Flowserve 1878 Swing Check Valves with Pressure Seal - Manual (Page 7)

1878 Swing Check Valves with Pressure Seals FCD ADENIM0007-00
7
9.0 Maintenance Instructions
(Continued)
9.1.2 Reassembly
REASSEMBLY OF THE VALVE is simply the reverse of disassembly, Paragraph 9.1.1. Read the following
special instructions carefully.
First, all dirt, scale and foreign matter should be removed from inside the valve body and bonnet.
Before reassembling the valve, check the seating surfaces to determine that no scratches or minor
imperfections are on the disc or seat ring. If any are evident – lap these surfaces until none are visible.
(Reference Paragraph 9.2).
When replacing the bonnet capscrew (216) refer to Section 11.0 for correct torque to assure tightness of
seal.
Remember to lock weld the machine screws (224) to the retaining ring (015) after installing a new resilient
seat.
Use a nuclear grade lubricant on the bonnet capscrew thread reassembly.
9.2 Lapping Procedure
After the valve has been disassembled, a visual inspection of the seating surfaces of the Discs (004) and Seat Ring
(013) can be made to determine if lapping is necessary to remove any minor scratches on these parts prior to
assembling the valve. IF lapping is necessary, it may be accomplished in the following manner:
(1) Remove the Resilient Seat (306). Never lap the disc with the resilient seat in place.
(2) Place lapping compound between the Disc (004) and the Seat Ring (013) and, by hand, rotate the Disc (004)
in a circular motion against the Seat Ring. Check periodically for signs of defects. Repeat this process until
the defect is removed.
(3) A "medium" grade lapping compound should be used for the first and successive applications. A "fine" grade
compound similar to "Clover A Grit No. 280" should be used for the final lapping process.