The following guide details the technical specifications, mechanics of PTA SCC, and mandatory mitigation procedures outlined in the NACE SP0170 PDF standard . What is NACE SP0170?
SP0170 prescribes a multi-stage ECDA process. The classic four-step ECDA framework appears with refinements:
This article provides a comprehensive overview of the standard, its significance, and how to implement its requirements. What is Polythionic Acid SCC?
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 nace sp0170 pdf 2021
: Neutralizing acids by washing equipment surfaces with alkaline solutions (e.g., soda ash).
Note: Ensure you are obtaining the latest active revision, which may be labeled 2018 or updated with technical amendments labeled through 2021. Key Takeaways
For large vessels or complex internals where liquid washing is difficult, the standard may permit the use of soda ash blasting to neutralize surfaces. This form of cracking occurs when sensitized austenitic
For engineers, integrity managers, and technical professionals working in petroleum refining and petrochemical industries, the standard known as is indispensable. It is one of the key documents for ensuring plant safety during critical periods.
NACE (National Association of Corrosion Engineers) is a globally recognized organization that provides standards, guidelines, and best practices for corrosion prevention and control. One of its widely adopted standards is NACE SP0170, which provides guidelines for the design, fabrication, and inspection of equipment and components for corrosion prevention. This paper provides an overview of NACE SP0170 PDF 2021, highlighting its key aspects, updates, and implications for industries.
The National Association of Corrosion Engineers (NACE) developed the SP0170 standard to provide a comprehensive framework for corrosion prevention in carbon steel pipelines. The standard outlines the requirements for coatings and cathodic protection (CP) systems, which are essential for mitigating corrosion and ensuring the safe and reliable operation of pipelines. and reactors—during the downtime
The standard provides a documented framework for corrosion management during turnarounds, offering specific acceptable mitigation methods. Engineers may select one or a combination of the methods based on risk assessment.
The standard provides specific mitigation methods to protect equipment—such as heaters, tubes, and reactors—during the downtime, shutdown, and startup phases of refinery operations. PTA SCC occurs when sulfide corrosion products react with oxygen and water to form polythionic acids, which can rapidly cause cracking in sensitized austenitic alloys.
: Used to exclude oxygen and moisture from the equipment during shutdown. Alkaline Washing (Soda Ash Wash)