Industrial seal self study guide - SKF.com

Chapter 9—Troubleshooting
Preliminary Survey
The best way to troubleshoot is to follow a sequence of steps that
should lead you to the problem.
• What was the seal supposed to do? How well has it done the job in
the past? If there is a history of failures, the problem may not be
caused by the seal itself.
• Was it the right seal? Check the seal’s part number and look up its
recommended applications. If the correct seal has been installed and
there is no history of repeated failures, the problem requires further
investigation.
• Pinpoint the source of the leak. It may be either an I.D. leak or an
O.D. leak. Also, find out when the leak first occurred and see if this
relates to a change in maintenance or operating procedures.
• In the case of exceptional seal wear, what is the cause of this wear?
To find out requires failure analysis.
Basic Steps in Analyzing Sealing System Failures
Follow these steps in determining why a seal has failed:
• Inspect the seal before removal to check the condition of the area,
note the amount of leakage that has occurred, and determine the
source of the leakage (fig. 9a).
Inspect the seal and check for signs
of failure (fig. 9a).
• Wipe the area clean and inspect to determine if:
- There are nicks on the bore chamfer,
- The seal is cocked in the bore,
- The seal was installed improperly,
- There is shaft-to-bore-misalignment,
- The seal is loose in the bore,
- The seal case is deformed, and/or
- There is paint on the seal.
• Rotate the shaft to determine if there is excessive end play
or excessive run-out.
If the leakage cannot be located, follow this procedure:
• Add ultraviolet dye to the sump or spray the area with white powder.
• Operate for 15 minutes.
• Use ultraviolet or regular light to check for leakage.
• Mark the seal location at 12 o’clock and remove it carefully.
Check for nicks on the bore chamfer.
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