The spiral wound gasket was developed in the early 20th century to meet the increasingly demanding conditions encountered in oil refinery operations. This type of gasket is commonly used with flange surface finishes created using Mirage flange facing machines, which is why we decided to put together this simple overview as an introductory guide for the on-site machinist.
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 emphasized.
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 centering and controlling compression. This minimizes 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.
