Maintaining equipment at temperatures above the dew point.
As of 2025, the official NACE SP0170 PDF 2021 costs approximately $150–$250 for members (less if you join AMPP). For a piece of equipment that costs millions, this is a trivial investment.
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To appreciate the 2021 update, we must revisit history. In the 1970s, catastrophic failures in sour oil fields led to the creation of NACE MR0175 ("Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment"). For decades, this standard was the "golden rule" for any metal touching wet H₂S. nace sp0170 pdf 2021
This includes residual stresses introduced during fabrication and welding, as well as operational or structural loads. Corrosive Environment (PTA): Polythionic acids (
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Contain highly sensitive catalysts; vertical configurations prone to stagnant moisture trapping. Maintaining equipment at temperatures above the dew point
To stay compliant and safe, refinery operators typically follow three main protective routes outlined in the standard: Exclusion of Oxygen
Do not rely on a bootleg copy from a forum. Purchase the official PDF from AMPP, read it cover to cover, and integrate its requirements into your material selection and quality assurance workflows. In the sour service arena, the standard is not a suggestion—it is the law of physics, enforced by the potential for catastrophic failure.
NACE SP0170 is an industry standard practice officially titled For projects outside North America
To neutralize the polythionic acids formed on the surface of the metal.
For integrity engineers and plant operators, obtaining the official, most recent version of this document from a legal source like AMPP or an authorized standards store is not just a matter of compliance—it is an essential investment in operational safety and asset integrity. By implementing the specific mitigation methods detailed within, including nitrogen purging and alkaline washing, facilities can prevent catastrophic cracking failures and ensure the long-term reliability of their austenitic stainless steel equipment.
For projects outside North America, use ISO 15156. For any project in the U.S. (especially OCS and onshore sour gas), use NACE SP0170 PDF 2021 as the governing document.