1-1/4in Full Face Flange Gasket — Red Rubber 150#/125#, 1/8in Thick, 4-5/8in OD

A 1-1/4 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 — 1-1/4 in. pipe is 1.660 in. across the outside, and the gasket bore is cut at 1-5/8 in., rounded to the nearest eighth as it is on all the small sizes.

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 1-1/4 in. goes. The smallest flange size we stock — small circulators, equipment and instrument connections, bypass lines, and compact strainer and filter bodies. Easy to confuse with the 1-1/2 in.: both carry four 5/8 in. bolts, and the only real difference is the outside diameter, 4-5/8 in. against 5 in. If you are between the two, measure the flange face rather than counting holes.