PD 5500 Annex G and WRC 107/297 Stress Calculation Method

Hi
Could anyone please tell me what the differences between PD 5500 Annex G and WRC 107/297 Stress Calculation Method are?
which one is more conservative?
Furthermore regarding acceptance criteria I would like to know which one of above mentioned documents have better margin?
It is highly appreciated if you mention exact acceptance criteria in your response.

Hello Hamid

PD 5500 is much more conservative. It is the way it treats pressure loading. Pressure gives rise to the major stresses, and the pressure loads are added up in a different way from the method employed by WRC 107. If given a choice, use WRC 107.