Belled End fittings are used instead of buttwelded fittings. They are a lot faster to install because there is no nead to bevel the connecting pipe and because making up the weld is a lot faster. Additionally, the bell fitting is more forgiving for slight misalignments in pipe. A belled end fitting is similar to a socketweld fitting in that a single fillet weld is needed to attach the pipe to the fitting, proper. This type of weld is much faster and easier to make than a buttweld fitting, which may require multiple passes with the welding rod.
The size and dimensions of belled end fittings are governed by standard MSS SP-119 Factory-Made Wrought Belled End Socket-Welding Fittings and were standardized in 1996. Belled end pipe fittings are widely used in the process design for the chemical, petrochemical, pulp and paper, power generation, pharmaceuticals, and other specialty industries, such as Navy ships.
Belled end pipe fittings IAW MSS SP119 (2003 -latest edition) are equal to ANSI B16.9 standard dimensioned buttwelding pipe fittings in Maximum Allowable Design Internal Pressures. Belled end pipe fittings and B16.9 buttwelding fittings are now code recognized as equal in burst allowances.
Advantages to a belled end
- Belled end pipe fittings can be welded four to seven times faster than the standard buttwelding fittings!
- In most cases only one pass is needed to create a good fillet weld. In addition, nearly all the pre-weld end prep and fit up is eliminated with the belled end pipe fitting.
- The wrought cold formed belled end pipe fitting eliminates the problems of misalignment and wall thickness mismatch that are inherent to buttwelded joints.
- Less experienced welders can easily produce good fillet welds using belled end pipe fittings.
Disadvantages to a belled end
Belled end pipe fittings are used for low pressure type applications.