FAQ's

SS 304L for compressor pipeline and NACE MR0175

Question:

I have an application where I am supplying a pipeline from a gas compressor to a turbine generator. The pipe is 10 in. in diameter and contains natural gas with H2S. The H2S concentration is 250 ppm by volume. The gas is pressurized to 475 psi @152°F. I would like to know what table from Annex A this pipe would fall under. The material I would like to use is 304L SS, which satisfies the requirements in A.2. I would appreciate any guidance you can provide with this subject.

1a) NACE MR0175/ISO 15156-3, Table A.6 provides environmental and materials limits for austenitic stainless steels used in compressors. NACE MR0175/ISO 15156-3, Table A.2 applies to austenitic stainless steels used for any equipment or components.
b) The limits on austenitic stainless steels in NACE MR0175/ISO 15156-3, Table A.6 (when compared to those of NACE MR0175/ISO 15156-3, Table A.2) are based upon industry experience with these alloys in compressors.
c) The latest editions of API Standard 618 for Reciprocating compressors and API Standard 617 for Axial and Centrifugal compressors define the scope of equipment associated with the compressor environment including accessories, instrumentation, and piping systems.
d) It is the user’s responsibility to determine if the pipe mentioned in your inquiry is directly associated with the compressor and experiences the same service environment as inferred for compressors in NACE MR0175/ISO 15156-3,Table A.6.
e) The Maintenance Panel cannot review individually designed equipment and pressure stations to make this interpretation.
2a) The manufacturer and user may consider documenting previous experience with pipelines in accordance with NACE MR0175/ISO 15156-1, Paragraphs 8.2 and 9.0.
b) NACE MR0175/ISO 15156-1:2001 provides minimal requirements for these issues and the user is ultimately responsible for ensuring the alloy in final fabricated form has adequate resistance to the types of cracking listed in the Scope 1.0 of NACE MR0175/ISO 15156-1:2001.
3. The ISO Maintenance Panel cannot comment on the suitability of using the 304L SS materials compared to alternative alloys.

This question is in relation to NACE MR0175/ISO 15156-3 Table A.2

Reference: ISO 15156 Maintenance Panel Inquiry #2004-02

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