-53 Gr. B, Seamless Corrosion Allowance = 0.0625" Vessel is 100% Radiographed Nozzle does not through Vessel Weld Seam
NPS 8 Nozzle (8.625" OD) 0.5" Thick
0.5625" Thick Shell, 48" Inside Diameter
Figure 4.16 73
Instructor’s Outline 1. Sample Problem 3 illustrates evaluation of an opening for adequate reinforcement.
Major Learning Points Sample Problem to illustrate evaluation of nozzle reinforcement.
2. Review the given information. 3. Review the problem solution with the Participants.
85
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 3 - Solution • Calculate required reinforcement area, A A = dtrF Where: d = Finished diameter of circular opening, or finished dimension of nonradial opening in plane under consideration, in. tr = Minimum required thickness of shell using E = 1.0, in. F = Correction factor, normally 1.0 74
Instructor’s Outline 1. Required replacement area is based on the cross-sectional area removed.
Major Learning Points Sample Problem 3 solution.
2. Calculated using the required shell thickness, not the actual.
86
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate diameter, d. d = Diameter of Opening – 2 (Thickness + Corrosion Allowance) d = 8.625 – 1.0 + .125 = 7.750 in. • Calculate required shell thickness, t r (Figure 4.6) tr = 0.487 in. • Assume F = 1.0 75
Instructor’s Outline 1. Corrosion allowance is ed for.
Major Learning Points Sample Problem 3 solution.
2. tr is calculated using the appropriate shell equation.
87
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate A A = dtr F A = (8.625 - 1.0 + 0.125) × 0.487 × 1 = 3.775 in.2 • Calculate available reinforcement area in vessel shell, A 1, as larger of A 11 or A1 2 A1 1 = (E lt - Ftr)d 76
Instructor’s Outline 1. Required area is calculated using the previously calculated parameters.
A1 2 = 2 (Elt-Ftr)(t + tn)
Major Learning Points Sample Problem 3 solution.
2. Two equations must be checked to determine the reinforcement area available in the shell.
88
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d Where: E l = 1.0 when opening is in base plate away from welds, or when opening es through circumferential t in shell (excluding head to shell ts). E l = ASME Code t efficiency when any part of opening es through any other welded t. F = 1 for all cases except integrally reinforced nozzles inserted into a shell or cone at angle to vessel longitudinal axis. See Fig. UG-37 for this special case. tn = Nominal thickness of nozzle in corroded condition, in. 77
Instructor’s Outline Review the relevant parameters.
Major Learning Points Sample Problem 3 solution.
89
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d A 11 = (Elt - Ftr)d = (0.5625 - 0.0625 - 0.487) × 7.75 = 0.1 in.2 A 12 = 2 (Elt - Ftr ) (t + t n) = 2(0.5625-0.0625-0.487) × (0.5625-0.0625+0.5 -0.0625) = 0.0243 in. 2 Therefore, A1 = 0.1 in.2 available reinforcement in shell 78
Instructor’s Outline Available shell reinforcement area is determined.
Major Learning Points Sample Problem 3 solution.
90
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 3 Solution, cont’d • Calculate reinforcement area available in nozzle wall, A2, as smaller of A21 or A22. A21 = (tn-tr n) 5t A22 = 2 (t n-tr n) (2.5 tn + t e)
79
Instructor’s Outline Available reinforcement area in the nozzle is determined by checking two equations.
Major Learning Points Sample Problem 3 solution.
91
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d Where: trn =
Required thickness of nozzle wall, in.
r =
Radius of nozzle, in.
te =
0 if no reinforcing pad.
te =
Reinforcing pad thickness if one installed, in.
te =
Defined in Figure UG-40 for self-reinforced nozzles, in.
80
Instructor’s Outline Review the relevant parameters.
Major Learning Points Sample Problem 3 solution.
92
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate required nozzle thickness, trn (Figure 4.6)
t rn =
t rn =
Pr SE1 − 0. 6P
300 (3. 8125 + 0. 0625) = 0. 0784 in. 15,000 × 1 − 0. 6 × 300
81
Instructor’s Outline Calculate required thickness using the equation for a cylinder.
Major Learning Points Sample Problem 3 solution.
93
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate A2. A21 = (tn - trn)5t = (0.5 - 0.0625 - 0.0784) × 5 (0.5625 - 0.0625) = 0.898 in.2 A22 = 2 (tn - t rn) (2.5 tn + te) = 2 (0.5 - 0.0625 - 0.0784) [2.5 × (0.5 - 0625) + 0] = 0.786 in.2 Therefore, A2 = 0.786 in.2 available reinforcement in nozzle. 82
Instructor’s Outline 1. The available reinforcement in the nozzle is determined.
Major Learning Points Sample Problem 3 solution.
2. Note that in this case, the nozzle has much more excess metal available than the shell.
94
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Determine total available reinforcement area, A T; compare to required area. AT = A1 + A2 = 0.1 + 0.786 = 0.886 in.2 AT < A, nozzle not adequately reinforced, reinforcement pad required. • Determine reinforcement pad diameter, Dp. A5 = A - AT A5 = (3.775 - 0.886) = 2.889 in.2 83
Instructor’s Outline 1. The nozzle is not adequately reinforced because it does not have enough reinforcement available.
Major Learning Points Sample Problem 3 solution.
2. The problem now proceeds to determine the required dimensions of a reinforcement pad. Note, however, that the additional reinforcement could also be added by using a thicker nozzle or by using a thicker shell section near the nozzle.
95
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate Dp te = 0.5625 in. (reinforcement pad thickness) A 5 = [Dp - (d + 2 t n)] te 2.889 = [Dp - (7.75 + 2(0.5 - 0.0625)] 0.5625 Dp = 13.761 in. • Confirm Dp within shell reinforcement zone, 2d 2d = 2 × 7.75 = 15.5 in. 84
Instructor’s Outline 1. The reinforcement pad thickness was assumed to be equal to the shell thickness. This is common practice.
Therefore, Dp = 13.761 in. acceptable
Major Learning Points Sample Problem 3 solution.
2. A final check is made to ensure that the reinforcement pad is within the reinforcement zone.
96
Overview of Pressure Vessel Design Instructor’s Personal Notes Flange Rating • Based on ASME B16.5 • Identifies acceptable pressure/temperature combinations • Seven classes (150, 300, 400, 600, 900, 1,500, 2,500) • Flange strength increases with class number • Material and design temperature combinations without pressure indicated not acceptable 85
Instructor’s Outline 1. ASME B16.5 provides standard flange dimensional details. 2. Flange strength is based on dimensions and material used.
Major Learning Points The flange rating establishes acceptable temperature/pressure combinations and is based on ASME B16.5
97
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Specification List Material Groups Material Group Number
Nominal Designation Steel
1.1
Carbon
1.2
C-Mn-Si Carbon 2 ½ Ni 3 ½ Ni
Product Forms Forgings
Castings
Plates
Spec. No.
Grade
Spec. No.
Grade
Spec. No.
Grade
A105 A350 ----A350
-LF2 ----LF3
A216 --A216 A352 A352 A352
WCB --WCC LCC LC2 LC3
A515 A516 A537 --A203 A203
70 70 Cl.1 --B E
ASME B16.5, Table 1a, Material Specification List (Excerpt)
Figure 4.17 86
Instructor’s Outline 1. Acceptable flange materials are grouped based on similarities in strength.
Major Learning Points Flange Material Group Number is based on material specification and product form.
2. The Material Group is determined based on the specified material.
98
Overview of Pressure Vessel Design Instructor’s Personal Notes Pressure - Temperature Ratings Material Group No. Classes Temp., °F -20 to 100 200 300 400 500 600 650 700 750 800 850 900 950 1000
1.1
1.2
1.3
150
300
400
150
300
400
150
300
400
285 260 230 200 170 140 125 110 95 80 65 50 35 20
740 675 655 635 600 550 535 535 505 410 270 170 105 50
990 900 875 845 800 730 715 710 670 550 355 230 140 70
290 260 230 200 170 140 125 110 95 80 65 50 35 20
750 750 730 705 665 605 590 570 505 410 270 170 105 50
1000 1000 970 940 885 805 785 755 670 550 355 230 140 70
265 250 230 200 170 140 125 110 95 80 65 50 35 20
695 655 640 620 585 534 525 520 475 390 270 170 105 50
925 875 850 825 775 710 695 690 630 520 355 230 140 70
Figure 4.18 87
Instructor’s Outline 1. This table combines information for three Material Groups for illustrative purposes.
Major Learning Points Pressure/temperature rating is a function of Material Group and design temperature.
2. Review the information in this table and how it is used to determine the appropriate flange rating.
99
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 4 Determine Required Flange Rating Pressure Vessel Data: Shell and Heads:
SA-516 Gr.70
Flanges:
SA-105
Design Temperature: 700°F Design Pressure:
275 psig
88
Instructor’s Outline 1. Sample Problem 4 illustrates how to determine flange rating.
Major Learning Points Sample Problem to illustrate determining flange rating.
2. Review the given information. 3. Review the problem solution with the Participants.
100
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 4 - Solution • Identify flange material specification SA-105 • From Figure 4.17, determine Material Group No. Group 1.1 • From Figure 4.18 with design temperature and Material Group No. determined in Step 3 – Intersection of design temperature with Material Group No. is maximum allowable design pressure for the flange Class 89
Instructor’s Outline Review the problem solution.
Major Learning Points Sample Problem 4 solution.
101
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 4 Solution, cont’d – Table 2 of ASME B16.5, design information for all flange Classes – Select lowest Class whose maximum allowable design pressure ≥ required design pressure.
• At 700°F, Material Group 1.1: Lowest Class that will accommodate 275 psig is Class 300. • At 700°F, Class 300 flange of Material Group 1.1: Maximum design pressure = 535 psig. 90
Instructor’s Outline 1. Use the lowest flange class that is suitable for the design conditions. Flange cost increases as the class increases.
Major Learning Points Sample Problem 4 solution.
2. A given flange class is good for a range of temperature/pressure combinations for a particular Material Group.
102
Overview of Pressure Vessel Design Instructor’s Personal Notes
Flange Design • Bolting requirements – During normal operation (based on design conditions) – During initial flange boltup (based on stress necessary to seat gasket and form tight seal Am =
W S
91
Instructor’s Outline 1. Division 1 Appendix 2 procedure for custom-designed flanges.
Major Learning Points ASME procedure must be used for custom-designed flanges.
2. Used if flange size not covered by ASME B16.5 or ASME B16.47. 3. Typical application is girth flange for shell-and-tube heat exchanger.
103
Overview of Pressure Vessel Design Instructor’s Personal Notes
Flange Loads and Moment Arms Flange Ring
Gasket h
t A
hG
W
hT
hD
C
g1
HT G
HG
HD
B
g0 Flange Hub
Figure 4.19 92
Instructor’s Outline 1. Applied loads act at different flange locations.
Major Learning Points Various flange loads are applied on corresponding moment arms.
2. Flange moments are calculated for the operating and gasket seating cases.
104
Overview of Pressure Vessel Design Instructor’s Personal Notes
Stresses in Flange Ring and Hub • Calculated using: – Stress factors (from ASME code) – Applied moments – Flange geometry • Calculated for: – Operating case – Gasket seating case 93
Instructor’s Outline 1. Various stresses are calculated for each case and must be kept within allowable limits. 2. Flange dimensions are adjusted as needed to meet allowable stresses (e.g., increase thickness, change hub dimensions, etc.).
Major Learning Points •
Flange stresses are calculated and compared to allowable values.
•
Both operating and gasket seating cases must be checked.
3. Equipment suppliers use computer programs to “optimize” flange design to be least weight (i.e., lowest cost).
105
Overview of Pressure Vessel Design Instructor’s Personal Notes
Flange Design and In-Service Performance Factors affecting design and performance • ASME Code m and y parameters. • Specified gasket widths. • Flange facing and nubbin width, w • Bolt size, number, spacing
94
Instructor’s Outline
Major Learning Points
1. Flange is designed for specific gasket type, dimensions, and facing details. Changing any of these after flange is fabricated (e.g., gasket type) can adversely affect in-service performance.
Various parameters affect flange design and performance.
2. TEMA specifies minimum gasket width and bolt spacing criteria.
106
Overview of Pressure Vessel Design Instructor’s Personal Notes
ASME Code m and y Factors Gasket Factor, m
Min. Design Seating Stress y, psi
Flat metal, jacketed asbestos filled: Soft aluminum Soft copper or brass Iron or soft steel Monel 4-6% chrome Stainless steels and nickel-base alloys
3.25 3.50 3.75 3.50 3.75 3.75
5,500 6,500 7,600 8,000 9,000 9,000
(1a), (1b), (1c), (1d); (2); Column II
Solid flat metal: Soft aluminum Soft copper or brass Iron or soft steel Monel or 4-6% chrome Stainless steels and nickel-base alloys
4.00 4.75 5.50 6.00 6.50
8,800 13,000 18,000 21,800 26,000
(1a), (1b), (1c), (1d); (2), (3), (4), (5); Column I
Gasket Type and Material
Facing Sketch and Column in ASME Table 2-5.2 (Figure 4.21)
Figure 4.20 95
Instructor’s Outline
Major Learning Points
1. This is an excerpt from Table 2-5.1.
•
2. Review the variation in m and y with gasket type.
Gasket m and y factors are based on gasket type.
•
Gasket type also affects gasket width used in calculations.
107
Overview of Pressure Vessel Design Instructor’s Personal Notes
ASME Code Gasket Widths Basic Gasket Seating Width bo
Facing Sketch (Exaggerated)
N
(1a)
Column I
Column II
N 2
N 2
N
N
N
(1b) w
T N
(1c) w
(1d)
w ≤N
w + T ; w + N max 2 4
T N
w+ T w+ N ; max 2 4
w ≤N HG
HG
G O.D. Face
hG b
G
hG Gasket C L Face
For b o > ¼ in.
For b o< ¼in.
