Flowserve Swing Check Valves 2.5-24 - Manual (Page 27)

Swing Check Valves FCD ADENIM0013-00
26
6.0 ASSEMBLY
(Continued)
6.1.2
Bonnet
Prior to lowering the cap (003) into position, a new gasket (100) should be placed in the gasket groove
on the body flange. The bonnet can then be lowered into place. On valves where the hinge is attached
to the bonnet, care should be taken to insure that the disc is aligned correctly with the seat. This is
accomplished by lining up the dowel pin with the holes in the body and bonnet. With the bonnet in
place, the studs (200) and nuts (230) can be installed. Prior to installation the studs and nuts should be
cleaned and thoroughly lubricated with a high quality lubricant. Any nuts or studs with damaged
threads should be replaced. It is very important that the body—bonnet bolting be torqued to specific
values in accordance with the procedure listed below. The torque values are shown in Table 2 for
various diameter studs and materials. The nuts should be tightened evenly using a crisscross pattern
similar to the one shown in Fig. 18. Tighten all of the nuts to 1/3 of the recommended value initially.
Then repeat the sequence raising the torque to 2/3 of full torque. Finally, torque all the nuts to the
recommended value following the criss-cross pattern. It is essential that the flange faces remain
parallel and all the bolting has uniform tension. Failure to achieve this may cause gasket weepage
when the joint is subjected to operating pressures and temperatures.
FIGURE 18