Understanding the Limitations of Austenitic Stainless Steel in Sour Gas Treatment Units

Addressing the Challenge of Chloride Content in Gas Streams

This page provides a Q&A section that addresses the limitation of austenitic stainless steel application in sour gas treatment units as per NACE MR0175/ISO 15156. This standard has been implemented for design purposes in a sour gas refinery. The question is related to the chloride content in the gas stream and how to comply with the criteria provided in Table A.2.

: Clarifying the Assumptions of Table A.2

The answer provided clarifies that Table A.2 assumes a mixed-phase environment with both gas and liquid phases. The responsibility to determine the service conditions, including the chloride content, lies with the operator, as mentioned in ISO 15156-1, 6.1.

Understanding the Collective Application of Limits

The limits regarding temperature, pH₂S, Cl, pH, and S in Table A.2 apply collectively, as stated in ISO 15156-3, A.1.3, Paragraph 2.

Exploring Alternative Environmental Limits

However, if the equipment user feels that Table A.2 does not address their expected field conditions, they have the freedom to test materials under alternative environmental limits and use the results to justify the use of a material outside the standard limits, according to ISO 15156-3, 6.1, Para. 5.

Additional Information

This question pertains to NACE MR0175/ISO 15156-3 Table A.2, and the reference provided is ISO 15156 Maintenance Panel Inquiry #2004-21.

It is important to note that this information is crucial for operators and engineers involved in sour gas treatment units. By understanding the limitations of austenitic stainless steel and the assumptions of Table A.2, they can make informed decisions about material selection and compliance with industry standards.”