FAQ's

Does NACE MR0175 accepts 26HRC for temporary pipework?

Question:

We need a clarification on MR0175/ISO 15156 Part 2, Annex A. We are a manufacturer of temporary pipe work, flowlines, etc., for sour gas service in well testing and process use in a surface application. As such we believe Paragraphs A.2.1 through A.2.4 and Table A.1 with a hardness limit of 22 HRC are applicable in these circumstances. However, pipe suppliers in this region tell us that 26 HRC is acceptable in such applications. I believe the 26 HRC limit is only applicable to material used in a downhole application as in Paragraph A.2.2.3, etc. (i.e., not a surface application) and that this is in error in terms of our usage.

Answer:

ISO 15156-2, A.2.2.1 indicates that carbon and low alloy steels for use in any product form must comply with the requirements of A.2.1 which include the hardness requirement of maximum 22 HRC for the parent material. Exceptions to this rule are named specifically in other paragraphs of Annex A.
Welds in such materials shall comply with the requirements of A.2.1.4 that also refers to Table A.1 that sets hardness requirements for welds.
Sub-clause A.2.2.2 provides examples of materials that can comply with A.2.1, including some examples of tubular products in Table A.2.
Sub-clause A.2.2.3 addresses downhole components only.
The standard allows materials, such as AISI 4130, to be qualified at higher hardness than 22 HRC for possible use as pipe in sour service by laboratory testing in accordance with Annex B and Table B.1 or on the basis of field experience as described in ISO 15156-1, 8.2. Welds must be shown to comply with the requirements of Paragraph 7.3.3.4.

This question is in relation to NACE MR0175/ISO 15156-2 Annex A.2.2.1, A.2.2.2 and A.2.2.3

Reference: ISO 15156 Maintenance Panel Inquiry #2005-23

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