Previously, standards allowed some interpretation of "crack-free" welds. SP0170-2021 mandates specific non-destructive examination (NDE) methods—including phased array UT and wet fluorescent magnetic particle inspection (WFMT)—to verify compliance.
NACE SP0170-2018 remains the active standard for protecting austenitic stainless steels from polythionic acid stress corrosion cracking (PTA SCC) during refinery shutdowns as of 2021, focusing on nitrogen purging and alkaline washing to mitigate risks. The standard, now managed by AMPP, outlines critical procedures for preventing corrosion in sensitized austenitic alloys common in hydrotreating and cracking units. Access the standard through the ANSI Webstore . nace sp0170 pdf 2021