Instruction Manual
D100399X012
EW Valve
July 2017
10
Packing Maintenance
Note
For valves with ENVIRO‐SEAL live‐loaded packing, see the Fisher instruction manual, ENVIRO‐SEAL Packing System for Sliding‐Stem
Valves,
, for packing instructions. For valves with HIGH‐SEAL live‐loaded packing, see the Fisher instruction manual,
HIGH‐SEAL Live‐Loaded Packing System,
Key numbers refer to figure 4 for PTFE V‐ring packing and to figure 5 for PTFE/composition packing, unless otherwise
indicated.
For spring‐loaded single PTFE V‐ring packing, the spring (key 8, figure 4) maintains a sealing force on the packing. If
leakage is noted around the packing follower (key 13, figure 4), 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 (key 5, figure 21)
until the shoulder is against the bonnet. If leakage cannot be stopped in this manner, go to the Replacing Packing
procedure.
Figure 5. Detail of PTFE/Composition Packing Arrangements
UPPER WIPER
(KEY 12)
PACKING
FOLLOWER
(KEY 13)
LANTERN RING
(KEY 8)
PACKING BOX
RING (KEY 11)
PACKING RING
(KEY 7)
9.5 mm
(3/8 INCH)
STEM
12.7 mm
(1/2 INCH)
STEM
19.1, 25.4, OR
31.8 mm
(3/4, 1, OR
1‐1/4 INCH) STEM
TYPICAL (DOUBLE) ARRANGEMENTS
12A8188‐A
12A7815‐A
12A8173‐A
A2619‐1
If there is undesirable packing leakage with other than spring‐loaded packing, first try to limit the leakage and
establish a stem seal by tightening the packing flange nuts.
If the packing is relatively new and tight on the stem and if tightening the packing flange nuts does not stop the
leakage, the valve stem may be worn or nicked so that a seal cannot be made. The surface finish of a new valve stem is
critical for making a good packing seal. If the leakage comes from the outside diameter of the packing, the leakage
may be caused by nicks or scratches around the packing box wall. If performing any of the following procedures,
inspect the valve stem and packing box wall for nicks and scratches.
Replacing Packing
WARNING
Avoid personal injury or property damage from sudden release of process pressure. Before performing any maintenance
operations: