To understand why NACE SP0170 is necessary, it is vital to look at how PTA-SCC occurs. The mechanism requires the simultaneous presence of three distinct factors:
The NACE SP0170 PDF standard offers several benefits to the petroleum refining and petrochemical industries, including:
You need both standards. MR0175 tells you which material to buy. SP0170 tells you how to protect that material when you shut down the unit.
: Utilizing dry air or nitrogen to prevent liquid water from forming on surfaces.
Monitor relative humidity continuously if using the dry-air method. Quality Control nace sp0170 pdf
What specific (e.g., 304, 347) is your equipment made of?
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.
(formerly designated NACE RP0170) is a standard practice titled: "Protection of Austenitic Stainless Steels and Other Austenitic Alloys from Polythionic Acid Stress Corrosion Cracking During Shutdowns and Start-ups."
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. To understand why NACE SP0170 is necessary, it
Indirectly. New austenitic stainless steel that has never been in high-temperature service is not sensitized and does not require soda ash washing during its first shutdown. However, after the first service cycle above the sensitization range, SP0170 becomes applicable.
The alkaline wash neutralizes any polythionic acid as soon as it forms.
NACE SP0170 (now managed by ) outlines essential, industry-standard practices to prevent Polythionic Acid Stress Corrosion Cracking (PTA SCC) in austenitic stainless steels and alloys during refinery shutdowns. It is primarily applied to high-risk units, including hydrotreaters and hydrocrackers. 1. Core Mitigation Methods
Identify all assets constructed from 300-series stainless steels operating within the sensitization temperature window. SP0170 tells you how to protect that material
Looking for more resources on corrosion prevention? Check out our other guides on NACE MR0175 and API 570 inspection codes.
Engineers and inspectors search for the because it provides the specific "how-to" for preventing this specific type of failure. It isn't just theoretical; it is a practical guide.
: Neutralizes any formed acids using a soda-ash (sodium carbonate) solution. Dry Nitrogen Purging
—a common scenario when equipment is opened during a turnaround. Intertek Inform Key Mitigation Methods
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