This article provides a comprehensive overview of the standard, its significance, and how to implement its requirements. What is Polythionic Acid SCC?
: Maintaining a dry air environment to prevent the liquid water formation necessary for PTA to develop. ANSI Webstore Standard Structure General scope and application Selection of materials and fabrication practices Dry nitrogen purging to exclude oxygen Alkaline washing of equipment surfaces Use of dry air to prevent water formation Special considerations for reactors Appendix A Background information on the PTA SCC mechanism Accessing the PDF As NACE is now part of
provides detailed instructions on the required concentration of the solution, typically recommending a concentration of 0.5% to 1.0% Na₂CO₃ by weight, along with instructions on maintaining high pH levels during the neutralization process. How to Obtain the NACE SP0170 PDF (2021/Latest Revision)
Massive internal surface areas with complex stainless steel fractionation trays. nace sp0170 pdf 2021
While NACE International merged with the Society for Protective Coatings (SSPC) in 2021 to form the , the most recent active version of this specific standard was released in 2018 . Key Purpose and Scope
: Neutralizing acids by washing equipment surfaces with alkaline solutions (e.g., soda ash).
In the high-stakes environment of the oil and gas industry, a single drop of water can be a ticking time bomb. When that water mixes with hydrogen sulfide ($H_2S$) and stresses a piece of steel, the result is not just corrosion—it is cracking, potential failure, and catastrophic safety hazards. This article provides a comprehensive overview of the
The standard (last officially updated in 2018 but widely applied through 2021) tells a "deep story" not of people, but of the silent, invisible war against Polythionic Acid Stress Corrosion Cracking (PTASCC) .
The following represents a summary of the key consequences for non-compliance with NACE SP0170:
: Maintaining a dry, oxygen-free environment using a nitrogen blanket to prevent the formation of polythionic acid. Dehumidification Key Purpose and Scope : Neutralizing acids by
ensuring no dead-legs are skipped, followed by preservation under an inert nitrogen blanket. Standard Information & Authorized Access
This includes residual stresses from fabrication and welding, or operational stresses remaining in the components.
The reference to "PDF 2021" likely indicates you're seeking the 2021 version of this standard in PDF format. Standards like these are periodically updated to reflect advancements in technology, changes in industry practices, and lessons learned from field experiences.
NACE SP0170-2021 is an indispensable tool for protecting sensitized austenitic stainless steel equipment from the disastrous effects of PTA SCC. By following the procedures for alkaline washing and excluding oxygen during shutdowns, refiners can significantly extend the life of their equipment and prevent catastrophic failures during startup.
: Utilizing stabilized grades of stainless steel (like 321 or 347) or specific fabrication practices to reduce sensitization. Document Information NACE SP0170-2018