Angle Type Blowdown Valve 5n4e14

INSTRUCTION MANUAL BLOW DOWN VALVE SIZE : 1”,1-1/2” CLASS 1500,2000

Bharat Heavy Electricals Limited Tiruchirapalli

PUB.NO.7048 1

HIGH PRESSURE BLOW DOWN VALVES NOMINAL BORE: 1",1-1/2"

RATING: Class 1500,2000

Orifice Sizes -. 1/8", 3/16",1/4",5/16",3/8",7/16" & 1/2" FOR 1" 3/8", 7/16", 1/2",5/8", 3/4", 7/8", 1" FOR 1-1/2".

1.GENERAL The valve is operated easily by rotating the handle clockwise to close and counterclockwise to open. Graduations are available in the dial to indicate 1/20th of the handwheel turn. This valve recommended for blow-down service from very high pressure. Suitable orifice size is to be selected based on the blow-down capacity required for the given pressure. 2. HANDLING Care should be exercised when handling the valves to prevent damage to handle, stem, actuator or other parts. 3. STORAGE Valves should be stored under cover and protected from excessive dust and dirt. Ensure that valve ports are properly closed with end caps. 4. PRE-INSTALLATION Prior to installation, the following steps should be taken: (1) Keep the valve ends closed with end caps till the time of installation. (11) Inspect valve flow age and connecting pipeline for obstructions or foreign materials. Clean where necessary. (111) Check packing gland bolting to make sure that the packing is compressed. If the nuts are loose, tighten as per the procedure given in this manual. 5. INSTALLATION (1) Mount the valve in the line with pressure in the upper side. The flow direction in the high Pressure Blow down Valve is from sidewards to bottom, which is also indicated by an arrow on the valve to aid installation. (11) Valves should be fully open prior to welding. Care should be taken not to ground to valve yoke, stem or handwheel when welding. For further instructions on storage and installation refer Publication No. 700 1. 6. OPERATION The valve is operated by rotating the handle in clockwise direction to close and counter-clockwise to open. If the valve does not shut off tightly when closed, opening the valve and re-closing may flush out any foreign material entrapped in the seats. Do not use a wrench to close the valve. If there 2

is leakage through the seats, when seating surfaces are free of foreign material, the seats will have to be refinished as per the procedure given in this manual. When putting the valve in service and when the valve has been brought up temperature, the packing should be checked for leakage. If leakage is noticed the packing gland should be adjusted immediately. Continued leakage through the gland packings may damage the valve beyond repair. The packing gland flange should be adjusted an equal amount on each side to ensure proper compression of the packing and to avoid binding of the gland follower with the stem. If adjustment of the packing does not eliminate leakage, additional packing rings should be inserted or the valve should be completely repacked. Refer to the section entitled ,maintenance’ in this manual for instructions on addition or replacement of packings. For extended packing life when the valves are operated in open position, they should be fully opened and back seated. 7. MAINTENANCE The valve can be easily disassembled for inspection, maintenance or replacement of internal parts by using the procedure and tools outlined in this manual. (i) Disassembly Refer assembly cross-sectional drawing for part names. Open the valve until with the back seat is felt. Turn the tee-handle in the closing direction through onefourth of a turn. Remove the lock nut (015) and the tee-handle. The yoke bush (014) can now be removed. The rotation of yoke bush is arrested by staking as shown in figure. The staking must be flattened or filed smooth to enable the removal of yoke bush. After removing the staking, hold the stem by the pyramid to prevent rotation and remove the yoke bush. Remove the packing gland studs(O 10) and nuts (0 11). Lift the gland flange and remove the split type gland follower. Now pulling the Stem will remove the packing ring alongwith the stop ring. WARNING: The High Pressure Valve is designed with Loose Back Seat and hence is not suitable for repacking of gland during service.Also since the flow is from top to bottom, the packings are always under line pressure. Hence, no attempt shall be made either to remove the packings or add additional packing during service. (ii) Renewal of Packing The valve glands are packed with high quality asbestos rings having certain special features. Since the use of the right packing is essential for proper performance of the valve, replacement packing shall be procured only from BHEL or sources approved by BHEL. The valve is NOT provided with a fixed back seat arrangement. These valves belong to the so-called Loose Backseat design category and hence renewal of packing when valve is in service is strictly prohibited. If it becomes absolutely necessary to add packings, the same shall be done by isolating the line and then dismantling required parts. (a) Adding Packing After isolating from line and ensuring that there is no pressure, the following procedure shall be adapted for addition of packing. Unscrew the gland nuts and remove them. Raise the gland flange and remove the split type gland follower. The gland flange may be tied by a wire to the tee packing. Additional rings may be added as required. When inserting new rings the slit in the rings shall be staggered 90' apart. The gland follower can now be inserted and the gland nuts assembled. Tighten 3

