Acceptance Criteria i453f
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ACCEPTANCE CRITERIA (ASME Sec VIII Div.1): UW-51: RADIOGRAPHIC AND RADIOSCOPIC EXAMINATION OF WELDED TS (a) All welded ts to be radiographed shall be examined in accordance with Article 2 of Section V except as specified below. (1) A complete set of radiographs and records, as described in T-291 and T-292 of Article 2 of Section V, for each vessel or vessel part shall be retained by the Manufacturer until the Manufacturer’s Data Report has been signed by the Inspector. (2) The Manufacturer shall certify that personnel performing and evaluating radiographic examinations required by this Division have been qualified and certified in accordance with their employer’s written practice. SNT-TC-1A11 shall be used as a guideline for employers to establish their written practice for qualification and certification of their personnel. Alternatively, the ASNT Central Certification Program (AC),11 or -18911 may be used to fulfill the examination and demonstration requirements of SNT-TC-1A and the employer’s written practice. Provisions for training, experience, qualification, and certification of NDE personnel shall be described in the Manufacturer’s Quality Control System [see Appendix 10]. (3) A written radiographic examination procedure is not required. Demonstration of density and penetrameter image requirements on production or technique radiographs shall be considered satisfactory evidence of compliance with Article 2 of Section V. (4) The requirements of T-285 of Article 2 of Section V are to be used only as a guide. Final acceptance of radiographs shall be based on the ability to see the prescribed penetrameter image and the specified hole or the designated wire of a wire penetrameter. (b) Indications shown on the radiographs of welds and characterized as imperfections are unacceptable under the following conditions and shall be repaired as provided in UW-38, and the repair radiographed to UW-51 or, at the option of the Manufacturer, ultrasonically examined in accordance with the method described in Appendix 12 and the standards specified in this paragraph, provided the defect has been confirmed by the ultrasonic examination to the satisfaction of the Authorized Inspector prior to making the repair. For material thicknesses in excess of 1 in. (25 mm), the concurrence of the shall be obtained. This ultrasonic examination shall be noted under remarks on the Manufacturer’s Data Report Form: (1) Any indication characterized as a crack or zone of incomplete fusion or penetration; (2) Any other elongated indication on the radiograph which has length greater than: (a) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm) (b) 1⁄3t for t from 3⁄4 in. (19 mm) to 21⁄4 in. (57 mm) (c) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm) Where, t = the thickness of the weld excluding any allowable reinforcement. For a butt weld ing two having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t. (3) any group of aligned indications that have an aggregate length greater than t in a length of 12t, except when the distance between the successive imperfections exceeds 6L where L is the length of the longest imperfection in the group; (4) Rounded indications in excess of that specified by the acceptance standards given in Appendix 4. (c) All welded ts to be examined by Real Time Radioscopic Examination shall be examined in accordance with Appendix II of Article 2 of Section V as specified below.
(1) A complete set of records, as described in II-292, shall be evaluated by the Manufacturer prior to being presented to the Inspector. Imperfections listed in UW-51(b)(1), (2), (3), and (4) are unacceptable and shall be repaired as provided in UW-38 and the repair reexamined by either film or Real Time Radioscopic Examination. Records shall be retained by the Manufacturer until the Data Report has been signed by the Inspector. (2) Provisions for training, experience, qualification, and certification of personnel responsible for equipment setup, calibration, operation, and evaluation of examination data shall be described in the Manufacturer’s Quality Control System [see Appendix 10]. (3) The use of Real Time Radioscopic Examination shall be noted under remarks on the Manufacturer’s Data Report. UW-52: SPOT EXAMINATION OF WELDED TS NOTE: Spot radiographing of a welded t is recognized as an effective inspection tool. The spot radiography rules are also considered to be an aid to quality control. Spot radiographs made directly after a welder or an operator has completed a unit of weld proves that the work is or is not being done in accordance with a satisfactory procedure. If the work is unsatisfactory, corrective steps can then be taken to improve the welding in the subsequent units, which unquestionably will improve the weld quality. Spot radiography in accordance with these rules will not ensure a fabrication product of predetermined quality level throughout. It must be realized that an accepted vessel under these spot radiography rules may still contain defects which might be disclosed on further examination. If all radiographically disclosed weld defects must be eliminated from a vessel, then 100% radiography must be employed. (a) Butt welded ts which are to be spot radiographed shall be examined locally as provided herein. (b) Minimum Extent of Spot Radiographic Examination (1) One spot shall be examined on each vessel for each 50 ft (15 m) increment of weld or fraction thereof for which a t efficiency from column (b) of Table UW-12 is selected. However, for identical vessels or parts, each with less than 50 ft (15 m) of weld for which a t efficiency from column (b) of Table UW-12 is selected, 50 ft (15 m) increments of weld may be represented by one spot examination. (2) For each increment of weld to be examined, a sufficient number of spot radiographs shall be taken to examine the welding of each welder or welding operator. Under conditions where two or more welders or welding operators make weld layers in a t, or on the two sides of a doublewelded butt t, one spot may represent the work of all welders or welding operators. (3) Each spot examination shall be made as soon as practicable after completion of the increment of weld to be examined. The location of the spot shall be chosen by the Inspector after completion of the increment of welding to be examined, except that when the Inspector has been notified in advance and cannot be present or otherwise make the selection, the fabricator may exercise his own judgment in selecting the spots. (4) Radiographs required at specific locations to satisfy the rules of other paragraphs, such as UW-9(d), UW-11(a)(5)(b), and UW-14(b), shall not be used to satisfy the requirements for spot radiography. (c) Standards for Spot Radiographic Examination: Spot examination by radiography shall be made in accordance with the technique prescribed in UW-51(a). The minimum length of spot radiograph shall be 6 in. Spot radiographs may be retained or be discarded by the Manufacturer after acceptance of the vessel by the Inspector. The acceptability of welds examined by spot radiography shall be judged by the following standards. (1) Welds in which indications are characterized as cracks or zones of incomplete fusion or penetration shall be unacceptable. (2) Welds in which indications are characterized as slag inclusions or cavities shall be
unacceptable if the length of any such indication is greater than 2⁄3t where t is the thickness of the weld excluding any allowable reinforcement. For a butt weld ing two having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t. If several indications within the above limitations exist in line, the welds shall be judged acceptable if the sum of the longest dimensions of all such indications is not more than t in a length of 6t (or proportionately for radiographs shorter than 6t) and if the longest indications considered are separated by at least 3L of acceptable weld metal where L is the length of the longest indication. The maximum length of acceptable indications shall be 3⁄4 in. (19 mm). Any such indications shorter than 1⁄4 in. (6 mm) shall be acceptable for any plate thickness. (3) Rounded indications are not a factor in the acceptability of welds not required to be fully radiographed. (d) Evaluation and Retests: (1) When a spot, radiographed as required in (b)(1) or (b)(2) above, is acceptable in accordance with (c)(1) and (c)(2) above, the entire weld increment represented by this radiograph is acceptable. (2) When a spot, radiographed as required in (b)(1) or (b)(2) above, has been examined and the radiograph discloses welding which does not comply with the minimum quality requirements of (c)(1) or (c)(2) above, two additional spots shall be radio graphically examined in the same weld increment at locations away from the original spot. The locations of these additional spots shall be determined by the Inspector or fabricator as provided for the original spot examination in (b) (3) above. (a) If the two additional spots examined show welding which meets the minimum quality requirements of (c)(1) and (c)(2) above, the entire weld increment represented by the three radiographs is acceptable provided the defects disclosed by the first of the three radiographs are removed and the area repaired by welding. The weld repaired area shall be radio-graphically examined in accordance with the foregoing requirements of UW-52. (b) If either of the two additional spots examined shows welding which does not comply with the minimum quality requirements of (c)(1) or (c)(2) above, the entire increment of weld represented shall be rejected. The entire rejected weld shall be removed and the t shall be re-welded or, at the fabricator’s option, the entire increment of weld represented shall be completely radiographed and only defects need be corrected. (c) Repair welding shall be performed using a qualified procedure and in a manner acceptable to the Inspector. The re-welded t, or the weld repaired areas, shall be spot radio-graphically examined at one location in accordance with the foregoing requirements of UW-52. MANDATORY APPENDIX 4: ROUNDED INDICATIONS CHARTS ACCEPTANCE STANDARD FOR RADIOGRAPHICALLY DETERMINED ROUNDED INDICATIONS IN WELDS. 4-1 APPLICABILITY OF THESE STANDARDS These standardsare applicable to ferritic, austenitic, and nonferrous materials. 4-2 TERMINOLOGY (a) Rounded Indications: Indications with a maximum length of three times the width or less on the radiograph are defined as rounded indications. These indications may be circular, elliptical, conical, or irregular in shape and may have tails. When evaluating the size of an indication, the tail shall be included. The indication may be from any imperfection in the weld, such as porosity, slag, or tungsten. (b) Aligned Indications: A sequence of four or more rounded indications shall be considered to be aligned when they touch a line parallel to the length of the weld drawn through the center of the two outer rounded indications. (c) Thickness t: t is the thickness of the weld, excluding any allowable reinforcement. For a butt weld ing two having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t. (a) Image Density: Density within the image of the indication may vary and is not a criterion for acceptance or
