Pipe Fittings

A pipe fitting is a piping component that is used to join piping, change the direction or diameter of piping or end the pipe.  They are a versatile piping component which are necessary in modern piping system.

Abbreviations

  • BW - butt weld or buttweld
  • BWF - butt weld fitting
  • FTG - fitting
  • SKT - socket
  • SOC - socket
  • SW - socket weld
  • SWF - socket weld fitting
  • THRD - threaded
  • THRDF - threaded fitting

End Connections

There are four different type of connections that are used for fittings:PTrap 1P-Trap where the elbows are connected by flanges and fitting make up

  • Butt Weld Fittings – Probably the most common type of fitting.  They are easily manufactured and are easily installed. Butt weld fittings can be connected directly to each other.  This is called fitting make up.
  • Flanged Fittings – Flanged fittings are piping components where the flange is an integral component of the fitting.  These are most often used in water treatment applications or lined piping where welding would be destructive to the liner.
  • Socket Weld Fittings – These fittings have a socket weld connection on each end.  They might be used for smaller diameter piping.  These fittings utilize a single fillet weld to join the piping with the fitting.
  • Threaded Fittings – Threaded fittings are generally four inches and smaller.  The reason for this size constraint is the pipe end needs to be threaded with a male type connection and die sizes are unobtainable in the larger diameters.

Types of Fittings

Pipe fittings can be broken down into several categories:

  • Branch Connections –  Branch connections are used when two or more pipes come together. These can be in the form of a complete fitting, such as a tee or cross.  They can also be in the form of an O’let which is a branch connection that is designed to attach directly to the pipe.  Branch connections are available in buttweld, socket weld, threaded and flanged.
  • Caps – Weld caps are used to seal the end of the piping.  It might be used when old pipe is being abandoned or with a tee to form a hydraulic elbow. Caps are available in buttweld only.
  • Couplings – Couplings are used to join two different threaded pieces of pipe.  When a coupling is used, it is important not to over torque the piping, otherwise damage to the coupling or union can occur. Couplings are available for threaded pipe only.
  • Elbows – These are useful when needing to change direction of flow.  Typical elbow directions are 45, 90 and 180 degrees. Elbows are available in buttweld, socket weld, threaded and flanged.
  • Reducers – Reducers are used when the pipe needs to change diameter.  Reducers are available in buttweld, socket weld, threaded and flanged.

Standards

There are many different standards that cover pipe fittings.  It is up to the designer to understand the piping code, specification and company standards when designing a piping system. 

Display #
Title
Bleed Ring
Branch Connection Fitting
Buttweld Fittings
Fitting Specification, ASME
Fitting Specification, BSI
Fitting, Material Specifications, ASTM
General Fitting Standards
Socket Weld Fittings
Threaded Fitting
Thrust Block