Non-Metallic Materials | Failed Gaskets

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  9. Non-Metallic Materials-Failed Gaskets

Why are these failures critical? Their consequences can be as significant as those of metallic components. For example, the Space Shuttle Challenger Disaster in 1986, which shocked and changed the world, was due to o-ring failures. The temperature during launch was so low that the gaskets did not seal. Below, we have illustrated different gaskets that failed after less than a week in an oilfield vessel. What happened?

The top left image shows failed fluoroelastomer (FKM) Gasket 1: it has some adhered material, compression set, and through-wall cracks. The top right image shows the damaged gasket’s cross-sections.  The gasket adhered material was identified as being a spray-on adhesive used during installation – the adhesive contained a compound that was incompatible with FKM. The deformation pattern of the gasket suggested it had slipped out of place before being fully compressed. The gasket had been subjected during installation to compression set above the manufacturer’s recommended values. What caused the failure? The adhesive, and the compression set resulted in the gasket cracking, and extruding out of the joint such that it could not seal. 

The disintegrated bottom left Gasket 2 was from the same service as Gasket 1.  It was tested by Energy Dispersive X-ray (EDX) analysis to identify if it contained fluorine, an element characteristic for FKM. The gasket did not contain fluorine and no further identification was performed. Using a gasket incompatible with process conditions can lead to rapid failure. 

Ultimately, a gasket suitable for this service was found by careful evaluation of the installation procedures and by choosing a stiffer gasket in a different material compatible with the process.  The bottom right image shows a new replacement gasket after 10 days of service. The use of a spray adhesive was also stopped.