Full definition
Spiral wound gaskets are a type of semi-metallic gasket that combines the unique properties of a metal strip and a soft filler material, creating a sealing solution that effectively manages high pressures and temperatures. The construction involves winding a V-shaped metal strip, typically made from 304 or 316 stainless steel, Monel, Inconel, or titanium, around a core of flexible filler material such as graphite or PTFE. This design allows the metal to provide the necessary structural strength and recovery (spring-back), while the filler material ensures excellent sealing capabilities, especially useful in applications where flange surface irregularities are present.
The spiral design consists of alternating layers of the metal strip and filler, forming a spiral disc that can conform to various flange profiles. The outer centering ring serves to position the gasket properly on the flange bolts, while the inner ring prevents inward buckling under high bolt loads, thereby enhancing the gasket's performance under extreme operational conditions. The versatility in materials used allows spiral wound gaskets to excel in diverse environments, including corrosive applications and extreme temperatures up to 1,000°C, depending on the selected materials.
Spiral wound gaskets are commonly designated by the combination of materials used in the inner ring, winding, filler, and outer ring, which can be tailored to meet specific operational needs. According to ASME B16.20, these gaskets are precisely defined by their dimensions and tolerances, making them suitable for ASME raised-face and ring-joint flanges found in industries such as oil and gas, chemical processing, and power generation. Their ability to withstand pressures up to 250 bar makes them a preferred choice for many critical applications where reliability and durability are paramount.