Dear All,

In stress analysis of FRP piping system,

plz give the information regarding Load case need to be checked as per BS 7159 code?

If we are not using Kn then

Are stresses need to be checked in expansion case?

plz give sample of load case list for analysis.


Thanks & Regards
Shamalia Bhavin D.

Also,

FRP Vendor has given allowable design stress.

Allowable design stress is based on hoop stresses or longitudinal stresses?

Dear Mr.Bhavin,

Load cases consideration is similar to Steel piping.
Exp.cases should be considered.
The Allowable Design Stress is based on both Axial and Hoop stress,
Since it is a anisotropic material. (Not a Isotropic like steel).

The Material property is vary with axial and hoop windings and also
varies with vendors.

Dear Mr Satpiping,

Thank you very much for your response.


Should we check Expansion case for fatigue loading?

If we are using Kn ( As per BS 7159 ), then is it needed to considered above case.




For FRP piping material, we are limiting the allowable upto elastic range.
So, Secondary stresses check is not required.


Thanks & Regards
Shamalia Bhavin D

Please double-check the code (although BS7159 is not that clear on load cases) or check ISO14692, which has a good explanation of load cases.
Checking expansion stresses as we do for steel piping is not an issue for FRP.
For steel piping this is done because we consider two criteria, primary and secondary stresses (or not-self-limiting and self-limiting loads). The latter is important to check for fatigue damage in the elastic/plastic zone.
As FRP has a lineair elastic behaviour and can thus not yield to relax the self-limiting loads the expansion stress can't be checked as for steel pipe.