Spiral wound gaskets

The sealing element of a spiral wound gasket consists of alternating windings of:

• a metal strip profiled in V;
• a softer filler material, generally graphite, PTFE or mica, depending on the application.

The V-shaped geometry acts as a spring, allowing the gasket to compress during tightening and retain recovery as the assembly experiences changes in load, pressure or temperature.

Depending on gasket type and standard, various thicknesses are available, including 2.5 mm, 3.2 mm and 4.5 mm.

Metal rings can be added to suit the spiral wound gasket to the flange.

Outer ring

It assists gasket centring and acts as a compression stop in many configurations.

Inner ring

It protects the winding at the inner diameter, limits the effect of the fluid on the winding and may be required depending on the service, pressure, filler or applicable standard.

Type C

Wound sealing element without a guide ring, for confined or grooved flanges and other assemblies where flange geometry provides positioning and compression control.

Type GI

Spiral wound gasket with an inner ring, used for certain male-and-female flanges or configurations requiring an inner guide.

Type GE

Gasket with an outer ring, commonly used on flat-face or raised-face flanges where permitted by the construction and standard.

Type GEGI

Gasket with outer and inner rings for applications requiring enhanced protection and guidance of the wound sealing element.

Metal winding

Depending on the application, the metal strip can be produced from various stainless steels or alloys. The current range includes:

• 304 / 304L;
• 316 / 316L;
• 321;
• 310;
• nickel alloys such as Inconel;
• Monel;
• Duplex / Super Duplex;
• Hastelloy;
• titanium;
• other special alloys, subject to availability.

Filler

Principal fillers include:

• graphite;
• PTFE;
• mica / high-temperature fillers.

Selection depends on the fluid, temperature, pressure and any contamination constraints.

For hydrogen applications, H₂ READY spiral wound gaskets are available within the relevant range. The applicable construction and qualification are confirmed case by case.

Depending on the configuration, gaskets can be supplied to:

• ASME B16.20;
• ASME flange dimensions;
• DIN / EN standards;
• special dimensions to drawing.

For many spiral wound gasket applications, Flexitallic® documentation specifies a typical surface finish of approximately Ra 3.2 to 6.3 µm. The finish must nevertheless be confirmed for the gasket construction and flange.

Tightening must be controlled and appropriate to the bolting, flanges and gasket used.

EST can assess:

• non-standard diameters;
• rings in special alloys;
• oval or obround shapes where manufacturing permits;
• winding density adapted to specific applications;
• urgent requirements.