A spiral wound gasket is a semi-metallic gasket that combines the strength of metal with the resilience of a soft filler material. It is constructed by winding alternating layers of a thin metal strip (like stainless steel) and a non-metallic filler material (such as graphite or PTFE) into a continuous spiral. This design makes them ideal for sealing in high-pressure, high-temperature, and corrosive environments in industrial applications like flanged connections.  

Construction and components

• Inner and outer rings: 

  Some designs include solid inner and outer rings. The outer ring acts as a centering and compression-restricting device. The inner ring prevents the filler material from extruding into the pipeline. 

• Winding: 

  The alternating layers are wound in a continuous spiral to form the gasket. 

• Metal strip: 

  A thin, V-shaped metal strip, often made of stainless steel, provides strength and recovery. 

• Filler material: 

  A soft, non-metallic material, such as graphite or PTFE, provides the sealing properties. 

Key features and applications

• Resilience: 

  The spiral design allows the gasket to dynamically recover under varying loads, making it suitable for systems with temperature fluctuations, pressure surges, and vibration. 

• Sealing efficiency: 

  The combination of metal and filler provides a high-performance, reliable seal in demanding conditions. 

• Wide temperature and pressure range: 

  They can be used from cryogenic temperatures up to very high temperatures and in pressure services ranging from vacuum to high-pressure flange ratings. 

• Corrosion resistance: 

  Because they can be made from various metals, they can be used with almost any corrosive medium. 

• Common uses: 

  They are widely used in industries such as oil and gas, chemical, and power generation for sealing pipelines, valves, and heat exchangers. 

Installation considerations

• Centering: 

  The outer ring helps to center the gasket within the flange, ensuring even compression. 

• One-time use: 

  Spiral wound gaskets are designed for one-time use; after compression, they deform and should not be reused. 

• Testing: 

  It is often recommended to use a separate gasket for initial pressure testing before the final installation.