This image was created with artificial intelligence – marked under Art. 50 of the AI Act, Regulation (EU) 2024/1689. It is a placeholder until the company's photos arrive.Typical causes of seal failure and how to avoid them
Understanding and avoiding typical causes of seal failure. Practical tips on material, installation and application.
Seals perform a central function in technical systems: they prevent the escape of media, maintain pressure conditions and protect adjacent components from contamination or damage. In almost all industrial applications, they are a critical element for operational safety and service life.
During operation, mechanical, chemical and thermal loads act on the seal simultaneously. Small deviations in material selection, design or installation often lead to creeping damage that only later manifests as leakage or failure.
Anyone who knows typical damage patterns and assesses them systematically can avoid failures in a targeted manner and significantly increase service life.
Why seals fail
In practice, seal failures arise from the interaction of several factors. Even at the design stage, it is decided whether a seal will function permanently or wear out prematurely.
An unsuitable material reacts sensitively to media or temperature. Faulty geometry creates uneven loading. In addition, pressure, movement and environmental influences accelerate wear.
A creeping process is typical: the seal loses elasticity, changes its shape or shows initial surface damage. This develops into a leak, which ultimately leads to failure.
Mechanical causes of seal damage
Mechanical loads act directly on the structure of the seal and are among the most common causes of failure.
Overload and incorrect compression
Surface pressure largely determines the sealing effect. Excessive load leads to plastic deformation or material fracture. Too little compression reduces contact with the sealing surface and allows leaks.
Errors often arise from incorrect dimensioning or unsuitable groove geometries. Point loads are particularly critical, as they lead to local wear and premature failure.
Wear caused by movement
Dynamic applications create friction between the seal and the mating surface. This friction leads to continuous material removal and changes the surface structure.
Rotating or oscillating movements also generate heat, which accelerates wear. The sealing effect decreases with increasing operating time.
Chemical influences and material incompatibility
The choice of material determines resistance to media such as oil, acids or solvents.
Typical damage patterns:
- Swelling due to media absorption
- Embrittlement due to chemical reaction
- Loss of elasticity due to ageing
Material examples
| Material | Properties | Typical weaknesses | Guide values |
|---|---|---|---|
| NBR | good oil resistance | limited temperature resistance | approx. -30 to +100 °C |
| FKM | high temperature and chemical resistance | higher costs | approx. -20 to +250 °C |
| EPDM | resistant to water and ozone | sensitive to oil | approx. -40 to +150 °C |
Selection should always be based on the actual operating conditions and take limit ranges into account with a safety margin.
Thermal load and ageing
Temperature directly influences the physical properties of seals. High temperatures accelerate ageing processes and lead to material hardening. Low temperatures reduce elasticity and increase the risk of cracks.
Typical consequences are shrinkage, cracking and loss of recovery capability.
Installation errors as a common cause
A considerable proportion of all damage occurs during installation.
Typical errors are twisted seals, damaged edges or missing lubrication. An incorrect installation position also significantly affects function.
Clean, stress-free installation forms the basis for a long service life.
Design errors in the application
The design determines how the seal is loaded.
Unfavourable groove dimensions, insufficient surface quality or a lack of tolerance consideration lead to uneven loading. This creates local weak points that accelerate wear.
Environmental conditions
Environmental influences act on the seal over long periods. UV radiation changes the material structure and reduces elasticity. Ozone leads to fine surface cracks that spread over time. Moisture in combination with temperature fluctuations creates additional stresses in the material.
These influences develop their effect gradually and lead to loss of function in the long term.
Typical damage patterns and causes
| Damage pattern | Cause | Measure |
|---|---|---|
| porous | ageing, ozone | select a suitable material |
| swollen | wrong medium | check chemical resistance |
| cracks | temperature, stress | adapt material |
| abrasion | friction | optimise lubrication and geometry |
| deformation | overload | design compression correctly |
Differences by seal type
- O-rings: react sensitively to incorrect groove geometry and twisting during installation, resulting in extrusion and uneven deformation.
- Flat gaskets: require an even bolt load, as uneven tightening leads to settling behaviour and leaks.
- Rotary shaft seals: are subject to continuous wear at the sealing lip, so that missing lubrication or unsuitable surfaces quickly lead to wear.
Measures to prevent seal failures
- Select material to suit the medium
- Take temperature and pressure ranges into account
- Design geometry and tolerances precisely
- Carry out installation cleanly and without stress
- Schedule regular checks during operation
Fault diagnosis step by step
- Check the damage pattern: identify porous, swollen, cracks, abrasion or deformation.
- Record the operating conditions: document medium, temperature, pressure, movement.
- Compare the material: check the resistance of the material used to the medium and temperature.
- Assess the geometry: check groove, compression and tolerances for plausibility.
- Check the installation: analyse installation marks, edge damage, twisting.
- Derive a measure: change material, adapt geometry or optimise the installation process.
Which seal for which application
| Application | Recommendation |
|---|---|
| Oil-containing media | NBR or FKM |
| High temperatures | FKM (typically up to approx. 200–250 °C depending on grade) |
| Water and outdoor area | EPDM (typically up to approx. 120–150 °C) |
| Dynamic movement | low-wear elastomers, optimised lubrication |
Have a seal selected or request a dimensionally accurate cut – a suitable solution speeds up implementation and reduces failure risks.
Further information can be found on suitable pages such as /gummidichtungen/, /o-ringe/ or /materialien/.
| Application | Recommendation |
|---|---|
| Oil-containing media | NBR or FKM |
| High temperatures | FKM |
| Water and outdoor area | EPDM |
| Dynamic movement | low-wear elastomers |
For individual requirements, targeted advice or a dimensionally accurate cut is recommended.
Avoiding seal failures in a targeted manner
Seal failures arise from the interaction of several influencing factors that intensify over the operating time. Mechanical load, chemical reactions, temperature and environmental influences interlock and lead step by step to loss of function.
Practical example: In an oil-carrying system, an EPDM seal was used. Contact with the medium caused swelling and loss of elasticity within a few weeks. Switching to FKM stabilised the application permanently and prevented further failures.
A sustainable solution is based on a clean harmonisation of all parameters. The right material selection, a well-thought-out design and professional installation form the basis for high operational safety. In addition, regular inspection ensures that initial signs of wear are detected early.
Anyone who takes these factors into account significantly increases service life and reduces unplanned downtime.
FAQ
Why do seals break?
Common causes are the wrong material selection, mechanical overload, chemical influences or installation errors.
How can the service life of seals be extended?
Suitable material selection, clean installation, correct design and regular inspection can significantly increase service life.
Which seal is the best?
The suitable seal always depends on temperature, medium, pressure and application.
What happens if the wrong seal is selected?
The seal can swell, become brittle or lose its sealing effect, which leads to leaks.
How do you recognise a defective seal?
Typical signs are leaks, visible damage, deformation or material changes.
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