Approved Import 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assembly of the joint before welding, the pipe or tube shall be inserted into the socket to the maximum depth and then withdrawn approximately 1/16" (1.6 mm) away from contact between the end of the pipe and the shoulder of the socket.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.

Size & Dimension table for Flanges

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

Material Description for Flanges

This is a socket weld flange. 2 inch, raised face, 150 pound, socket weld flange. Remember, all flanges have a stamping here that shows the size, the pressure rating, the country of origin, the specification, the material. A socket weld flange, as you can see right here, has a little socket. The pipe goes in here and it fits in the socket and then you can weld it. You can see from the backside, this is a standard schedule pipe, this is a standard bore socket weld flange, and it is very flush from the backside.

On the socket weld flange, you have to specify the pipe schedule. The pipe schedule, this is a 2 inch nominal pipe, and this is a standard schedule pipe, and this is a standard schedule socket weld. The pipe schedule and the bore of the socket weld flange has to match so that there is no raised face, there is no protrusion on the backside. The difference between a socket weld flange that has a bore of schedule 40 or schedule 80 is that this inner bore will change so it matches the bore of the pipe. That’s what you’re trying to do.

Remember, on a socket weld flange, other than specifying if it’s a 150 pound or 300 pound, you also have to mention if it is for a schedule 40, schedule 80, schedule 120, schedule 160, what is the schedule of the pipe where you’re trying to use this socket weld flange.