rejection. (b) Relevant Indications: (See Table 4-1 for examples.): Only those rounded indications which exceed the following dimensions shall be considered relevant. (1) 1⁄10t for t less than 1⁄8 in. (3 mm) (2) 1⁄64 in. (0.4mm) for t from 1⁄8 in. to 1⁄4 in. (3 mm to6 mm), incl. (3) 1⁄32 in. (0.8mm) for t greater than 1⁄4 in. to 2 in. (6 mm to 50 mm), incl. (4) 1⁄16 in. (1.6mm) for t greater than 2 in. (50 mm). (c) Maximum Size of Rounded Indication. (See Table4-1 for examples.): The maximum permissible size of any indication shall be 1⁄4t, or 5⁄32 in. (4 mm), whichever is smaller; except that an isolated indication separated from an adjacent indication by 1in. (25 mm) or more may be 1⁄3t, or 1⁄4 in. (6 mm), whichever is less. For t greater than 2 in. (50 mm) the maximum permissible size of an isolated indication shall be increased to 3⁄8 in. (10 mm). (d) Aligned Rounded Indications: Aligned rounded indications are acceptable when the summation of the diameters of the indications is less than t in a length of 12t. See Fig. 4-1. The length of groups of aligned rounded indications and the spacing between the groups shall meet the requirements of Fig. 4-2. (e) Spacing: The distance between adjacent rounded indications is not a factor in determining acceptance or rejection, except as required for isolated indications or groups of aligned indications. (f) Rounded Indication Charts: The rounded indications characterized as imperfections shall not exceed that shown in the charts. The charts in Figs. 4-3 through 4-8 illustrate various types of assorted, randomly dispersed and clustered rounded indications for different weld thicknesses greater than 1⁄8 in. (3 mm). These charts represent the maximum acceptable concentration limits for rounded indications. The charts for each thickness range represent full-scale 6 in. (150 mm) radiographs, and shall not be enlarged or reduced. The distributions shown are not necessarily the patterns that may appear on the radiograph, but are typical of the concentration and size of indications permitted. (g) Weld Thickness t less than 1/8 in. (3 mm): For t less than 1⁄8 in. (3 mm) the maximum number of rounded indications shall not exceed 12 in a 6 in. (150 mm) length of weld. A proportionally fewer number of indications shall be permitted in welds less than 6 in. (150 mm) in length. (h) Clustered Indications: The illustrations for clustered indications show up to four times as many indications in a local area, as that shown in the illustrations for random indications. The length of an acceptable cluster shall not exceed the lesser of 1 in. (25 mm) or 2t. Where more than one cluster is present, the sum of the lengths of the clusters shall not exceed 1 in. (25 mm) in a 6 in. (150 mm) length weld. ***Table for maximum size of acceptable rounded indication (Table 4.1): (ASME Sec VIII Div.1) Thickness t, (in.) Maximum Size of Acceptable Rounded Indication (in.) Maximum Size of Non relevant Indication, in. Random Isolated Less than Thickness t, (mm.) Maximum Size of Acceptable Rounded Indication (mm.) Maximum Size of Non relevant Indication, mm. Random Isolated Less than NOTE: This Table contains examples only (P.138 UW-51, 368 editions: 2004). *For more information see Table 4.2-4.8 Page: 370~375(ASME Sec VIII Div.1editions: 2004) ACCEPTANCE CRITERIA (API-1104): 9.3 RADIOGRAPHIC TESTING: Note: All densities referred to in 9.3.1 through 9.3.13 are based on negative images. 9.3.1 Inadequate Penetration without High-low
Inadequate penetration without high-low (IP) is defined as the incomplete filling of the weld root. This condition is shown schematically in Figure 13. IP shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IP exceeds 1 in. (25 mm). b. The aggregate length of indications of IP in any continuous 12 in. (300 mm) length of weld exceeds 1 in. (25 mm). c. The aggregate length of indications of IP exceeds 8% of the weld length in any weld less than 12 in. (300 mm) in length. 9.3.2 Inadequate Penetration Due to High-low Inadequate penetration due to high-low (IPD) is defined as the condition that exists when one edge of the root is exposed (or unbonded) because adjacent pipe or fitting ts are misaligned. This condition is shown schematically in Figure 14. IPD shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IPD exceeds 2 in. (50 mm). b. The aggregate length of indications of IPD in any continuous 12 in. (300 mm) length of weld exceeds 3 in. (75 mm). 9.3.3 Inadequate Cross Penetration Inadequate cross penetration (I) is defined as a subsurface imperfection between the first inside and the first outside that is caused by inadequately penetrating the vertical land faces. This condition is shown schematically in Figure 15. I shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of I exceeds 2 in. (50 mm). b. The aggregate length of indications of I in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). 9.3.4 Incomplete Fusion Incomplete fusion (IF) is defined as a surface imperfection between the weld metal and the base material that is open to the surface. This condition is shown schematically in Figure 16. IF shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IF exceeds 1 in. (25 mm). b. The aggregate length of indications of IF in any continuous 12 in. (300 mm) length of weld exceeds 1 in. (25 mm). c. The aggregate length of indications of IF exceeds 8% of the weld length in any weld less than 12 in. (300 mm) in length. 9.3.5 Incomplete Fusion Due to Cold Lap Incomplete fusion due to cold lap (IFD) is defined as an imperfection between two adjacent weld beads or between the weld metal and the base metal that is not open to the surface. This condition is shown schematically in Figure 17. IFD shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IFD exceeds 2 in. (50 mm). b. The aggregate length of indications of IFD in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). c. The aggregate length of indications of IFD exceeds 8% of the weld length. 9.3.6 Internal Concavity Internal concavity (IC) is defined in 3.2.8 and is shown schematically in Figure 18. Any length of internal concavity is acceptable, provided the density of the radiographic image of the internal concavity does not exceed that of the thinnest adjacent parent material. For areas that exceed the density of the thinnest adjacent parent material, the criteria for burn through (see 9.3.7) are applicable. 9.3.7 Burn-through 9.3.7.1 A burn-through (BT) is defined as a portion of the root bead where excessive penetration has caused the weld puddle to be blown into the pipe. 9.3.7.2 For pipe with an outside diameter greater than or equal to 2.375 in. (60.3 mm), a BT shall be considered a defect should any of the following conditions exist: a. The maximum dimension exceeds 1/4 in. (6 mm) and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material. b. The maximum dimension exceeds the thinner of the nominal wall thicknesses ed, and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material.
c. The sum of the maximum dimensions of separate BTs whose image density for any portion of the BTs exceeds that of the thinnest adjacent parent material and exceeds 1/2 in. (13 mm) in any continuous 12 in. (300 mm) length of weld or the total weld length, whichever is less. 9.3.7.3 For pipe with an outside diameter less than 2.375 in. (60.3 mm), a BT shall be considered a defect when any of the following conditions exists: a. The maximum dimension exceeds 1/4 in. (6 mm) and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material. b. The maximum dimension exceeds the thinner of the nominal wall thicknesses ed, and the density in any portion of the BT’s image exceeds that of the thinnest adjacent parent material. c. More than one BT of any size is present and the density in any portion of the BTs image *exceeds that of the thinnest adjacent parent material. 9.3.8 Slag Inclusions 9.3.8.1 A slag inclusion is defined as a nonmetallic solid entrapped in the weld metal or between the weld metal and the parent material. Elongated slag inclusions (ESIs)— e.g., continuous or broken slag lines or wagon tracks-are usually found at the fusion zone. Isolated slag inclusions (ISIs) are irregularly shaped and may be located anywhere in the weld. For evaluation purposes, when the size of a radiographic indication of slag is measured, the indication’s maximum dimension shall be considered its length. 9.3.8.2 For pipe with an outside diameter greater than or equal to 2.375 in. (60.3 mm), slag inclusions shall be considered a defect should any of the following conditions exist: a. The length of an ESI indication exceeds 2 in. (50 mm). Note: Parallel ESI indications separated by approximately the width of the root bead (wagon tracks) shall be considered a single indication unless the width of either of them exceeds 1/32 in. (0.8 mm). In that event, they shall be considered separate indications. b. The aggregate length of ESI indications in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). c. The width of an ESI indication exceeds 1/16 in. (1.6 mm). d. The aggregate length of ISI indications in any continuous12 in. (300 mm) length of weld exceeds 1/2 in. (13 mm). e. The width of an ISI indication exceeds 1/8 in. (3 mm). f. More than four ISI indications with the maximum width of 1/8 in. (3 mm) are present in any continuous 12 in. (300 mm) length of weld. g. The aggregate length of ESI and ISI indications exceeds 8% of the weld length. 9.3.8.3 For pipe with an outside diameter less than 2.375 in. (60.3 mm), slag inclusions shall be considered a defect should any of the following conditions exist: a. The length of an ESI indication exceeds three times the thinner of the nominal wall thicknesses ed. Note: Parallel ESI indications separated by approximately the width of the root bead (wagon tracks) shall be considered a single indication unless the width of either of them exceeds 1/32 in. (0.8 mm). In that event, they shall be considered separate indications. b. The width of an ESI indication exceeds 1/16 in. (1.6 mm). c. The aggregate length of ISI indications exceeds two times the thinner of the nominal wall thicknesses ed and the width exceeds one-half the thinner of the nominal wall thicknesses ed. d. The aggregate length of ESI and ISI indications exceeds 8% of the weld length. 9.3.9 Porosity *9.3.9.1 Porosity is defined as gas trapped by solidifying weld metal before the gas has a chance to rise to the surface of the molten puddle and escape. Porosity is generally spherical but may be elongated or irregular in shape, such as piping (wormhole) porosity. When the size of the radiographic indication produced by a pore is measured, the maximum dimension of the indication shall apply to the criteria given in 9.3.9.2 through 9.3.9.4. 9.3.9.2 Individual or scattered porosity (P) shall be considered a defect should any of the following conditions exist: a. The size of an individual pore exceeds 1/8 in. (3 mm). b. The size of an individual pore exceeds 25% of the thinner of the nominal wall thicknesses ed. c. The distribution of scattered porosity exceeds the concentration permitted by Figures 19 or 20. 9.3.9.3 Cluster porosity () that occurs in any except the finish shall comply with the criteria of 9.3.9.2. that occurs in the finish shall be considered a defect should any of the following conditions exist. a. The diameter of the cluster exceeds 1/2 in. (13 mm). b. The aggregate length of in any continuous 12 in. (300 mm) length of weld exceeds 1/2 in.
