For refinery professionals and engineers, (now maintained by AMPP ) is a critical standard practice for maintaining the integrity of stainless steel equipment during maintenance periods.
: Neutralizing any acidic species by washing internal surfaces with an alkaline solution, such as soda ash (sodium carbonate).
: If nitrogen isn't used, maintaining the air at a very low dew point to ensure liquid water cannot form on the metal surfaces. nace sp0170 pdf
This guide explains the technical scope of NACE SP0170, the mechanisms of the corrosion it prevents, and how to access the official PDF documentation. What is NACE SP0170?
The full title of the standard is .
The standard outlines several mandatory and recommended procedures to prevent PTA formation or neutralize it before damage occurs:
In a refinery environment, equipment made from austenitic stainless steels (like 300-series alloys) often develops sulfide scales on internal surfaces during operation. When the unit is shut down and opened, these sulfides react with moisture and oxygen in the air to form . These acids can cause rapid, catastrophic cracking in sensitized metals—sometimes within hours of exposure. Key Mitigation Strategies in SP0170 For refinery professionals and engineers, (now maintained by
: Keeping oxygen out by maintaining a positive pressure of dry nitrogen within the equipment.