Flowserve 1878 Piston Check Valve - Manual (Page 10)

1878 Piston Check Valves FCD ADENIM0005-00
10
9.0 Maintenance Instructions
(Continued)
9.3.3 Resilient Seat Assembly (if so equipped)
a) Carefully place the resilient seat over the disc.
b) Reassembly of the balance of the assembly is the reverse of that described in 9.1.3.
c) Use nuclear grade thread lubricant on the threads, making sure that it does not come in
contact with the resilient seat material.
d) The disc skirt (005) is to be screwed firmly against the disc (004) shoulder prior to
installing the retaining ring (245).
9.3.4 Reassembly of the valve is accomplished by inserting the disc or disc assembly (004) and spring
(429), followed by the bonnet (002), pressure seal gasket (030) and spacer ring (032). Use a
nuclear grade thread lubricant on the threads, making sure that it does not come in contact with the
resilient seat material. Then screw in the bonnet retainer (034). The bonnet capscrew (216) is then
threaded into the bonnet through the hole in the retainer (034). A maximum of 5 ft-lbs of torque
should be exerted on the bonnet capscrew. Insert the anti-rotation pin (258) in hole in top of the
body (001).
NOTE: Consolidation of graphite during initial system pressurization is normal and will often cause the
bonnet capscrew to become finger tight or even loose.
9.3.5 Retorque the bonnet capscrew to 50 to 60 inch-lbs. when the system is initially pressurized to
ensure that the bonnet will not move out of the sealed position when the pressure is relieved.
9.4 Trouble Shooting
A. Leakage Between the Disc (004) and Seat Ring (013)
This could be an indication that there is foreign matter on the seating surfaces.
Disassemble the valve and remove the source of the trouble. If no foreign matter is found,
inspect the seating surfaces of the valve for signs of a scarred or damaged seat - in which
case the seating surfaces of the Disc (004) and Seat Ring (013) should be lapped until no
visible defects remain. (Refer to Para. 9.2)