A pipe fitting is defined as a part used in a piping system, for changing direction, branching or for change of pipe diameter, and which is mechanically joined to the system. There are many different types of fittings and they are the same in all sizes and schedules as the pipe, basically fittings are divided in:

 

• Buttweld (BW) 

• Socket Weld (SW) 

• Threaded (THD) 

 

A piping system using buttweld fittings has many inherent advantages over other forms:

 

• Welding a fitting to the pipe means it is permanently leakproof

• The continuous metal structure formed between pipe and fitting adds strength to the system

• Smooth inner surface and gradual directional changes reduce pressure losses and turbulence and minimize the action of corrosion and erosion

• A welded system utilizes a minimum of space.

 

Bevelled Ends The ends of all buttweld fittings are bevelled, exceeding wall thickness 4 mm for austenitic stainless steel, or 5 mm for ferritic stainless steel. The shape of the bevel depending upon the actual wall thickness. This bevelled ends are needed to be able to make a "Butt weld". ASME B16.25 covers the preparation of buttwelding ends of piping components to be joined into a piping system by welding. 

 

Material and Performance The most common materials used in fittings produced is carbon steel, stainless steel, cast iron, aluminium, copper, glass, rubber, the various types of plastics.