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Common Causes of O-Ring Failure and Prevention Methods

O-ring failure is often caused by a combination of factors including improper installation, allowing for too much or too little compression in the gland design, inadequate lubrication, abrasion, or using an O-ring seal that is the incorrect size or type of elastomer for your application. Here are a few common sources of rubber oring failure and what you can do to prevent issues.

Abrasion

Abrasion is a common cause of o ring failure and can result from an improper finish of the surface in dynamic contact with the O-ring. If the surface around the O-ring is too abrasive, or even too smooth, the surface will be unable to hold lubricant. Issues with O-ring abrasion can also occur when a system fluid is not providing proper lubrication, the system fluid contains abrasive particles, or the operating environment involves excessive temperatures.

Solutions to this problem include adding a proper surface finish and adequately lubricating the O-ring to reduce friction and the risk of wear over time. Another way to prevent abrasion caused by excessive temperatures is to choose an elastomer that is designed to tolerate the operating temperatures where the O-ring is going to be installed.

Also, check your system fluid regularly for contamination and to ensure that it provides enough lubrication for the O-ring and type of elastomer. If you continue to experience issues, try using a rubber o ring made from an elastomer that provides more abrasion resistance or that is internally lubricated.

Excessive Swelling

Swelling of the O-ring is caused by the absorption of surrounding fluids. The o ring will continue to swell past the appropriate point if the seal materials are not compatible with the system environment including temperature and fluid type. O-ring swell can eventually lead to issues such as land fill, extrusion and loss of sealing.

Compression Set

A compression set is the most common cause of O-ring failure. It is caused when the integrity of the seal line is affected by an improper amount of seal squeeze. Typically, an O-ring will return to its original shape when the cross-section is compressed but when a rubber Oring is stretched, it reduces the cross-section and turns the O-ring into a flat oval, which significantly decreases its sealing ability.

This happens because of several conditions, including the O-ring being made with inherently poor compression set properties. It can also be caused by improper gland design, excessive temperature, swelling, or over-tightening. Using fluids that are incompatible with your elastomer can also cause compression and O-ring failure.

By inspecting your O-rings for effective properties before use, you can prevent this condition. You can also reduce the operating temperature and check for any built-up heat at the seal interface. Use low-set material when possible and make sure the elastomer is compatible with your application temperature and fluids.

Compare & Contrast: Silicone vs. EPDM

Silicone and EPDM are similar in many ways, and the two materials offer a variety of similar characteristics. Both offer good resistance to weathering, UV exposure, and ageing, making them suitable for outdoor applications. Silicone and EPDM also exhibit high ozone resistance and an ability to remain flexible in low temperatures.

However, silicone provides far greater high-temperature resistance. Unlike EPDM, silicone will maintain its stability and physical properties in temperatures as high as 450°F (232°C).

Proper Lubrication Helps Prevent O-Ring Failure

Rubber O-rings, when not properly lubricated, can fail due to abrasion or pinching. Using an oil- or grease-based lubricant helps protect the surface of the O-ring and can prevent the degradation of the elastomer material. This will prevent failure and help extend the life of your O-ring.