1511 Series - Maintenance Manual

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XVI. ContinuedASME Boiler andPressure VesselCode Section andSymbolVCODE SYMBOLSTAMPASME Section IUVCODE SYMBOLSTAMPASME Section VIIITable 9Set Pressure Tolerance (The valve must“POP” open within the range indicatedbelow.)If valve set pressure is less than or equal to70 psig (4.83 barg):±2 psig (±0.14 barg)If valve set pressure is 71 psig (4.9 barg) upto and including 300 psig (20.68 barg):±3% of set pressureIf valve set pressure is 301 psig (20.75 barg)up to and including 1000 psig (68.95 barg):±10 psig (±0.69 barg)If valve set pressure is 1001 psig (69.02barg) or greater±1% of set pressureIf valve set pressure is less than or equal to70 psig (4.83 barg):±2 psig (±0.14 barg)If valve set pressure is 71 psig (4.9 barg) orgreater±3% of set pressureBlowdown RequirementsAfter opening, the valve must reclosewithin a range of 98% to 96%, however,if the valve set pressure is 100 psig(6.9 barg) or less the valve must reclosewithin a range of 2 to 4 psig (0.14 to 0.28barg) below set pressure.After opening the valve must reclosebefore the system pressure returns tonormal operating pressure.DRESSER RECOMMENDS THAT THE MAXIMUM OPERATING PRESSURE NEVER EXCEEDS 94% OF THE SETPRESSURE OF 1511 SERIES SAFETY VALVE.5 When presetting is complete, remove the gag andreplace the cap and lifting lever assembly. Attach arope to the lever and stand by to hold the valve openif necessary. Now the valve is ready to test.6. Increase the boiler pressure at a rate not to exceed2 psi (0.14 bar) per second. Note and record thepressure indicated on the pressure guage when thevalve pops open. After the valve pops open, reducethe fire in the boiler and lower the pressure until thevalve closes. Note and record the pressure when thevalve closes.7. Determine if the valve popping point and reseatingpoint comply with the ASME requirements.a. If the valve operation meets the appropriatestandard, raise the pressure in the boiler andconduct two more verification tests.b. If in raising the boiler pressure, the valve doesnot pop open within 3% overpressure (for ASMESection I valves), or 10% overpressure (for ASMESection VIII valves), reduce the fire in theboiler and pull the rope to open the valve.Release the rope and allow the valve to closewhen the boiler pressure returns to operatinglevel. Allow the boiler to reduce to approximately85% of the set pressure. Remove the cap andlifting lever assembly from the valve, and turn thecompression screw lock nut counter-clockwise(as viewed from the top of the valve) until it movesfreely. Reduce the compression in the spring byturning the adjusting screw counter clockwiseone turn (as viewed from the top of the valve).Replace the cap and lifting lever and retest thevalve. Continue repeating this procedure untilthe valve opens at, or below, the set pressurerecorded on the nameplate.c. If the valve opens at a pressure below therecorded set pressure, allow the valve to closeand the boiler pressure to reduce to 85% of setpressure. Increase the compression on the springby turning the compression screw clockwise1/6th of a turn. Tighten the adjusting screw locknut and replace the cap and lifting lever assembly.22 | Dresser Consolidated ®
XVI. ContinuedRetest the valve as described in Step 6. If thevalve continues to open below the required setpressure, calculate how many turns to move theadjusting screw to cause the valve to open at thecorrect set pressure. Adjust as necessary.d. If the valve opens and closes rapidly, (called“chattering”) hold the valve open to preventdamage to the valve. Reduce the fire in theboiler and allow the boiler pressure to reduce toapproximately 85% of the set pressure. Gag thevalve, and reset the adjusting rings according topresetting instructions, (see Section XI).e. If the valve indicates simmer at a pressure greaterthan 1% of the set pressure of the valve, allow thevalve to reseat and the boiler pressure to reduceto 85% of set pressure. Gag the valve to preventaccidental lifting while making adjustments.Remove the lower adjusting ring pin and raisethe lower adjusting ring. As viewed through thering pin hole, move the adjusting ring from leftto right one or two notches. Remove the gag,retest and note when simmer occurs and repeatas necessary.NOTE: The lower adjusting ring should be adjusted tothe notch that provides a minimum of simmerand does not interfere with the blowdown of thevalve.f. If the valve “pops” open then drops out of lift, likeit was going to close, but remains open at a verylow lift, this is called a “hang up” and indicatesthat the position of the lower adjusting ring isinterfering with the blowdown of the valve. Tocorrect a hang up, gag the valve, remove thelower ring pin and lower the adjusting ring onenotch (as viewed through the ring pin hole, movethe adjusting ring from the right to the left to lowerthe adjusting ring). Remove the gag, retest andnote the reseating pressure of the valve it shouldclose sharply at a higher pressure.g. If the valve closes sharply but the reseatingpressure is too low in comparison to the standardin Table 9, blowdown is excessive. Gag thevalve, remove the upper ring pin, raise theupper adjusting ring 10 notches, replace the ringpin, remove the gag and retest the valve. If thereseating pressure has not risen enough to meetthe blowdown standard, repeat the procedureuntil the blowdown standard is achieved.NOTE: It may be possible that in raising the upperadjusting ring to reduce the blowdown, the valvemay develop a hang up, correct it as describedin Step f. above, and then continue if necessaryto reduce the blowdown.h. If the blowdown is less than the standardrequired, the reseating pressure can be loweredby gagging the valve, removing the upper ringpin and lowering the upper adjusting ring 10notches (as viewed through the ring pin hole,move the adjusting ring from the right to the left.)Remove the gag, replace the adjusting ring pinand retest the valve. If the reseating pressureis not reduced enough to meet the standard,repeat this procedure until the standard isachieved. The upper adjusting ring should bepositioned to provide no more blowdown thanthat indicated in Table 9.8. Once the valve has tested in compliance withthe appropriate standard, conduct two moreverification tests. All external adjustments shouldbe sealed after completing final setting.9. Proceed to the next valve to be tested.XVII. Electronic Valve Testing (EVT)Periodic tests may be required for verification of valve setpressure. The Dresser Consolidated ® EVT provides forthis capability. However, set pressure is the only factorwhich can be verified. Valves should be initially set usingfull system pressure (as outlined in Section XVI.). The EVTmay be used for subsequent checks of set pressure.Accuracy of results obtained by the use of this devicedepends on several factors. First, friction must be reducedas a source of error so that, for a given pressure, theEVT repeatedly produces exactly the same lifting force.Second, gauge calibration and vibration, and the effectiveseating area between valves of the same size and type,will also affect accuracy. With well calibrated gauges andvalve seats in good condition, accuracy on the order of1% of set pressure may be expected. Upon request,Dresser Consolidated ® will provide pertinent writtenmaterial concerning the EVT. This material specifies allrequired information necessary to insure proper usage ofthis device.1511 Series Safety Valve (July/2010) | 23
Page 3: Conversion TableAll the USCS values
Page 11 and 12: IX. Recommended Installation Practi
Page 13 and 14: XI. Presetting the Adjusting RingsI
Page 15 and 16: XIII.B. Continued1511 Flat Solid Di
Page 19 and 20: XIV. ContinuedC. Lapping Procedures
Page 21: XV. ReassemblyDuring reassembly, th
Page 25 and 26: XIX. Maintenance Tools and Supplies
Page 27 and 28: XXI. Recommended Spare PartsTable 1
Page 29 and 30: XXIII. ContinuedB. Field ServiceUti
Page 31 and 32: Sales Office LocationsMALAYSIADress

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