Gaskets - Bolting Specifications

A gasket's mechanical environment must be known. Are the flanges flat, raised, grooved, etc.? Flange and bolt size is determined by the size of piping and the operating pressure. Bolts should be located central to the flange width. The bolt spacing for low pressure service should not exceed seven (7) times the bolt diameter. The bolt spacing for high pressure service should not exceed 3 1/2 times the bolt diameter. Weak flanges and high internal pressure may both reduce the maximum workable bolt spacing.

FORGED STEEL FLANGES (CHART)

(click image to enlarge)

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