Spiral wound Gaskets

A requirement of any gasket is the ability to recover under variable loads. The effects of pressure and temperature fluctuations, the temperature difference across the flange face, along with flange rotation, bolt stress relaxation and creep, demand a gasket with adequate flexibility and recovery, to maintain a seal under variable working conditions. A spiral wound gasket is manufactured by spirally winding a preformed metal strip and a filler on the outer periphery of metal winding mandrels. The winding mandrel outside diameter forms the inner diameter of the gasket and the superposed metal and non-metallic windings are continually wound until the required outer diameter is attained. Normal practice is to reinforce the inner and outer diameters with several plies of metal without fillers. This engineered product is “tailor made” to be compatible with the flange closure in which it is to be used. For example, a closure designed for vacuum service may require a gasket of exactly the same dimensions as a closure designed for 1500 psi service. The closure designed for the vacuum service would have relatively light bolting indicating the necessity for a soft gasket, while the 1500 psi application would have heavy bolting requiring a relatively dense gasket. It is usually within our capability to satisfy both requirements.

The “v” and “w” shaped crown centered in the metal strip acts as a spring, giving gaskets greater resilience under varying conditions. If the load available to compress a gasket is limited, gasket construction and dimensions can be altered to provide an effective seal.

A spiral wound gasket may include a centering ring, an inner ring or both. The outer centering ring guides / enters the gasket within the flange and acts as a compression limit, while the inner ring provides additional radial strength prevents from blow out force. The inner ring also reduces flange erosion and protects the sealing element. Resilience and strength make spiral wound gaskets an ideal choice under a variety of conditions and applications.