(13 mm). 9.3.9.4 Hollow-bead porosity (HB) is defined as elongated linear porosity that occurs in the root . HB shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of HB exceeds 1/2 in. (13 mm). b. The aggregate length of indications of HB in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). c. Individual indications of HB, each greater than 1/4 in. (6 mm) in length, are separated by less than 2 in. (50 mm). d. The aggregate length of all indications of HB exceeds 8% of the weld length. 9.3.10 Cracks Cracks (C) shall be considered a defect should any of the following conditions exists: a. The crack, of any size or location in the weld, is not a shallow crater crack or star crack. b. The crack is a shallow crater crack or star crack with a length that exceeds 5/32 in. (4 mm). Note: Shallow crater cracks or star cracks are located at the stopping point of weld beads and are the result of weld metal contractions during solidification. 9.3.11 Undercutting Undercutting is defined as a groove melted into the parent material adjacent to the toe or roots of the weld and left unfilled by weld metal. Undercutting adjacent to the cover (EU) or root (IU) shall be considered a defect should any of the following conditions exists: a. The aggregate length of indications of EU and IU, in any combination, in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). b. The aggregate length of indications of EU and IU, in any combination, exceeds one-sixth of the weld length. Note: See 9.7 for acceptance standards for undercutting when visual and mechanical measurements are employed. 9.3.12 Accumulation of Imperfections Excluding incomplete penetration due to high-low and undercutting, any accumulation of imperfections (AI) shall be considered a defect should any of the following conditions exist: a. The aggregate length of indications in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). b. The aggregate length of indications exceeds 8% of the weld length. ***( For more information see page: 22, 24~26; API-1104, 20TH Edition Nov’2005). *ACCEPTANCE CRITERIA (ASME B31.1): 136.4 Examination Methods of Welds *136.4.1 Nondestructive Examination. Nondestructive examinations shall be performed in accordance with the requirements of this Chapter. The types and extent of mandatory examinations for pressure welds and welds to pressure retainingcomponents are specified in Table 136.4. For welds other than those covered by Table 136.4, only visual examination is required. Welds requiring nondestructive examination shall comply with the applicable acceptance standards for indications as specified in paras. 136.4.2 through 136.4.6. As a guide, the detection capabilities for the examination method are shown in Table 136.4.1. Welds not requiring examination (i.e. RT; UT, MT, or PT) by this Code or the Engineering design shall be judged acceptable if they meet the examination requirements of para. 136.4.2 and the pressure test requirements specified in Para. 137. 136.4.5 Radiography: When required by this Chapter (see Table 136.4), radiographic examination shall be performed in accordance with Article 2 of Section V of the ASME Boiler and Pressure Vessel Code, except that the requirements of T-285 are to be used as a guide but not for the rejection of radiographs unless the geometrical unsharpness exceeds 0.07 in. (A) Acceptance Standards. Welds that are shown by radiography to have any of the following types of discontinuities are unacceptable: (A.1) any type of crack or zone of incomplete fusion or penetration; (A.2) any other elongated indication which has a length greater than: (A.2.1) 1/4 in. (6.0 mm) for t up to 3/4 in. (19.0 mm), inclusive; (A.2.2) 1/3t for t from 3/4 in. (19.0 mm) to 2 1/4 in.(57.0 mm), incl.; (A.2.3) 3/4 in. (19.0 mm) for t over 2 1/4 in. (57.0 mm) where t is the thickness of the thinner portion of the weld. (2.0 mm). (NOTE: z referred to in (A.2.1). (A.2.2). and (A.2.3) above pertains to the thickness of the weid being examined; if a weld s two having different thickness at the weld, t is the thinner of these two thickness.) (A.3) any group of indications in line that have an aggregate length greater than t in a length of 12, except where the distance between the successive indications exceeds 6L where L is the
longest indication in the group; (A.4) porosity in excess of that shown as acceptable in Appendix A-250 of Section I of the *ASME Boiler and Pressure Vessel Code; (A.5) root concavity when there is an abrupt change in density, as indicated on the radiograph. 136.4.2 Visual Examination: Visual examination as defined in para. 100.2. shall be performed, as necessary, during the fabrication and erection of piping components to provide verification that the design and WPS requirements are being met. In addition, visual examination shall be performed to that all completed welds inpipe and piping components comply with the acceptance standards specified in (A) below or with the limitations on imperfections specified in the material specification under which the pipe or component was furnished. (A) Acceptance Standards. The following indications are unacceptable: (A. I) cracks-external surface; (A.2) undercut on surface which is greater than 1/32 in. (1.0 mm) deep; Table 127.4.2; (A.3) weld reinforcement greater than specified in (A.4) lack of fusion on surface; (A.5) incomplete penetration (applies only when inside surface is readily accessible); (A.6) any other linear indications greater than 3/16 in. (5.0 mm) long; (A.7) surface porosity with rounded indications having dimensions greater than in.3/16 in.(5.0 mm) or four or more rounded indications separated by 1/16 in. (2.0 mm) or less edge to edge in any direction. Rounded indications are indications which are circular or elliptical with their length less than three times their width. 136.4.3 Magnetic Particle Examination: Whenever required by this Chapter (see Table 136.4), magnetic particle examination shall be performed in accordance with the methods of Article 7, Section V, of the ASh4E Boiler and Pressure Vessel Code. (A) Evaluation of Indications (A. 1) Mechanical discontinuities at the surface will be indicated by the retention of the examination medium. All indications are not necessarily defects; however, certain metallurgical discontinuities and magnetic permeability variations may produce similar indications which are not relevant to the detection of unacceptable discontinuities. (A.2) Any indication which is believed to be nonrelevant shall be reexamined to whether or not actual defects are present. Surface conditioning may precede the reexamination. Nonrelevant indications which would mask indications of defects are unacceptable. (A.3) Relevant indications are those which result from unacceptable mechanical discontinuities. Linear indications are those indications in which the length is more than three times the width. Rounded indications are indications which are circular or elliptical with the length less than three times the width. (A.4) An indication of a discontinuity may be larger than the discontinuity that causes it; however, the size of the indication and not the size of the discontinuity is the basis of acceptance or rejection. (B) Acceptance Standards. The following relevant indications are unacceptable: (B.1) any cracks or linear indications; (B.2) rounded indications with dimensions greater than 3/16 in. (5.0 mm); (B.3) four or more rounded indications in a line separated by t / , j in. (2.0 mm) or less edge to edge; (B.4) Ten or more rounded indications in any 6 sq in. (3870 mm’) of surface with the major dimension of this area not to exceed 6 in. (150 mm) with the area taken in the most unfavorable location relative to the indications being evaluated. 136.4.4 Liquid Penetrant Examination: Whenever required by this Chapter (see Table 136.4), liquid penetrant examination shall be performed in accordance with the methods of Article 6, Section V, of the ASME Boiler and Pressure Vessel Code. (A) Evaluation of Indications (A.]) Mechanical discontinuities at the surface will be indicated by bleeding out of the penetrant; however, localized surface imperfections, such as may occur from machining marks or surface conditions, may produce similar indications which are nonrelevant to the detection of unacceptable discontinuities. (A.2) Any indication which is believed to be nonrelevant shall be regarded as a defect and shall be reexamined to whether or not actual defects are present.
