The standard NACE SP0170-2018 (reaffirmed and active through 2021) is the industry's safeguard against one of the refinery world’s most aggressive "silent" threats: Polythionic Acid Stress Corrosion Cracking (PTA SCC). The Story of a Refinery Shutdown

Imagine a massive refinery hydrocracker unit. For months, it runs at high temperatures, processing sulfur-heavy feeds. Inside, a thin layer of iron sulfide scale naturally forms on the austenitic stainless steel pipes and reactors. As long as the unit is running hot and oxygen-free, it's safe.

💡 Why this standard matters: Oxygen ingress is a silent threat in injection systems, pipelines, and storage tanks. The NACE SP0170-2021 standard provides the latest recommended practices for the detection, removal, and control of dissolved oxygen in water used in oil and gas operations.

Goals: use indirect techniques to identify locations with elevated probability of external corrosion without directly excavating the pipe.
Techniques include close-interval potential surveys (CIPS), DCVG/ACVG (for coating defect identification), coupon or probe measurements, soil resistivity grids, leakage/IR drop analysis, and aerial/remote-sensing indicators. The 2021 update emphasizes integrating multiple indirect measures and applying statistical or machine-learning scoring to rank threats.

Nace Sp0170 Pdf 2021 [portable] < HIGH-QUALITY MANUAL >

Goals: use indirect techniques to identify locations with elevated probability of external corrosion without directly excavating the pipe.
Techniques include close-interval potential surveys (CIPS), DCVG/ACVG (for coating defect identification), coupon or probe measurements, soil resistivity grids, leakage/IR drop analysis, and aerial/remote-sensing indicators. The 2021 update emphasizes integrating multiple indirect measures and applying statistical or machine-learning scoring to rank threats.