ASME Code Gasket Widths (Table 2-5.2 excerpt)
Figure 4.21 96
Instructor’s Outline 1. This is an excerpt from Table 2-5.2. 2. Review the flange facings shown.
Major Learning Points The gasket width used in the calculations depends on the type of flange facing.
108
Overview of Pressure Vessel Design Instructor’s Personal Notes
Gasket Materials and Facings Gasket Materials and Facings Gasket Factors m for Operating Conditions and Minimum Design Seating Stress y Gasket Material
Gasket Factor m
Min. Design Seating Stress y, psi
Flat metal, jacketed asbestos filled: Soft aluminum Soft copper or brass Iron or soft steel Monel 4% - 6% chrome Stainless steels and nickel-base alloys
3.25 3.50 3.75 3.50 3.75 3.75
5500 6500 7600 8000 9000 9000
Sketches
Facing Sketch and Column in Table 2-5.2 (1a), (1b), (1c),2, (1d) 2, (2)2, Column II
Figure 4.22 97
Instructor’s Outline Review the additional gasket information shown.
Major Learning Points Information on additional gasket types.
109
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Working Pressure (MAWP) Maximum permitted gauge pressure at top of vessel in operating position for designated temperature • MAWP ≥ Design Pressure • Designated Temperature = Design Temperature • Vessel MAWP based on weakest component
98
Instructor’s Outline 1. Emphasize that MAWP is based on the as-supplied component thicknesses.
– Originally based on new thickness less corrosion allowance – Later based on actual thickness less future corrosion allowance needed
Major Learning Points MAWP is defined.
2. Thicknesses used exclude corrosion allowance and thickness added to absorb other loads. 3. MAWP is useful to know for potential future rerate.
110
Overview of Pressure Vessel Design Instructor’s Personal Notes
Local Loads • Piping system • Platforms, internals, attached equipment • attachment
99
Instructor’s Outline 1. Review the typical external loads that may be applied.
Major Learning Points Externally applied loads must also be considered in vessel design.
2. External loads cause local stresses that must be evaluated. 3. Other industry standards must be used to evaluate local stresses (e.g., WRC 107 and 297).
111
Overview of Pressure Vessel Design Instructor’s Personal Notes
Types of Vessel Internals • Trays • Inlet Distributor • Anti-vortex baffle • Catalyst bed grid and beams • Outlet collector • Flow distribution grid • Cyclone and plenum chamber system 100
Instructor’s Outline
Major Learning Points
1. Different types of internals are used to perform various process functions.
Several types of vessel internals may be installed.
2. Review list of internals. 3. ASME Code does not cover design of internals. End-, vessel vendor, and/or contractor must develop requirements.
112
Overview of Pressure Vessel Design Instructor’s Personal Notes
ASME Code and Vessel Internals • Loads applied from internals on vessel to be considered in design • Welding to pressure parts must meet ASME Code
101
Instructor’s Outline Discuss ASME requirements for loads applied to vessel and welding to pressure parts.
Major Learning Points ASME Code requires that internals be considered only to extent of their effect on pressure shell.
113
Overview of Pressure Vessel Design Instructor’s Personal Notes
Corrosion Allowance For Vessel Internals • Removable internals: CA = CA of shell – Costs less – Easily replaced
• Non-removable internals: CA = 2 (CA of shell) – Corrosion occurs on both sides 102
Instructor’s Outline 1. Potential corrosion of internals should not be ignored.
Major Learning Points Corrosion allowance should be considered in the design of internals.
2. Corrosion allowance should be considered in a practical and costeffective manner.
114
Overview of Pressure Vessel Design Instructor’s Personal Notes
Head-to-Shell Transitions l y
Thinner part
th Thinner part
th
l
Tangent Line
y
t
ts
th
Tangent Line
t
y Thinner part
l
Thinner part
y
s
th
l
t
s
s
Fillet Weld
Butt Weld Intermediate Head Attachment
Figure 6.1 103
Instructor’s Outline 1. Review typical acceptable welding and fabrication details.
Major Learning Points ASME Code specifies acceptable welding and fabrication details.
2. Details for openings were previously reviewed. 3. Highlight thickness taper. 4. Intermediate heads should retain fillet weld in refinery applications.
115
Overview of Pressure Vessel Design Instructor’s Personal Notes
Typical Shell Transitions CL
In all cases, l shall not be less than 3y.
CL
y
l l
C L
Figure 6.2 104
Instructor’s Outline Review thickness taper requirements.
Major Learning Points ASME Code fabrication details.
116
Overview of Pressure Vessel Design Instructor’s Personal Notes
Nozzle Neck Thickness Tapers
Figure 6.3 105
Instructor’s Outline Thickness taper may be required in nozzle neck.
Major Learning Points ASME Code fabrication details.
117
Overview of Pressure Vessel Design Instructor’s Personal Notes
Stiffener Rings
In-Line Intermittent Weld Staggered Intermittent Weld
Continuous Fillet Weld On One Side, Intermittent Weld On Other Side
Figure 6.4 106
Instructor’s Outline 1. Vacuum stiffening ring attachment details.
Major Learning Points ASME Code fabrication details.
2, ASME Code specifies weld spacing, size, and length.
118
Overview of Pressure Vessel Design Instructor’s Personal Notes Post Weld Heat Treatment • Restores material properties • Relieves residual stresses • ASME Code PWHT requirements – Minimum temperature and hold time – Adequate stress relief – Heatup and cooldown rates
107
Instructor’s Outline 1. ASME Code specifies PWHT requirements only for relief of residual stresses.
Major Learning Points ASME Code PWHT requirements.
2. Need for PWHT due to other reasons must be specified by end- or contractor. •
Service considerations (e.g., wet H 2S, caustic)
•
Weld hardness reduction
119
Overview of Pressure Vessel Design Instructor’s Personal Notes Inspection and Testing Inspection includes examination of:
• Base material specification and quality • Welds • Dimensional requirements • Equipment documentation 108
Instructor’s Outline Highlight main areas included in inspection.
Major Learning Points ASME Code inspection requirements.
120
Overview of Pressure Vessel Design Instructor’s Personal Notes Common Weld Defects Between Weld Bead and Base Metal
Between Adjacent es
Lack of Fusion
Incomplete Filling at Root on One Side Only
Incomplete Filling at Root
Incomplete Penetration ExternalUndercut
Internal Undercut
Undercut
Figure 7.1 109
Instructor’s Outline Review common types of weld defects.
Major Learning Points Particular types of weld defects may occur.
121
Overview of Pressure Vessel Design Instructor’s Personal Notes Weld Defects Presence of defects: • Reduces weld strength below that required • Reduces overall strength of fabrication • Increases risk of failure
110
Instructor’s Outline Review why weld defects can reduce vessel integrity.
Major Learning Points Presence of unacceptable weld defects reduces vessel integrity.
122
Overview of Pressure Vessel Design Instructor’s Personal Notes
Types of NDE NDE TYPE Radiographic
Visual
Liquid Penetrant
Magnetic Particle Ultrasonic
DEFECTS DETECTED Gas pockets, slag inclusions, incomplete penetration, cracks Porosity holes, slag inclusions, weld undercuts, overlapping Weld surface-type defects: cracks, seams, porosity, folds, pits, inclusions, shrinkage Cracks, porosity, lack of fusion Subsurface flaws: laminations, slag inclusions
ADVANTAGES Produces permanent record. Detects small flaws. Most effective for butt-welded ts. Helps pinpoint areas for additional NDE.
LIMITATIONS Expensive. Not practical for complex shapes. Can only detect what is clearly visible.
Used for ferrous Can only detect and nonferrous surface materials. Simple imperfections. and less expensive than RT, MT, or UT. Flaws up to ¼ in. beneath surface can be detected. Can be used for thick plates, welds, castings, forgings. May be used for welds where RT not practical.
Cannot be used on nonferrous materials. Equipment must be constantly calibrated.
Figure 7.2 111
Instructor’s Outline 1. Review NDE methods and types of defects detected. 2. Review advantages and limitations of each NDE method.
Major Learning Points •
Different NDE methods are best suited to detect particular defect types.
•
Each NDE method has advantages and disadvantages.
123
Overview of Pressure Vessel Design Instructor’s Personal Notes Typical RT Setup X-Ray Tube
X-Ray
Film
Test Specimen
Figure 7.3 112
Instructor’s Outline Review typical setup for RT inspection.
Major Learning Points Typical RT setup.
124
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pulse Echo UT System Cathode Ray Tube (CRT)
A
C
Read Out
B
BaseLine
Input-Output Generator
Cable
Transducer A Couplant Test Specimen
B C
Flaw
Figure 7.4 113
Instructor’s Outline Review how pulse echo UT system can detect defects.
Major Learning Points Typical pulse echo UT system.
125
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pressure Testing • Typically use water as test medium • Demonstrates structural and mechanical integrity after fabrication and inspection • Higher test pressure provides safety margin • PT = 1.5 P (Ratio)
114
Instructor’s Outline 1. Water is a safer test medium than air. Pneumatic testing should only be used on an exception basis.
Major Learning Points Pressure test is used as final demonstration of vessel integrity.
2. “Ratio” is the lowest value of:
S( test temperatur e) S ( design temperatur e)
126
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pressure Testing, cont’d Hydrotest pressures must be calculated: • For shop test. Vessel in horizontal position. • For field test. Vessel in final position with uncorroded component thicknesses. • For field test. Vessel in final position and with corroded component thicknesses. • PT ≤ Flange test pressure • Stress ≤ 0.9 (MSYS) • Field test with wind 115
Instructor’s Outline Review additional pressure test design considerations.
Major Learning Points Pressure test considerations.
127
Overview of Pressure Vessel Design Instructor’s Personal Notes
Summary • Overview of pressure vessel mechanical design • ASME Section VIII, Division 1 • Covered – Materials – Fabrication – Testing
– Design – Inspection
116
Instructor’s Outline 1. Highlight the subjects covered in the course.
Major Learning Points Summarize course.
2. Note that much more time is required for an in-depth discussion of pressure vessel design. This course provides a good starting point to proceed further for those who need to. 3. Provide the evaluation form for the class to complete. Collect these and return them to the sponsoring unit. 4. Distribute the CEU form to the participants and point out that they will have to mail it in themselves, with the required standard fee. All the information is on the form.
128
Appendix A Reproducible Overheads
Appendix B Course & Instructor Evaluation Form
ASME Career Development Series Course Evaluation Course Title: ________________________________________________ Location: ___________________________________________________ Instructor: __________________________________________________ Please assist us in the evaluation of this program. Answer the following questions by circling only one answer unless otherwise stated. We will be using your to plan future programs. Your assistance is most appreciated. Please return to instructor as requested. A.
Course Evaluation Please record your overall reaction to the program by placing a circle around the appropriate number on the scale. 10 9 Excellent
876 Good
Fair
543 Poor
210
Please evaluate the course by circling E (excellent), G (good), F (fair), or P (poor) in the appropriate location. 1.
Course content Relevance of New matches brochure course notes/ Applicability Knowledge Overall description workbook to your job Gained
1.1 E G F P
1.2 E G F P
1.3 E G F P
Rating
1.4 E G F P 1.5 E G F P
2.
What do you think was the best feature of the course?
3.
What changes, if any, would you make in the program content and/or format?
4.
Can you share with us any comments about this program that we coul use as a quote on our course literature?
Optional Information: Name: _______________________________ Company: ____________________________
Title: _______________________________ City, State: __________________________
131
B.
5.
Instructor’s Evaluation Please evaluate the instructor(s) by circling E (excellent), G (good), F (fair), or P (poor) in the appropriate location Effective knowledge of subject matter
1.1 E G F P
Effectiveness Effective of teaching use of Class method class time
1.2 E G F P
1.3 E G F P
Openness to Overall Participation Rating
1.4 E G F P 1.5 E G F P
C. 6.
Facilities How would you rate the meeting site?
7.
How would you rate the overnight accommodations (if applicable)?
8.
In what other cities would you like to see this course held?
9.
Additional Comments:
D. 10.
Future Courses and Educational Products (Video, Self Study, Software) What other courses would you like to see sponsored?
11.
What educational products would you like to see sponsored by ASME and in what medium?
E. 12.
On-Site Company Training Would your organization be interested in holding this course or other ASME courses at your facility? If so, please indicate the area of interest and the person. Thank you.
13.
Course Name/Topic: _________________________________________________________
14.
Name: ________________________________ Phone No.: ___________________
132
Appendix C
Continuing Education Unit (CEU) Submittal Form Course Improvement Form
133
ASME Career Development Series Continuing Education Unit (CEU) Request Form Each 4-hour ASME Career Development Series Course earns 0.4 CEU’s PLEASE PRINT ALL YOUR INFORMATION CLEARLY YOUR CERTIFICATE WILL BE PREPARED FROM THIS FORM Title of Program: _____________________________________________________ Date Held: __________________________________________________________ Instructor: __________________________________________________________ Location: ___________________________________________________________ Number of CEU’s Earned: (0.4 per 4-hour module) ____________ Last Name: __________________________________________ First Name, Middle Initial: ______________________________ Title/Position: ________________________________________ Company: ___________________________________________ Address: ____________________________________________ City: _______________________ State: __ Zip: ____________ Telephone: __________________ Fax: ____________________ Email: _________________________ Please send this form, along with a check made out to ASME for the standard fee of $15.00 to: ASME Continuing Education Institute Three Park Avenue New York, NY 10016-5990 Your Certificate will be prepared and sent to the address you indicated above.
134
ASME Career Development Series Course Improvement Form
Important Note: Submission of this form is optional. However, we would like to solicit the comments of the Instructor so that we may continuing improve on the Career Development Series. Any instructors who would like to write a course should indicate so on this form and an authors package will be forwarded to you. Thank you for helping us with the Career Development Series Name: _________________________________________________________ Address: _______________________________________________________ City/State/Zip: __________________________________________________ Telephone: ______________________________ Fax: ____________________________________ Email: __________________________________ Comments:
Please send this form to: ASME Continuing Education Institute Three Park Avenue New York, NY 10016-5990
135
ASME Career Development Series Instructor’s Biography Form
Important Note: Submission of this form is required every time a Career Development Series Course is taught. ASME cannot process attendees’ CEU requests without this form. Attachments to this form must include: 1. A biographical sketch of the instructor. 2. Course evaluations filled out by the participants at the completion of the course.
