Dear All

What is elastic bend redius and how it is calculated for 32" pipeline?

I mean what is the procedure for calculating elastic bend radius?

pl reply

My assumtion :
A bend have a radius like 1,5 D for 32" ==> 812,8 mm.
With a load (moment) the bend radius change.
Elastic bend radius is this radius when the load removed an the bend shape will be as unloaded shape before.
Thats mean you have only elastic strain in the bend.
You can solve with a FE programm like FEPIPE, ANSYS etc.., but you becomes not a result like explicit elastic bend radius.
You can find the elastic bend radius from the changed geomtrie under elastic load.

The elastic bend radius can be calculated by the formula :
SBa/ (D/2) =E/R
R/D=E/2SBa
Where
R= The elastic bending radius
E= Young modulus of the material
D= the outside diameter of the pipe
SBa= the maximum allowable stress for bending.

Some references will give also this formula (which is more conservative)
R/D=3E/2SBa
The most important thing about the above two formulas is to calculate how much is the allowable bending stress, which can be done by calculating the max. allowable longitudinal stresses , and then deducting from that the internal pressure related stresses, the thermal expansion stresses,,, etc.