SUBJECT : A quick reference guide for mechanical seal failure 4-11

Of all the seal related activities, analyzing mechanical seal failure continues to be the single greatest problem for both the consumer and the seal company representative. I've addressed this problem in several of my other technical papers. If you will take a little bit of time to familiarize yourself with the following outline you should feel a lot more comfortable the next time you're called upon to do some seal troubleshooting.

As you look over the failed seal components, keep in mind that a rebuilt seal may have some marks that occurred during a previous failure, making them especially difficult to analyze, but regardless of the design, mechanical seals fail for only two reasons:

We'll start with damage. This damage is almost always visible. Look for :

Corrosion - The elastomer swells or the other seal parts become "sponge like" or pitted.

Physical damage.

The seal faces opening prematurely is the second cause

Scoring or wear of the hard face is the most common symptom of this failure. The scoring occurs because the solids imbed into the softer carbon face after they open. The seal faces must stay in contact, but there are all kinds of conditions that are trying to force or pull them open.

Physical causes

Product problems . With a loss of an environmental control the fluid can:

The common causes of shaft displacement.

How to prevent product problems that cause premature seal failure.

Control the environment in the stuffing box.

Build the seal to compensate for operating extremes.

Slurry features that can be part of seal design.

Design for higher temperature capability

Design for pressure resistance

Design for corrosion resistance

If you need cryogenic capability

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