Resources: Engineer FAQs
O-Ring Failure Modes
Like any device subject to judgment in design or to human error during installation, O-ring seals are susceptible to failure. The following brief summary of O-ring failure patterns is intended to give the designer/engineer a brief overview of the more common types of failure and a listing of recommended corrective actions. While there are a number of different types and causes of sealfailure, we intend to cover only the types encountered most frequently. For a more complete listing of O-ring failure modes, Parker suggests the engineer obtain a copy of Publication AIR1707, Patterns of O-Ring Failure, available from: SAE Inc.400 Commonwealth Drive Warrendale, PA 15095 www.sae.org
AIR1707, Patterns of O-Ring Failure, contains extensive material and some excellent photographs and will be most helpful for identifying the less common modes of O-ring failure not covered in this guide.
Why an O-Ring Fails Prematurely
The premature failure of an O-ring in service can usually be attributed to a combination of causes and not merely a single failure mode. It is important to maximize sealing life and reliability by educing the probability of seal failure at the onset by the use of good design practices, proper compound selection, pre-production testing, and continued education and training of assembly personnel.
In 1998, the Society of Aerospace Engineers (SAE) issued Aerospace Recommended Practice (ARP) 5316. It was intended to fully replace Mil-HDBK-695C as the industry standard for the shelf life of aerospace elastomeric seals. However, ARP 5316 can also be used as a useful guideline for shelf life of many industrial and commercial grade elastomers as well. The information in ARP 5316, and the chart below, is intended to be utilized by those organizations that do not already have specific recommendations for the control of elastomeric seals. It should be noted that the packaging of the elastomeric seals prior to assembly into a product is an integral part of the controlled storage procedure. It provides a positive means of product identity from the time of manufacture, to the time of assembly.
ARP 5316 does not establish limitations for storage times in assembled components, nor does it in any way provide a guideline for the operating lifespan of a particular compound.