Course: ____________________________________________________ Date Presented: ______________________________________________ Location: ___________________________________________________ Instructor: __________________________________________________ Number of participants: ________________________________________ Sponsoring Unit: _____________________________________________
136
Your Path to Lifelong Learning ASME offers you exciting, rewarding ways to sharpen your technical skills, enhance personal development and prepare for advancement. Short Courses – More than 200 short courses offered each you keep you up to speed in the technology fast lane—or, help you fill in any gaps in your technical background. Customized Training at your organization’s site – Do you have ten or more people at your site who could benefit from an ASME course? Most of our courses can be offered in -house and tailored to your latest engineering project. Bring course to your company too. Self-study materials meet the needs of individuals who demand substantive, practical information, yet require flexibility, quality and convenience. Return to each program again and again, as a refresher or as an invaluable addition to your reference library. FE Exam Review– A of seasoned educators outline a wide range of required topics to provide a thorough review to help practicing engineers as well as engineering students prepare for this challenging examination. Videotape Review PE Exam Review– A comprehensive review of all the major exam topics that demonstrates the necessary math, logic and theory. Videotape, Online, or Online Live Revie w available. FOR MORE INFORMATION CALL 1-800-THE-ASME __________________________________________________________________________ INFORMATION REQUEST FORM Please mail to ASME at 22 Law Drive, P. O. Box 2900, Fairfield, NJ 07007-2900, or fax to 973-882-1717, call 1-800-THE-ASME, or email [email protected]. Send me information on the following: ____ Short Courses ____ In-House Training ____ Self-Study Programs ____ FE Exam Review ____ PE Exam Review (videotape) ____ PE Exam Review (Online) ____ PE Exam Review (Online Live) Name: ______________________________________________ Title: _______________________________________________ Organization: _________________________________________ Business Address: _____________________________________ City: _________________ State: __ Zip Code: _____________ Business Phone: _________________ Fax: ________________ Email: ______________________________________________
137
Instructor’s Guide
1
INFORMATION ASME Headquarters 1-800-THE-ASME ASME Professional Development 1-800-THE-ASME
Eastern Regional Office 8996 Burke Lake Road – Suite L102 Burke, VA 22015-1607 703-978-5000 800-221-5536 703-978-1157 (FAX)
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International Regional Office 1-800-THE-ASME You Youcan canalso alsofind findinformation informationon onthese these courses and all of ASME, including courses and all of ASME, includingASME ASME Professional ProfessionalDevelopment, Development,the theVice Vice President Presidentof ofProfessional ProfessionalDevelopment, Development, and other s and other sat atthe theASME ASMEWeb Web site...... site...... http://www.asme.org http://www.asme.org
2
Overview of Pressure Vessel Design By: Vincent A. Carucci Carmagen Engineering, Inc.
Copyright © 1999 by
All Rights Reserved
3
TABLE OF CONTENTS
Abstract………………………………………………………………… 5 Introduction…………………………..…………………………………6 Organizing Unit Responsibilities……………………………………..7 Instructor Guidelines and Responsibilities………………………….9 Overview of Pressure Vessel Design Outline/ Teaching Plan…………………………………………………………11 Instructor Notes……………………………………………………….13 Appendix A: Reproducible Overheads Appendix B: Course and Instructor Evaluation Form Appendix C: Continuing Education Unit (CEU) Submittal Form Course Improvement Form Instructor’s Biography Form
4
ABSTRACT
Pressure vessels are typically designed, fabricated, installed, inspected, and tested in accordance with the ASME Code Section VIII. Section VIII is divided into three separate divisions. This course outlines the main differences a mong the divisions. It then concentrates on and presents an overview of Division I. This course also discusses several relevant items that are not included in Division I.
5
INTRODUCTION
This Overview of Pressure Vessel Design course is part of the ASME International Career Development Series – an educational tool to help engineers and managers succeed in today’s business/engineering world. Each course in this series is a 4hour (or half-day) self-contained professional development seminar. The course material consists of a participant manual and an instructor’s guide. The participant manual is a self-contained text for students/participants, while the guide (this booklet) provides the instructional material designed to be presented by a local knowledgeable instructor with a minimum of preparation time. The balance of this instructor’s guide focuses on: 1. 2. 3.
Organizing Unit Responsibilities Instructor Guidelines and Responsibilities Comprehensive teaching materials which may be used “as is” or adapted to incorporate experiences and perspective of the instructor.
Welcome to the ASME International Career Development Series! We wish you all the best in your presentation, operation and delivery of this course.
6
7
8
9
10
Suggested Outline/Teaching Plan Time, min.
Major Interval 10
Class Segment Introduction
Sub-Segment Interval 5 5
25
General
10 10
5 20
Materials of Construction
15
5 10
Exercise
10
10 55
Break Design
10 10
25
20
Sub-Segment Introduction/Logistics Outline Module Module based primarily on the ASME Code Section VIII, Division 1. Divisions 2 and 3 will be briefly described Main Pressure Vessel Components Scope of ASME Code Section VIII • Division 1 • Division 2 • Division 3 Structure of Section VIII, Division 1 Material Selection Factors • Strength • Corrosion Resistance • Resistance to Hydrogen Attack • Fracture Toughness • Fabricability Maximum Allowable Stress Material Selection Based On Fracture Toughness Design Conditions and Loadings • Pressure • Temperature • Other Loadings Design for Internal Pressure • Weld ts • Cylindrical Shells • Heads • Conical Sections Sample Problem Design for External Pressure and Compressive Stresses • Cylindrical Shells • Other Components • Sample Problem
Overheads/ Participant Pages OV – 1 Part. – 65 OV – 2 Part. – 65
OV – 3-9 Part. – 67 OV – 10-13 Part. – 75
OV – 14 Part. –78 OV – 15-31 Part. – 79
OV – 32-34 Part. – 87 OV – 35-38 Part. – 91 OV – 39-43 Part. – 92
OV – 44-55 Part. - 98
OV – 56-65 Part. – 109
11
Suggested Outline/Teaching Plan, continued Time, min.
Major Interval 10 - 50
Class Segment
Sub-Segment Interval
Major Break
Sub-Segment
Overheads/ Participant Pages
Lunch or Major Break
15
Exercise
15
Required Thickness for Internal Pressure
OV – 66-68 Part. - 118
50
Design (Cont’d.)
20
Reinforcement of Openings (Include Sample Problem) Flange Rating (Including Sample Problem) Flange Design
OV – 69-84 Part. – 119 OV – 85-90 Part. – 127 OV – 91-97 Part. – 131 OV – 98 Part. – 138
10 15
10 20
20
15
10
Break Other Design Considerations
Fabrication
Inspection and Testing
Closure
5
Maximum Allowable Working Pressure (MAWP)
10
Local Loads
10
Vessel Internals
10
Acceptable Welding Details
10
Postweld Heat Treatment (PWHT)Requirements
10
Inspection
5
Pressure Testing
10
Summary Questionnaire (fill in and collect) CEU Form (hand out – individual responsibility to return)
OV – 99 Part. – 139 OV – 100-102 Part. – 141 OV – 103-106 Part. – 143 OV – 107 Part. – 146 OV – 108-113 Part. – 148 OV – 114-115 Part. – 152 OV – 116 Part. - 155
12
Overview of Pressure Vessel Design Instructor’s Personal Notes
OVERVIEW OF PRESSURE VESSEL DESIGN By: Vincent A. Carucci Carmagen Engineering, Inc .
1
Instructor’s Outline 1. Course discusses pressure vessel design and is introductory in nature.
Major Learning Points Course Introduction
2. Based on ASME Code Section VIII. 3. Preliminary emphasis is on Division 1 but Divisions 2 and 3 are highlighted. 4. Introduces several items that are not covered in the ASME Code.
13
Overview of Pressure Vessel Design Instructor’s Personal Notes Course Overview • General • Materials of Construction • Design • Other Design Considerations • Fabrication • Inspection and Testing 2
Instructor’s Outline 1. The objective: Provide a general knowledge of design requirements for pressure vessels.
Major Learning Points •
Establish course objectives.
•
Outline course content, a road map.
2. This is not a comprehensive course. It provides sufficient information for management personnel to have an overall understanding of this subject. Individuals having more detailed responsibility will receive a solid starting point to proceed further. 3. Review outline. 4. Establish schedule. 5. Participation is key: •
Questions
•
Discussion/interaction
14
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pressure Vessels • Containers for fluids under pressure • Used in variety of industries – Petroleum refining – Chemical – Power – Pulp and paper – Food 3
Instructor’s Outline
Major Learning Points
1. Describe what a pressure vessel is.
•
Define pressure vessels.
2. Note that pressure vessels are used in a wide variety of industries. They can be designed for a wide variety of conditions and in a broad range of sizes.
•
Identify wide variety of industrial applications.
15
Overview of Pressure Vessel Design Instructor’s Personal Notes Horizontal Drum on Saddle s Nozzle
A
Shell
Head
Head
Saddle (Sliding)
Saddle (Fixed) A
SectionA-A
Figure 2.1 4
Instructor’s Outline
Major Learning Points
1. Use this and following overheads to describe main pressure vessel components and shapes.
Main pressure vessel components and configurations.
2. Shell is primary component that contains pressure. Curved shape. 3. Vessel always closed by heads. 4. Components typically welded together. 5. Vessel shell may be cylindrical, spherical, or conical. 6. Multiple diameters, thicknesses or materials are possible. 7. Saddle s used for horizontal drums. •
Spreads load over shell.
•
One fixed, other slides.
16
Overview of Pressure Vessel Design Instructor’s Personal Notes Vertical Drum on Leg s Head
Shell
Nozzle
Head
Leg
5
Instructor’s Outline 1. Most heads are curved shape for strength, thinness, economy.
Figure 2.2
Major Learning Points Main pressure vessel components and shapes.
2. Semi-elliptical shape is most common head shape. 3. Small vertical drums typically ed by legs. •
Typically maximum 2:1 ratio of leg length to diameter.
•
Number, size, and attachment details depend on loads.
17
Overview of Pressure Vessel Design Instructor’s Personal Notes
Tall Vertical Tower Nozzle Head
Trays
Shell
Nozzle
Cone
Nozzle Shell
Nozzle
6
Instructor’s Outline 1. Nozzles used for: •
Piping systems
•
Instrument connections
•
Manways
•
Attaching other equipment
Head Skirt
Figure 2.3
Major Learning Points Main pressure vessel components and shapes.
2. Ends typically flanged, may be welded. 3. Sometimes extend into vessel.
18
Overview of Pressure Vessel Design Instructor’s Personal Notes
Vertical Reactor Inlet Nozzle Head
Upper Catalyst Bed
Shell
Catalyst Bed Grid
Lower Catalyst Bed Outlet Collector Head Outlet Nozzle Skirt
7
Figure 2.4
Instructor’s Outline
Major Learning Points
1. Skirt s typically used for tall vertical vessels:
Main pressure vessel components and shapes.
•
Cylindrical shell
•
Typically ed from grade
2. General design (not just for skirts) •
Design for weight, wind, earthquake.
•
Pressure not a factor.
•
Temperature also a consideration for material selection and thermal expansion.
19
Overview of Pressure Vessel Design Instructor’s Personal Notes
Spherical Pressurized Storage Vessel Shell
Leg
Cross Bracing
Figure 2.5 8
Instructor’s Outline 1. Spherical storage vessels typically ed on legs.
Major Learning Points Main pressure vessel components and shapes.
2. Cross-bracing typically used to absorb wind and earthquake loads.
20
Overview of Pressure Vessel Design Instructor’s Personal Notes Vertical Vessel on Lug s
9
Instructor’s Outline 1. Vessel size limits for lug s: •
1 – 10 ft diameter
•
2:1 to 5:1 height/diameter ratio
Figure 2.6
Major Learning Points Main pressure vessel components and configurations.
2. Vessel located above grade. 3. Lugs bolted to horizontal structure.
21
Overview of Pressure Vessel Design Instructor’s Personal Notes Scope of ASME Code Section VIII • Section VIII used worldwide • Objective: Minimum requirements for safe construction and operation • Division 1, 2, and 3
10
Instructor’s Outline 1. Section VIII is most widely used Code.
Major Learning Points Define scope of ASME Code Section VIII.
2. Assures safe design. 3. Three divisions have different emphasis.
22
Overview of Pressure Vessel Design Instructor’s Personal Notes Section VIII Division 1 • 15 psig < P ≤ 3000 psig • Applies through first connection to pipe • Other exclusions – Internals (except for attachment weld to vessel) – Fired process heaters – Pressure containers integral with machinery – Piping systems
11
Instructor’s Outline
Major Learning Points
1. Review scope of Division 1.
•
Scope of Division 1
2. Division 1 not applicable below 15 psig.
•
Exclusions from scope
3. Additional rules required above 3000 psig. 4. Items that are connected to pressure vessels not covered by Division 1, except for: •
Their effect on pressure part.
•
Welded attachment to pressure part.
23
Overview of Pressure Vessel Design Instructor’s Personal Notes
Section VIII, Division 2, Alternative Rules • Scope identical to Division 1 but requirements differ – Allowable stress – Stress calculations – Design – Quality control – Fabrication and inspection
• Choice between Divisions 1 and 2 based on economics
12
Instructor’s Outline 1. Review differences between Divisions 1 and 2.
Major Learning Points Differences between Division 1 and 2.
2. Division 2 allowable membrane stress is higher. 3. Division 2 requires more complex calculations. 4. Division 2 does not permit some design details that are permitted in Division 1. 5. Division 2 requires more stringent material quality control, fabrication, and testing requirements.
