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Troubleshooting Packing Failures
Packings may fail for a variety of reasons.
Besides improper installation, packing failures
are often due to worn or faulty equipment, shaft
misalignment, uneven take-up on the gland bolts,
and other causes.
If you are having troubles, carefully remove
and examine the old packing set. DO NOT THORW
THE SET AWAY, because it often gives clues as
to the condition of the equipment and may be
the means of solving the problem. The following
clues and possible causes were found by examining
sets of packing which failed in service:
Clue 1: Excessive reduction
in cross-section of packing directly beneath
the rod, shaft, or plunger.
Clue 2: Excessive reduction
in the thickness of the packing directly over
or on either side of the rod or shaft.
Possible Cause: Rod or plunger
out of alignment, and in the case of the rod
or shaft, the bearings may be badly worn, causing
whipping of the shaft.
Clue 3: A whole ring or part
of a ring is missing from set.
Possible Cause: Bottom of stuffing
box badly worn, with packing being extruded
into the system.
Clue 4: Wear on the outside
of one or more rings.
Possible Cause: Rings rotating
with shaft or loose in the box. Packing too
small.
Clue 5: Axial bulge in one
or more rings.
Possible Cause: Adjacent rings
cut too short or too long, depending on the
style of material used, causing packing under
pressure to be deformed.
Clue 6: Packings show tendency
to extrude between rod or shaft and the gland
follower.
Possible Cause: Excessive gland
bolt pressure and/or too much clearance between
rod or shaft and the gland follower.
Clue 7: Rings next to gland
follower badly damaged, with bottom rings in
fair condition.
Possible Cause: Improper installation
of packings and excessive gland bolt pressure
used.
Clue 8: Wearing surface of
rings dried and charred with rest of packings
in good condition.
Possible Cause: High temperatures
and lack of adequate lubrication.
Clue 9: Innermost ring deteriorated.
Possible Cause: Packing incompatible
with fluid handled.
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