Surface conditioning may precede the reexamination. Nonrelevant indications and broad areas of pigmentation which would mask indications of defects are unacceptable. (A.3) Relevant indications are those which result from mechanical discontinuities. Linear indications are those indications in which the length is more than three times the width. Rounded indications are indications which are circular or elliptical with the length less than three times the width. (A.4) An indication of a discontinuity may be larger than the discontinuity that causes it; however, the size of the indication and not the size of the discontinuity is the basis of acceptance or rejection. (B) Acceptance Standards. Indications whose major dimensions are greater than 1/16 in. (2.0 mm) shall be considered relevant. The following relevant indications are unacceptable: (B.1) any cracks or linear indications; (B.2) rounded indications with dimensions greater than 3/16 in. (5.0 mm); (B.3) four or more rounded indications in a line separated by 1/16 in. (2.0 mm) or less edge to edge; (B.4) ten or more rounded indications in any 6 sq in. (3870 mm2) of surface with the major dimension of this area not to exceed 6 in. (150 mm) with the area taken in the most unfavorable location relative to the indications being evaluated. 136.4.6 Ultrasonic Examination: When required by this Chapter (see Table 136.4), ultrasonic examination (UT) shall be performed in accordance with the ASME Boiler and Pressure Vessel Code, Section V, Article 5 and the following additional requirements. (A) The following criteria shall also be met when performing ultrasonic examinations. (A.1) The nominal thickness of the material being examined shall be greater that 5; in (12.5 mm). (A.2) The equipment used to perform the examination shall be capable of recording the UT data including the scanning positions. (A.3) NDE personnel collecting and analyzing UT data shall have demonstrated their ability to perform an acceptable examination using written procedures. The procedure shall have been demonstrated to perform. Acceptably on a qualification block with imbedded flaws. (B) Acceptance Standards: Welds that are shown by ultrasonic examination to have discontinuities which produce an indication greater than 20% of the reference level shall be investigated to the extent that ultrasonic examination personnel can determine their shape, identity, and location so that they may evaluate each discontinuity for acceptance in accordance with (B.l) and (B.2) below. (B.1) Discontinuities evaluated as being cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length. (B.2) Other discontinuities are unacceptable if the indication exceeds the reference level and their length exceeds the following: (B.2.1). 1/4 in. (6.0 mm) for t up to 3/4 in. (19.0 mm); (B.2.2). 1/3 t for t from 3/4 in. (19.0 mm) to 2 1/4 in. (57.0 mm) (B.2.3). 3/4 in (19.0 mm) for t over 2 1/4 in. (57.0 mm) where t is the thickness of the weld being examined. If the weld s two having different thicknesses at the weld, t is the thinner of these two thicknesses. (Page: 95~99).= 0 = ACCEPTANCE CRITERIA (ASME B31.3): Process Piping See Page: 68, 71-76, 98, 127-129. Details on page129. ACCEPTANCE CRITERIA (ASME Sec.1): FOR INSPECTION: REQUIRED RADIOGRAPHIC AND ULTRASONIC EXAMINATION OF WELDED BUTT TS: SEE TABLE PW-11 PW-50. QUALIFICATION OF NONDESTRUCTIVE EXAMINATION PERSONNEL PW-50.1 The Manufacturer shall be responsible for assuring that nondestructive examination (NDE) personnel have been qualified and certified in accordance with their employer’s written practice prior to performing or evaluating radiographic or ultrasonic examinations required by this Section. SNT-TC-1A3 or -189 shall be used as a guideline for employers to establish their written practice. National or international Central Certification Programs, such as the ASNT Central Certification Program (AC), may be used to fulfill the examination and demonstration requirements of the employer’s written practice. Provisions for training, experience, qualification, and certification of NDE personnel shall be described in the Manufacturer’s quality control
system (see PG-105.4). PW-50.2 NDE personnel shall be qualified by examination. Qualification of NDE Level III personnel certified prior to the 2004 Edition of Section I may be based on demonstrated ability, achievement, education, and experience. Such qualification shall be specifically addressed in the written practice. When NDE personnel have been certified in accordance with a written practice based on an edition of SNT-TC-1A or -189 earlier than that referenced in A-360, their certification shall be valid until their next scheduled recertification. PW-50.3 Recertification shall be in accordance with the employer’s written practice based on the edition of SNT-TC-1A or -189 referenced in A-360. Recertification may be based on evidence of continued satisfactory performance or by reexamination(s) deemed necessary by the employer. PW-51. ACCEPTANCE STANDARDS FOR RADIOGRAPHY , Edition: 2004 (page.105,106) PW-51.1 All welds for which a complete radiographic examination is required by PW-11 shall be radiographically examined throughout their entire length by the X-ray or gammaray method in accordance with Article 2 of Section V, except that the requirements of T-274 are to be used as a guide but not for the rejection of radiographs unless the geometrical unsharpness exceeds 0.07 in. (1.8 mm). PW-51.2 A single-welded circumferential butt t with backing strip may be radio-graphed without removing the backing strip, provided it is not to be removed subsequently and provided the image of the backing strip does not interfere with the interpretation of the resultant radiographs. PW-51.3 Indications shown on the radiographs of welds and characterized as imperfections are unacceptable under the following conditions, and shall be repaired as provided in PW-40 and the repair radio-graphed to PW-51: PW-51.3.1 Any indication characterized as a crack, or zone of incomplete fusion or penetration. PW-51.3.2 Any other elongated indication on the radiograph that has a length greater than (a) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm) (b)1 ⁄ 3 tf o r t from 3⁄4 in. (19 mm) to 21⁄4 in. (57 mm) (c) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm), where t is the thickness of the weld PW-51.3.3 Any group of aligned indications that have an aggregate length greater thant in a length of 12t, except when the distance between the successive imperfections exceeds 6L whereL is the length of the longest imperfection in the group. PW-51.3.4 Rounded indications in excess of those shown in A-250. PW-51.4 A complete set of radiographs for each job shall be retained by the Manufacturer and kept on file for a period of at least 5 years. PW-52 ACCEPTANCE STANDARDS FOR ULTRASONIC EXAMINATION PW-52.1 Technique and standards for ultrasonic examination shall follow Section V, Article 4. PW-52.2 The Manufacturer’s report, as required by T-490 of Section V, shall be retained by the Manufacturer for a minimum of 5 years. PW-52.3. Acceptance-Rejection Standards. Imperfections that cause an indication greater than 20% of the reference level shall be investigated to the extent that the ultrasonic examination personnel can determine their shape, identity, and location, and evaluate them in of PW52.3.1 and PW-52.3.2. PW-52.3.1 Cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length. the indication exceeds the reference level and their length exceeds the following: (a) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm) (b)1 ⁄ 3tf o r t from 3⁄4 in. (19 mm) to 21⁄4 in. (57 mm) (c) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm). Wheret is the thickness of the weld being examined. If the weld s two having different thicknesses at the weld,t is the thinner of these two thicknesses. (For more informationSee page no. 79, 80). A-250. ACCEPTANCE STANDARD FOR RADIOGRAPHICALLY DETERMINED ROUNDED INDICATIONS IN WELDS: A-250.1 Applicability of These Standards: These standards are applicable to ferritic, austenitic, and nonferrous materials. A-250.2 Terminology A-250.2.1 Rounded Indications: Indications with a maximum length of three times the width or less on the radiograph are defined as rounded indications. These indications may be circular, elliptical, conical, or irregular in shape and may have tails. When evaluating the size of an indication, the tail shall be included. The indication may be from any imperfection in the weld, such as porosity, slag, or tungsten. A-250.2.2 Aligned Indications: A sequence of four or more rounded indications shall be considered to be aligned
when they touch a line parallel to the length of the weld drawn through the center of the two outer rounded indications. A-250.2.3 Thickness t. t is the thickness of the weld, of the pressure–retaining material, or of the thinner of the sections being ed, whichever is least. If a full penetration weld includes a fillet weld, the thickness of the fillet weld throat shall be included in t. A-250.3 Acceptance Criteria A-250.3.1 Image Density: Density within the image of the indication may vary and is not a criterion for acceptance or rejection. A-250.3.2 Relevant Indications (See Table A- 250.3.2 for Examples): Only those rounded indications which exceed the following dimensions shall be considered relevant: (a) 1⁄10 t for t less than 1⁄8 in. (3 mm) (b) 1⁄64 in. (0.4 mm) for t 1⁄8 in. to 1⁄4 in. (6 mm), inclusive (c) 1⁄32 in. (0.8 mm) for t 1⁄4 in. (6 mm) to 2 in. (50 mm), inclusive (d) 1⁄16 in. (1.6 mm) for t greater than 2 in. (50 mm) *A-250.3.3 Maximum Size of Rounded Indication (See Table A-250.3.2 for Examples): The maximum permissible size of any indication shall be 1⁄4t, or 5⁄32 in. (4 mm), whichever is smaller; except that an isolated indication separated from an adjacent indication by 1 in. (25 mm) or more may be 1⁄3t, or 1⁄4 in. (6 mm), whichever is less. For t greater than 2 in. (50 mm) the maximum permissible size of an isolated indication shall be increased to 3⁄8 in. (10 mm). TABLE A-250.3.2 MAXIMUM PERMISSIBLE SIZE OF ROUNDED INDICATION (Examples Only) (ASME Sec. I, Edition 2004, page: 178) Thickness t, (in.) Maximum Size of Acceptable Rounded Indication (in.) Maximum Size of Non relevant Indication, in. Random Isolated Less than *For more information see Page: 179~185 (ASME Sec. I Editions: 2004) A-250.3.4 Aligned Rounded Indications: Aligned rounded indications are acceptable when the summation of the diameters of the indications is less than t in a length of 12t. (See Fig. A- 250.3.4-1.) The length of groups of aligned rounded indications and the spacing between the groups shall meet the requirements of Fig. A-250-3.4-2. A-250.3.5 Spacing: The distance between adjacent rounded indications is not a factor in determining acceptance or rejection, except as required for isolated indications or groups of aligned indications. A-250.3.6 Rounded Indication Charts: The rounded indications characterized as imperfections shall not exceed that shown in the charts. The charts in Figs. A-250.3.6-1 through A-250.3.6-6 illustrates various types of assorted, randomly dispersed, and clustered rounded indications for different weld thicknesses greater than 1⁄8 in. (3 mm). These charts represent the maximum acceptable concentration limits for rounded indications. The chart for each thickness range represents full-scale 6 in. (150 mm) radiographs, and shall not be enlarged or reduced. The distributions shown are not necessarily the patterns that may appear on the radiograph, but are typical of the concentration and size of indications permitted. A-250.3.7. Weld Thickness t Less Than 1⁄8 in. (3 mm): For t less than 1⁄8 in. (3 mm), the maximum number of rounded indications shall not exceed 12 in a 6 in. (150 mm) length of weld. A proportionally fewer number of indications shall be permitted in welds less than 6 in. (150 mm) in length. A-250.3.8 Clustered Indications: The illustrations for clustered indications show up to four times as many indications in a local area, as that shown in the illustrations for random indications. The length of an acceptable cluster shall not exceed the lesser of 1 in. (25 mm) or 2t. Where more than one cluster is present, the sum of the lengths of the clusters shall not exceed 1 in. (25 mm) in a 6 in. (150 mm) length of weld.