the nuts on either side evenly and by an amount j . just sufficient to arrest leakage. Overcompression of packings will reduce the life of packings and also make the operation of valve difficult. (b) Replacement of Packing If a valve is to be completely repacked, isolate the valve to relieve the pressure on the packing rings. Turn the tee-handle counter-clockwise until the valve is fully opened. Remove the Tee-handle and then the Yoke bush. Remove the gland nuts (0 11). Lift the gland flange and remove the split gland follower. Wire the gland flange and follower to the handwheel to allow more room for changing the packing. Now pull the Stem Assembly with a jerk. The packing rings followed by the metallic Stop ring come out of the valve. Remove all old packing taking care not to damage the stem or the stuffing box bore. Clean the stem, stop ring and stuffing box. Lap seat surfaces also if necessary. Inspect the stem and stuffing box bore to ensure that there is no damage to the surfaces. Insert back the Stop ring and then required number of newpacking rings over the Stem shank so that the slit in the rings shall be staggered 90 apart. Now insert the Stem-Packing assembly back into the valve. Sufficient number of rings shall be added to ensure that there will be provision for further tightening to arrest any leakage in service. Assemble the Gland follower and tighten the gland nuts evenly on either side, taking care not to compress the packings too much. Open the valve fully. Now assemble the Yoke Bush and tighten it. Fix the Tee-handle and the nut over it. Put the valve back in service. Turn the tee-handle in the closing direction by ‘/2 turn and check for leakage. If leakage continues, tighten the nuts by another V2 turn. Turn tee-handle back and forth ‘/2 turn to check easeness of operation. If leakage has stopped, but the operation is difficult, loosen the gland nuts by 1/4 turn. Check for leakage and operational ease. The objective is to tighten the packing just sufficiently to prevent leakage with a minimum amount of resistance to stem movement. (iii) Reconditioning of seats The valves have integral hard faced seats of stellite. The hard faced seats can be reconditioned as follows: (a) Assemble the re-seating tool and insert in the valve. A course 60 or 80 Grit abrasive cloth is recommended. (b) Drive the re-seating tool using an electric drill. Application of light pressure is recommended (c) Replace the abrasive cloth frequently and check for a uniform finish over the entire seating surface. (d) Remove the reseating tool and lap the seating surfaces together using the stem assembly. (iv) Assembly The procedure as told in the section for replacement of packing shall be adapted. STAKING DIMENSION Lubricate the stem threads and the external thread on yoke bushing. Install the yoke bushing over the stem and tighten on to the yoke. The yoke bushing must now be stake locked as shown in figure. The packing gland nuts shall now be adjusted evenly on either side. Install the handle and lock nut (183). Lubrication of threaded parts during assembly shall be done with molybdenum di-sulphide, graphite and kerosene. 4

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SIZE OF VALVE 1” 1-1/2”

LOCK NUT (015)

GLAND NUT (011)

14.27 26.97

19.05 28.58

SIZE OF VALVE 1” 1-1/2”

YOKE BRUSHING (014) 41.3 54.0

OUTSIDE INSIDE THICKNESS DIA (OD) DIA(ID) T 34. 1 17.4 7.9 46.7 27.15 9.5

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INDEX