Spiral Wound Gasket

Spiral Wound Gaskets [SWGs] belong to the group of semi-metallic gaskets.

They consist of thin metal strip which are embedded between layers of non-metallic filler material. The metal sheets and layers of filler are alternately wounded in continuous spiral forms which gives this gasket its name.

Spiral Wound Gaskets are the most common used gaskets in diverse industrial applications. They are manufactured in a wide range of material, styles and sizes. They are commonly used in the oil and gas-, chemical-, petrochemical-, food industry and as well in conventional- and nuclear power plants. Their main goal is to prevent leaks through flanged joints even under severe temperature and pressure fluctuations.

Spiral Wound Gaskets can be used in the condition with low and fluctuating bolt loads. Basically there are three elements that constitute a spiral wound gasket, according to requirements related to operating circumstances, different types might be used. Spiral wound gaskets are proven to have advantages related to high-temperature/pressure applications and are often used in corrosive environments. Another positive aspect is that they also show improved sealing performance although with increased roughness of the sealing surfaces of flange.

Following three elements are constituting a Spiral Wound Gasket

Outer ring: Commonly known as a guide ring or centering ring. The outer ring of a spiral wound gasket is usually made of austenitic-/ or carbon steel depending on its planned application. The key purpose of the outer ring is to center the gasket within the bolted flange joint and is also providing the blow out resistance.

Inner ring: The inner ring plays a key role as it prevents windings from buckling inside the flanged connection. Without the inner ring, buckling of sealing material could occur and get sucked into the system, this would lead to a foreign material introduction within the system and could cause for example plant shut downs in the worst case. Furthermore it provides the gasket a greater resistance against thermal shocks.

Sealing element: This element of the spiral wound gasket creates a tight seal to prevent leaks. The sealing element encompasses both windings and filler material. In general, spiral wound gaskets use a flexible graphite filler material rated for high temperatures. The graphite as filler material also helps the gasket to avoid flange distortion and joint misalignment. Another common filler material is PTFE (Polytetrafluoroethylene). However, PTFE is not suitable for use in high-temperature applications. The most widely used winding materials are Stainless Steel and Monel.