Instruction Manual
D104197X012
NPS 8 CHP Valve
September 2016
6
Table 2. CL2500 Recommended Torque for Packing Flange Nuts (non live‐loaded)
VALVE STEM
DIAMETER
PRESSURE RATING
TORQUE
N
S
m
lbf
S
ft
mm
Inches
Min
Max
Min
Max
31.8
1‐1/4
CL2500
81
122
60
90
Table 3. Torque for Body‐to‐Bonnet Bolting Using Anti‐Seize Lubricant
VALVE RATING
BOLT TORQUES
SA193‐B7, B16
N
S
m
lbf
S
ft
CL2500
4240
3130
Table 4. Valve Stem Connection Torque and Hole Size for Pin
VALVE STEM DIAMETER
TORQUE, MINIMUM TO MAXIMUM
HOLE SIZE
(1)
mm
Inches
N
S
m
Lbf
S
ft
mm
Inch
31.8
1‐1/4
735-993
544-736
6.38-6.45
0.251-0.254
1. VSC (Valve Stem Connection) size is 1 1/4-inch.
CAUTION
The CHP valve uses spiral‐wound gaskets which are crushed to provide their seal. A spiral‐wound gasket should never be
reused. Whenever a gasket seal is disturbed by removing or shifting gasketed parts, a new gasket must be installed upon
reassembly. This is necessary to ensure a good gasket seal, since the used gasket will not seal properly.
The spiral‐wound gaskets are of special design. Failure to use genuine Fisher replacement parts may result in valve damage
and/or failure.
Packing Maintenance
WARNING
To avoid personal injury or equipment damage resulting from packing leakage, inspect the valve plug stem and packing
box wall for nicks or scratches while performing the following procedures. Use care to avoid damaging these surfaces.
For spring‐loaded single PTFE V‐ring packing, the spring maintains a sealing force on the packing. If leakage is noted
around the packing follower, check to be sure the shoulder on the packing follower is touching the bonnet. If the
shoulder is not touching the bonnet, tighten the packing flange nuts until the shoulder is against the bonnet. If
leakage cannot be stopped in this manner, proceed to the Replacing Packing procedure.
If there is undesirable packing leakage with other than spring‐loaded PTFE V‐ring packing, first try to limit the leakage
and establish a stem seal by tightening the packing flange nuts to at least the minimum recommended torque in table
2. However, do not exceed the maximum recommended torque in table 2
or excessive friction may result. If leakage
continues, replace the packing by following the numbered steps presented in the Replacing Packing procedure.
If the packing is relatively new and tight on the valve plug stem, and if tightening the packing flange nuts does not stop
the leakage, it is possible that the stem is worn or nicked so that a seal cannot be made. The surface finish of a new
stem is critical for making a good packing seal. If the leakage comes from the outside diameter of the packing, it is
possible that the leakage is caused by nicks or scratches around the packing box wall. While replacing the packing
according to the Replacing Packing procedure, inspect the valve plug stem and packing box wall for nicks or scratches.
