Note: Be aware of unauthorized or outdated versions. The 2018 update includes significant updates compared to earlier versions. Summary of NACE SP0170-2018 Contents
Understanding NACE SP0170: Protection Against Polythionic Acid SCC
: Guidance on fabrication practices to reduce susceptibility. Nitrogen Purging : Using dry nitrogen to exclude oxygen.
NACE SP0170 is a critical document for ensuring the mechanical integrity of high-temperature refinery units during turnaround cycles. By strictly controlling the intersection of oxygen, moisture, and sulfide scales, plant operators can safely maintain austenitic stainless steel assets without the fear of sudden, catastrophic cracking. When designing turnaround checklists, integrating the precise chemistry and pressure requirements laid out in NACE SP0170 is non-negotiable for safe modern refining operations. nace sp0170 pdf
During circulation of the alkaline wash, the pH of the effluent must be regularly checked. It must remain highly basic (pH > 9). If the pH drops, it indicates that acids are actively neutralizing the solution, and more soda ash must be added.
Washing the internal surfaces of equipment with an alkaline solution, typically a soda ash ( Na2CO3cap N a sub 2 cap C cap O sub 3 ) solution, usually within a concentration range of
“Dave, listen to me. You’re going to lift the pipe. Not much. Just half an inch.” Note: Be aware of unauthorized or outdated versions
: Special considerations for refinery reactors.
What specific (e.g., 304H, 321, 347) is your equipment made of?
A corrosion inhibitor (typically a nitrate-based compound) is added to the solution to prevent chloride stress corrosion cracking, as soda ash solutions can sometimes concentrate chlorides. Nitrogen Purging : Using dry nitrogen to exclude oxygen
Engineers, inspectors, and maintenance personnel frequently search for the to establish safe protocols for handling sensitized stainless steel components. This article provides a comprehensive overview of the standard, the science behind PTA-SCC, and practical mitigation strategies.
Understanding NACE SP0170: Protection of Austenitic Stainless Steels from Polythionic Acid Stress Corrosion Cracking
“I’m telling you,” Marina said, finally leaning back, “that nobody reads the boring standards until something’s on fire. But the people who wrote SP0170 in 2017—they were thinking about this exact Tuesday night. They already saved your line. I’m just reading the instructions.”
The culprit was often , known as "Sour Gas." The Solution: The Birth of SP0170