FAQ's

What are the NACE MR0175 hardness requirements for a buttweld with inner CRA cladding?

It is understood that the section A.2.1.5 and Table A.1 of NACE MR0175 / ISO 15156-2 and section A.13.1 of NACE MR0175 / ISO 15156-3 for cladding, lining and overlay deal with the cladding, lining and overlay of the overall internal surface of a carbon steel component and in contact with the fluid. In the case of CRA girth welding of a clad pipe, it is understood that the above mentioned sections are not applicable to the carbon steel HAZ of the CRA girth weld (except the portion which crosses the carbon steel HAZ of the overlay). See  below figure. Could you confirm that our understanding is correct?

ANSWER:
NACE MR0175/ISO 15156-2 Section A.2.1.5 does permit the waiver of the maximum hardness requirements in accordance with NACE MR0175 / ISO 15156-3 Section A.13.1. The NACE MR0175 / ISO 15156-3 Section A.13.1 define the conditions and requirements for waiving the maximum hardness. Specifically, the user must demonstrate and document the likely long term integrity of the cladding or overlay. The long term integrity can be affected by (1) application of heat or stress-relief treatments, (2) environmental cracking under intended service conditions, (3) other corrosion mechanisms, (4) mechanical damage and (5) dilution of the overlay.
This question is in relation to NACE MR0175/ISO 15156-2 A.2.1.4 and A.2.1.5

Reference: ISO 15156 Maintenance Panel Inquiry #2016-07

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