3in Full Face Flange Gasket — Red Rubber 150#/125#, 1/8in Thick, 7-1/2in OD

A 3 inch full face gasket in 1/8 in. red rubber, cut to ASME B16.21 for 150 lb flanges. Pipe size is a name, not a measurement — 3 in. pipe is 3-1/2 in. across the outside, which is why the bore reads 3-1/2 in. and the outer edge 7-1/2 in.

Fits 150 lb steel and 125 lb cast iron flanges — Class 125 and Class 150 share the same bolt pattern, so one gasket covers both. A Class 300 flange is wider on a different bolt circle and takes a different gasket. Red rubber (SBR) suits water, brine, air and low-pressure service; for oil, fuel, solvents or acids ask for Buna, Viton, EPDM or non-asbestos.

Where a 3 in. goes. Small pump suction and discharge, booster sets, pool and spa equipment pads, irrigation laterals, and the strainer and valve flanges on branch lines. It is the largest size in the range with only four bolts — the 4 in. steps up to eight, so if your flange has eight holes you are already past a 3 in.