(1) A complete set of records, as described in II-292, shall be evaluated by the Manufacturer prior to being presented to the Inspector. Imperfections listed in UW-51(b)(1), (2), (3), and (4) are unacceptable and shall be repaired as provided in UW-38 and the repair reexamined by either film or Real Time Radioscopic Examination. Records shall be retained by the Manufacturer until the Data Report has been signed by the Inspector. (2) Provisions for training, experience, qualification, and certification of personnel responsible for equipment setup, calibration, operation, and evaluation of examination data shall be described in the Manufacturer’s Quality Control System [see Appendix 10]. (3) The use of Real Time Radioscopic Examination shall be noted under remarks on the Manufacturer’s Data Report. UW-52: SPOT EXAMINATION OF WELDED TS NOTE: Spot radiographing of a welded t is recognized as an effective inspection tool. The spot radiography rules are also considered to be an aid to quality control. Spot radiographs made directly after a welder or an operator has completed a unit of weld proves that the work is or is not being done in accordance with a satisfactory procedure. If the work is unsatisfactory, corrective steps can then be taken to improve the welding in the subsequent units, which unquestionably will improve the weld quality. Spot radiography in accordance with these rules will not ensure a fabrication product of predetermined quality level throughout. It must be realized that an accepted vessel under these spot radiography rules may still contain defects which might be disclosed on further examination. If all radiographically disclosed weld defects must be eliminated from a vessel, then 100% radiography must be employed. (a) Butt welded ts which are to be spot radiographed shall be examined locally as provided herein. (b) Minimum Extent of Spot Radiographic Examination (1) One spot shall be examined on each vessel for each 50 ft (15 m) increment of weld or fraction thereof for which a t efficiency from column (b) of Table UW-12 is selected. However, for identical vessels or parts, each with less than 50 ft (15 m) of weld for which a t efficiency from column (b) of Table UW-12 is selected, 50 ft (15 m) increments of weld may be represented by one spot examination. (2) For each increment of weld to be examined, a sufficient number of spot radiographs shall be taken to examine the welding of each welder or welding operator. Under conditions where two or more welders or welding operators make weld layers in a t, or on the two sides of a doublewelded butt t, one spot may represent the work of all welders or welding operators. (3) Each spot examination shall be made as soon as practicable after completion of the increment of weld to be examined. The location of the spot shall be chosen by the Inspector after completion of the increment of welding to be examined, except that when the Inspector has been notified in advance and cannot be present or otherwise make the selection, the fabricator may exercise his own judgment in selecting the spots. (4) Radiographs required at specific locations to satisfy the rules of other paragraphs, such as UW-9(d), UW-11(a)(5)(b), and UW-14(b), shall not be used to satisfy the requirements for spot radiography. (c) Standards for Spot Radiographic Examination: Spot examination by radiography shall be made in accordance with the technique prescribed in UW-51(a). The minimum length of spot radiograph shall be 6 in. Spot radiographs may be retained or be discarded by the Manufacturer after acceptance of the vessel by the Inspector. The acceptability of welds examined by spot radiography shall be judged by the following standards. (1) Welds in which indications are characterized as cracks or zones of incomplete fusion or penetration shall be unacceptable. (2) Welds in which indications are characterized as slag inclusions or cavities shall be
unacceptable if the length of any such indication is greater than 2⁄3t where t is the thickness of the weld excluding any allowable reinforcement. For a butt weld ing two having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t. If several indications within the above limitations exist in line, the welds shall be judged acceptable if the sum of the longest dimensions of all such indications is not more than t in a length of 6t (or proportionately for radiographs shorter than 6t) and if the longest indications considered are separated by at least 3L of acceptable weld metal where L is the length of the longest indication. The maximum length of acceptable indications shall be 3⁄4 in. (19 mm). Any such indications shorter than 1⁄4 in. (6 mm) shall be acceptable for any plate thickness. (3) Rounded indications are not a factor in the acceptability of welds not required to be fully radiographed. (d) Evaluation and Retests: (1) When a spot, radiographed as required in (b)(1) or (b)(2) above, is acceptable in accordance with (c)(1) and (c)(2) above, the entire weld increment represented by this radiograph is acceptable. (2) When a spot, radiographed as required in (b)(1) or (b)(2) above, has been examined and the radiograph discloses welding which does not comply with the minimum quality requirements of (c)(1) or (c)(2) above, two additional spots shall be radio graphically examined in the same weld increment at locations away from the original spot. The locations of these additional spots shall be determined by the Inspector or fabricator as provided for the original spot examination in (b) (3) above. (a) If the two additional spots examined show welding which meets the minimum quality requirements of (c)(1) and (c)(2) above, the entire weld increment represented by the three radiographs is acceptable provided the defects disclosed by the first of the three radiographs are removed and the area repaired by welding. The weld repaired area shall be radio-graphically examined in accordance with the foregoing requirements of UW-52. (b) If either of the two additional spots examined shows welding which does not comply with the minimum quality requirements of (c)(1) or (c)(2) above, the entire increment of weld represented shall be rejected. The entire rejected weld shall be removed and the t shall be re-welded or, at the fabricator’s option, the entire increment of weld represented shall be completely radiographed and only defects need be corrected. (c) Repair welding shall be performed using a qualified procedure and in a manner acceptable to the Inspector. The re-welded t, or the weld repaired areas, shall be spot radio-graphically examined at one location in accordance with the foregoing requirements of UW-52. MANDATORY APPENDIX 4: ROUNDED INDICATIONS CHARTS ACCEPTANCE STANDARD FOR RADIOGRAPHICALLY DETERMINED ROUNDED INDICATIONS IN WELDS. 4-1 APPLICABILITY OF THESE STANDARDS These standardsare applicable to ferritic, austenitic, and nonferrous materials. 4-2 TERMINOLOGY (a) Rounded Indications: Indications with a maximum length of three times the width or less on the radiograph are defined as rounded indications. These indications may be circular, elliptical, conical, or irregular in shape and may have tails. When evaluating the size of an indication, the tail shall be included. The indication may be from any imperfection in the weld, such as porosity, slag, or tungsten. (b) Aligned Indications: A sequence of four or more rounded indications shall be considered to be aligned when they touch a line parallel to the length of the weld drawn through the center of the two outer rounded indications. (c) Thickness t: t is the thickness of the weld, excluding any allowable reinforcement. For a butt weld ing two having different thicknesses at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t. (a) Image Density: Density within the image of the indication may vary and is not a criterion for acceptance or
rejection. (b) Relevant Indications: (See Table 4-1 for examples.): Only those rounded indications which exceed the following dimensions shall be considered relevant. (1) 1⁄10t for t less than 1⁄8 in. (3 mm) (2) 1⁄64 in. (0.4mm) for t from 1⁄8 in. to 1⁄4 in. (3 mm to6 mm), incl. (3) 1⁄32 in. (0.8mm) for t greater than 1⁄4 in. to 2 in. (6 mm to 50 mm), incl. (4) 1⁄16 in. (1.6mm) for t greater than 2 in. (50 mm). (c) Maximum Size of Rounded Indication. (See Table4-1 for examples.): The maximum permissible size of any indication shall be 1⁄4t, or 5⁄32 in. (4 mm), whichever is smaller; except that an isolated indication separated from an adjacent indication by 1in. (25 mm) or more may be 1⁄3t, or 1⁄4 in. (6 mm), whichever is less. For t greater than 2 in. (50 mm) the maximum permissible size of an isolated indication shall be increased to 3⁄8 in. (10 mm). (d) Aligned Rounded Indications: Aligned rounded indications are acceptable when the summation of the diameters of the indications is less than t in a length of 12t. See Fig. 4-1. The length of groups of aligned rounded indications and the spacing between the groups shall meet the requirements of Fig. 4-2. (e) Spacing: The distance between adjacent rounded indications is not a factor in determining acceptance or rejection, except as required for isolated indications or groups of aligned indications. (f) Rounded Indication Charts: The rounded indications characterized as imperfections shall not exceed that shown in the charts. The charts in Figs. 4-3 through 4-8 illustrate various types of assorted, randomly dispersed and clustered rounded indications for different weld thicknesses greater than 1⁄8 in. (3 mm). These charts represent the maximum acceptable concentration limits for rounded indications. The charts for each thickness range represent full-scale 6 