O rings, also known as packing joints, are small ring-shaped gaskets you can install on several static and dynamic applications. They are used in electronics, food manufacturing, transportation, and more. They’re easy to use, manufacture, and are pretty dependable.
Because they’re made from different rubbers and polymers, you need to be mindful of how to store your o rings to make them last a very long time. Here are some things you need to know about keeping them:
The O Ring’s Shelf Life Varies
There’s a misconception that as long as your o rings are inside their box, they will always last long. While this is true to a certain extent, it will still depend on several factors. These include their material, how they’re packaged, and where they’re stored.
O rings today are typically made from silicone, neoprene, TFE/P, or polyurethane, among others, and these materials have a varying shelf life. Some may only last five years, while others can survive more than 15. Under proper conditions, some rubber o rings, like those made from silicone and fluorocarbon, last indefinitely.
The O Ring’s Shelf Life Can Be Calculated
If you want to know how long your o ring will last in storage, there’s a way to calculate its shelf life. It is generally calculated in quarter-year units. For example, if an o ring were made in January 2020, the manufacturing date would be 1Q20.
Rubber products have a curing period or a process where the long chains of its molecules are cross-linked by heat. It allows the material to stretch and return to its original state. The curing date is the day that the material is fully molded. Since it can happen within the first three months after its manufacturing date, its aging doesn’t begin after its first quarter.
For instance, if the curing began in January 2020, it would only start aging on April 2020. Therefore, if the o ring has a shelf life span of five years, it will most likely expire on April 2025.
O Ring Storage Is Standardized
The rubber industry today follows the specifications set by the SAE International Standard. It considers several factors that can affect the durability and condition of your o rings. If o rings are correctly stored, cracking, deforming, and prematurely aging can be avoided. Some of the recommendations listed on the SAE-ARP5316 are the following:
- Store Rubber Products Below 100°F – High temperatures can cause the rubber to deteriorate and age faster. If it’s kept at high temperatures for a long time, your o ring will experience a change in its chemical composition. It should also be stored as far away as possible from direct sources of heat, including radiators, boilers, and more.
- Keep Light and UV Away From Your O Rings – Although some types of rubber are resilient to UV exposure, keeping them away from direct sunlight is still recommended. If stored in storage bags, they must be UV resistant as well.
- Store Your O Rings on Low Humidity – Humidity can also affect the o ring’s structure and performance. Too much moisture can make the seal absorb water, changing its dimension and shape. When storing o rings away, keeping them in a moisture-proof bag is best. The humidity should also be less than 75% for most rubber o rings. For polyurethane o rings, it should be less than 65%.
- Ozone Can Have Negative Effects on O Rings – Ozone can also ruin o rings. As such, where you store your o rings should not have any machine or equipment that can generate ozone. These include mercury vapor lamps, high-voltage electrical equipment, etc.
- Additional Recommendations – O rings are also not allowed to get into contact with liquids like gasoline, acids, disinfectants, and others and their vapors. Some rubber materials may also have a chemical reaction with certain metals and alloys like copper, iron, and manganese. As such, it’s best to keep them away from o rings as possible.
Manufacturers also follow the guidelines in ISO 2230: Rubber Products when storing o rings. It’s mainly similar to SAE-ARP5316 but has a few notable differences. For example, the ISO recommends keeping o rings below 77°F instead of 100°F. It also suggests that humidity should be less than 70% for most rubber o rings.
O rings are durable and reliable when stored under proper conditions. As long as you follow the recommended guidelines, you can be sure you won’t have any immediate issues with your o rings when you use them.
