TL;DR
Stem packing leakage is either backed-off packing gland nuts or packing rings at end of life. Re-torque gland nuts first; if leakage continues, replace the packing set.
What you might see
- liquid or vapor weeping at the packing box
- wet staining on the stem below the packing follower
- loss of containment alarm on a monitored stem
- visible fluid dripping onto the actuator
Likely causes
Packing gland nuts loosened by vibration or not retorqued after initial installation
PTFE or graphite packing rings compressed past minimum service height
Stem scored or corroded, providing a leak path past the packing
Wrong packing material for the process fluid temperature or chemistry
Required tools
- Torque wrench sized to the packing gland nuts
- Packing hook or pick
- 320-grit abrasive cloth
- Replacement packing set per Fisher easy-e service class
- LOTO kit
Safety first
- Never work on the packing of a pressurized, in-service valve carrying hazardous or high-temperature fluid. Isolate and bleed first.
- Graphite packing dust is a respiratory irritant. Wear an N95 mask when removing old packing.
Procedure
- 1
Verify that the valve and the process line are at the lowest safe pressure for packing work. For volatile or high-pressure service, follow the site valve-isolation procedure.
Warning: Working on the packing box of a pressurized valve risks a sudden release of hot or hazardous process fluid. Follow site valve-isolation and bleed-down procedures before loosening the packing gland. - 2
Wipe the stem clean and confirm where the leak is originating: along the stem above the packing, or at the gland flange face.
- 3
Tighten the packing gland nuts evenly, one quarter turn at a time, until leakage stops. Do not exceed the torque value in the Fisher easy-e valve instruction manual.[1]
- 4
Run the valve through 5 full cycles from fully open to closed. Re-inspect the packing box after cycling. Cycling settles PTFE packing rings and can stop minor leakage.
- 5
If leakage continues after gland tightening to the maximum specified torque, the packing set is at end of life and must be replaced.
- 6
Isolate the valve completely. Remove the actuator if required to access the packing box. Remove the old packing rings with a packing hook or pick.[1]
- 7
Inspect the stem surface in the packing travel zone. Light scoring can be polished with 320-grit abrasive cloth. Deep scoring requires stem replacement.
- 8
Install the new packing rings per the Fisher easy-e packing arrangement drawing for the body and service class. Alternate ring direction for multi-ring sets as specified.[1]
- 9
Reinstall the gland and tighten to the initial installation torque. Cycle the valve and re-check for leakage.
Sources
Fisher easy-e ED, ET, EZ Sliding-Stem Control Valve Instruction Manual, Fisher Controls (Emerson)
Fisher easy-e ED, ET, EZ Sliding-Stem Control Valve Instruction Manual, packing replacement and torque specifications (general)
View source
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