in. (150 mm) radiographs, and shall not be enlarged or reduced. The distributions shown are not necessarily the patterns that may appear on the radiograph, but are typical of the concentration and size of indications permitted. (g) Weld Thickness t less than 1/8 in. (3 mm): For t less than 1⁄8 in. (3 mm) the maximum number of rounded indications shall not exceed 12 in a 6 in. (150 mm) length of weld. A proportionally fewer number of indications shall be permitted in welds less than 6 in. (150 mm) in length. (h) Clustered Indications: The illustrations for clustered indications show up to four times as many indications in a local area, as that shown in the illustrations for random indications. The length of an acceptable cluster shall not exceed the lesser of 1 in. (25 mm) or 2t. Where more than one cluster is present, the sum of the lengths of the clusters shall not exceed 1 in. (25 mm) in a 6 in. (150 mm) length weld. ***Table for maximum size of acceptable rounded indication (Table 4.1): (ASME Sec VIII Div.1) Thickness t, (in.) Maximum Size of Acceptable Rounded Indication (in.) Maximum Size of Non relevant Indication, in. Random Isolated Less than Thickness t, (mm.) Maximum Size of Acceptable Rounded Indication (mm.) Maximum Size of Non relevant Indication, mm. Random Isolated Less than NOTE: This Table contains examples only (P.138 UW-51, 368 editions: 2004). *For more information see Table 4.2-4.8 Page: 370~375(ASME Sec VIII Div.1editions: 2004) ACCEPTANCE CRITERIA (API-1104): 9.3 RADIOGRAPHIC TESTING: Note: All densities referred to in 9.3.1 through 9.3.13 are based on negative images. 9.3.1 Inadequate Penetration without High-low
Inadequate penetration without high-low (IP) is defined as the incomplete filling of the weld root. This condition is shown schematically in Figure 13. IP shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IP exceeds 1 in. (25 mm). b. The aggregate length of indications of IP in any continuous 12 in. (300 mm) length of weld exceeds 1 in. (25 mm). c. The aggregate length of indications of IP exceeds 8% of the weld length in any weld less than 12 in. (300 mm) in length. 9.3.2 Inadequate Penetration Due to High-low Inadequate penetration due to high-low (IPD) is defined as the condition that exists when one edge of the root is exposed (or unbonded) because adjacent pipe or fitting ts are misaligned. This condition is shown schematically in Figure 14. IPD shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IPD exceeds 2 in. (50 mm). b. The aggregate length of indications of IPD in any continuous 12 in. (300 mm) length of weld exceeds 3 in. (75 mm). 9.3.3 Inadequate Cross Penetration Inadequate cross penetration (I) is defined as a subsurface imperfection between the first inside and the first outside that is caused by inadequately penetrating the vertical land faces. This condition is shown schematically in Figure 15. I shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of I exceeds 2 in. (50 mm). b. The aggregate length of indications of I in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). 9.3.4 Incomplete Fusion Incomplete fusion (IF) is defined as a surface imperfection between the weld metal and the base material that is open to the surface. This condition is shown schematically in Figure 16. IF shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IF exceeds 1 in. (25 mm). b. The aggregate length of indications of IF in any continuous 12 in. (300 mm) length of weld exceeds 1 in. (25 mm). c. The aggregate length of indications of IF exceeds 8% of the weld length in any weld less than 12 in. (300 mm) in length. 9.3.5 Incomplete Fusion Due to Cold Lap Incomplete fusion due to cold lap (IFD) is defined as an imperfection between two adjacent weld beads or between the weld metal and the base metal that is not open to the surface. This condition is shown schematically in Figure 17. IFD shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of IFD exceeds 2 in. (50 mm). b. The aggregate length of indications of IFD in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). c. The aggregate length of indications of IFD exceeds 8% of the weld length. 9.3.6 Internal Concavity Internal concavity (IC) is defined in 3.2.8 and is shown schematically in Figure 18. Any length of internal concavity is acceptable, provided the density of the radiographic image of the internal concavity does not exceed that of the thinnest adjacent parent material. For areas that exceed the density of the thinnest adjacent parent material, the criteria for burn through (see 9.3.7) are applicable. 9.3.7 Burn-through 9.3.7.1 A burn-through (BT) is defined as a portion of the root bead where excessive penetration has caused the weld puddle to be blown into the pipe. 9.3.7.2 For pipe with an outside diameter greater than or equal to 2.375 in. (60.3 mm), a BT shall be considered a defect should any of the following conditions exist: a. The maximum dimension exceeds 1/4 in. (6 mm) and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material. b. The maximum dimension exceeds the thinner of the nominal wall thicknesses ed, and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material.
c. The sum of the maximum dimensions of separate BTs whose image density for any portion of the BTs exceeds that of the thinnest adjacent parent material and exceeds 1/2 in. (13 mm) in any continuous 12 in. (300 mm) length of weld or the total weld length, whichever is less. 9.3.7.3 For pipe with an outside diameter less than 2.375 in. (60.3 mm), a BT shall be considered a defect when any of the following conditions exists: a. The maximum dimension exceeds 1/4 in. (6 mm) and the density in any portion of the BTs image exceeds that of the thinnest adjacent parent material. b. The maximum dimension exceeds the thinner of the nominal wall thicknesses ed, and the density in any portion of the BT’s image exceeds that of the thinnest adjacent parent material. c. More than one BT of any size is present and the density in any portion of the BTs image *exceeds that of the thinnest adjacent parent material. 9.3.8 Slag Inclusions 9.3.8.1 A slag inclusion is defined as a nonmetallic solid entrapped in the weld metal or between the weld metal and the parent material. Elongated slag inclusions (ESIs)— e.g., continuous or broken slag lines or wagon tracks-are usually found at the fusion zone. Isolated slag inclusions (ISIs) are irregularly shaped and may be located anywhere in the weld. For evaluation purposes, when the size of a radiographic indication of slag is measured, the indication’s maximum dimension shall be considered its length. 9.3.8.2 For pipe with an outside diameter greater than or equal to 2.375 in. (60.3 mm), slag inclusions shall be considered a defect should any of the following conditions exist: a. The length of an ESI indication exceeds 2 in. (50 mm). Note: Parallel ESI indications separated by approximately the width of the root bead (wagon tracks) shall be considered a single indication unless the width of either of them exceeds 1/32 in. (0.8 mm). In that event, they shall be considered separate indications. b. The aggregate length of ESI indications in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). c. The width of an ESI indication exceeds 1/16 in. (1.6 mm). d. The aggregate length of ISI indications in any continuous12 in. (300 mm) length of weld exceeds 1/2 in. (13 mm). e. The width of an ISI indication exceeds 1/8 in. (3 mm). f. More than four ISI indications with the maximum width of 1/8 in. (3 mm) are present in any continuous 12 in. (300 mm) length of weld. g. The aggregate length of ESI and ISI indications exceeds 8% of the weld length. 9.3.8.3 For pipe with an outside diameter less than 2.375 in. (60.3 mm), slag inclusions shall be considered a defect should any of the following conditions exist: a. The length of an ESI indication exceeds three times the thinner of the nominal wall thicknesses ed. Note: Parallel ESI indications separated by approximately the width of the root bead (wagon tracks) shall be considered a single indication unless the width of either of them exceeds 1/32 in. (0.8 mm). In that event, they shall be considered separate indications. b. The width of an ESI indication exceeds 1/16 in. (1.6 mm). c. The aggregate length of ISI indications exceeds two times the thinner of the nominal wall thicknesses ed and the width exceeds one-half the thinner of the nominal wall thicknesses ed. d. The aggregate length of ESI and ISI indications exceeds 8% of the weld length. 9.3.9 Porosity *9.3.9.1 Porosity is defined as gas trapped by solidifying weld metal before the gas has a chance to rise to the surface of the molten puddle and escape. Porosity is generally spherical but may be elongated or irregular in shape, such as piping (wormhole) porosity. When the size of the radiographic indication produced by a pore is measured, the maximum dimension of the indication shall apply to the criteria given in 9.3.9.2 through 9.3.9.4. 9.3.9.2 Individual or scattered porosity (P) shall be considered a defect should any of the following conditions exist: a. The size of an individual pore exceeds 1/8 in. (3 mm). b. The size of an individual pore exceeds 25% of the thinner of the nominal wall thicknesses ed. c. The distribution of scattered porosity exceeds the concentration permitted by Figures 19 or 20. 9.3.9.3 Cluster porosity () that occurs in any except the finish shall comply with the criteria of 9.3.9.2. that occurs in the finish shall be considered a defect should any of the following conditions exist. a. The diameter of the cluster exceeds 1/2 in. (13 mm). b. The aggregate length of in any continuous 12 in. (300 mm) length of weld exceeds 1/2 in.
