Lethal Service and Its Requirments

hi lethal service is in radiography test. It shall be performed after PWHT when required. 100% R.T is required for all vessels in lethal service as per ASME code UW-2(a).Material requiring impact testing for low temperature service shall be pwht (ASME Code, UCS-67(C)

Does the Code have a sufficient index, so that you can look it up? (Too long ago for me to remember, but I have my doubts.)

By "lethal substances" are meant poisonous gases or liquids of such a nature that a very small amount of the gas or of the vapor of the liquid mixed or unmixed with air is dangerous to life when inhaled. Also, substances of this nature which are stored under pressure or may generate a pressure if stored in a closed vessel.

When a vessel is to contain fluids of such a nature that a very small amount mixed or unmixed with air is dangerous to life when inhaled, it shall be the responsibility of theuser and/or his designated agent to determine if it is lethal.

If determined as lethal, the user and/or his designated agent [see U-2(a)] shall so advise the designer and/or Manufacturer.

further check UW2 for service restrictions.

Is PWHT (post weld heat treatment) require for STAINLESS STEEL material welding while the service is LETHAL?

Please specify the material exactly.