Sealing the Joint: A Guide to Spiral Wound Gaskets and Heavy Hex Bolts
1. The Spiral Wound Gasket (SWG) The most common gasket for high-pressure flanges (ASME B16.20). It consists of a V-shaped metallic strip spirally wound with a soft filler (typically Graphite or PTFE).
- Inner Ring: Prevents “buckling” of the windings into the pipe.
- Outer Ring: Centers the gasket and prevents “blowout.”
2. Structural Fasteners: ASTM A193 B7 & A194 2H A flange joint is only as strong as its bolts.
- A193 B7 Stud Bolts: Chrome-molybdenum steel, heat-treated for high-strength pressure service.
- A194 2H Heavy Hex Nuts: Designed to match the high-tensile strength of B7 studs.
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