If you are currently using the 2015 or 2012 version, upgrading to the is not optional—it is a matter of safety. Here are the major revisions:
Thorough prior to opening manways for mechanical inspections. Process Piping & Heat Exchangers
If left unmitigated, these acids rapidly attack the chromium-depleted grain boundaries, causing severe cracking within hours of exposure to the atmosphere. Core Mitigation Strategies in NACE SP0170
When oxygen and water mix with sulfide scales, they rapidly react to form ( H2SxO6cap H sub 2 cap S sub x cap O sub 6 nace sp0170 pdf 2021
The standard aims to provide a comprehensive framework for preventing and controlling corrosion in equipment and components, ensuring safe and reliable operation, and minimizing the risk of corrosion-related failures.
The 2021 revision provides sharper thresholds for defining sour environments. While ISO 15156 uses partial pressure of H₂S (>0.05 psi or 0.3 kPa), SP0170-2021 adds specific footnotes for low-temperature and high-pressure scenarios where traditional rules may fail.
Formerly known as , SP0170-2021 is the industry standard for “Protection of Steel in Concrete from Corrosion Using Thermal-Sprayed Zinc Anodes” . It provides guidelines for designing, applying, and maintaining zinc-based thermal spray coatings (metallizing) as a galvanic cathodic protection (CP) system for reinforced concrete structures. If you are currently using the 2015 or
View regional standard listings through the Accuris Standards Store or the national adoption catalog at Intertek Inform .
) form rapidly when metal sulfide corrosion scales—deposited on internal surfaces during regular operation—are simultaneously exposed to moisture ( ) and oxygen ( ) during a shutdown. Internal vs. External Environments
Understanding and applying NACE SP0170 is critical for corrosion engineers, inspection personnel, and refinery maintenance managers during turnarounds. Core Mitigation Strategies in NACE SP0170 When oxygen
) and stop them from triggering intergranular stress corrosion cracking (IGSCC) in sensitized alloys.
Sensitized Alloy + Sulfide Scale + Oxygen & Water = Rapid PTA SCC
The standard provides essential mitigation methods for refinery equipment—such as desulfurizing, hydrocracking, and hydrotreating units—where the risk of PTA SCC is high. PTA SCC typically occurs when metal sulfides on equipment surfaces react with oxygen and moisture during a shutdown, forming polythionic acids that attack sensitized stainless steels. Mitigation Methods Outlined in SP0170
The standard is periodically reviewed by Task Group 173 (TG 173) and administered by Specific Technology Group (STG) 34—Petroleum Refining and Gas Processing.
Contain highly sensitive catalysts; vertical configurations prone to stagnant moisture trapping.