(13 mm). 9.3.9.4 Hollow-bead porosity (HB) is defined as elongated linear porosity that occurs in the root . HB shall be considered a defect should any of the following conditions exist: a. The length of an individual indication of HB exceeds 1/2 in. (13 mm). b. The aggregate length of indications of HB in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). c. Individual indications of HB, each greater than 1/4 in. (6 mm) in length, are separated by less than 2 in. (50 mm). d. The aggregate length of all indications of HB exceeds 8% of the weld length. 9.3.10 Cracks Cracks (C) shall be considered a defect should any of the following conditions exists: a. The crack, of any size or location in the weld, is not a shallow crater crack or star crack. b. The crack is a shallow crater crack or star crack with a length that exceeds 5/32 in. (4 mm). Note: Shallow crater cracks or star cracks are located at the stopping point of weld beads and are the result of weld metal contractions during solidification. 9.3.11 Undercutting Undercutting is defined as a groove melted into the parent material adjacent to the toe or roots of the weld and left unfilled by weld metal. Undercutting adjacent to the cover (EU) or root (IU) shall be considered a defect should any of the following conditions exists: a. The aggregate length of indications of EU and IU, in any combination, in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). b. The aggregate length of indications of EU and IU, in any combination, exceeds one-sixth of the weld length. Note: See 9.7 for acceptance standards for undercutting when visual and mechanical measurements are employed. 9.3.12 Accumulation of Imperfections Excluding incomplete penetration due to high-low and undercutting, any accumulation of imperfections (AI) shall be considered a defect should any of the following conditions exist: a. The aggregate length of indications in any continuous 12 in. (300 mm) length of weld exceeds 2 in. (50 mm). b. The aggregate length of indications exceeds 8% of the weld length. ***( For more information see page: 22, 24~26; API-1104, 20TH Edition Nov’2005). *ACCEPTANCE CRITERIA (ASME B31.1): 136.4 Examination Methods of Welds *136.4.1 Nondestructive Examination. Nondestructive examinations shall be performed in accordance with the requirements of this Chapter. The types and extent of mandatory examinations for pressure welds and welds to pressure retainingcomponents are specified in Table 136.4. For welds other than those covered by Table 136.4, only visual examination is required. Welds requiring nondestructive examination shall comply with the applicable acceptance standards for indications as specified in paras. 136.4.2 through 136.4.6. As a guide, the detection capabilities for the examination method are shown in Table 136.4.1. Welds not requiring examination (i.e. RT; UT, MT, or PT) by this Code or the Engineering design shall be judged acceptable if they meet the examination requirements of para. 136.4.2 and the pressure test requirements specified in Para. 137. 136.4.5 Radiography: When required by this Chapter (see Table 136.4), radiographic examination shall be performed in accordance with Article 2 of Section V of the ASME Boiler and Pressure Vessel Code, except that the requirements of T-285 are to be used as a guide but not for the rejection of radiographs unless the geometrical unsharpness exceeds 0.07 in. (A) Acceptance Standards. Welds that are shown by radiography to have any of the following types of discontinuities are unacceptable: (A.1) any type of crack or zone of incomplete fusion or penetration; (A.2) any other elongated indication which has a length greater than: (A.2.1) 1/4 in. (6.0 mm) for t up to 3/4 in. (19.0 mm), inclusive; (A.2.2) 1/3t for t from 3/4 in. (19.0 mm) to 2 1/4 in.(57.0 mm), incl.; (A.2.3) 3/4 in. (19.0 mm) for t over 2 1/4 in. (57.0 mm) where t is the thickness of the thinner portion of the weld. (2.0 mm). (NOTE: z referred to in (A.2.1). (A.2.2). and (A.2.3) above pertains to the thickness of the weid being examined; if a weld s two having different thickness at the weld, t is the thinner of these two thickness.) (A.3) any group of indications in line that have an aggregate length greater than t in a length of 12, except where the distance between the successive indications exceeds 6L where L is the
longest indication in the group; (A.4) porosity in excess of that shown as acceptable in Appendix A-250 of Section I of the *ASME Boiler and Pressure Vessel Code; (A.5) root concavity when there is an abrupt change in density, as indicated on the radiograph. 136.4.2 Visual Examination: Visual examination as defined in para. 100.2. shall be performed, as necessary, during the fabrication and erection of piping components to provide verification that the design and WPS requirements are being met. In addition, visual examination shall be performed to that all completed welds inpipe and piping components comply with the acceptance standards specified in (A) below or with the limitations on imperfections specified in the material specification under which the pipe or component was furnished. (A) Acceptance Standards. The following indications are unacceptable: (A. I) cracks-external surface; (A.2) undercut on surface which is greater than 1/32 in. (1.0 mm) deep; Table 127.4.2; (A.3) weld reinforcement greater than specified in (A.4) lack of fusion on surface; (A.5) incomplete penetration (applies only when inside surface is readily accessible); (A.6) any other linear indications greater than 3/16 in. (5.0 mm) long; (A.7) surface porosity with rounded indications having dimensions greater than in.3/16 in.(5.0 mm) or four or more rounded indications separated by 1/16 in. (2.0 mm) or less edge to edge in any direction. Rounded indications are indications which are circular or elliptical with their length less than three times their width. 136.4.3 Magnetic Particle Examination: Whenever required by this Chapter (see Table 136.4), magnetic particle examination shall be performed in accordance with the methods of Article 7, Section V, of the ASh4E Boiler and Pressure Vessel Code. (A) Evaluation of Indications (A. 1) Mechanical discontinuities at the surface will be indicated by the retention of the examination medium. All indications are not necessarily defects; however, certain metallurgical discontinuities and magnetic permeability variations may produce similar indications which are not relevant to the detection of unacceptable discontinuities. (A.2) Any indication which is believed to be nonrelevant shall be reexamined to whether or not actual defects are present. Surface conditioning may precede the reexamination. Nonrelevant indications which would mask indications of defects are unacceptable. (A.3) Relevant indications are those which result from unacceptable mechanical discontinuities. Linear indications are those indications in which the length is more than three times the width. Rounded indications are indications which are circular or elliptical with the length less than three times the width. (A.4) An indication of a discontinuity may be larger than the discontinuity that causes it; however, the size of the indication and not the size of the discontinuity is the basis of acceptance or rejection. (B) Acceptance Standards. The following relevant indications are unacceptable: (B.1) any cracks or linear indications; (B.2) rounded indications with dimensions greater than 3/16 in. (5.0 mm); (B.3) four or more rounded indications in a line separated by t / , j in. (2.0 mm) or less edge to edge; (B.4) Ten or more rounded indications in any 6 sq in. (3870 mm’) of surface with the major dimension of this area not to exceed 6 in. (150 mm) with the area taken in the most unfavorable location relative to the indications being evaluated. 136.4.4 Liquid Penetrant Examination: Whenever required by this Chapter (see Table 136.4), liquid penetrant examination shall be performed in accordance with the methods of Article 6, Section V, of the ASME Boiler and Pressure Vessel Code. (A) Evaluation of Indications (A.]) Mechanical discontinuities at the surface will be indicated by bleeding out of the penetrant; however, localized surface imperfections, such as may occur from machining marks or surface conditions, may produce similar indications which are nonrelevant to the detection of unacceptable discontinuities. (A.2) Any indication which is believed to be nonrelevant shall be regarded as a defect and shall be reexamined to whether or not actual defects are present.
