To:
Subject: Ring gasket evaluation.
Question:
How should I evaluate a ring gasket? I know it should have a smooth
surface condition, but if it has some handling damage, how much damage
does it take to disqualify its utilization? Can I reuse a gasket? Could
you provide some photographs with a reference to scale?
Answer:
Many operators make a serious effort to preserve and
protect ring grooves in flanges. They seem to do this because of
awareness that a damaged and rusted ring groove will not allow a seal
and costs substantially to repair. Operators pay less attention to ring
gaskets even though they constitute half of any ring joint connection seal.
The photographs below, of BX-152 S4 ring gaskets,
show (left to right) a new undamaged gasket, an unused gasket with
handling damage, and a used gasket with clearly visible
coined sealing
areas.
Click on a Ring Gasket image to see an enlarged
view with information about the condition
of the example in the
photograph.
New undamaged BX-152 gasket.
The O.D. and I.D. edges of this gasket show no
visible damage. Installation of this gasket into a “satisfactory” pair
of ring grooves between flanges or hubs, should produce a leak free seal
after connection tightening. Small serrations
(machine marks), discoloration or very
light rust should not affect sealing. Use steel wool or fine grade emery
cloth to remove light rust if necessary before use. Stainless steel ring
gaskets do not rust but may discolor.
Click here to see Field
Appraisal of Ring Grooves
Unused BX-152 ring gasket with handling damage.
This unused ring gasket has somehow received damage
on one of its O.D. sealing surfaces. The damage constitutes a dent or “ding”
that crosses the surface that must “coin” to seal.
This gasket, if used, will almost certainly
leak. 1
This damage may have occurred by mishandling at any time after final
inspection by the manufacturer. Merely dropping the gasket accidentally
can cause damage like that shown. BX ring gasket
design specifically intends the gasket to seal on its’ O.D. Any damage to
the O.D. “corners” beyond minor scratching or discoloration may cause
leakage.
Click here to see: Ring Gasket
Handling and Inspection Before Assembly
Used BX-152 ring gasket with “coined” sealing surfaces.
This used ring gasket clearly shows the flattening of
the corners, called “coining”. This “coining” occurs as a result of
tightening the connection sealed by the gasket. Only by “coining” does
the gasket close off any possible gap and create a seal.
Note: Coining yields or deforms
the gasket so that any reuse will not reliably achieve a seal. 1
Operators referencing this
information, using a BX 152 gasket, should consider this example typical
for all ring gaskets. 1
Click
here to see: Test Rack Tips
| 1 |
Words in bold
italic indicate they have
subjective meaning and persons using this information must use
experience to improve the reliability of their judgement when the meaning
of these words can have impact on performance.
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Other Q & A's related to Ring Grooves and Ring
Gaskets include:
To see more related information,
click on these links:
Field Appraisal of Ring Grooves
Ring
Gasket Selection
Flange Make-up, Stand-off and Drift
What
Flange Does This Ring Gasket Fit?
Flange Gasket,
Bolt and Torque Reference Chart
For a Catalog for Bolts,
Nuts, Ring Gaskets and Wrenches, Click Here.