24
Overview of Pressure Vessel Design Instructor’s Personal Notes Division 3, Alternative Rules High Pressure Vessels • Applications over 10,000 psi • Pressure from external source, process reaction, application of heat, combination of these • Does not establish maximum pressure limits of Division 1 or 2 or minimum limits for Division 3. 13
Instructor’s Outline 1. Review application of Division 3.
Major Learning Points Scope of Division 3
2. Newest Division of Section VIII and has least applicability. 3. After this point, this course only addresses Division 1 requirements when code-specific items are discussed.
25
Overview of Pressure Vessel Design Instructor’s Personal Notes
Structure of Section VIII, Division 1
• Subsection A
– Part UG applies to all vessels
• Subsection B – Requirements based on fabrication method – Parts UW, UF, UB
• Subsection C – Requirements based on material class – Parts UCS, UNF, UHA, UCI, UCL, UCD, UHT, ULW, ULT
• Mandatory and Nonmandatory Appendices
14
Instructor’s Outline 1. Review Division 1 organization 2. Fabrication methods: •
Welded
•
Forged
•
Brazed
Major Learning Points Basic organizational structure of Division 1.
3. Material classes •
Carbon and low-alloy steel
•
Non-ferrous metals
•
High alloy steel
•
Cast iron
•
Clad and lined material
•
Ductile iron
•
Heat treated steels
•
Layered construction
•
Low-temperature material
4. Highlight several mandatory and nonmandatory appendices.
26
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Selection Factors • • • • •
Strength Corrosion Resistance Resistance to Hydrogen Attack Fracture Toughness Fabricability
15
Instructor’s Outline 1. ASME Code does not specify particular materials to use in each application. Owner must do this.
Major Learning Points Primary factors that influence pressure vessel material selection.
2. ASME Code specifies permitted materials and the requirements that these must meet.
27
Overview of Pressure Vessel Design Instructor’s Personal Notes
Strength • Determines required component thickness • Overall strength determined by: – Yield Strength – Ultimate Tensile Strength – Creep Strength – Rupture Strength
16
Instructor’s Outline 1. Strength: Material’s ability to withstand imposed loading.
Major Learning Points Material strength and pressure vessel design.
2. Higher strength material → thinner component. 3. Describe properties that are used to define strength.
28
Overview of Pressure Vessel Design Instructor’s Personal Notes
Corrosion Resistance • Deterioration of metal by chemical action • Most important factor to consider • Corrosion allowance supplies additional thickness • Alloying elements provide additional resistance to corrosion
17
Instructor’s Outline 1. Corrosion is thinning of metal. 2. Adding extra component thickness (i.e., corrosion allowance) is most common method to address corrosion.
Major Learning Points Importance of corrosion resistance in materials selection.
3. Alloy materials are used in services where corrosion allowance would be unreasonably high if carbon steel were used.
29
Overview of Pressure Vessel Design Instructor’s Personal Notes
Resistance to Hydrogen Attack • At 300 - 400°F, monatomic hydrogen forms molecular hydrogen in voids • Pressure buildup can cause steel to crack • Above 600°F, hydrogen attack causes irreparable damage through component thickness 18
Instructor’s Outline 1. Low-temperature H 2 attack can cause cracking.
Major Learning Points Hydrogen attack can damage carbon and low-alloy steel.
2. Higher temperature H 2 attack causes through-thickness strength loss and is irreversible. 3. H2 attack is a function of H 2 partial pressure and design temperature. •
Increased alloy content (i.e., Cr) increases H 2 attack resistance.
•
Reference API-941 for “Nelson Curves.”
30
Overview of Pressure Vessel Design Instructor’s Personal Notes Brittle Fracture and Fracture Toughness • Fracture toughness: Ability of material to withstand conditions that could cause brittle fracture • Brittle fracture – Typically at “low” temperature – Can occur below design pressure – No yielding before complete failure 19
Instructor’s Outline 1. Describe brittle fracture as equivalent to dropping a piece of glass.
Major Learning Points Brittle fracture and its consequences.
2. Material selection must ensure that brittle fracture will not occur.
31
Overview of Pressure Vessel Design Instructor’s Personal Notes Brittle Fracture and Fracture Toughness, cont’d • Conditions required for brittle fracture – High enough stress for crack initiation and growth – Low enough material fracture toughness at temperature – Critical size defect to act as stress concentration 20
Instructor’s Outline 1. A brittle fracture will occur the first time the appropriate conditions occur.
Major Learning Points Three conditions that are required for a brittle fracture to occur.
2. Brittle fracture occurs without warning and is catastrophic.
32
Overview of Pressure Vessel Design Instructor’s Personal Notes Factors That Influence Fracture Toughness • Fracture toughness varies with: - Temperature - Type and chemistry of steel - Manufacturing and fabrication processes
• Other factors that influence fracture toughness:
21
Instructor’s Outline 1. Describe influence of material and temperature factors on fracture toughness.
- Arc strikes, especially if over repaired area - Stress raisers or scratches in cold formed thick plate
Major Learning Points Primary factors that influence material fracture toughness.
2. Other factors increase brittle fracture risk.
33
Overview of Pressure Vessel Design Instructor’s Personal Notes
Charpy V-Notch Test Setup
Scale Starting Position Hammer
Pointer
h'
End of swing Specimen h' Anvil
22
Instructor’s Outline 1. Charpy V-Notch test is most widely used measure of material fracture toughness.
Major Learning Points Charpy V-Notch testing.
2. Describe test set-up.
34
Overview of Pressure Vessel Design Instructor’s Personal Notes ASME Code and Brittle Fracture Evaluation • Components to consider – Shells – Manways – Heads – Reinforcing pads – Backing strips that remain in place
– Nozzles – Tubesheets – Flanges – Flat cover plates – Attachments essential to structural integrity that are welded to pressure parts
23
Instructor’s Outline
Major Learning Points
1. ASME Code contains brittle fracture evaluation procedure.
Components to consider is ASME Code brittle fracture evaluation.
2. Review components to be included only items that relate to structural integrity of pressure-containing shell.
35
Overview of Pressure Vessel Design Instructor’s Personal Notes
Temperatures to Consider • Minimum Design Metal Temperature (MDMT) – Lowest temperature at which component has adequate fracture toughness
• Critical Exposure Temperature (CET) – Minimum temperature at which significant membrane stress will occur
24
Instructor’s Outline 1. Describe the distinction between MDMT and CET. •
MDMT is a material property.
•
CET is an environmental factor.
Major Learning Points Two temperatures to be considered in brittle fracture evaluation.
2. Important to understand this distinction.
36
Overview of Pressure Vessel Design Instructor’s Personal Notes Simplified ASME Evaluation Approach • Material specifications classified into Material Groups A through D • Impact test exemption curves – For each Material Group – Acceptable MDMT vs. thickness where impact testing not required
• If combination of Material Group and thickness not exempt, then must impact test at CET 25
Instructor’s Outline 1. Outline ASME procedure. 2. Details described in following overheads.
Major Learning Points Simplified ASME brittle fracture evaluation procedure.
37
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Groups MATERIAL GROUP Curve A
APPLICABLE MATERIALS • All carbon and low alloy steel plates, structural shapes, and bars not listed in Curves B, C & D • SA-216 Gr. WCB & WCC, SA-217 Gr. WC6, if normalized and tempered or water-quenched and tempered
Curve B
• SA-216 Gr. WCA, if normalized and tempered or water-quenched and tempered • SA-216 Gr. WCB & WCC for maximum thickness of 2 in., if produced to fine grain practice and water-quenched and tempered • SA-285 Gr. A & B • • • •
SA-414 Gr. A SA-515 Gr. 60 SA-516 Gr. 65 & 70, if not normalized Except for cast steels, all materials of Curve A if produced to fine grain practice and normalized which are not included in Curves C & D
• All pipe, fittings, forging, and tubing which are not included in Curves C & D
Table 3.1 (Excerpt) 26
Instructor’s Outline 1. Materials are grouped based on common fracture toughness properties.
Major Learning Points Material group classifications for brittle fracture evaluations.
2. Groups A through D move from worst to best fracture toughness. 3. Point out several common materials. •
SA-516 Gr. 65 and 70 are Curve B if not normalized.
•
Most pipe, fittings and forgings are Curve B.
38
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Groups, cont’d MATERIAL GROUP Curve C
Curve D
Bolting and Nuts
APPLICABLE MATERIALS • •
SA-182 Gr. 21 & 22, if normalized and tempered SA-302 Gr. C & D
•
SA-336 Gr. F21 & F22, if normalized and tempered
•
SA-387 Gr. 21 & 22, if normalized and tempered
• •
SA-516 Gr. 55 & 60, if not normalized SA-533 Gr. B & C
•
SA-662 Gr. A
•
All material of Curve B if produced to fine grain practice and normalized which are not included in Curve D
•
SA-203
•
SA-537 Cl. 1, 2 & 3
•
SA-508 Cl. 1
•
SA-612, if normalized
•
SA-516, if normalized
•
SA-662, if normalized
•
SA-524 Cl. 1 & 2
•
SA-738 Gr. A
•
See Figure UCS-66 of the ASME Code Section VIII, Div. 1, for impact test exemption temperatures for specified material specifications
Table 3.1 (Excerpt) 27
Instructor’s Outline 1. Identify other common materials. •
SA-516 Gr. 55 and 60 are Curve C if not normalized.
•
SA-516 (all grades) is Curve D if normalized.
Major Learning Points Material group classifications for brittle fracture evaluations.
2. Highlight points. •
Lower strength grades of same specification have better fracture toughness.
•
Normalization improves fracture toughness.
39
Overview of Pressure Vessel Design Instructor’s Personal Notes
Impact Test Exemption Curves for Carbon and Low-Alloy Steel 140 120
Minimum Design Metal Temperature, F
100 B
A
80 60
C 40 D
20 0 -20 -40 -55 -60
Impact testing required
-80 0.394
1
2
3
4
5
Nominal Thickness, in. (Limited to 4 in. for Welded Construction)
Figure 3.1 28
Instructor’s Outline 1. Describe relationship between Material Group, component thickness, and MDMT.
Major Learning Points Impact test exemption curves.
2. Impact testing not required if point is at or below curve (i.e., OK if MDMT ≤ CET). 3. Example: 1.5 in. thick Group B material does not require impact testing if CET ≥ 50°F. 4. If not exempt, must impact test material at CET. 5. “Exemption” means there is enough experience that material has adequate fracture toughness without need for further testing.
40
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional ASME Code Impact Test Requirements • Required for welded construction over 4 in. thick, or nonwelded construction over 6 in. thick, if MDMT < 120°F • Not required for flanges if temperature ≥ -20°F • Required if SMYS > 65 ksi unless specifically exempt
29
Instructor’s Outline 1. Review additional requirements.
Major Learning Points Additional impact test requirements.
2. Note that most flanges will not require impact testing.
41
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional ASME Code Impact Test Requirements, cont’d • Not required for impact tested low temperature steel specifications – May use at impact test temperature
• 30°F MDMT reduction if PWHT P-1 steel and not required by code • MDMT reduction if calculated stress < allowable stress 30
Instructor’s Outline 1. Review additional requirements.
Major Learning Points Additional impact test requirements.
2. PWHT reduces MDMT by 30°F provided PWHT not required by Code and resulting MDMT ≥ -55°F. 3. Can take MDMT credit if component thickness greater than needed (i.e., calculated stress < allowable stress).
42
Overview of Pressure Vessel Design Instructor’s Personal Notes
Fabricability • Ease of construction • Any required special fabrication practices • Material must be weldable
31
Instructor’s Outline Describe fabricability.
Major Learning Points Definition of fabricability.
43
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Stress • Stress: Force per unit area that resists loads induced by external forces • Pressure vessel components designed to keep stress within safe operational limits • Maximum allowable stress: – Includes safety margin – Varies with temperature and material
• ASME maximum allowable stress tables for permitted material specifications 32
Instructor’s Outline 1. Discuss the use of allowable stress in determining vessel component design.
Major Learning Points •
Description of allowable stress.
•
ASME Code allowable stress tables
2. Section II, Part D, Appendix I contains allowable stress criteria for materials other than bolting. 3. Section II, Part D contains allowable stress tables.
44
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Stress, cont’d ALLOWABLE STRESS IN TENSION FOR CARBON AND LOW-ALLOY STEEL Nominal P-No. Group No. Min. Yield Min. Tensile Composition (ksi) (ksi) Carbon Steel Plates and Sheets SA-515 55 C-Si 1 1 30 55 60 C-Si 1 1 32 60 65 C-Si 1 1 35 65 70 C-Si 1 2 38 70 Spec No.
SA-516
Grade
55 60 65 70
C-Si C-Mn-Si C-Mn-Si C-Mn-Si
Plate - Low Alloy Steels SA-387 2 Cl.1 1/2Cr-1/2Mo 2 Cl.2 1/2Cr-1/2Mo 12 Cl.1 1Cr-1/2Mo 12 Cl.2 1Cr-1/2Mo 11 Cl.1 1 1/4Cr-1/2Mo-Si 11 Cl.2 1 1/4Cr-1/2Mo-Si 22 Cl.1 2 1/4Cr-1Mo 22 Cl.2 2 1/4Cr-1Mo
1 1 1 1
1 1 1 2
30 32 35 38
55 60 65 70
3 3 4 4 4 4 5 5
1 2 1 1 1 1 1 1
33 45 33 40 35 45 30 45
55 70 55 65 60 75 60 75
ASME Maximum Allowable Stress (Table 1A Excerpt) Figure 3.2 33
Instructor’s Outline 1. Describe information contained in first section of table.
Major Learning Points ASME Code allowable stress tables.
