Troubleshooting guide
Common Causes of Seal Failure
Seals rarely fail without a reason. Looking carefully at how a seal failed usually points to a cause that, if fixed, stops the same failure recurring. This guide covers the most common causes in mechanical seals, hydraulic seals, O-rings and gaskets, and what to record before you order a replacement.
- Dry running
- Wrong material
- Installation damage
- Contamination
Start with the evidence
Keep the failed seal and do not clean it before inspection. Photograph it, note where the leak occurred, how long it lasted and what changed beforehand (new pump, new fluid, process upset, maintenance work). Also record the symptoms: continuous leak, intermittent weep, noise, heat, vibration or short life.
Common causes
| Cause | What you may see | Typical remedy to investigate |
|---|---|---|
| Dry running or loss of lubricating film | Heat cracking or blistering of faces, burnt elastomers | Check priming, flush plan, suction conditions |
| Wrong material for the medium | Swelling, softening, cracking, hardening, surface attack | Review the medium and material compatibility |
| Excessive temperature | Hardened, brittle or extruded elastomer; discoloured parts | Check operating temperature and cooling or flush |
| Installation damage | Cuts, nicks, twisted O-rings, rolled lips, cracked seat | Use lubricant, assembly sleeves and care; check lead-in chamfers |
| Shaft or rod condition | Scored, worn or rough surface; grooves under the seal | Repair or sleeve the shaft; see shaft repair sleeves |
| Misalignment or vibration | Uneven face wear, fretting, early failure | Check alignment, bearings, balance, cavitation |
| Contamination and abrasives | Scratched faces, embedded particles, scoring | Check filtration, flushing, barrier fluid, wipers |
| Excess pressure or extrusion | Nibbled or extruded edges on O-rings and seals | Check pressure peaks, clearances, backup rings |
| Incorrect fit or dimensions | Leaking from the start, unusual wear pattern | Re-measure groove or housing |
| Flange or bolting problems | Gasket crushed, blown out or leaking at one side | Check flange finish, alignment, bolt load and sequence |
Mechanical seals
Face damage patterns, such as heat checking, chipping and uneven wear tracks, often point to operating conditions: dry running, vibration, cavitation or poor flushing. Excessive leakage can also come from face distortion, a seized spring or wrong setting. For identification and replacement, see the guide on identifying a mechanical seal and our mechanical seal replacement service.
Hydraulic and O-ring seals
Typical hydraulic failures include scored rods, contamination, excessive heat, side loading and wrong profile selection. O-rings may show compression set, twisting, spiral failure on moving parts, or explosive decompression damage in gas service. For related guides, see measuring a hydraulic seal and measuring an O-ring.
Gaskets
Gasket leaks often come from uneven or insufficient bolt load, damaged flange faces, wrong thickness or material, reuse of an old gasket, or thermal cycling. Following a tightening sequence and recommended practice usually helps more than switching materials. See gasket material selection guide.
Preventing repeat failures
- Identify the cause, not just the part.
- Fix the root condition, such as shaft wear, misalignment or cavitation.
- Confirm the medium and temperature and review the material.
- Install carefully with correct tools, cleanliness and lubricants.
- Keep a record so patterns can be spotted. See the pump and seal maintenance guide.
Limitations
- Visual diagnosis can be misleading; several causes can leave similar marks.
- A photograph is not a failure analysis report.
- Equipment and process problems may need on-site investigation; see on-site technical support.
- Failures in oxygen, hydrogen, aerospace, food-contact, pharmaceutical or potable water duty need technical review and the correct certification documents.
Send us the details
Send photographs of the failed seal, equipment details, medium, temperature, pressure and service history through Find My Seal or request a quote.
Options & specifications
| Common causes | Dry running, wrong material, heat, installation damage, contamination |
|---|
Options, materials and turnaround are confirmed on your written quote.
How ordering works
- 1
Keep the part
Do not clean first.
- 2
Record
Leak, timing and changes.
- 3
Find cause
Match marks to conditions.
- 4
Fix and replace
Address the root cause.
Frequently asked questions
What is the most common cause of mechanical seal failure?
Operating conditions such as dry running, poor flushing, vibration and misalignment are frequent causes, though each case differs.
Why does my new seal fail quickly?
The root cause may still be present: shaft damage, misalignment, wrong material, or contamination.
Can I reuse a gasket?
Reuse is generally not recommended for compressible gaskets, because they take a permanent set.
Can you help with failure analysis?
Send photographs and conditions for review. On-site support is confirmed when you enquire.
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Send photos of the failed seal for review.
Send your brief, quantities and deadline. We reply with a clear written quote and confirm the turnaround before anything goes to production.
