Threaded & Socket-Welded Fittings

Threaded and socket weld fittings are used for small diameter pipe sizes 2" NPS and down. 

The majority of the screwed fittings will have female (internal) threads per NPT (National Pipe Thread). 

The exception will be swages, plugs, and street elbows where they will have male (external) threads. 

Socket-Weld fittings have a deep socket into which the pipe slips and aligns itself. 

The weld is then made on the outer surface of the pipe and fitting.

Threaded and socket-Weld fittings are specified per the pressure class in which in stainless steel are commonly available are class 150#, 3000#, and 6000#. 

Cast (150#) fittings are generally used for air and water services at a low temperature and pressure, whereas forged (3000#, 6000#) fittings are normally used for higher pressures and temperatures as well as for the more complex media.