2. Information is grouped by material chemistry and material form.
45
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Stress, cont’d ALLOWABLE STRESS IN TENSION FOR CARBON AND LOW ALLOY STEEL Max Allowable Stress, ksi (Multiply by 1,000 to Obtain psi) for Metal Temperature, °F, Not Exceeding 650
700
750
800
13.8 15.0 16.3 17.5
13.3 14.4 15.5 16.6
12.1 13.0 13.9 14.8
10.2 10.8 11.4 12.0
8.4 8.7 9.0 9.3
6.5 6.5 6.5 6.5
4.5 4.5 4.5 4.5
2.5 2.5 2.5 2.5
Spec No. 1050 1100 1150 1200 Carbon Steel Plates and Sheets ----SA-515 ----SA-515 ----SA-515 ----SA-515
13.8 15.0 16.3 17.5
13.3 14.4 15.5 16.6
12.1 13.0 13.9 14.8
10.2 10.8 11.4 12.0
8.4 8.7 9.0 9.3
6.5 6.5 6.5 6.5
4.5 4.5 4.5 4.5
2.5 2.5 2.5 2.5
-----
13.8 17.5 13.8 16.3 15.0 18.8 15.0 17.7
13.8 17.5 13.8 16.3 15.0 18.8 15.0 17.2
13.8 17.5 13.8 16.3 15.0 18.8 15.0 17.2
13.8 17.5 13.8 16.3 15.0 18.8 15.0 16.9
13.8 17.5 13.4 15.8 14.6 18.3 14.4 16.4
13.3 16.9 12.9 15.2 13.7 13.7 13.6 15.8
9.2 9.2 11.3 11.3 9.3 9.3 10.8 11.4
5.9 5.9 7.2 7.2 6.3 6.3 8.0 7.8
Plate-Low Alloy Steels (Cont'd) ----SA-387 ----SA-387 4.5 2.8 1.8 1.1 SA-387 4.5 2.8 1.8 1.1 SA-387 4.2 2.8 1.9 1.2 SA-387 4.2 2.8 1.9 1.2 SA-387 5.7 3.8 2.4 1.4 SA-387 5.1 3.2 2.0 1.2 SA-387
850
900
950
1000
-----
-----
-----
SA-516 SA-516 SA-516 SA-516
ASME Maximum Allowable Stress (Excerpt), cont'd Figure 3.2, cont'd 34
Instructor’s Outline 1. Review allowable stress vs. design temperature.
Major Learning Points ASME Code allowable stress tables.
2. Most ferritic materials have a constant allowable stress at temperatures through 650°F.
46
Overview of Pressure Vessel Design Instructor’s Personal Notes Material Selection Based on Fracture Toughness Exercise 1 • • • • • • • •
New horizontal vessel CET = - 2°F Shell and heads: SA-516 Gr. 70 Heads hemispherical: ½ in. thick Cylindrical shell: 1.0 in. thick No impact testing specified Is this correct? If not correct, what should be done?
35
Instructor’s Outline
Major Learning Points
1. This independent Exercise gives the Participants practice in material selection based on fracture toughness.
Participant Exercise 1 covering fracture toughness.
2. Review the given information together. 3. Allow approximately 10 minutes for the Participants to solve the problem. Then review the solution with them.
47
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 1 - Solution • Must assume SA-516 Gr. 70 not normalized. Therefore, Curve B material (Ref. Table 3.1). • Refer to Curve B in Figure 3.1. – ½ in. thick plate for heads: MDMT = -7°F – ½ in. thick plate exempt from impact testing since MDMT < CET
• 1 in. shell plate: MDMT = +31°F – Not exempt from impact testing
36
Instructor’s Outline 1. Review difference between normalized and non-normalized material with respect to fracture toughness.
Major Learning Points Solution to Participant Exercise.
2. Review MDMT determination in each case. 3. Note difference between MDMT and CET in each case.
48
Overview of Pressure Vessel Design Instructor’s Personal Notes Exercise 1 - Solution, cont’d • One approach to correct: Impact test 1 in. plate at -2°F. If es, material acceptable. • Another approach: Order 1 in. plate normalized – Table 3.1: normalized SA-516 is Curve D material – Figure 3.1: 1 in. thick Curve D, MDMT = -30°F – Normalized 1 in. thick plate exempt from impact testing
37
Instructor’s Outline 1. Review possible solutions for the 1 in. plate.
Major Learning Points Solution to Participant Exercise.
49
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 1 - Solution, cont’d • Choice of option based on cost, material availability, whether likely that 1 in. thick nonnormalized plate would impact testing
38
Instructor’s Outline 1. Review rationale for which option to select.
Major Learning Points Solution to Participant Exercise 1.
50
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design Conditions and Loadings • Determine vessel mechanical design • Design pressure and temperature, other loadings • Possibly multiple operating scenarios to consider • Consider startup, normal operation, anticipated deviations, shutdown 39
Instructor’s Outline 1. Review conditions to be considered. 2. Worst case operating scenario determines mechanical design.
Major Learning Points Design conditions and loadings to be considered in pressure vessel mechanical design.
51
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design Pressure PT = Design Pressure at Top of Vessel
γ = Weight Density of Liquid in Vessel
H = Height of Liquid
PBH = Design Pressure of Bottom Head
Figure 4.1 40
Instructor’s Outline 1. May have internal of external pressure, or both at different times.
Major Learning Points Design pressure as a mechanical design condition.
2. Must have margin between maximum operating pressure at top of vessel and design pressure. 3. Hydrostatic pressure of operating liquid (if present) must be considered at corresponding vessel elevation.
52
Overview of Pressure Vessel Design Instructor’s Personal Notes Temperature Zones in Tall Vessels Section 4 (T-Z)
Section 3 (T-Y)
Section 2 (T-X)
Section 1 (T) F Skirt Grade
Figure 4.2 41
Instructor’s Outline 1. Margin required between operating temperature and design temperature.
Major Learning Points Design temperature as a mechanical design condition.
2. Maximum design temperature needed to determine allowable stress and thermal expansion considerations. 3. CET needed for material selection considering brittle fracture. 4. There may be a wide temperature variation between the bottom and top of a tall tower.
53
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional Loadings • Weight of vessel and normal contents under operating or test conditions • Superimposed static reactions from weight of attached items (e.g., motors, machinery, other vessels, piping, linings, insulation) • Loads at attached internal components or vessel s • Wind, snow, seismic reactions 42
Instructor’s Outline 1. Highlight other loads that must be considered in the mechanical design.
Major Learning Points Loadings other than pressure and temperature must also be considered.
2. These other loads may govern the mechanical design in local areas.
54
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional Loadings, cont’d • Cyclic and dynamic reactions caused by pressure or thermal variations, equipment mounted on vessel, and mechanical loadings • Test pressure combined with hydrostatic weight • Impact reactions (e.g., from fluid shock) • Temperature gradients within vessel component and differential thermal expansion between vessel components 43
Instructor’s Outline 1. Review these additional other loads.
Major Learning Points Additional other loadings to consider.
55
Overview of Pressure Vessel Design Instructor’s Personal Notes
Weld t Categories C
C
C A
A A D
B
D B
A
C
B
C
D
A
D
B
B
D
A C
Figure 4.3 44
Instructor’s Outline 1. Review the ASME Code Weld t Categories.
Major Learning Points ASME Code defines welded ts by category.
2. Only specific weld types may be used in each category.
56
Overview of Pressure Vessel Design Instructor’s Personal Notes
Weld Types Butttsasattainedbydouble-weldingorbyother means which will obtain the same quality of deposited weld metal on the inside and outside weld surface.
1
Backing strip, if used, shall be removed after completionofweld. Single-welded butt t with backing strip which remainsinplaceafterwelding.
2
For circumferential t only
3
Single-welded butt t without backing strip.
4
Double-fullfilletlapt.
5
Single-full fillet lap t with plug welds.
6
Single-full fillet lap t without plug welds.
Figure 4.4 45
Instructor’s Outline 1. Review the different weld types. 2. Limited applications for Types 3 through 6.
Major Learning Points ASME Code defines specific weld types that may be used.
57
Overview of Pressure Vessel Design Instructor’s Personal Notes Weld t Efficiencies t Type
Acceptable t Categories
Degree of Radiographic Examination Full
Spot
None
1
A, B, C, D
1.00
0.85
0.70
2
A, B, C, D (See ASME Code for limitations)
0.90
0.80
0.65
3
A, B, C
NA
NA
0.60
4
A, B, C (See ASME Code for limitations)
NA
NA
0.55
5
B, C (See ASME Code for limitations)
NA
NA
0.50
6
A, B, (See ASME Code for limitations)
NA
NA
0.45
Figure 4.5 46
Instructor’s Outline 1. Weld t efficiency, E, is a measure of weld quality and s for stress concentrations.
Major Learning Points Weld t efficiency vs. t Type, Category, Radiographic Examination.
2. E is needed in component thickness calculations. 3. Review information in table. 4. Note that corrosion allowance was previously discussed.
58
Overview of Pressure Vessel Design Instructor’s Personal Notes
Summary Of ASME Code Equations Part
Thickness, tp , in.
Cylindrical shell
Pr SE1 − 0.6P
SE 1t r + 0.6t
P(r + 0.6t) tE1
Spherical shell
Pr 2SE1 − 0.2P
2SEt r + 0.2t
P(r + 0.2t ) 2tE
PD 2SE − 0.2P
2SEt D + 0.2t
P(D + 0.2t ) 2tE
0.885PL SE − 0.1P
SEt 0.885L + 0.1t
P (0.885L + 0.1t ) tE
PD 2 cos α (SE − 0.6P)
2SEt cos α D + 1.2t cos α
P(D + 1.2t cos α) 2tE cos α
2:1 Semi - Elliptical head Torispherical head with 6% knuckle Conical Section ( α = 30°)
Pressure, P, psi
Stress, S, psi
Figure 4.6 47
Instructor’s Outline 1. Circumferential stress governs minimum required component thickness in most cases.
Major Learning Points ASME Code equations for various components under internal pressure.
2. Longitudinal stress may govern local thickness in some cases (e.g., under wind or earthquake loads). 3. Review ASME Code equations for internal pressure design. •
May calculate required thickness, permitted pressure, component stress.
•
Must for corrosion allowance.
59
Overview of Pressure Vessel Design Instructor’s Personal Notes Typical Formed Closure Heads t
t R sf sf ID
ID
Flanged
Hemispherical t t
h sf
h
Elliptical
α
sf Flanged and Dished (torispherical)
α
t
t
sf r ID Toriconical
ID Conical
48
Instructor’s Outline 1. Review the different head types. 2. The 2:l semi-elliptical head is the most common.
Figure 4.7
Major Learning Points Different types of closure heads may be used.
60
Overview of Pressure Vessel Design Instructor’s Personal Notes
Hemispherical Head to Shell Transition th
l ≥ 3y
Thinner Part
Thinner Part
th
l ≥ 3y Tangent Line
y
Length of required taper, l, may include the width of the weld ts
y
ts
Figure 4.8 49
Instructor’s Outline
Major Learning Points
1. Required thickness of a hemispherical head is about half that of the connected cylindrical shell.
Thickness transition at a hemispherical head.
2. Must have a tapered thickness transition in the head to end up matching the shell thickness.
61
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Hemispherical
4' - 0" 60' - 0"
DESIGN INFORMATION Design Pressure = 250 psig Design Temperature = 700° F Shell and Head Material is SA-515 Gr. 60 Corrosion Allowance = 0.125" Both Heads are Seamless Shell and Cone Welds are Double Welded and will be Spot Radiographed The Vessel is in All Vapor Service Cylinder Dimensions Shown are Inside Diameters
10' - 0"
6' - 0" 30' - 0"
2:1 Semi-Elliptical
Figure 4.9 50
Instructor’s Outline 1. Sample Problem 1 illustrates calculation of required shell and head thicknesses for internal pressure.
Major Learning Points Sample Problem to illustrate calculation of required thickness for internal pressure.
2. Review the given information. 3. Review the problem solution with the Participants.
62
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 1 - Solution • Required thickness for internal pressure of cylindrical shell (Figure 4.6):
tp =
Pr SE1 − 0. 6P
• Welds spot radiographed, E = 0.85 (Figure 4.5) • S = 14,400 psi for SA- 515/Gr. 60 at 700°F (Figure 3.2) • P = 250 psig 51
Instructor’s Outline 1. Review the relevant equation for a cylindrical shell.
Major Learning Points Sample Problem 1 solution.
2. Note the sources used for the various parameters.
63
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Solution, cont’d • For 6 ft. - 0 in. shell r = 0.5D + C = 0.5 × 72 + 0.125 = 36.125 in. Pr 250 × 36.125 tp = = S E1 − 0.6P 14,400 × 0.85 − 0.6 × 250 = 0.747 in. t = tp + c = 0.747 + 0.125 t = 0.872 in., including corrosion allowance 52
Instructor’s Outline 1. The corrosion allowance must be added to obtain the inside radius.
Major Learning Points Sample Problem 1 solution.
2. The corrosion allowance must be added to the calculated thickness.
64
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 1 Solution, cont’d • For 4 ft. - 0 in. shell r = 0.5 × 48 + 0.125 = 24.125 in. tp =
250 × 24.125 14,400 × 0. 85 − 0. 6 × 250
= 0.499 in.
t = 0.499 + 0.125 t = 0.624 in., including corrosion allowance 53
Instructor’s Outline 1. The calculation is repeated for the other cylindrical shell section.
Major Learning Points Sample Problem 1 solution.
65
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Solution, cont’d Both heads are seamless, E = 1.0. Top Head - Hemispherical (Figure 4.6) r = 24 + 0.125 = 24.125 in.
tp =
Pr 250 × 24.125 = 0.21 in. = 2SE1 − 0.2P 2 × 14,400 × 1 − 0.2 × 250 t = tp + c = 0.21 + 0.125 t = 0.335 in., including corrosion allowance
54
Instructor’s Outline 1. Review the relevant equation for a hemispherical head.
Major Learning Points Sample Problem 1 solution.
