Socket Weld Flange This is similar to a slip-on flange in outline,
but the bore is counter-bored to accept pipe. The diameter of the
remaining bore is the same as the inside diameter of the pipe.
The flange is attached to the pipe by a fillet weld around the hub
of the flange. An optional internal weld may be applied in high
stress applications. Its biggest use is in high pressure systems
such as hydraulic and steam lines