Domestic Socket Weld Flanges
Socket Weld flanges were initially developed for use on small-size high pressure piping. Their static strength is equal to Slip On flanges, but their fatigue strength 50% greater than Slip On flanges.
The connection with the pipe is done with one fillet weld at the outside of the flange. But before welding, a space must be created between flange and the end pipe.
ASME B31.1 1998 127.3 Preparation for Welding (E) Socket Weld Assembly says:
In assembly of the joint before welding, the pipe or tube shall be inserted into the socket to the maximum depth and then withdrawn approximately 1/16" (1.6 mm) away from contact between the end of the pipe and the shoulder of the socket.
The purpose for this bottoming clearance in a Socket Weld is to reduce the residual stress at the root of the weld that could occur during solidification of the weld metal. The image shows you the X measure for the expansion gap.
The disadvantage of this flange is due to this gap. In piping system using mainly stainless steel pipe and corrosive products, the crack between pipe and flange can give corrosion problems.
All Domestic Socket Weld Flanges are made from material forged and machined in USA.
A105 - The standard forged carbon steel piping components for ambient and high temperature / pressure systems
SS304 - A common standard for stainless steel due to its malleability, high corrosive resistance weld-ability
SS316 - A molybdenum stainless steel that provides excellent tensile, creep and stress-rupture strengths at elevated temperatures