2. Note the sources for the relevant parameters and how corrosion allowance is ed for.
66
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 1 Solution, cont’d • Bottom Head - 2:1 Semi-Elliptical (Figure 4.6) D = 72 + 2 × 0.125 = 72.25 in.
tp =
PD 250 × 72 .25 = = 0.628 in. 2SE − 0.2P 2 × 14,400 × 1 − 0.2 × 250 t = 0.628 + 0.125 t = 0.753 in., including corrosion allowance
55
Instructor’s Outline 1. Review the relevant equation for a semi-elliptical head.
Major Learning Points Sample Problem 1 solution.
2. Note the sources for the relevant parameters and how corrosion allowance is ed for.
67
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design For External Pressure and Compressive Stresses • Compressive forces caused by dead weight, wind, earthquake, internal vacuum • Can cause elastic instability (buckling) • Vessel must have adequate stiffness – Extra thickness – Circumferential stiffening rings
56
Instructor’s Outline
Major Learning Points
1. Buckling of a shell under external pressure or compressive forces is analogous to column buckling under a compressive force.
Different procedures are used to design for external pressure or compressive loads.
2. Addition of stiffener rings reduces effective buckling length.
68
Overview of Pressure Vessel Design Instructor’s Personal Notes
Design For External Pressure and Compressive Stresses, cont’d • ASME procedures for cylindrical shells, heads, conical sections. Function of: – Material – Diameter – Unstiffened length
– Temperature – Thickness
57
Instructor’s Outline 1. Highlight the main parameters that affect buckling strength.
Major Learning Points Parameters that affect compressive strength.
2. ASME Code has design procedure for each type of shell or head.
69
Overview of Pressure Vessel Design Instructor’s Personal Notes
Stiffener Rings Moment Axis of Ring h/3
L
L
L
L
L
L
L
L
L
L
h/3 h = Depth of Head
Figure 4.10 58
Instructor’s Outline 1. Stiffener rings reduce the buckling length of a shell and may be either inside or outside.
Major Learning Points Use and location of stiffener rings.
2. Stiffener rings are not used for heads.
70
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 DESIGN INFORMATION Design Pressure = Full Vacuum Design Temperature = 500° F Shell and Head Material is SA-285 Gr. B, Yield Stress = 27 ksi Corrosion Allowance = 0.0625" Cylinder Dimension Shown is Inside Diameter
4' - 0"
150' - 0"
2:1 Semi-Elliptical (Typical)
Figure 4.11 59
Instructor’s Outline
Major Learning Points
1. Sample Problem 2 illustrates procedure for calculation of required cylindrical shell thickness for external pressure.
Sample Problem to illustrate calculation of required cylindrical shell thickness for external pressure.
2. The problem does not cover all aspects of the general procedure since it is geometry-specific. 3. Review the given information. 4. Review the problem solution with the participants.
71
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 - Solution • Calculate L and Do of cylindrical shell. L = Tangent Length + 2 × 1/3 (Head Depth) L = 150 × 12 + 2/3 × (48/4) = 1,808 in. Do = 48 + 2 × 7/16 = 48.875 in. • Determine L/Do and Do/t for corrosion allowance: t = 7/16 – 1/16 = 6/16 = 0.375 in. Do/t = 48.875 / 0.375 = 130 L/Do = 1808 / 48.875 = 37 60
Instructor’s Outline 1. Corroded shell diameter and thickness are used in the calculations.
Major Learning Points Sample Problem 2 solution.
2. The unstiffened length of the shell must include part of the head depth.
72
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d • Determine A. • Use Figure 4.12, Do /t, and L/Do. Note:
If L/Do > 50, use L/Do = 50. For L/Do < 0.05, use L/Do = 0.05
61
Instructor’s Outline 1. Factor A is determined based only on geometry.
Major Learning Points Sample Problem 2 solution.
2. Note the source of Factor A.
73
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d
4 5 6 789
Do/t = 100 D o/t = 125 D o/t = 150 D /t = 200
2 1.6 1.4
2.0 1.8
2.5
3.5 3.0
6.0
4.0
7.0
5.0
8.0
10.0 9.0
14.0
20.0 18.0
16.0
25.0
30.0
35.0
40.0
50.0
12.0
0 00 ,00 00 00 800 = 4 t=5 t = 6 =1 /t / / /t = /t Do Do Do Do Do
D o/t = 300
.00001
3
o
D o/t = 250
1.2
Do /t = 130
.0001
A = 0.000065
Length + Outside Diameter = L/Do
L/Do = 37
Factor A Figure 4.12 62
Instructor’s Outline 1. Note how Factor A is determined from these curves.
Major Learning Points Sample Problem 2 solution.
2. After determine Factor A, go to applicable material chart.
74
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d up to 300°F 500°F
14,000
700°F
12,000
800°F
10,000
900°F
9,000 8,000 7,000
E=29.0 x 106
6,000
E=27.0 x 106
5,000
E=24.5 x 106 E=22.8 x 106
4,000
E=20.8 x 106
3,500 3,000 2,500 2,000
2 .00001
3 4 5 6 789 .0001
A=0.000065
63
Instructor’s Outline 1. Different material charts are used for different material types. This is chart used for most carbon and lowalloy steels.
2
3
4 5 6 789
2
3 4 5 6789
.001
2
3
4 5 6 789
.01
.1
FACTOR A
Factor B Figure 4.13
Major Learning Points Sample Problem 2 solution.
2. If A is under curves: •
Move up to intersect with temperature line.
•
Move right to get B.
•
B is then used to calculate allowable external pressure.
3. Since A is to left of curves in our case, must use alternate procedure.
75
FACTOR B
20,000 18,000 16,000
GENERAL NOTE: See Table CS-1 for tabular values
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d • Calculate maximum allowable external pressure
Pa =
2AE 3(Do / t )
Where: E = Young's modulus of elasticity E = 27 × 106 psi (Figure 4.13) at T = 500°F P a = 9 psi 64
Instructor’s Outline 1. Pa is calculated using indicated equation because A is not under curves.
Major Learning Points Sample Problem 2 solution.
2. Must use E from curves at design temperature.
76
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 2 Solution, cont’d Since Pa < 15 psi, 7/16 in. thickness not sufficient • Assume new thickness = 9/16 in., corroded thickness L = 1/2 in.
Do 48. 875 = = 97.75 t 0. 5
A = 0.000114
Pa =
L = 3 7 (as before) Do
2 × 0.000114 × 27 × 10 6 = 15. 7 psi 3 × 130. 33
65
Instructor’s Outline 1. Since P a < 15 psi, must either increase shell thickness or add stiffeners to decrease L.
Major Learning Points Sample Problem 2 solution.
2. Problem illustrates results if increase thickness. 3. Choice of whether to increase thickness or add stiffeners depends on cost.
77
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 2 - Required Thickness for Internal Pressure • • • • • • • •
Inside Diameter - 10’ - 6” Design Pressure - 650 psig Design Temperature - 750°F Shell & Head Material - SA-516 Gr. 70 Corrosion Allowance - 0.125 in. 2:1 Semi-Elliptical heads, seamless 100% radiography Vessel in vapor service
66
Instructor’s Outline
Major Learning Points
1. This independent Exercise gives the Participants practice in determining required vessel thicknesses for internal pressure.
Participant Exercise 2 covering required thickness for internal pressure.
2. Review the given information together. 3. Allow approximately 15 minutes for the Participants to solve the problem. Then review the solution with them. 4. Note that this Exercise may be skipped and assigned as homework if available class time is an issue.
78
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 2 - Solution • For shell
tp =
Pr SE 1 − 0 .6P
P = 650 psig r = 0.5 × D + CA = (0.5 × 126) + 0.125 = 63.125 in. • S = 16,600 psi, Figure 3.3 for SA-516 Gr. 70 • E = 1.0, Figure 4.8 for 100% radiography
tp =
650 × 63. 125 = 2. 53 in. (16,600 ×1 .0 ) − (0 .6 × 650)
67
Instructor’s Outline 1. Note the relevant equation for the cylindrical shell and the appropriate parameters.
Major Learning Points Exercise 2 solution.
2. Note how corrosion allowance is ed for.
79
Overview of Pressure Vessel Design Instructor’s Personal Notes
Exercise 2 - Solution, cont’d Add corrosion allowance tp = 2.53 + 0.125 = 2.655 in. • For the heads tp =
PD 2 SE − 0. 2P
tp =
650 (126 × 0 . 9) + 0 . 250 = 2 . 23 in. (2 × 16, 600) − (0 . 2 × 650 )
Add corrosion allowance 68
Instructor’s Outline 1. Note the relevant equation for the heads and the appropriate parameters.
tp = 2.23 + 0.125 = 2.355 in.
Major Learning Points Exercise 2 solution.
2. Note how corrosion allowance is ed for.
80
Overview of Pressure Vessel Design Instructor’s Personal Notes
Reinforcement of Openings • Simplified ASME rules - Area replacement • Metal used to replace that removed: -
Must be equivalent in metal area Must be adjacent to opening
69
Instructor’s Outline 1. Simplified ASME rules do not require stress calculations. Use “area replacement” approach.
Major Learning Points Openings must be reinforced to for metal removed.
2. Metal removed must be replaced by equivalent metal.
81
Overview of Pressure Vessel Design Instructor’s Personal Notes
Cross Sectional View of Nozzle Opening Dp tn
te
2.5t or 2.5t n + te Use smaller value
t
2.5t or 2.5t n Use smaller value
Rn
t rn
tr
c
h
d
d or R n + tn + t
d or R n + tn + t
Use larger value
Use larger value
For nozzle wall inserted through the vessel wall
For nozzle wall abutting the vessel wall
Figure 4.14 70
Instructor’s Outline 1. Review cross-sectional view of region and associated nomenclature. 2. Note the different areas involved in the calculations and the “reinforcement zone” in the nozzle and shell.
Major Learning Points Region near opening and nomenclature.
82
Overview of Pressure Vessel Design Instructor’s Personal Notes
Nozzle Design Configurations (a) Full Penetration Weld With Integral Reinforcement
(a-1)
(a-2)
(a-3)
Separate Reinforcement Plates Added
(b)
(c)
(d)
(e)
Full Penetration Welds to Which Separate Reinforcement Plates May be Added
(f-1)
(f-3)
(f-2) (f-4)
(g)
Self - Reinforced Nozzles
71
Instructor’s Outline 1. Note the different nozzle design details that may be used.
Figure 4.15
Major Learning Points Typical nozzle configurations.
2. The actual detail used in each case depends on the design conditions and the needed reinforcement.
83
Overview of Pressure Vessel Design Instructor’s Personal Notes
Additional Reinforcement • Necessary if insufficient excess thickness • Must be located within reinforcement zone • Allowable stress of reinforcement pad should be ≥ that of shell or head • Additional reinforcement sources – Pad – Additional thickness in shell or lower part of nozzle 72
Instructor’s Outline 1. The method used to provide additional reinforcement depends on the particular situation.
Major Learning Points Requirements for additional reinforcement.
2. The ASME Code specifies circumstances where nozzle reinforcement evaluation is not needed. The opening is considered to be “inherently” reinforced in these cases.
84
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 DESIGN INFORMATION Design Pressure = 300 psig Design Temperature = 200° F Shell Material is SA-516 Gr. 60 Nozzle Material is SA-53 Gr. B, Seamless Corrosion Allowance = 0.0625" Vessel is 100% Radiographed Nozzle does not through Vessel Weld Seam
NPS 8 Nozzle (8.625" OD) 0.5" Thick
0.5625" Thick Shell, 48" Inside Diameter
Figure 4.16 73
Instructor’s Outline 1. Sample Problem 3 illustrates evaluation of an opening for adequate reinforcement.
Major Learning Points Sample Problem to illustrate evaluation of nozzle reinforcement.
2. Review the given information. 3. Review the problem solution with the Participants.
85
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 3 - Solution • Calculate required reinforcement area, A A = dtrF Where: d = Finished diameter of circular opening, or finished dimension of nonradial opening in plane under consideration, in. tr = Minimum required thickness of shell using E = 1.0, in. F = Correction factor, normally 1.0 74
Instructor’s Outline 1. Required replacement area is based on the cross-sectional area removed.
Major Learning Points Sample Problem 3 solution.
2. Calculated using the required shell thickness, not the actual.
86
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate diameter, d. d = Diameter of Opening – 2 (Thickness + Corrosion Allowance) d = 8.625 – 1.0 + .125 = 7.750 in. • Calculate required shell thickness, t r (Figure 4.6) tr = 0.487 in. • Assume F = 1.0 75
Instructor’s Outline 1. Corrosion allowance is ed for.
Major Learning Points Sample Problem 3 solution.
2. tr is calculated using the appropriate shell equation.
87
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate A A = dtr F A = (8.625 - 1.0 + 0.125) × 0.487 × 1 = 3.775 in.2 • Calculate available reinforcement area in vessel shell, A 1, as larger of A 11 or A1 2 A1 1 = (E lt - Ftr)d 76
Instructor’s Outline 1. Required area is calculated using the previously calculated parameters.
A1 2 = 2 (Elt-Ftr)(t + tn)
Major Learning Points Sample Problem 3 solution.
2. Two equations must be checked to determine the reinforcement area available in the shell.
88
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d Where: E l = 1.0 when opening is in base plate away from welds, or when opening es through circumferential t in shell (excluding head to shell ts). E l = ASME Code t efficiency when any part of opening es through any other welded t. F = 1 for all cases except integrally reinforced nozzles inserted into a shell or cone at angle to vessel longitudinal axis. See Fig. UG-37 for this special case. tn = Nominal thickness of nozzle in corroded condition, in. 77
Instructor’s Outline Review the relevant parameters.
Major Learning Points Sample Problem 3 solution.
89
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d A 11 = (Elt - Ftr)d = (0.5625 - 0.0625 - 0.487) × 7.75 = 0.1 in.2 A 12 = 2 (Elt - Ftr ) (t + t n) = 2(0.5625-0.0625-0.487) × (0.5625-0.0625+0.5 -0.0625) = 0.0243 in. 2 Therefore, A1 = 0.1 in.2 available reinforcement in shell 78
Instructor’s Outline Available shell reinforcement area is determined.
