Full definition
A semi-metallic gasket constructed by winding a V-shaped metal strip and a soft filler material (graphite or PTFE) in alternating layers into a spiral disc, combining the resilience and sealability of the filler with the structural strength and blow-out resistance of the metal strip. The metal provides recovery (spring-back) while the soft filler conforms to flange surface irregularities and provides the actual sealing. Metal: 304/316 stainless steel (standard), Monel, Inconel, or titanium (corrosive service). Filler: flexible graphite (most common, -200 to +650°C), PTFE (chemical service, -200 to +260°C), or ceramic (extreme temperature). Components: centering ring (outer, positions gasket on flange bolts), winding (spiral of metal + filler), and inner ring (prevents inward buckling under high bolt load). Per ASME B16.20 (dimensions and tolerances for ASME flanges). Pressure/temperature: up to 250 bar and 1,000°C depending on materials. Designated by inner ring / winding / filler / outer ring materials. The most widely specified gasket for ASME raised-face and ring-joint flanges in refineries, chemical plants, and power generation. Brands: Flexitallic (inventor — Flexitallic Spiral Wound), Garlock, Klinger, Lamons.