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Seal protection – part 2

Failure analysis and extending seal life

Continuing on from common failure modes, part two of this series looks at troubleshooting the root cause of seal failures. Here, you’ll find a few tips on failure analysis and preventing future damage.

In part one of this two-part series on troubleshooting failures, we explained commonly encountered issues. However, there are many specific issues that can be avoided if you can identify their root cause. This requires a thorough inspection, which your seal provider can often support you with.

On initial inspection…

To understand why a seal is not performing, there are a few initial areas that a machine operator or engineer should explore. Checking the seal’s part number and recommended applications is a good place to start, taking into account whether there is a history of failures with seals in this machine. A history of failures could mean that the seal is not the culprit or that the wrong seal has been chosen for this application. If an unsuitable seal was chosen for an application, then a premature failure was inevitable and a new, well-suited seal type should be chosen as a replacement. Operators can find more information on suitable seal types in the manufacturer’s recommendations or by asking advice from the seal provider or a service specialist.

Failure analysis: finding the source

In the case of exceptional wear or leakage, failure analysis should be carried out. For this, troubleshooting begins even before the seal is removed. Checking the condition of the area surrounding the seal can provide a few tell-tale signs. Rotating the shaft helps determine whether there is excessive end play or excessive run out, which can indicate misalignment issues.

If the source of a leak cannot be located, ultraviolet dye can be added to the sump. Alternatively, the area can be sprayed with white powder and put into operation for 15 minutes. This allows the operator to easily see where the leak is occurring and know whether it stems from the inner diameter or the outer diameter of the seal. When the seal is removed, it should be checked for coked lubricant or excessive lip wear, which both suggest that the seal is not getting enough lubrication.


Checklist: Are you getting the most out of your seals?

There are a few key ways that operators can make sure they are optimizing seal performance and maximizing seal lifespan. These can be broken down into three areas:
Seal storage

  • Store seals properly in a cool area at 40 percent to 0 percent humidity
  • Do not hang a seal on a peg or nail to avoid distortion and/or corrosion
  • Ensure the storage area is free from grit and contaminants, particularly in cases of pre-lubricated seals

Seal installation

  • Select the correct seal for the application and the speed it will operate at
  • Confirm that the lubricant is compatible with lip material
  • Chamfer the leading edge of the shaft with the correct bore according to recommendations

Seal operation

  • Compare operating temperature against lip material specs
  • Vent the seal cavity to prevent pressure buildup

A proactive approach helps seals last longer

Some seal failure modes are common due to improper storage, installation, or maintenance. Knowing what has caused a seal to fail is crucial in making sure it does not happen in the future. By conducting proper failure analysis, or employing the skills of the supplier to do so, operators can better understand how to maximize the performance and lifespan of their seals.

Missed part 1? Learn more on common failure modes for mechanical and industrial seals here.

Related articles

Tools & Guides
Seal protection – part 1
Troubleshooting common seal failure modes