Seal repair kits are essential for maintaining hydraulic and pneumatic systems, but their performance depends heavily on how they are stored. Improper storage can lead to premature aging, hardening, cracking, or swelling, rendering the seals useless before they ever see service. Follow these best practices to keep your seal kits in top condition for as long as possible.
1. Control Temperature and Humidity
Seals are typically made from elastomers like nitrile (NBR), Viton (FKM), polyurethane (PU), or silicone. These materials are sensitive to extreme temperatures and moisture.
· Temperature: Store kits at a stable room temperature, ideally between 10°C and 25°C (50°F–77°F). Avoid heat sources such as radiators, steam pipes, or direct sunlight. High temperatures accelerate oxidation and hardening. Never store seals below 0°C (32°F) unless specified, as some materials become brittle.
· Humidity: Keep relative humidity below 65%. Excess moisture can cause metal parts (e.g., springs in lip seals) to corrode, and some polyurethanes may hydrolyze. Use silica gel packs in storage cabinets if needed.
2. Protect from Light – Especially UV
Direct sunlight and strong fluorescent light emit ultraviolet (UV) radiation, which degrades most elastomers. UV causes surface cracking and loss of elasticity. Store seal kits in opaque containers or closed cabinets. If clear bags are used for visibility, keep them inside a dark drawer or box.
3. Avoid Ozone and Chemical Contamination
Ozone, even at very low concentrations, attacks unsaturations in rubber chains, leading to cracking. Common ozone sources include:
· Electric motors and generators (sparks produce ozone)
· Welding equipment
· Photocopiers and air purifiers with corona discharge Additionally, keep seal kits away from: · Solvents, fuels, hydraulic fluids (vapors can cause swelling)
· Acids, alkalis, and disinfectants
· Copper, manganese, or iron dust (promote oxidation)
Store seals in a separate, clean area – never near chemical storage or maintenance bays where sprays are used.
4. Prevent Deformation and Physical Damage
Elastomers creep under sustained pressure. Avoid:
· Hanging seals on hooks or nails – this causes local stretching and distortion.
· Stacking heavy items on top of soft seal kits – flat gaskets and O-rings can take a permanent set.
· Twisting or folding lip seals; store them flat or loosely coiled in their natural shape.
For large O-rings, lay them flat on a shelf. For small kits, keep components in partitioned trays or original sealed bags so they are not compressed.
5. Preserve Original Packaging
Manufacturers design seal kit packaging to protect against dust, light, and oxidation. The plastic bags are often low-density polyethylene (LDPE) which does not react with most rubbers. Do not open the kit until use. If a bag is damaged, re-seal it in a clean, airtight container – but avoid PVC or shrink wrap containing plasticizers that can migrate into the seals.
6. Apply First-In, First-Out (FIFO) Stock Rotation
Elastomers have a finite shelf life even under ideal conditions. Typical recommendations:
· Nitrile (NBR): 5–7 years
· Viton (FKM): up to 10 years (if not exposed to high heat)
· Polyurethane (PU): 3–5 years
· Silicone: 5–10 years (but mechanical properties may degrade)
Label each kit with the received date. Use older stock first. Inspect seals annually for signs of hardening, stickiness, or surface cracks.
7. Avoid Contact with Certain Materials
Never store seal kits directly on or near:
· Copper or brass (catalyze degradation of some rubbers)
· Cardboard (acidic lignin can attack elastomers over time)
· Rubber mats containing sulfur (causes cross-linking reactions)
· Polystyrene or PVC (plasticizer migration) Use stainless steel, anodized aluminum, polyethylene, or polypropylene trays and shelves.
8. Special Considerations for Hydraulic Seal Kits
Many seal repair kits include multiple components: O-rings, back-up rings, wipers, and rod seals. Store them assembled in their original compartments. If re-bagging, group by size and material. Never mix different rubber types in direct contact without separation, as plasticizers or chemicals can migrate between them.
