Hi,

In one of our project, a 20" thin walled duplex pipe(thickness=5.54mm) is flattened to some degree. They found the ovality in the pipe when they were welding the elbows and other fittings on it. They have found out the maximum eccentricity where the weld comes and it is about 9mm.

The project has asked us whether we can approve this pipe for stress. I have checked B31.3 and it says about the limit for the flattening of the bends. But the Norsok M-601 standrad Table A.3 says about the maximum limit should be within 0.15*t or max.4mm for pipes. But in my case for some of the welds, the eccentricity are more than 4mm and the maximum measured value is 9mm.

We have to find out the Stress Concentarion Factors at these weld points, I believe. But I don't know about any equations to find out this for a Butt weld connection.

Can you please give some idea how to proceed with this?

Thank you in advance for your kind reples.

Regards,
Kumar

Have a look a discontinuity stresses, for example in ASME VIII Div. 2