Gaskets used to seal flanged joints have two failure modes: the gasket may leak, usually slowly, or it may suffer a sudden, catastrophic failure – a condition commonly referred to as “blowout”. The latter condition is the subject of this blog.
What is gasket blowout?
“Gasket blowout” is a term used to describe the sudden and catastrophic failure of a gasket. Blowout usually occurs when the application pressure exceeds the physical strength of a gasket. The high internal load forms a hole or tear in the gasket that suddenly releases the media being sealed. A blowout condition creates a hazard for personnel, equipment and the environment – hot, toxic or hazardous fluids or gases can rapidly escape from the ruptured gasket, possibly injuring personnel and damaging equipment, while escaping into the environment.
How can gasket blowout be prevented?
Because the forces in a flanged joint are complex, there is no one single solution to preventing gasket blowout. Rather, multiple factors must be considered and addressed to reduce the risk of gasket blowout. These include the following:
- Choose a gasket material with sufficient tensile strength to resist the internal load. Gaskets made from materials which have insufficient tensile strength to resist the maximum pressures encountered in an application will be more likely to blow out.
- Choose a gasket material with low creep. Creep relaxation is a measure of how much a particular gasket material spreads or thins out when force is applied. Gasket material which permits too much creep will thin out and be unable to resist the internal load.
- Consider the effects of application temperature. As application temperatures rise, fastening bolts can lengthen, reducing the clamping force applied to the gasket. This can cause creep.
- Follow the recommended tightening pattern for a flanged joint. Failure to follow the recommended tightening pattern can result in a reduction of fastening force on some areas of the gasket. Similarly, fasteners should not be overtightened, crushing the gasket material or causing the material to deform at its outer edge.
- Minimize vibration at the joint. Vibration can cause fasteners to loosen, causing a reduction in clamping force.
- Choose thinner material. Buyers are often misled into thinking that thicker gaskets perform better. In actual fact, thicker gaskets tend to exhibit greater material creep, providing less resistance to blowout. Torque retention and blowout resistance tend to be better with thinner materials.
While there is no single solution to preventing gasket blowout, following the above tips will lessen the risk of a blowout occurring.
As a leading provider of custom cut gaskets, CRG sealing specialists will be pleased to provide further information on material selection and best practices to reduce the risk of gasket failure and blowout. For more information on the products we can supply, please contact us at firstname.lastname@example.org