Surface conditioning may precede the reexamination. Nonrelevant indications and broad areas of pigmentation which would mask indications of defects are unacceptable. (A.3) Relevant indications are those which result from mechanical discontinuities. Linear indications are those indications in which the length is more than three times the width. Rounded indications are indications which are circular or elliptical with the length less than three times the width. (A.4) An indication of a discontinuity may be larger than the discontinuity that causes it; however, the size of the indication and not the size of the discontinuity is the basis of acceptance or rejection. (B) Acceptance Standards. Indications whose major dimensions are greater than 1/16 in. (2.0 mm) shall be considered relevant. The following relevant indications are unacceptable: (B.1) any cracks or linear indications; (B.2) rounded indications with dimensions greater than 3/16 in. (5.0 mm); (B.3) four or more rounded indications in a line separated by 1/16 in. (2.0 mm) or less edge to edge; (B.4) ten or more rounded indications in any 6 sq in. (3870 mm2) of surface with the major dimension of this area not to exceed 6 in. (150 mm) with the area taken in the most unfavorable location relative to the indications being evaluated. 136.4.6 Ultrasonic Examination: When required by this Chapter (see Table 136.4), ultrasonic examination (UT) shall be performed in accordance with the ASME Boiler and Pressure Vessel Code, Section V, Article 5 and the following additional requirements. (A) The following criteria shall also be met when performing ultrasonic examinations. (A.1) The nominal thickness of the material being examined shall be greater that 5; in (12.5 mm). (A.2) The equipment used to perform the examination shall be capable of recording the UT data including the scanning positions. (A.3) NDE personnel collecting and analyzing UT data shall have demonstrated their ability to perform an acceptable examination using written procedures. The procedure shall have been demonstrated to perform. Acceptably on a qualification block with imbedded flaws. (B) Acceptance Standards: Welds that are shown by ultrasonic examination to have discontinuities which produce an indication greater than 20% of the reference level shall be investigated to the extent that ultrasonic examination personnel can determine their shape, identity, and location so that they may evaluate each discontinuity for acceptance in accordance with (B.l) and (B.2) below. (B.1) Discontinuities evaluated as being cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length. (B.2) Other discontinuities are unacceptable if the indication exceeds the reference level and their length exceeds the following: (B.2.1). 1/4 in. (6.0 mm) for t up to 3/4 in. (19.0 mm); (B.2.2). 1/3 t for t from 3/4 in. (19.0 mm) to 2 1/4 in. (57.0 mm) (B.2.3). 3/4 in (19.0 mm) for t over 2 1/4 in. (57.0 mm) where t is the thickness of the weld being examined. If the weld s two having different thicknesses at the weld, t is the thinner of these two thicknesses. (Page: 95~99).= 0 = ACCEPTANCE CRITERIA (ASME B31.3): Process Piping See Page: 68, 71-76, 98, 127-129. Details on page129. ACCEPTANCE CRITERIA (ASME Sec.1): FOR INSPECTION: REQUIRED RADIOGRAPHIC AND ULTRASONIC EXAMINATION OF WELDED BUTT TS: SEE TABLE PW-11 PW-50. QUALIFICATION OF NONDESTRUCTIVE EXAMINATION PERSONNEL PW-50.1 The Manufacturer shall be responsible for assuring that nondestructive examination (NDE) personnel have been qualified and certified in accordance with their employer’s written practice prior to performing or evaluating radiographic or ultrasonic examinations required by this Section. SNT-TC-1A3 or -189 shall be used as a guideline for employers to establish their written practice. National or international Central Certification Programs, such as the ASNT Central Certification Program (AC), may be used to fulfill the examination and demonstration requirements of the employer’s written practice. Provisions for training, experience, qualification, and certification of NDE personnel shall be described in the Manufacturer’s quality control
system (see PG-105.4). PW-50.2 NDE personnel shall be qualified by examination. Qualification of NDE Level III personnel certified prior to the 2004 Edition of Section I may be based on demonstrated ability, achievement, education, and experience. Such qualification shall be specifically addressed in the written practice. When NDE personnel have been certified in accordance with a written practice based on an edition of SNT-TC-1A or -189 earlier than that referenced in A-360, their certification shall be valid until their next scheduled recertification. PW-50.3 Recertification shall be in accordance with the employer’s written practice based on the edition of SNT-TC-1A or -189 referenced in A-360. Recertification may be based on evidence of continued satisfactory performance or by reexamination(s) deemed necessary by the employer. PW-51. ACCEPTANCE STANDARDS FOR RADIOGRAPHY , Edition: 2004 (page.105,106) PW-51.1 All welds for which a complete radiographic examination is required by PW-11 shall be radiographically examined throughout their entire length by the X-ray or gammaray method in accordance with Article 2 of Section V, except that the requirements of T-274 are to be used as a guide but not for the rejection of radiographs unless the geometrical unsharpness exceeds 0.07 in. (1.8 mm). PW-51.2 A single-welded circumferential butt t with backing strip may be radio-graphed without removing the backing strip, provided it is not to be removed subsequently and provided the image of the backing strip does not interfere with the interpretation of the resultant radiographs. PW-51.3 Indications shown on the radiographs of welds and characterized as imperfections are unacceptable under the following conditions, and shall be repaired as provided in PW-40 and the repair radio-graphed to PW-51: PW-51.3.1 Any indication characterized as a crack, or zone of incomplete fusion or penetration. PW-51.3.2 Any other elongated indication on the radiograph that has a length greater than (a) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm) (b)1 ⁄ 3 tf o r t from 3⁄4 in. (19 mm) to 21⁄4 in. (57 mm) (c) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm), where t is the thickness of the weld PW-51.3.3 Any group of aligned indications that have an aggregate length greater thant in a length of 12t, except when the distance between the successive imperfections exceeds 6L whereL is the length of the longest imperfection in the group. PW-51.3.4 Rounded indications in excess of those shown in A-250. PW-51.4 A complete set of radiographs for each job shall be retained by the Manufacturer and kept on file for a period of at least 5 years. PW-52 ACCEPTANCE STANDARDS FOR ULTRASONIC EXAMINATION PW-52.1 Technique and standards for ultrasonic examination shall follow Section V, Article 4. PW-52.2 The Manufacturer’s report, as required by T-490 of Section V, shall be retained by the Manufacturer for a minimum of 5 years. PW-52.3. Acceptance-Rejection Standards. Imperfections that cause an indication greater than 20% of the reference level shall be investigated to the extent that the ultrasonic examination personnel can determine their shape, identity, and location, and evaluate them in of PW52.3.1 and PW-52.3.2. PW-52.3.1 Cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length. the indication exceeds the reference level and their length exceeds the following: (a) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm) (b)1 ⁄ 3tf o r t from 3⁄4 in. (19 mm) to 21⁄4 in. (57 mm) (c) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm). Wheret is the thickness of the weld being examined. If the weld s two having different thicknesses at the weld,t is the thinner of these two thicknesses. (For more informationSee page no. 79, 80). A-250. ACCEPTANCE STANDARD FOR RADIOGRAPHICALLY DETERMINED ROUNDED INDICATIONS IN WELDS: A-250.1 Applicability of These Standards: These standards are applicable to ferritic, austenitic, and nonferrous materials. A-250.2 Terminology A-250.2.1 Rounded Indications: Indications with a maximum length of three times the width or less on the radiograph are defined as rounded indications. These indications may be circular, elliptical, conical, or irregular in shape and may have tails. When evaluating the size of an indication, the tail shall be included. The indication may be from any imperfection in the weld, such as porosity, slag, or tungsten. A-250.2.2 Aligned Indications: A sequence of four or more rounded indications shall be considered to be aligned
when they touch a line parallel to the length of the weld drawn through the center of the two outer rounded indications. A-250.2.3 Thickness t. t is the thickness of the weld, of the pressure–retaining material, or of the thinner of the sections being ed, whichever is least. If a full penetration weld includes a fillet weld, the thickness of the fillet weld throat shall be included in t. A-250.3 Acceptance Criteria A-250.3.1 Image Density: Density within the image of the indication may vary and is not a criterion for acceptance or rejection. A-250.3.2 Relevant Indications (See Table A- 250.3.2 for Examples): Only those rounded indications which exceed the following dimensions shall be considered relevant: (a) 1⁄10 t for t less than 1⁄8 in. (3 mm) (b) 1⁄64 in. (0.4 mm) for t 1⁄8 in. to 1⁄4 in. (6 mm), inclusive (c) 1⁄32 in. (0.8 mm) for t 1⁄4 in. (6 mm) to 2 in. (50 mm), inclusive (d) 1⁄16 in. (1.6 mm) for t greater than 2 in. (50 mm) *A-250.3.3 Maximum Size of Rounded Indication (See Table A-250.3.2 for Examples): The maximum permissible size of any indication shall be 1⁄4t, or 5⁄32 in. (4 mm), whichever is smaller; except that an isolated indication separated from an adjacent indication by 1 in. (25 mm) or more may be 1⁄3t, or 1⁄4 in. (6 mm), whichever is less. For t greater than 2 in. (50 mm) the maximum permissible size of an isolated indication shall be increased to 3⁄8 in. (10 mm). TABLE A-250.3.2 MAXIMUM PERMISSIBLE SIZE OF ROUNDED INDICATION (Examples Only) (ASME Sec. I, Edition 2004, page: 178) Thickness t, (in.) Maximum Size of Acceptable Rounded Indication (in.) Maximum Size of Non relevant Indication, in. Random Isolated Less than *For more information see Page: 179~185 (ASME Sec. I Editions: 2004) A-250.3.4 Aligned Rounded Indications: Aligned rounded indications are acceptable when the summation of the diameters of the indications is less than t in a length of 12t. (See Fig. A- 250.3.4-1.) The length of groups of aligned rounded indications and the spacing between the groups shall meet the requirements of Fig. A-250-3.4-2. A-250.3.5 Spacing: The distance between adjacent rounded indications is not a factor in determining acceptance or rejection, except as required for isolated indications or groups of aligned indications. A-250.3.6 Rounded Indication Charts: The rounded indications characterized as imperfections shall not exceed that shown in the charts. The charts in Figs. A-250.3.6-1 through A-250.3.6-6 illustrates various types of assorted, randomly dispersed, and clustered rounded indications for different weld thicknesses greater than 1⁄8 in. (3 mm). These charts represent the maximum acceptable concentration limits for rounded indications. The chart for each thickness range represents full-scale 6 in. (150 mm) radiographs, and shall not be enlarged or reduced. The distributions shown are not necessarily the patterns that may appear on the radiograph, but are typical of the concentration and size of indications permitted. A-250.3.7. Weld Thickness t Less Than 1⁄8 in. (3 mm): For t less than 1⁄8 in. (3 mm), the maximum number of rounded indications shall not exceed 12 in a 6 in. (150 mm) length of weld. A proportionally fewer number of indications shall be permitted in welds less than 6 in. (150 mm) in length. A-250.3.8 Clustered Indications: The illustrations for clustered indications show up to four times as many indications in a local area, as that shown in the illustrations for random indications. The length of an acceptable cluster shall not exceed the lesser of 1 in. (25 mm) or 2t. Where more than one cluster is present, the sum of the lengths of the clusters shall not exceed 1 in. (25 mm) in a 6 in. (150 mm) length of weld.
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