Socket welding
flange, a popular type of pipe flange, was initially developed for use
on small-sized high- pressure piping. The fabrication of this type of
flange is similar to that of a slip-on flange. However, the internal
pocket of a socket weld flange allows for a smooth bore and better fluid
flow. When provided with an internal weld, the static strength of this
flange is equal to slip-on flange, but the fatigue strength is 50%
greater than double welding slip-on flanges. Smooth bore conditions in
such a flange can easily be attained without having to bevel the flange
face and, after welding, to reface the socket weld flange as would be
required with slip-on flanges. For this reason, the internally welded
flange is popular in chemical process piping.