Dear All,

I am currently working on the analysis of a buried CHW network. The client has requested to qualify the network in accordance to B31.3. [which is very unorthodox for CHW application.]

The network is 750 m (2460 ft). VAL is 60 m.

For B31.3 in the restrained part of the network are failing at all junctions.

If I would analyse this network with B31.1 with axial stress activated the network will pass. To my knowledge, the only difference between B31.1 with axial and B31.3 is the SIF value io ii, but the calculated code stress from B31.3 is 6 times higher than the calculated stress from B31.1 at junctions.

1) can anyone explain to me how is this happening?

I think B31.3 is applying io to axial stress and B31.1 with axial is not. Is that correct?

2) If yes, then is B31.3 overestimating the stress for this application or B31.1 underestimating it?

Thank you.

Amr Elsawy.
Perma Pipe.