A socket weld fitting is a type of pipe attachment detail where the pipe is inserted into a recessed area of a fitting, valve, or flange. To join the pipes or valves to other sections of the pipe, fillet-type seal welds are applied. Socket weld fittings are a good choice in certain cases due to their advantages of strong structural strength and high leakage integrity. These factors are important considerations when designing a pipeline project.

In the case of SW fittings, they are relatively easy to install. A gap of approximately 1/6 inches at the bottom of the gap is required to allow access for the socket and accommodate thermal expansion. However, this gap can lead to over-stressing, causing cracks in the fillet weld of the fitting. Additionally, SW fittings have been found to be problematic in corrosive fluid services due to crevice corrosion. They are also prone to corrosion due to the discontinuity of smooth pipe internals.

On the other hand, butt weld fittings have been found to be superior in terms of fatigue resistance, strength, temperature compliance, and corrosion resistance. However, they can be more challenging to weld and properly fit-up. This requires more time and the expertise of skilled welders.

● For socket weld joints, the pipe can be inserted into the recessed area of the fitting and both pipe and the fitting do not need bevelled preparation. This makes the installation and soldering process simple.

● Temporary tack welding is no needed for alignment because in principle the socket weld fitting ensures proper alignment.

● The weld metal cannot penetrate into the bore of the pipe.

● They can be used in place of forged threaded pipe fittings so the risk of leakage is much smaller.

● Construction costs are lower than with butt-welded joints due to the lack of exacting fit-up requirements and elimination of special machining for butt weld end preparation.