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O-Ring Shelf Life
O-ring shelf life compliance standards
All KODA elastomer products strictly adhere to the SAE International Aerospace Standard AS5316 regarding shelf life and storage conditions. Formerly known as ARP5316, this standard is an industry recommended practice, developed based on long-term research into storage limitations and industry feedback. It also explicitly mandates that inventory follow the First-In, First-Out (FIFO) principle. It’s important to note that compliance with this standard is voluntary, but KODA can meet all related customer requirements. The various limitations in the standard are derived from testing and examining rubber seals stored for extended periods (some over 30 years). Besides being supported by practical experience, these recommendations also align with theoretical principles: theoretically, materials that can be stored indefinitely should not undergo chemical changes upon exposure to air, and their chemical and physical properties should remain stable.
Recommended shelf life of O-rings (compliant with AS5316 standard)
The table below, based on SAE Aerospace Recommendation ARP 5316, summarizes the recommended shelf life for different elastomer (rubber) sealing materials. KODA considers this specification to be the most comprehensive reference for determining the shelf life of seals, but it is not a mandatory standard. You can refer to the information in this table to formulate your company’s seal shelf life requirements.
| Elastomer Family | Materials and Testing | Shelf Life |
|---|---|---|
| AFLAS | Unlimited | |
| Butyl Rubber, Isobutylene Isoprene | IIR | Unlimited |
| Chloroprene (Neoprene) | CR | 15 Years |
| Epichlorohydrin (Hydrin) | ECO | NA |
| Ethylene Acrylic (Vamac) | AEM | 15 Years |
| Ethylene Propylene, EPDM or EP | EP | Unlimited |
| Fluorocarbon (Viton) | FKM | Unlimited |
| Fluorosilicone | FVMQ | Unlimited |
| Hydrogenated Nitrile, HNBR or HSN | HNBR | 15 Years |
| Nitrile (Buna-N or NBR) | NBR | 15 Years |
| Perfluorelastomer | FFKM | Unlimited |
| Polytetrafluoroethylene (Teflon) | PTFE | Unlimited |
| Polyacrylate | ACM | 15 Years |
| Polyurethane (Polyester or Polyether) | AU / EU | 5 Years |
| Silicone | VMQ | Unlimited |
| Styrene Butadiene (Buna-S) | SBR | 3 Years |
*Note AS5316 deals only with the storage of elastomeric parts and carries no justification for components post application/assembly
Storage conditions:
Proper storage conditions are essential to ensure the shelf life of sealing materials meets standards. Below are some key factors affecting shelf life and the specific requirements of the AS5316 standard:
Temperature: Storage temperature should be maintained between 15°C and 38°C (59°F to 100°F).
Humidity: Relative humidity should be below 75%; this humidity restriction does not apply if the material is stored in a sealed moisture-proof bag.
Light: Do not expose the material to direct sunlight or near artificial lights that emit strong ultraviolet rays.
Radiation: Take precautions to block ionizing radiation that may damage the material.
Ozone: Do not place mercury vapor lamps, high-voltage electrical appliances, or other equipment that generates ozone in the storage room, and keep flammable gases or vapors away.
Deformation: The material should not be squeezed or stretched during storage; it should be kept in a stress-free state to avoid deformation.
Material Isolation: Do not allow the material to come into contact with liquids or semi-solids such as gasoline, grease, acids, and disinfectants. Also keep it away from metals such as copper, manganese, and iron, and other elastomers.
Packaging requirements:
The ARP 5316 standard recommends individual packaging for rubber seals to protect them and facilitate batch traceability. However, we’ve found that our bulk packaging achieves the same effect. Furthermore, a study testing seals stored for 32 years showed no performance difference between bulk and individually packaged seals. Therefore, we believe individual packaging is not a necessary condition for seals to reach their shelf life; however, we can provide individual packaging if required by our customers.
Cure Date:
The ARP 5316 standard does not mention “curing quarter,” only using the term “production time.” At KODA, we record the last day of each curing quarter as the product’s production time.
History:
Following World War II, the aging control of seals in aircraft hydraulic, fuel, and lubrication systems became a requirement. In 1958, the first document on seal aging control was published, summarizing numerous post-war studies. Later, with further research and publications, the MIL-STD 1523 standard was introduced in 1973, specifying a maximum shelf life of 12 quarters for seals. In 1984, the MIL-STD-1523A standard was released, extending the shelf life to 40 quarters. In 1995, the AS1933 standard was introduced, superseding the MIL-STD 1523 standard. However, the full title of the AS1933 standard is “Aging Control of Hoses Containing Aging-Sensitive Elastomers,” and it only applies to elastomeric hoses; rubber seals have since lacked corresponding aging control standards.
In the past, MIL-HDBK-695C, MIL-STD-1523A, and its replacement standard AS1933 were all used in rubber seals. When MIL-STD-1523A was phased out in 1995, the announcement stated that AS1933 could be a potential replacement standard. However, AS1933 was specifically designed for rubber hoses and could not meet the actual needs of the seal industry. While MIL-HDBK-695C is applicable to all rubber products, it also failed to meet the specific control requirements for seals. To fill this gap, the ARP 5316 standard was developed. Its purpose is to establish a practical shelf-life standard system for seal manufacturers, distributors, and users.
Summary:
Because the ARP 5316 standard contains the latest and most accurate information regarding the shelf life of elastomeric seals, KODA recommends that all distributors and customers adopt this new guideline in the way best suited to their needs. ARP 5316 is a copyrighted document; you can purchase a copy from SAE by calling +8618730921709 or visiting standards.sae.org/arp5316c