The socket welding flange is similar to a slip-on flange except it has a bore and a counterbore dimension.

The counterbore is sightly larger than the O. D. Of the matching pipe, allowing the pipe to be inserted into the flange similar to a slip-on flange.

The diameter of the smaller bore is the same as the I. D. Of the matching pipe A restriction is built into the bottom of the bore which sets as a shoulder for the pipe to rest on. This eliminates any restriction in flow when using a socket flange.