NACE MR 0175 Requirements
NACE MR 0175 Requirements
(OP)
Code: ASME Div 1
Vessel: A516 Gr 70 + 3mm SS316L clad
Re clause 5.2.1 under section titled Fabrication. It says
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Overlays applied to carbon and low ally steel or to martensitic stainless steels by thermal processes such as welding, silver brazing, or spray metallizing systems are satisfactory for use in sour environments, provided the ****substrate does not exceed the lower critical temperature during application****. In those cases in which the lower critical temepratures are exceeded, the componenet must be heat treated or thermally stress relieved in accordance with procedures that have been shown to return the base metal to 22 HRC maximum.
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Can someone please tell me what "substrate does not exceed the lower critical temperature during application*" means? Does the lower critical temperature get exceeded every time production welds are made on the vessel and thus PWHT of the vessel becomes inevitable?
Thanks.
Vessel: A516 Gr 70 + 3mm SS316L clad
Re clause 5.2.1 under section titled Fabrication. It says
==========================================================
Overlays applied to carbon and low ally steel or to martensitic stainless steels by thermal processes such as welding, silver brazing, or spray metallizing systems are satisfactory for use in sour environments, provided the ****substrate does not exceed the lower critical temperature during application****. In those cases in which the lower critical temepratures are exceeded, the componenet must be heat treated or thermally stress relieved in accordance with procedures that have been shown to return the base metal to 22 HRC maximum.
==========================================================
Can someone please tell me what "substrate does not exceed the lower critical temperature during application*" means? Does the lower critical temperature get exceeded every time production welds are made on the vessel and thus PWHT of the vessel becomes inevitable?
Thanks.





RE: NACE MR 0175 Requirements
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: NACE MR 0175 Requirements
Thanks.
RE: NACE MR 0175 Requirements
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: NACE MR 0175 Requirements
RE: NACE MR 0175 Requirements
On the other hand, in my opinion, HRC<22 is more a statistical observation, that could be justified by taking into account that a certain granulation leads to a corresponding hardness, and, in the mean time, assures a better corrosion resistance-due to the fact carbures are put into solid solution, and they are not precipitating at granule limit. I must warn you that these are memories since 15 years. I could be wrong; therefore, please check "Materials" manuals.