Gaskets used in the oil, gas and petrochemical industries need to be engineered to cope with high pressures, extreme temperatures and chemical attack. Fluctuations in the above, along with temperature differential across the flange face and bolt stress relaxation, demand a gasket with flexibility and recovery. The need for the gasket to recover from changing conditions cannot be over emphasised.
The spiral wound gasket is semi-metallic, comprising of a spirally wound v shaped stainless steel strip and a non-metallic filler material, such as graphite or PTFE. Also on the gasket, is a solid outer ring used for centring and controlling compression. This minimises the risk of material creep through over-tightening.
For the toughest conditions, spiral wound gaskets are available with an additional inner ring. This protects the windings (particularly the filler), from contamination, or attack by the product travelling past the pipeline joint.