Flange Facing

The gasket seating surface of a flange — raised face, flat face or ring type joint — and the finish machined into it.

Raised face with a 125 to 250 AARH serrated finish is the default for spiral wound gaskets; a smoother finish can let the gasket slip and a rougher one can cut it. Flat face is used against cast iron equipment so the bolt load does not crack the flange. Ring type joint relies on metal-to-metal contact in a machined groove, which is why the groove hardness and finish are inspected separately from the flange body.

Related terms

Pressure Class
Spiral Wound Gasket

Where this applies

flanges, gaskets-fasteners

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