NACE SP0170, also known as "Protection of Refinery Equipment from Corrosion," provides guidelines and practices for protecting equipment in refineries from corrosion. This standard is crucial for industries that deal with refining petroleum products, as corrosion can lead to significant safety risks, environmental hazards, and financial losses.
To appreciate the 2021 update, we must revisit history. In the 1970s, catastrophic failures in sour oil fields led to the creation of NACE MR0175 ("Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment"). For decades, this standard was the "golden rule" for any metal touching wet H₂S.
In 2003, the standard was restructured into two parts:
By 2021, the need for a cohesive update was clear. The industry had moved toward higher-strength materials, deeper wells, and more extreme pressure/temperature (P/T) regimes. The NACE SP0170 PDF 2021 was released to address these gaps, clarify ambiguities, and harmonize with updated ISO standards.
Do not waste time on shady websites. Purchase directly from:
AMPP Store (formerly NACE International)
ANSI Webstore (authorized reseller)
Techstreet (subscription-based access for enterprises)
Pro tip: If you work for an EPC firm or major operator, they likely have an enterprise subscription. Check your internal document portal before purchasing individually.
The search for "nace sp0170 pdf 2021" is more than a quest for a file—it represents an engineer's commitment to integrity, safety, and regulatory compliance. The 2021 edition tightens critical limits on hardness, welding, and alloy selection, closing loopholes that previous versions left open. nace sp0170 pdf 2021
Do not rely on a bootleg copy from a forum. Purchase the official PDF from AMPP, read it cover to cover, and integrate its requirements into your material selection and quality assurance workflows. In the sour service arena, the standard is not a suggestion—it is the law of physics, enforced by the potential for catastrophic failure.
Final Checklist for Engineers:
Stay safe, stay compliant, and always refer to the most current standard.
Disclaimer: This article is for informational purposes only and does not constitute engineering advice. Always consult directly with a licensed materials engineer and refer to the official NACE SP0170-2021 document for specific applications.
NACE SP0170 is a critical Standard Practice (SP) focused on protecting austenitic stainless steels and other austenitic alloys from Polythionic Acid (PTA) Stress Corrosion Cracking (SCC) during the shutdown of refinery equipment.
While NACE International merged with the Society for Protective Coatings (SSPC) in 2021 to form the Association for Materials Protection and Performance (AMPP), the most recent active version of this specific standard was released in 2018. Key Purpose and Scope
The standard provides essential mitigation methods for refinery equipment—such as desulfurizing, hydrocracking, and hydrotreating units—where the risk of PTA SCC is high. PTA SCC typically occurs when metal sulfides on equipment surfaces react with oxygen and moisture during a shutdown, forming polythionic acids that attack sensitized stainless steels. Mitigation Methods Outlined in SP0170
The standard details several primary techniques to prevent the formation or impact of polythionic acids:
Alkaline Washing: Neutralizing acids by washing equipment surfaces with alkaline solutions (e.g., soda ash). NACE SP0170, also known as "Protection of Refinery
Nitrogen Purging: Using dry nitrogen to exclude oxygen and water from the system.
Dry Air Purging: Preventing the formation of liquid water by maintaining a dry air environment.
Material Selection: Utilizing stabilized grades of stainless steel (like 321 or 347) or specific fabrication practices to reduce sensitization. Document Information NACE SP0170-2018
The NACE SP0170 standard, titled "Protection of Austenitic Stainless Steels and Other Austenitic Alloys from Polythionic Acid Stress Corrosion Cracking During a Shutdown of Refinery Equipment," is a critical standard practice used by the petroleum refining industry. While users often search for a "2021" edition, it is important to note that as of May 2026, the NACE SP0170-2018 edition remains the most current and active version of the standard. In 2021, NACE International merged with the Society for Protective Coatings (SSPC) to form AMPP (Association for Materials Protection and Performance), which now maintains the standard under Task Group 173. Overview of NACE SP0170
The primary objective of SP0170 is to provide reliable mitigation methods to prevent Polythionic Acid Stress Corrosion Cracking (PTA SCC). This form of cracking occurs when sensitized austenitic stainless steels react with oxygen and water in the presence of sulfide corrosion products—common in refinery units like hydrocrackers and hydrotreaters—during shutdown periods. Core Mitigation Practices
The standard outlines several proven methods to protect vulnerable alloys during refinery downtime, including the shutdown and startup phases. NACE SP0170-2018
NACE SP0170-2018 remains the active standard for protecting austenitic stainless steels from polythionic acid stress corrosion cracking (PTA SCC) during refinery shutdowns as of 2021, focusing on nitrogen purging and alkaline washing to mitigate risks. The standard, now managed by AMPP, outlines critical procedures for preventing corrosion in sensitized austenitic alloys common in hydrotreating and cracking units. Access the standard through the ANSI Webstore.
Here’s a useful, actionable piece of content about NACE SP0170 (2021 edition) — structured for engineers, inspectors, and asset integrity professionals who need a quick yet thorough reference.
The new edition provides updated charts for maximum H₂S partial pressure versus pH. Carbon steels that passed in 2015 may now be disqualified under the 2021 thresholds, especially in low-pH (acidic) environments. By 2021, the need for a cohesive update was clear
If you're looking for the 2021 version of this document in PDF format, here are some steps you can take:
AMPP (Association for Materials Protection and Performance) Website: The official source for NACE standards is the AMPP website. You can visit www.ampp.org and search for the document using the designation "SP0170."
Document Store or Library: Some documents might be available for purchase or free access through digital libraries or document stores like IHS Standards Store, ANSI Webstore, or your country's national standards body.
Industry Associations: Sometimes, industry-specific associations or organizations provide access to relevant standards for their members.
If you are currently using the 2015 or 2012 version, upgrading to the 2021 PDF is not optional—it is a matter of safety. Here are the major revisions:
| Feature | NACE SP0170-2021 | ISO 15156:2020 | | :--- | :--- | :--- | | Scope | U.S. supplement for specific alloys and hardness limits | Global general requirements | | CRA Limits | More conservative for nickel alloys | Broader, with user responsibility | | Hardness Testing | Mandatory HRC conversion table | Refers to general practices | | Welding | Stricter HAZ limits for sour gas wells | Similar but less prescriptive | | PDF Availability | AMPP website | ISO/ANSI website |
Recommendation: For projects outside North America, use ISO 15156. For any project in the U.S. (especially OCS and onshore sour gas), use NACE SP0170 PDF 2021 as the governing document.
The specific interest in the "NACE SP0170 PDF 2021" highlights a shift in how the industry consumes safety data. In the past, these standards were massive binders locked in a lead engineer's office. Today, the immediate availability of the PDF format allows for real-time compliance.
Field engineers can now reference the standard on tablets during a turnaround. If a question arises about the required alkaline solution concentration for a specific vessel, the answer is a search bar away. This immediacy is vital; in a shutdown scenario, delays cost millions of dollars per day, and cutting corners on corrosion prevention can cost lives.