Spiral Wound Gaskets are made of a preformed thin metallic strip combined with a soft sealing composite material, wound together under pressure to energize the sealing element to act like a spring when compressed between two flange faces. The sealing element can be used stand-alone or in
conjunction with inner and/or outer rings depending on the application.
Spiral Wound Gaskets are available in a full range of styles and materials and are manufactured in accordance with ASME B16.20 for use in all industry flanges, including ASME/ANSI B16.5, ASME B 16.47, Series A & B.
Spiral Wound Gaskets can be made from a large selection of alloys and filler materials in a variety of shapes and sizes. Some of the most common shapes are as follows.
Style S Gasket– Sealing Element
Designed for tongue and grove applications, the style S gasket is a stand alone sealing element where the ID is reinforced with several layers of metal winding, filler material is then introduce to offer greater sealing ability and the gasket is finished with several more layers of metal to help insure stability.
Style SI Gasket– Sealing Element with Inner Ring
The SI configuration is the same as the S except that a solid inner ring is utilized to prevent over compression. This design is also helpful in turbulent applications which are prone to cause erosion of the flange faces.
Style CS Gasket– Centering Ring with Sealing Element
The CS gasket utilizes an external ring where the ID is grooved to insert a sealing element. The external ring or centering ring is designed to properly guide the gasket on a bolted flange accurately centering gasket. The Centering also provides additional radial strength to prevent gasket blowout and acts as a compression limiter.
Style CSI Gasket- Centering Ring with Sealing Element and Inner Ring
The CSI gasket is best suited where high pressure and temperature is a factor or in applications where corrosive or toxic media maybe present. Like the CS profile, the CSI gasket includes an inner ring which has proven to be very helpful to eliminate inward buckling of the sealing element.
ASME B16.20 requires the use of CSI gaskets when PTFE is used as the filler in all ANSI B16.5 applications as well as:
• Pressure Class 900, nominal pipe sizes 24” and larger
• Pressure Class 1500, nominal pipe sizes 12” and larger
• Pressure Class 2500, nominal pipe sizes 4” and larger
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)