Socket Weld Flange

A socket weld flange is a type of pipe flange designed for small-bore, high-pressure piping systems. The pipe end is inserted into a recessed socket on the flange bore, then secured with a fillet weld around the outside of the joint. This design creates a robust, leak-resistant connection well suited to demanding service conditions where joint integrity is critical.

How It Works

The pipe is inserted into the socket recess machined into the flange bore, leaving a small gap at the base to allow for thermal expansion during welding. A continuous fillet weld is then applied around the pipe-to-flange interface, fusing the two components into a single, rigid assembly. The socket recess provides self-alignment during fit-up, reducing the risk of misalignment and improving weld quality.

Materials & Dimensions

Socket weld flanges are available in a range of materials to suit different process media and temperature requirements. Common material options include carbon steel (ASTM A105) for general-purpose and high-pressure applications, and stainless steel grades SS 316 and SS 304 for corrosive or hygienic environments. Size coverage spans from 1/2" to 4" nominal pipe size, with pressure classes conforming to ANSI/ASME B16.5 ratings from Class 150 through Class 2500, and DIN pressure ratings from PN10 to PN250.

Applications

Socket weld flanges are widely used in small-bore, high-pressure piping systems across the oil and gas, petrochemical, power generation, and process industries. They are particularly suited to hydraulic lines, instrument connections, and utility piping where pipe diameters are 4" or smaller and elevated pressures demand a secure, permanent joint. Their compact form factor and ease of alignment make them a preferred choice for confined spaces and complex piping layouts.