socketweld

A socket weld is a method of joining pipes to fittings in which the end of the pipe is inserted into a recessed socket in the fitting and a fillet weld is applied around the circumference where the pipe meets the fitting. This type of joint is commonly used for small-diameter piping, typically up to about 2 inches nominal pipe size, though some applications may use larger sizes with specialized fittings.

In practice, the pipe is deburred, inserted to a defined depth into the socket, and aligned so that a continuous fillet weld forms around the joint. The weld is generally performed around the exterior of the pipe within the socket area, creating a full circumferential weld without a weld bead inside the pipe.

Socket welds are favored for their simplicity, fast fit-up, and compact configuration, which makes them suitable for instrument lines, short runs, and small-diameter systems in chemical plants, water supply, and some process piping. They are commonly made from carbon steel, stainless steel, and other alloys, following appropriate welding procedures and fit-up practices.

Limitations include lower strength and tightness under high pressure or high-temperature service compared with butt-weld joints, as the joint relies on a fillet weld and the geometry of the socket. The weld root in the socket can be a site for leakage or stress concentration, especially under vibration or thermal cycling. Proper fit-up, material compatibility, adequate support, and appropriate testing are essential, with standards such as ASME B16.11 guiding socket-weld fittings and associated codes addressing inspection and testing requirements.