FAQ's

NACE MR0175 requirements for Gr. 660 flange bolting materials

Question 1:

Does NACE MR0175/ISO 15156-2, Paragraph A.2.2.4 apply to Gr. 660 flange bolting materials or only to carbon and low alloy steel bolting materials in Part 2?

Answer:

Paragraph A.2.2.4 only applies to materials in Part 2. See also response to MP Inquiry #2005-09Q2 posted under ISO 15156-3, Table A.26.

It is assumed in Table A.2 that this is a mixed-phase environment with both a gas phase and a liquid phase. This is always true throughout the document. The operator is responsible for determining the service conditions, including chloride content (see ISO 15156-1, 6.1) and the ISO Maintenance Panel cannot provide advice. As mentioned in ISO 15156-3, A.1.3, Paragraph 2: “The tables show the application limits with respect to temperature, pH2S, Cl, pH, S. These limits apply collectively.” However, if, as an equipment user, you feel that ISO 15156-3, Table A.2 does not address your expected field conditions you have the freedom to test materials under alternative environmental limits and to use the outcome of successful tests to justify the use of a material outside the limits set in the standard. (See ISO 15156-3, 6.1, Para. 5.)

Question 2:
Does NACE MR0175/ISO 15156-3 Table A.26 apply to Gr. 660 material used in subsea bolting applications external to the production wellbore environment when indirectly heated above 150°F?
Answer

Table A.26 does not apply to Grade 660 material used in subsea bolting applications external to the production wellbore environment

This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.2.4

Reference: ISO 15156 Maintenance Panel Inquiry #2005-09Q1 and Q2

At Oil & Gas Corrosion we help clients define bolt requirements to comply with NACE MR0175 including subsea bolting.

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