Storing seals correctly and preventing ageing

Seals perform a central task in technical applications: they secure media, prevent leaks and ensure stable operation. Even small changes in the material condition have a direct effect on function. This is exactly where the actual problem begins: ageing processes often start long before use, namely during storage.

A large proportion of later failures can be traced back to unsuitable storage conditions. Elastomers react sensitively to their environment, and this influence often remains invisible until the seal is installed. A targeted storage strategy ensures that material properties such as elasticity, recovery behaviour and sealing effect are preserved and function reliably in use.

Why correct storage decides the service life

The service life of a seal does not begin in use, but already with its manufacture. Between production and installation there is often a longer storage phase during which the material condition can change. These changes are gradual and often remain unnoticed.

Elastomers react to external influences with chemical and physical processes. These include oxidation, plasticiser loss or structural changes in the polymer. These processes cause the material to lose elasticity, harden or become brittle.

Controlled storage significantly slows down these processes. The aim is to preserve the original condition of the seal for as long as possible, so that on installation it exhibits exactly the properties for which it was designed.

The most important influencing factors during storage

Several environmental factors act on seals simultaneously. Their combination determines how quickly ageing processes proceed. Targeted control of these factors reduces material changes and ensures consistent quality during the storage period.

Temperature

Temperature directly influences the speed of chemical reactions in the material. As temperature rises, ageing processes proceed considerably faster.

The ideal storage temperature is between +5 °C and +25 °C. Constant conditions are more important here than short-term fluctuations. High temperatures lead to accelerated degradation of elastomers, while very low temperatures can temporarily reduce flexibility.

Light and UV radiation

Light, in particular UV radiation, acts directly on the surface of elastomers. The energy of the radiation changes the molecular structure and leads to degradation of the material.

Direct sunlight significantly accelerates this process. Visible consequences are discolouration, surface cracks and increasing embrittlement. Storage protected from light considerably reduces these effects.

Oxygen and ozone

Oxygen is a central factor in the ageing of elastomers. In combination with ozone, aggressive reactions occur on the material surface.

Ozone attacks the polymer chains and leads to typical crack patterns, particularly in stretched seals. Technical equipment such as electric motors, switchgear or welding devices can cause locally increased ozone concentrations and should be stored spatially separated.

Moisture

Humidity has a different effect depending on the material. Some elastomers react sensitively to permanently high moisture levels.

In addition to possible material changes, the combination with metallic components also plays a role. Corrosion or deposits can impair function. Controlled, moderate humidity ensures stable conditions.

Mechanical load

Mechanical influences are among the most common causes of loss of function. Even during storage, incorrect positioning or pressure load can lead to permanent deformation.

Seals should be stored free of stress. Stretching, compression or improper stacking change the geometry and impair the subsequent sealing effect.

Optimum storage conditions for different materials

The requirements differ depending on the material. In addition, industry-wide guide values from ISO 2230 (storage of rubber products) apply.

Material	Typical application thickness	Recommended storage period*	Special notes
NBR	Standard oil applications	up to 5 years	Cool, dry, protect from ozone
EPDM	Weathering/water	up to 10 years	Keep away from oils/greases
FKM	Chemicals/temperature	up to 10 years	Store with low light and ozone
Silicone	Food/medical	up to 10 years	Dust-free, low UV

*When recommended storage conditions according to ISO 2230 are observed.

Practical tip: label batches clearly and actively monitor storage period.

Typical mistakes when storing seals

• Storage near heat sources
• Direct sunlight
• Open storage without packaging
• Contact with solvents or chemicals
• Improper stacking or deformation
• Storage in an ozone-laden environment
• Missing labelling and overstocked inventories
• Mixing different materials without separation

Durability and storage period of seals

Storability depends heavily on the material and the conditions. ISO 2230 provides practical guide values. Compliance with stable environmental conditions remains decisive.

Quick decision logic

• Storage period within guide value + stable conditions → use possible
• Storage period near limit value → visual inspection + functional test
• Storage period exceeded → use only after testing or replacement

Typical damage patterns and causes

• Surface cracks → ozone/UV influence
• Hardening → temperature/oxidative ageing
• Sticky surface → plasticiser migration/contact with chemicals
• Permanent deformation → mechanical load during storage

Practical tips for industry and workshop

• Storage in closed, light-protected rooms
• Use of original packaging or airtight containers
• Labelling with date, material and batch
• Application of the FIFO principle
• Regular visual and functional inspection before use
• Separation of seals and ozone-generating devices
• Clear storage zones per material and application
• Documentation of storage conditions (temperature/humidity)
• Training of employees in handling elastomers

Checklist: implementing correct storage immediately

• Check temperature range and keep it constant
• Shield direct light sources
• Separate ozone sources spatially
• Store seals free of stress
• Keep packaging closed
• Label batches and apply FIFO
• Monitor storage period per material
• Carry out visual inspection before installation

Practical example from industry

A typical case: O-rings made of NBR are stored on an open shelf near a production line. Electric motors operate in the surrounding area and there is fluctuating temperature load. After several months, the seals show fine cracks and lose elasticity.

Cause: combination of ozone load, temperature and open storage.

Solution in practice:

• Relocation to a closed storage room
• Use of light-proof boxes
• Separation from machine areas
• Introduction of FIFO and batch labelling

Result: stable material properties and a significantly lower failure rate.

Internal link for further information

For the selection of suitable materials and applications, a more in-depth consideration of the following is recommended:

• NBR seals for oil-resistant applications
• EPDM seals for water and weathering
• FKM seals for chemical and thermal load

This content supports selection and correct application in subsequent use.

When to replace seals

Replacement is advisable as soon as recognisable changes occur or storage limits are reached.

• Visible cracks, discolouration or hardening
• Noticeably reduced recovery behaviour
• Storage period exceeded according to ISO 2230
• Unclear storage history or missing labelling

Storage as part of the quality strategy

Storage directly and permanently influences the performance of seals. Every step between manufacture and installation has an effect on subsequent use. Structured stockkeeping ensures constant material properties and reduces failures in operation.

Companies benefit from defined standards because they reduce complaints, lower maintenance effort and increase process reliability. Storage is developing into a fixed component of quality assurance and procurement strategy.

FAQ

How should seals be stored?

Seals should be stored at constant temperatures between +5 °C and +25 °C, protected from light, dry and without mechanical load. Closed packaging to protect against ozone and oxygen is also recommended.

How long are seals durable?

Durability depends on the material. NBR seals are generally storable for up to 5 years, EPDM, FKM and silicone for up to 10 years – provided the storage conditions comply with ISO 2230.

Which factors accelerate the ageing of seals?

High temperatures, UV radiation, ozone, oxygen and mechanical load accelerate ageing processes and lead to embrittlement, cracks or loss of elasticity.

How can aged seals be recognised?

Typical signs are cracks, discolouration, hardening or a sticky surface. Reduced recovery behaviour also indicates material ageing.

What does FIFO mean in the storage of seals?

FIFO stands for "First In, First Out". Older seals are used first in order to avoid long storage periods and the associated ageing.

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