- Define the leak. Where, when, how much, continuous or only at start, cold or hot?
- Check the history. What changed: part number, supplier lot, fluid, pressure, temperature, maintenance?
- Inspect the seal. Photograph before cleaning. Note position, colour, hardness, swelling, cracks, cuts, flattened section.
- Compare with new. Measure cross-section, inside diameter, hardness, weight against a new part.
- Check the groove. Dimensions, corner radii, burrs, scratches, surface finish.
- Check the counterface. Shaft or bore wear, roundness, hardness, coating loss, scoring.
- Check alignment. Eccentricity, side loading, run-out, vibration.
- Review the fluid. Compatibility, contaminants, additives, cleaning chemicals, water content.
- Review temperature and pressure. Peaks, rate of change, vacuum events, rapid decompression.
- Review installation. Lubricant, tools, torque, cleanliness, twist.
- Match damage to a failure mode with the field guide article: compression set, extrusion, spiral, abrasion, chemical, thermal, installation, decompression.
- Fix the margin. Change one thing at a time: design, compound, finish, assembly or operation. Test before releasing.
When to involve the maker
Send the failed seal, an unused seal from the same lot, drawings, fluid and operating data, and photos. A short report from the supplier saves weeks.
Prevention
Standardise gland drawings, assembly instructions and lubricants. Train fitters. Keep spare seals correctly stored. Record changes so you can correlate them with failures.
About this article. It is original writing prepared from public sources, standards and general industry practice. It is not a copy of any book or standard and it is not engineering advice. Confirm values against the current edition of the standard and test in your own application. Only analyse material you own or are entitled to analyse.
