Table 3-2. Control valve problem causes and countermeasures
Phenomenon Cause Countermeasure
Fluid leaks from the gland
packing.
Looseness of the gland packing or bolts
•
Tighten the gland packing or bolts.
Grease depleted (for graphite yarn
packing)
•
Replenish the grease.
The gland packing has deteriorated.
•
Replace the gland packing (consider using a
packing of a different material)
The valve stem, interior of the packing
box, etc., is damaged, corroded, or
eroded.
•
Disassemble and re-machine or replace
parts.
•
Attach a felt ring or rubber bellows to pro-
tect the valve stem (if there is a lot of foreign
matter).
The fluid leaks from the
gasket.
The gasket is damaged, corroded, or
eroded.
•
Replace the gasket (consider using a gasket
of a different material)
The amount of valve travel
or the control rangeability
have narrowed
The valve characteristic has changed
because the valve plug is corroded,
eroded, or abraded.
•
Replace the valve plug, seat ring, etc. (con-
sider using parts of a different material for
better corrosion-resistance and rigidity)
3-4
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