Long Radius Elbows and Short Radius Elbows – You Might Not Know Clearly

LR and SR Elbows

A pipe elbow is a specific, standard, engineered bend pre-fabricated as a spool piece and designed to either be screwed, flanged, or welded to the piping it is associated with.

An elbow can be 45o or 90o. There can also be custom-designed elbows, although most are catagorized as either “short radius” or long radius”.

A pipe bend can be an elbow; an elbow does not mean a bend. If you use the term elbow, it should also carry the qualifiers of type (45 or 90o) and radius (short or long) – besides the nominal size.

The ends may be machined for butt welding (SW) or socketed welding(SW) etc.

Most pipe elbows are available in short radius or long radius variants. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow.

Elbows are categorized based on various design features as below:

  • Long Radius (LR) Elbow is also called LR elbow – means the radius is 1.5 times the pipe diameter
    • L/R 45°Elbow: Long radius 45 degree elbow changes the direction by 45 degrees.
    • L/R 90°Elbow: Long radius 90 degree elbow changes the direction by 90 degrees.
    • L/R 180°Elbow: Long Radius 180 degree return bend allows complete reversal of flow.
  • Short Radius (SR) Elbow is also called SR elbow, – means the radius is 1.0 times the pipe diameter
    • Short radiu 45°Elbow: Short radius 45° elbow changes the direction by 45 degrees.
    • Short radius 90°Elbow: Short Radius 90° elbow is same as LR90 except for the measurement between end of elbow to center line is 1 x NPS.
    • Short radius 180° Elbow: Short Radius 180° return bend allows complete reversal of flow

The following is the criteria when deciding which to use:
Long Radius Elbows are used when:
there is a need to keep the frictional fluid pressure loss down to a minimum;
there is ample space and volume to allow for a wider turn and generate less pressure drop;
the fluid being transported is abrasive or has solids in it.

Short Radius Elbows are used when:
there is a need to reduce the cost of elbows;
there is a scarcity of space and volume to allow a Long Radius type.

SIZE RANGE:

  • Seamless elbow: 1/2″-24″ DN15-DN600
  • Welding elbow: 6″-72″ DN150-DN1800
  • Wall thickness: Sch5-Sch160 XXS

 


Post time: May-12-2021