The 2018 revision updated the previous version to reflect better understanding of materials sensitization and improved application techniques for alkaline cleaners. The focus remains on providing minimum requirements to ensure integrity, though many plants follow more stringent internal procedures based on this standard.
The standard was originally approved as a "Recommended Practice" (RP) by NACE in 1970—a fact reflected in its numerical designation: "SP" stands for Standard Practice, while "0170" breaks down to "01" (the first SP document) and "70" (the year 1970). The standard has since undergone several revisions, with active versions available from 2012 and 2018.
“Don’t clamp it,” Marina said, opening the PDF again. “I’m looking at SP0170 right now.”
Using "L-grade" stainless steels (like 304L or 316L) reduces the total carbon available to form chromium carbides, shifting the sensitization curve significantly. However, these grades have lower allowable design stresses at highly elevated temperatures.
On an autumn morning years later, a younger engineer found the scanned sticky note in that same PDF and smiled at the line: "If you follow this to the letter you'll miss what matters." He replicated Maya's human-factors checklist, adding his own observations. The standard remained, but so too did the culture it had shaped — a culture that honored both the rulebook and the people who walked the lines, listening for what paper could not prescribe. nace sp0170 pdf
NACE SP0170, also known as "Corrosion Prevention and Control in Petroleum Refining and Petrochemical Processes," is a standard developed by the National Association of Corrosion Engineers (NACE). The standard provides guidelines for preventing and controlling corrosion in petroleum refining and petrochemical processes. In this post, we'll dive into the details of NACE SP0170 PDF and its significance in the industry.
We strongly advise against it. Using an obsolete, corrupted, or unauthorized copy could lead to a catastrophic failure if a critical step is missing. Purchase the official nace sp0170 pdf from AMPP or an authorized reseller.
NACE SP0170 outlines procedures to protect austenitic stainless steels from polythionic acid stress corrosion cracking (PTA SCC) during refinery equipment shutdowns, downtimes, and startups. Key mitigation methods include dry nitrogen purging, alkaline washing, and dry air purging to prevent the formation of acids that cause rapid cracking. For the full standard, visit
One of the primary methods for preventing PTA SCC is to eliminate oxygen from the equipment environment. Equipment is purged with dry nitrogen ( N2cap N sub 2 ) to remove air. The 2018 revision updated the previous version to
Metal Sulfides+Oxygen (O2)+Liquid Water (H2O)⟶Polythionic Acid (H2SxO6)Metal Sulfides plus Oxygen open paren cap O sub 2 close paren plus Liquid Water open paren cap H sub 2 cap O close paren ⟶ Polythionic Acid open paren cap H sub 2 cap S sub x cap O sub 6 close paren
: Positive pressure must be continuously monitored and maintained throughout the entire shutdown period. This guarantees that even if small leaks exist, oxygen cannot migrate into the system. 2. Dry Air Purging (Excluding Liquid Water)
If you are planning an upcoming refinery turnaround or need to draft a formal facility procedure, tell me:
NACE SP0170 outlines several primary strategies to prevent PTA-SCC. The core objective of these methods is to prevent oxygen and moisture from interacting with sulfide scales, or to chemically neutralize the acids if they do form. 1. Nitrogen Purging and Blanketing The standard has since undergone several revisions, with
: Dehumidified, dry air with an exceptionally low dew point is circulated through the equipment.
Whether you are establishing a lay-up procedure for a turnaround or investigating a failure, this standard provides the roadmap you need. Don’t rely on guesswork—get the standard, study the prevention methods, and protect your assets.
When standard austenitic stainless steels (such as AISI 304 or 316) are exposed to temperatures between 425°C and 815°C (800°F to 1500°F) during service, they undergo a process called . At these elevated temperatures, carbon diffuses to the grain boundaries and combines with chromium to form chromium carbides (
She visited Site 7 the next morning. Gray fog lay over the concrete apron. The pipeline, a belching artery along the shoreline, had been retrofitted with impressed current anodes years ago. The technician handed her a digital logger and a steaming cup. He'd been at this site for twenty years; his face was as weathered as the rusted railings. "We do what the book says," he said. "Still, it keeps finding new places to rot."
: Applying an alkaline wash (often using soda ash) to neutralize any PTA that might form.