Page 176 - Reciprocating Compressors Operation Maintenance

Reciprocating Compressors: Operation and Maintenance

TABLE 3-8
TORQUE VALUES—WRENCH READING

Valve Covers Jam Screws
Thread Size Torqtie Torque
ft-lbs ft-lbs
MMO 24-28
r-n 47-56
3
/r-io 85-102 60-70
JT-9 138-166 110
r-s 207-248 150-165
1JT-8 307-370 225-250
1JT-8 435-522 315-350
ir~8 595-714 430-475
lM"-8 790-948 570-630
5
1 /T~8 1025-1230 740-820
p/r-8 1305-1566 950-1050
r/r-8 1619-1944 1170-1300

2"~8 2189-2356 1450-1600
2%"-8 2100-2300
2M"~8 2900-3200

mal valve operation. The valve cover nuts should be retorqued to
the proper value (see Table 3-8).
9. Check and record valve cover temperatures using an infrared tem-
perature measuring device.

A problem documented with some compressors is the single-bolt valve
restraining system. Under high torque, the gasket in the valve cover can
distort, allowing gas leakage and reduced loading on the cage and valve.
Continued operation with loose jack bolts can result in broken bolts, cages,
and valves. Debris in the cylinder and massive gas release can also occur.
A multi-bolt valve restraint assembly is available for retrofit application
to some compressors with weak single-bolt restraints (see Figure 3-22B).

The valves removed from the compressor should be sent to the valve
manufacturer's shop for cleaning, reconditioning, installation of all new
components (sealing elements, springs, etc.), and testing.