NACE ISO15156
NACE ISO15156
(OP)
I have a pressure vessel which is in sour service and needs to comply with NACE and the plate needs to be HIC tested.
Is it acceptable for the external welded attachments not in contact with the process fluid i.e support saddles etc to be non NACE compliant.
Does NACE only apply to wetted pressure parts?
Is it acceptable for the external welded attachments not in contact with the process fluid i.e support saddles etc to be non NACE compliant.
Does NACE only apply to wetted pressure parts?





RE: NACE ISO15156
Cheers,
gr2vessels
RE: NACE ISO15156
Thanks for the reply.
RE: NACE ISO15156
If you are welding those directly to the outer wall of the vessel. then it is definately reccomended that you qualify your weld procedure. It is my understanding that welding will create residual stresses in the wall of the vessel, that may lead to increased suceptibility to cracking, even if the weld iteself is not exposed to the process fluid.
-Vrf
RE: NACE ISO15156
Cheers,
gr2vessels
RE: NACE ISO15156
Precisely because if the flange leaks, they will be exposed. As to whether any other part of the system requires compliant material under insulation, that would be a matter of exposure risk assessment. The attachment weld zone will need to comply with ISO 15156 requirements; therefore, if the attachment material starts out too hard, it is unlikely that the weld will comply. Remember, the cracking mechanism is hydrogen driven and hydrogen does not just sit at the internal wetted surface. That's why hardness criteria apply at the external cap too.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: NACE ISO15156
Best regards,
VRF