What’s the difference between Socket welding and Butt welding?

What’s The Difference Between Socket Welding And Butt Welding?

May 15, 2018

What’s the difference between Socket welding and Butt welding?

There are various connecting types for the Pipe Flanges, fittings and valves: socket weld, butt weld, threaded and so on. Two of them to be quite popular: socket welding and butt welding. However, you might be confused about which one would be best for your construction projects, since both of them seem to have their own pros and cons. Therefor, we have taken the responsibility of drawing up a comparison between them.

Socket Weld(SW)

They are manufactured in accordance with ASME B16.11. In the manufacturing of this type of connection, a pipe would be inserted in to a recessed area of the fitting, or socketed so as to have a plain spigot end. Socket Welding pipe fittings are used for lines conveying flammable, toxic or expensive material where no leakage can be permitted, and for steam 300 to 600 psi. SW pipe fittings are family of high pressure fittings and they are available in three pressure ratings: Class 3000, 6000 and 9000.

Butt Weld(BW)

They are manufactured in accordance with ASME B16.9. In the process of butt welding, each end of the valve is bevelled to match with the thickness and bevel on the pipe. After this, the two ends are butted to the pipeline and are welded.In this case, the thickness would be the same as those of pipes. The material such as Titanium pipes, duplex steels and nickel based alloys are basically butt welded.

Socket welding VS Butt welding

Different welding groove and welding seam 

In the the welding process, socket welding formed fillet-weld. Considering the factor of the strength of the weld, the force condition and so on, the butt welding is better than the socket welding.

Different application

Since the socket weld would resist around half the strength of butt weld fittings. Socket Welding are mainly used for small pipe diameters (Small Bore Piping); generally for piping whose nominal diameter is NPS 2 or smaller.

Different detection

Generally speaking, butt welding requirements are higher than socket welding requirements as well as the testing requirements.The butt welding shall be 100% tested to ensure no leakage and it is necessary to do radiographic inspection, but for socket welding, magnetic particle detection or penetration detection is enough.(like magnetic powder of carbon steel and penetration of stainless steel).

Different costs

The price of Socket weld fittings is higher than Butt welding in similar size. However, butt welding fitting need extra more cost because it would also be more difficult to weld and fit-up properly. This would then require more time and the expertise of skilled welders.

In conclusion, Both the pressure level as well as cost of the socket welding is higher than that of butt welding. When the welding technology is required and fully meet the construction requirements, butt welding is a alternative choice. If the medium of the pipeline has no requirements for welding, it is recommended to use socket welding, just easy for detection.