Baker Hughes 13900 Series Maintenance Manual

Baker Hughes 13900 Series Maintenance Manual Manual pdf 30 page image

26 | BHGE© 2018 Baker Hughes, a GE company. All rights reserved.1. Due to large capacity of the main valve, it is impossibleto adjust the pilot and main valve as an assembly unlesson an actual installation. To obtain a valve settingon other than an actual installation, the pilot can beremoved from the main valve and adjusted on a smalltest facility complying with the following requirements.Reference Figures 20 and 21.a. The pressure source or the test header must havea minimum capacity of 6 ft3 (170 m3). Headermounting flange should be 4”-300# (101.6 mm -20.4 barg) RF ASA flange.b. The test fixture indicated in Figure 20 should beequipped with a 4”-300# (101.6 mm - 20.4 barg) RFASA flange on the lower end and have appropriatemachining and drilling on the top end to match thepilot flange (BHGE Part No. 4130901).c. The test set up should be equipped with P 1 and P 2pressure gauges as indicated in Figure 20. The P 1gauge will sense inlet pressure and P 2 will sensepressure equivalent to that back of the main valvedisc when the main valve is open.2. The following procedure should be used for testingthe pilot.a. Install pilot valve with sensing unit. Lower flangeand upper flange gasket on test fixture.b. Pressurize system and note pop pressureindicated by P 1 gauge. Adjust set pressure byloosening compression screw locknut and rotatingcompression screw clockwise (increase set point) orcounterclockwise (decrease set point) until properset pressure is established. Tighten compressionscrew locknut.c. Adjust blowdown by removing adjusting ring pinand rotating adjusting ring clockwise (decreaseblowdown) or counterclockwise (increaseblowdown) until proper value is established.Blowdown is intentionally set for 10-12% of setpressure at factory before installing on the mainvalve. Tighten adjusting ring pin.d. Pop pilot five times to ensure accurate settingsnoting P2 pressure at each pop. P 2 pressure shoulddrop to approximately 58% of P 1.e. Install lifting lever and cap on pilot. Bring systempressure up to just below the pilot set point and liftlever on pilot. Note that P2 does drop to approximatelythe same value indicated in Step d.f. Check pilot for leakage. Bring the inlet pressure ofthe valve up to 94% of set pressure. Pass a coldrod across the outlet of the pilot. Any moistureoccurring on the rod indicates valve leakage.g. Test of main valve and pilot assembly:(i) Install pilot back on main valve.(ii) Upon pressurizing the system, leakage aroundmain valve joints is permissible for approximatelyone hour till the valve is uniformly heated.(iii) Increase system pressure until pilot opens atset point. Continue to overpressure until mainvalve opens.(iv) Check valve for leakage with system pressure at90% of set.CAUTIONDo not expose any part of the human body to thedischarge side of either the pilot or main valve. Whentesting for leakage, stand 90° to the side of the outletdischarge. In this position it is safe to pass a metal roddownward across the outlet.h. All external adjustments to the valve should besealed in accordance with ASME Code Section VIIIrequirements.XIX. TestingDo not Stand or placehand in front of valvedischarge flange if valveis under pressure.