Major Learning Points Sample Problem 3 solution.
90
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 3 Solution, cont’d • Calculate reinforcement area available in nozzle wall, A2, as smaller of A21 or A22. A21 = (tn-tr n) 5t A22 = 2 (t n-tr n) (2.5 tn + t e)
79
Instructor’s Outline Available reinforcement area in the nozzle is determined by checking two equations.
Major Learning Points Sample Problem 3 solution.
91
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d Where: trn =
Required thickness of nozzle wall, in.
r =
Radius of nozzle, in.
te =
0 if no reinforcing pad.
te =
Reinforcing pad thickness if one installed, in.
te =
Defined in Figure UG-40 for self-reinforced nozzles, in.
80
Instructor’s Outline Review the relevant parameters.
Major Learning Points Sample Problem 3 solution.
92
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate required nozzle thickness, trn (Figure 4.6)
t rn =
t rn =
Pr SE1 − 0. 6P
300 (3. 8125 + 0. 0625) = 0. 0784 in. 15,000 × 1 − 0. 6 × 300
81
Instructor’s Outline Calculate required thickness using the equation for a cylinder.
Major Learning Points Sample Problem 3 solution.
93
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate A2. A21 = (tn - trn)5t = (0.5 - 0.0625 - 0.0784) × 5 (0.5625 - 0.0625) = 0.898 in.2 A22 = 2 (tn - t rn) (2.5 tn + te) = 2 (0.5 - 0.0625 - 0.0784) [2.5 × (0.5 - 0625) + 0] = 0.786 in.2 Therefore, A2 = 0.786 in.2 available reinforcement in nozzle. 82
Instructor’s Outline 1. The available reinforcement in the nozzle is determined.
Major Learning Points Sample Problem 3 solution.
2. Note that in this case, the nozzle has much more excess metal available than the shell.
94
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Determine total available reinforcement area, A T; compare to required area. AT = A1 + A2 = 0.1 + 0.786 = 0.886 in.2 AT < A, nozzle not adequately reinforced, reinforcement pad required. • Determine reinforcement pad diameter, Dp. A5 = A - AT A5 = (3.775 - 0.886) = 2.889 in.2 83
Instructor’s Outline 1. The nozzle is not adequately reinforced because it does not have enough reinforcement available.
Major Learning Points Sample Problem 3 solution.
2. The problem now proceeds to determine the required dimensions of a reinforcement pad. Note, however, that the additional reinforcement could also be added by using a thicker nozzle or by using a thicker shell section near the nozzle.
95
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 3 Solution, cont’d • Calculate Dp te = 0.5625 in. (reinforcement pad thickness) A 5 = [Dp - (d + 2 t n)] te 2.889 = [Dp - (7.75 + 2(0.5 - 0.0625)] 0.5625 Dp = 13.761 in. • Confirm Dp within shell reinforcement zone, 2d 2d = 2 × 7.75 = 15.5 in. 84
Instructor’s Outline 1. The reinforcement pad thickness was assumed to be equal to the shell thickness. This is common practice.
Therefore, Dp = 13.761 in. acceptable
Major Learning Points Sample Problem 3 solution.
2. A final check is made to ensure that the reinforcement pad is within the reinforcement zone.
96
Overview of Pressure Vessel Design Instructor’s Personal Notes Flange Rating • Based on ASME B16.5 • Identifies acceptable pressure/temperature combinations • Seven classes (150, 300, 400, 600, 900, 1,500, 2,500) • Flange strength increases with class number • Material and design temperature combinations without pressure indicated not acceptable 85
Instructor’s Outline 1. ASME B16.5 provides standard flange dimensional details. 2. Flange strength is based on dimensions and material used.
Major Learning Points The flange rating establishes acceptable temperature/pressure combinations and is based on ASME B16.5
97
Overview of Pressure Vessel Design Instructor’s Personal Notes
Material Specification List Material Groups Material Group Number
Nominal Designation Steel
1.1
Carbon
1.2
C-Mn-Si Carbon 2 ½ Ni 3 ½ Ni
Product Forms Forgings
Castings
Plates
Spec. No.
Grade
Spec. No.
Grade
Spec. No.
Grade
A105 A350 ----A350
-LF2 ----LF3
A216 --A216 A352 A352 A352
WCB --WCC LCC LC2 LC3
A515 A516 A537 --A203 A203
70 70 Cl.1 --B E
ASME B16.5, Table 1a, Material Specification List (Excerpt)
Figure 4.17 86
Instructor’s Outline 1. Acceptable flange materials are grouped based on similarities in strength.
Major Learning Points Flange Material Group Number is based on material specification and product form.
2. The Material Group is determined based on the specified material.
98
Overview of Pressure Vessel Design Instructor’s Personal Notes Pressure - Temperature Ratings Material Group No. Classes Temp., °F -20 to 100 200 300 400 500 600 650 700 750 800 850 900 950 1000
1.1
1.2
1.3
150
300
400
150
300
400
150
300
400
285 260 230 200 170 140 125 110 95 80 65 50 35 20
740 675 655 635 600 550 535 535 505 410 270 170 105 50
990 900 875 845 800 730 715 710 670 550 355 230 140 70
290 260 230 200 170 140 125 110 95 80 65 50 35 20
750 750 730 705 665 605 590 570 505 410 270 170 105 50
1000 1000 970 940 885 805 785 755 670 550 355 230 140 70
265 250 230 200 170 140 125 110 95 80 65 50 35 20
695 655 640 620 585 534 525 520 475 390 270 170 105 50
925 875 850 825 775 710 695 690 630 520 355 230 140 70
Figure 4.18 87
Instructor’s Outline 1. This table combines information for three Material Groups for illustrative purposes.
Major Learning Points Pressure/temperature rating is a function of Material Group and design temperature.
2. Review the information in this table and how it is used to determine the appropriate flange rating.
99
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 4 Determine Required Flange Rating Pressure Vessel Data: Shell and Heads:
SA-516 Gr.70
Flanges:
SA-105
Design Temperature: 700°F Design Pressure:
275 psig
88
Instructor’s Outline 1. Sample Problem 4 illustrates how to determine flange rating.
Major Learning Points Sample Problem to illustrate determining flange rating.
2. Review the given information. 3. Review the problem solution with the Participants.
100
Overview of Pressure Vessel Design Instructor’s Personal Notes Sample Problem 4 - Solution • Identify flange material specification SA-105 • From Figure 4.17, determine Material Group No. Group 1.1 • From Figure 4.18 with design temperature and Material Group No. determined in Step 3 – Intersection of design temperature with Material Group No. is maximum allowable design pressure for the flange Class 89
Instructor’s Outline Review the problem solution.
Major Learning Points Sample Problem 4 solution.
101
Overview of Pressure Vessel Design Instructor’s Personal Notes
Sample Problem 4 Solution, cont’d – Table 2 of ASME B16.5, design information for all flange Classes – Select lowest Class whose maximum allowable design pressure ≥ required design pressure.
• At 700°F, Material Group 1.1: Lowest Class that will accommodate 275 psig is Class 300. • At 700°F, Class 300 flange of Material Group 1.1: Maximum design pressure = 535 psig. 90
Instructor’s Outline 1. Use the lowest flange class that is suitable for the design conditions. Flange cost increases as the class increases.
Major Learning Points Sample Problem 4 solution.
2. A given flange class is good for a range of temperature/pressure combinations for a particular Material Group.
102
Overview of Pressure Vessel Design Instructor’s Personal Notes
Flange Design • Bolting requirements – During normal operation (based on design conditions) – During initial flange boltup (based on stress necessary to seat gasket and form tight seal Am =
W S
91
Instructor’s Outline 1. Division 1 Appendix 2 procedure for custom-designed flanges.
Major Learning Points ASME procedure must be used for custom-designed flanges.
2. Used if flange size not covered by ASME B16.5 or ASME B16.47. 3. Typical application is girth flange for shell-and-tube heat exchanger.
103
Overview of Pressure Vessel Design Instructor’s Personal Notes
Flange Loads and Moment Arms Flange Ring
Gasket h
t A
hG
W
hT
hD
C
g1
HT G
HG
HD
B
g0 Flange Hub
Figure 4.19 92
Instructor’s Outline 1. Applied loads act at different flange locations.
Major Learning Points Various flange loads are applied on corresponding moment arms.
2. Flange moments are calculated for the operating and gasket seating cases.
104
Overview of Pressure Vessel Design Instructor’s Personal Notes
Stresses in Flange Ring and Hub • Calculated using: – Stress factors (from ASME code) – Applied moments – Flange geometry • Calculated for: – Operating case – Gasket seating case 93
Instructor’s Outline 1. Various stresses are calculated for each case and must be kept within allowable limits. 2. Flange dimensions are adjusted as needed to meet allowable stresses (e.g., increase thickness, change hub dimensions, etc.).
Major Learning Points •
Flange stresses are calculated and compared to allowable values.
•
Both operating and gasket seating cases must be checked.
3. Equipment suppliers use computer programs to “optimize” flange design to be least weight (i.e., lowest cost).
105
Overview of Pressure Vessel Design Instructor’s Personal Notes
Flange Design and In-Service Performance Factors affecting design and performance • ASME Code m and y parameters. • Specified gasket widths. • Flange facing and nubbin width, w • Bolt size, number, spacing
94
Instructor’s Outline
Major Learning Points
1. Flange is designed for specific gasket type, dimensions, and facing details. Changing any of these after flange is fabricated (e.g., gasket type) can adversely affect in-service performance.
Various parameters affect flange design and performance.
2. TEMA specifies minimum gasket width and bolt spacing criteria.
106
Overview of Pressure Vessel Design Instructor’s Personal Notes
ASME Code m and y Factors Gasket Factor, m
Min. Design Seating Stress y, psi
Flat metal, jacketed asbestos filled: Soft aluminum Soft copper or brass Iron or soft steel Monel 4-6% chrome Stainless steels and nickel-base alloys
3.25 3.50 3.75 3.50 3.75 3.75
5,500 6,500 7,600 8,000 9,000 9,000
(1a), (1b), (1c), (1d); (2); Column II
Solid flat metal: Soft aluminum Soft copper or brass Iron or soft steel Monel or 4-6% chrome Stainless steels and nickel-base alloys
4.00 4.75 5.50 6.00 6.50
8,800 13,000 18,000 21,800 26,000
(1a), (1b), (1c), (1d); (2), (3), (4), (5); Column I
Gasket Type and Material
Facing Sketch and Column in ASME Table 2-5.2 (Figure 4.21)
Figure 4.20 95
Instructor’s Outline
Major Learning Points
1. This is an excerpt from Table 2-5.1.
•
2. Review the variation in m and y with gasket type.
Gasket m and y factors are based on gasket type.
•
Gasket type also affects gasket width used in calculations.
107
Overview of Pressure Vessel Design Instructor’s Personal Notes
ASME Code Gasket Widths Basic Gasket Seating Width bo
Facing Sketch (Exaggerated)
N
(1a)
Column I
Column II
N 2
N 2
N
N
N
(1b) w
T N
(1c) w
(1d)
w ≤N
w + T ; w + N max 2 4
T N
w+ T w+ N ; max 2 4
w ≤N HG
HG
G O.D. Face
hG b
G
hG Gasket C L Face
For b o > ¼ in.
For b o< ¼in.
ASME Code Gasket Widths (Table 2-5.2 excerpt)
Figure 4.21 96
Instructor’s Outline 1. This is an excerpt from Table 2-5.2. 2. Review the flange facings shown.
Major Learning Points The gasket width used in the calculations depends on the type of flange facing.
108
Overview of Pressure Vessel Design Instructor’s Personal Notes
Gasket Materials and Facings Gasket Materials and Facings Gasket Factors m for Operating Conditions and Minimum Design Seating Stress y Gasket Material
Gasket Factor m
Min. Design Seating Stress y, psi
Flat metal, jacketed asbestos filled: Soft aluminum Soft copper or brass Iron or soft steel Monel 4% - 6% chrome Stainless steels and nickel-base alloys
3.25 3.50 3.75 3.50 3.75 3.75
5500 6500 7600 8000 9000 9000
Sketches
Facing Sketch and Column in Table 2-5.2 (1a), (1b), (1c),2, (1d) 2, (2)2, Column II
Figure 4.22 97
Instructor’s Outline Review the additional gasket information shown.
Major Learning Points Information on additional gasket types.
109
Overview of Pressure Vessel Design Instructor’s Personal Notes
Maximum Allowable Working Pressure (MAWP) Maximum permitted gauge pressure at top of vessel in operating position for designated temperature • MAWP ≥ Design Pressure • Designated Temperature = Design Temperature • Vessel MAWP based on weakest component
98
Instructor’s Outline 1. Emphasize that MAWP is based on the as-supplied component thicknesses.
– Originally based on new thickness less corrosion allowance – Later based on actual thickness less future corrosion allowance needed
Major Learning Points MAWP is defined.
2. Thicknesses used exclude corrosion allowance and thickness added to absorb other loads. 3. MAWP is useful to know for potential future rerate.
110
Overview of Pressure Vessel Design Instructor’s Personal Notes
Local Loads • Piping system • Platforms, internals, attached equipment • attachment
99
Instructor’s Outline 1. Review the typical external loads that may be applied.
Major Learning Points Externally applied loads must also be considered in vessel design.
2. External loads cause local stresses that must be evaluated. 3. Other industry standards must be used to evaluate local stresses (e.g., WRC 107 and 297).
111
Overview of Pressure Vessel Design Instructor’s Personal Notes
Types of Vessel Internals • Trays • Inlet Distributor • Anti-vortex baffle • Catalyst bed grid and beams • Outlet collector • Flow distribution grid • Cyclone and plenum chamber system 100
Instructor’s Outline
Major Learning Points
1. Different types of internals are used to perform various process functions.
Several types of vessel internals may be installed.
