is a critical Standard Practice (SP) focused on protecting austenitic stainless steels and other austenitic alloys from Polythionic Acid (PTA) Stress Corrosion Cracking (SCC) during the shutdown of refinery equipment .
NACE SP0170-2021 is an indispensable tool for protecting sensitized austenitic stainless steel equipment from the disastrous effects of PTA SCC. By following the procedures for alkaline washing and excluding oxygen during shutdowns, refiners can significantly extend the life of their equipment and prevent catastrophic failures during startup.
: When implementing measures to control stray-current corrosion, adhering to the guidelines in NACE SP0170 can help ensure compliance with industry best practices. This is particularly important for maintaining asset integrity, safety, and environmental protection. nace sp0170 pdf 2021
) reacts with the steel elements to form (
: Using dry nitrogen to exclude oxygen and moisture from the equipment, preventing the formation of polythionic acid. Alkaline Washing is a critical Standard Practice (SP) focused on
This article provides an in-depth look at the standard, focusing on its requirements, mitigation methods, and importance in refinery operations based on the latest AMPP (formerly NACE) guidelines. 1. What is NACE SP0170?
) during welding or high-temperature process operations, chromium carbides precipitate along the grain boundaries. This depletes the adjacent zones of chromium, rendering them vulnerable to localized corrosion. Alkaline Washing This article provides an in-depth look
While you may see "2021" associated with this standard in search results, remains the current, active version. It was discussed heavily in 2021 at the AMPP CORROSION conference , where engineers shared new data on how different alloys—like those with higher Chromium and Nickel—handle these harsh shutdown environments.
The reaction of oxygen and water with metal sulfides generates polythionic acids ( H2SxO6cap H sub 2 cap S sub x cap O sub 6
, titled "Protection of Austenitic Stainless Steels and Other Austenitic Alloys from Polythionic Acid Stress Corrosion Cracking During a Shutdown of Refinery Equipment," is a standard practice established to prevent premature failures.