One of our Pressure Vessel is under Lethal service. Is it mandatory to have full penetration type welding for this Vessel attachments (intenal & external attachments)?

Sunil agrawal
Tecnimont ICB

Sunil,

that depends on the weld. I suggest to read UW-2, which provides guidance for all welds as per Catogory.
If your weld is not under Cat. A, B, C, D, there are no restrictions.
Your AI should be able to assist in the design review.

Please consider the mandatory PWHT for L service.

DK