2. Review list of internals. 3. ASME Code does not cover design of internals. End-, vessel vendor, and/or contractor must develop requirements.
112
Overview of Pressure Vessel Design Instructor’s Personal Notes
ASME Code and Vessel Internals • Loads applied from internals on vessel to be considered in design • Welding to pressure parts must meet ASME Code
101
Instructor’s Outline Discuss ASME requirements for loads applied to vessel and welding to pressure parts.
Major Learning Points ASME Code requires that internals be considered only to extent of their effect on pressure shell.
113
Overview of Pressure Vessel Design Instructor’s Personal Notes
Corrosion Allowance For Vessel Internals • Removable internals: CA = CA of shell – Costs less – Easily replaced
• Non-removable internals: CA = 2 (CA of shell) – Corrosion occurs on both sides 102
Instructor’s Outline 1. Potential corrosion of internals should not be ignored.
Major Learning Points Corrosion allowance should be considered in the design of internals.
2. Corrosion allowance should be considered in a practical and costeffective manner.
114
Overview of Pressure Vessel Design Instructor’s Personal Notes
Head-to-Shell Transitions l y
Thinner part
th Thinner part
th
l
Tangent Line
y
t
ts
th
Tangent Line
t
y Thinner part
l
Thinner part
y
s
th
l
t
s
s
Fillet Weld
Butt Weld Intermediate Head Attachment
Figure 6.1 103
Instructor’s Outline 1. Review typical acceptable welding and fabrication details.
Major Learning Points ASME Code specifies acceptable welding and fabrication details.
2. Details for openings were previously reviewed. 3. Highlight thickness taper. 4. Intermediate heads should retain fillet weld in refinery applications.
115
Overview of Pressure Vessel Design Instructor’s Personal Notes
Typical Shell Transitions CL
In all cases, l shall not be less than 3y.
CL
y
l l
C L
Figure 6.2 104
Instructor’s Outline Review thickness taper requirements.
Major Learning Points ASME Code fabrication details.
116
Overview of Pressure Vessel Design Instructor’s Personal Notes
Nozzle Neck Thickness Tapers
Figure 6.3 105
Instructor’s Outline Thickness taper may be required in nozzle neck.
Major Learning Points ASME Code fabrication details.
117
Overview of Pressure Vessel Design Instructor’s Personal Notes
Stiffener Rings
In-Line Intermittent Weld Staggered Intermittent Weld
Continuous Fillet Weld On One Side, Intermittent Weld On Other Side
Figure 6.4 106
Instructor’s Outline 1. Vacuum stiffening ring attachment details.
Major Learning Points ASME Code fabrication details.
2, ASME Code specifies weld spacing, size, and length.
118
Overview of Pressure Vessel Design Instructor’s Personal Notes Post Weld Heat Treatment • Restores material properties • Relieves residual stresses • ASME Code PWHT requirements – Minimum temperature and hold time – Adequate stress relief – Heatup and cooldown rates
107
Instructor’s Outline 1. ASME Code specifies PWHT requirements only for relief of residual stresses.
Major Learning Points ASME Code PWHT requirements.
2. Need for PWHT due to other reasons must be specified by end- or contractor. •
Service considerations (e.g., wet H 2S, caustic)
•
Weld hardness reduction
119
Overview of Pressure Vessel Design Instructor’s Personal Notes Inspection and Testing Inspection includes examination of:
• Base material specification and quality • Welds • Dimensional requirements • Equipment documentation 108
Instructor’s Outline Highlight main areas included in inspection.
Major Learning Points ASME Code inspection requirements.
120
Overview of Pressure Vessel Design Instructor’s Personal Notes Common Weld Defects Between Weld Bead and Base Metal
Between Adjacent es
Lack of Fusion
Incomplete Filling at Root on One Side Only
Incomplete Filling at Root
Incomplete Penetration ExternalUndercut
Internal Undercut
Undercut
Figure 7.1 109
Instructor’s Outline Review common types of weld defects.
Major Learning Points Particular types of weld defects may occur.
121
Overview of Pressure Vessel Design Instructor’s Personal Notes Weld Defects Presence of defects: • Reduces weld strength below that required • Reduces overall strength of fabrication • Increases risk of failure
110
Instructor’s Outline Review why weld defects can reduce vessel integrity.
Major Learning Points Presence of unacceptable weld defects reduces vessel integrity.
122
Overview of Pressure Vessel Design Instructor’s Personal Notes
Types of NDE NDE TYPE Radiographic
Visual
Liquid Penetrant
Magnetic Particle Ultrasonic
DEFECTS DETECTED Gas pockets, slag inclusions, incomplete penetration, cracks Porosity holes, slag inclusions, weld undercuts, overlapping Weld surface-type defects: cracks, seams, porosity, folds, pits, inclusions, shrinkage Cracks, porosity, lack of fusion Subsurface flaws: laminations, slag inclusions
ADVANTAGES Produces permanent record. Detects small flaws. Most effective for butt-welded ts. Helps pinpoint areas for additional NDE.
LIMITATIONS Expensive. Not practical for complex shapes. Can only detect what is clearly visible.
Used for ferrous Can only detect and nonferrous surface materials. Simple imperfections. and less expensive than RT, MT, or UT. Flaws up to ¼ in. beneath surface can be detected. Can be used for thick plates, welds, castings, forgings. May be used for welds where RT not practical.
Cannot be used on nonferrous materials. Equipment must be constantly calibrated.
Figure 7.2 111
Instructor’s Outline 1. Review NDE methods and types of defects detected. 2. Review advantages and limitations of each NDE method.
Major Learning Points •
Different NDE methods are best suited to detect particular defect types.
•
Each NDE method has advantages and disadvantages.
123
Overview of Pressure Vessel Design Instructor’s Personal Notes Typical RT Setup X-Ray Tube
X-Ray
Film
Test Specimen
Figure 7.3 112
Instructor’s Outline Review typical setup for RT inspection.
Major Learning Points Typical RT setup.
124
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pulse Echo UT System Cathode Ray Tube (CRT)
A
C
Read Out
B
BaseLine
Input-Output Generator
Cable
Transducer A Couplant Test Specimen
B C
Flaw
Figure 7.4 113
Instructor’s Outline Review how pulse echo UT system can detect defects.
Major Learning Points Typical pulse echo UT system.
125
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pressure Testing • Typically use water as test medium • Demonstrates structural and mechanical integrity after fabrication and inspection • Higher test pressure provides safety margin • PT = 1.5 P (Ratio)
114
Instructor’s Outline 1. Water is a safer test medium than air. Pneumatic testing should only be used on an exception basis.
Major Learning Points Pressure test is used as final demonstration of vessel integrity.
2. “Ratio” is the lowest value of:
S( test temperatur e) S ( design temperatur e)
126
Overview of Pressure Vessel Design Instructor’s Personal Notes
Pressure Testing, cont’d Hydrotest pressures must be calculated: • For shop test. Vessel in horizontal position. • For field test. Vessel in final position with uncorroded component thicknesses. • For field test. Vessel in final position and with corroded component thicknesses. • PT ≤ Flange test pressure • Stress ≤ 0.9 (MSYS) • Field test with wind 115
Instructor’s Outline Review additional pressure test design considerations.
Major Learning Points Pressure test considerations.
127
Overview of Pressure Vessel Design Instructor’s Personal Notes
Summary • Overview of pressure vessel mechanical design • ASME Section VIII, Division 1 • Covered – Materials – Fabrication – Testing
– Design – Inspection
116
Instructor’s Outline 1. Highlight the subjects covered in the course.
Major Learning Points Summarize course.
2. Note that much more time is required for an in-depth discussion of pressure vessel design. This course provides a good starting point to proceed further for those who need to. 3. Provide the evaluation form for the class to complete. Collect these and return them to the sponsoring unit. 4. Distribute the CEU form to the participants and point out that they will have to mail it in themselves, with the required standard fee. All the information is on the form.
128
Appendix A Reproducible Overheads
Appendix B Course & Instructor Evaluation Form
ASME Career Development Series Course Evaluation Course Title: ________________________________________________ Location: ___________________________________________________ Instructor: __________________________________________________ Please assist us in the evaluation of this program. Answer the following questions by circling only one answer unless otherwise stated. We will be using your to plan future programs. Your assistance is most appreciated. Please return to instructor as requested. A.
Course Evaluation Please record your overall reaction to the program by placing a circle around the appropriate number on the scale. 10 9 Excellent
876 Good
Fair
543 Poor
210
Please evaluate the course by circling E (excellent), G (good), F (fair), or P (poor) in the appropriate location. 1.
Course content Relevance of New matches brochure course notes/ Applicability Knowledge Overall description workbook to your job Gained
1.1 E G F P
1.2 E G F P
1.3 E G F P
Rating
1.4 E G F P 1.5 E G F P
2.
What do you think was the best feature of the course?
3.
What changes, if any, would you make in the program content and/or format?
4.
Can you share with us any comments about this program that we coul use as a quote on our course literature?
Optional Information: Name: _______________________________ Company: ____________________________
Title: _______________________________ City, State: __________________________
131
B.
5.
Instructor’s Evaluation Please evaluate the instructor(s) by circling E (excellent), G (good), F (fair), or P (poor) in the appropriate location Effective knowledge of subject matter
1.1 E G F P
Effectiveness Effective of teaching use of Class method class time
1.2 E G F P
1.3 E G F P
Openness to Overall Participation Rating
1.4 E G F P 1.5 E G F P
C. 6.
Facilities How would you rate the meeting site?
7.
How would you rate the overnight accommodations (if applicable)?
8.
In what other cities would you like to see this course held?
9.
Additional Comments:
D. 10.
Future Courses and Educational Products (Video, Self Study, Software) What other courses would you like to see sponsored?
11.
What educational products would you like to see sponsored by ASME and in what medium?
E. 12.
On-Site Company Training Would your organization be interested in holding this course or other ASME courses at your facility? If so, please indicate the area of interest and the person. Thank you.
13.
Course Name/Topic: _________________________________________________________
14.
Name: ________________________________ Phone No.: ___________________
132
Appendix C
Continuing Education Unit (CEU) Submittal Form Course Improvement Form
133
ASME Career Development Series Continuing Education Unit (CEU) Request Form Each 4-hour ASME Career Development Series Course earns 0.4 CEU’s PLEASE PRINT ALL YOUR INFORMATION CLEARLY YOUR CERTIFICATE WILL BE PREPARED FROM THIS FORM Title of Program: _____________________________________________________ Date Held: __________________________________________________________ Instructor: __________________________________________________________ Location: ___________________________________________________________ Number of CEU’s Earned: (0.4 per 4-hour module) ____________ Last Name: __________________________________________ First Name, Middle Initial: ______________________________ Title/Position: ________________________________________ Company: ___________________________________________ Address: ____________________________________________ City: _______________________ State: __ Zip: ____________ Telephone: __________________ Fax: ____________________ Email: _________________________ Please send this form, along with a check made out to ASME for the standard fee of $15.00 to: ASME Continuing Education Institute Three Park Avenue New York, NY 10016-5990 Your Certificate will be prepared and sent to the address you indicated above.
134
ASME Career Development Series Course Improvement Form
Important Note: Submission of this form is optional. However, we would like to solicit the comments of the Instructor so that we may continuing improve on the Career Development Series. Any instructors who would like to write a course should indicate so on this form and an authors package will be forwarded to you. Thank you for helping us with the Career Development Series Name: _________________________________________________________ Address: _______________________________________________________ City/State/Zip: __________________________________________________ Telephone: ______________________________ Fax: ____________________________________ Email: __________________________________ Comments:
Please send this form to: ASME Continuing Education Institute Three Park Avenue New York, NY 10016-5990
135
ASME Career Development Series Instructor’s Biography Form
Important Note: Submission of this form is required every time a Career Development Series Course is taught. ASME cannot process attendees’ CEU requests without this form. Attachments to this form must include: 1. A biographical sketch of the instructor. 2. Course evaluations filled out by the participants at the completion of the course.
Course: ____________________________________________________ Date Presented: ______________________________________________ Location: ___________________________________________________ Instructor: __________________________________________________ Number of participants: ________________________________________ Sponsoring Unit: _____________________________________________
136
Your Path to Lifelong Learning ASME offers you exciting, rewarding ways to sharpen your technical skills, enhance personal development and prepare for advancement. Short Courses – More than 200 short courses offered each you keep you up to speed in the technology fast lane—or, help you fill in any gaps in your technical background. Customized Training at your organization’s site – Do you have ten or more people at your site who could benefit from an ASME course? Most of our courses can be offered in -house and tailored to your latest engineering project. Bring course to your company too. Self-study materials meet the needs of individuals who demand substantive, practical information, yet require flexibility, quality and convenience. Return to each program again and again, as a refresher or as an invaluable addition to your reference library. FE Exam Review– A of seasoned educators outline a wide range of required topics to provide a thorough review to help practicing engineers as well as engineering students prepare for this challenging examination. Videotape Review PE Exam Review– A comprehensive review of all the major exam topics that demonstrates the necessary math, logic and theory. Videotape, Online, or Online Live Revie w available. FOR MORE INFORMATION CALL 1-800-THE-ASME __________________________________________________________________________ INFORMATION REQUEST FORM Please mail to ASME at 22 Law Drive, P. O. Box 2900, Fairfield, NJ 07007-2900, or fax to 973-882-1717, call 1-800-THE-ASME, or email [email protected]. Send me information on the following: ____ Short Courses ____ In-House Training ____ Self-Study Programs ____ FE Exam Review ____ PE Exam Review (videotape) ____ PE Exam Review (Online) ____ PE Exam Review (Online Live) Name: ______________________________________________ Title: _______________________________________________ Organization: _________________________________________ Business Address: _____________________________________ City: _________________ State: __ Zip Code: _____________ Business Phone: _________________ Fax: ________________ Email: ______________________________________________
137
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