Dear Pipeline Engineers,
I have been posed with a strange scenario for which I couldn't resolve a solution. I have to decide suitable pipeline wall thickness for a 48in pipeline, and the suggested wall thickness is 20.62mm. The preliminary wall thickness was based on DNV-OS-F101, and it did satisfy all requirements for minimum wall thickness criteria. However, propagation buckling check was ignored for operation conditions on the grounds that it is not susceptible to propagation buckling during operation. I do not agree with this. On further investigation, when corrosion allowance of 3mm is applied to the wall thickness, the D/t2 ratio of the pipeline exceeds 60. As per DNV-OS-F101 and its commentary notes, the analytical equations to check for propagation buckling is applicable for D/t2 ratio upto 45. Further from 45 to 60, elastic buckling needs to be checked through FEA. In my case, D/t2 ratio exceeds 60.

Is there any literature/recommendations or experience anyone here could share to resolve this issue for D/t2 > 60? Increasing the wall thickness is the last option I want to consider, are there any other approaches?

Thanks in advance.

Regards,
Uday