Welcome to the Damage Mechanisms unit of the Mechanical Integrity Professional Initiative. Inside this unit, you will learn about the numerous damage mechanisms that are relevant to the refining and petrochemical industries, as well as some important concepts that will help you to understand why they occur in the first place.

Much of the information found in this unit comes from API RP 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry. For the sake of consistency, this unit uses many of the same conventions that are found in API RP 571 such as damage mechanism groupings (e.g., Mechanical or Metallurgical Failure Mechanisms, High Temperature Corrosion, etc.).

In fact, this unit may certainly be used as a study reference for those who are interested in obtaining the API 571 certification. While it is not a replacement for detailed training or the Recommended Practice itself, it may provide additional context to help understand the API 571 body of knowledge.

Please note that this unit provides high level summaries of damage mechanisms. We highly recommend that you refer to comprehensive references such as API RP 571 to obtain a better understanding of each of the damage mechanisms. Some of them are very complex and beyond the scope of this project.

Exploring the Damage Mechanisms Unit

This unit contains 10 sections. The first two sections provide foundational information that will lead to a better understanding of the damage mechanisms themselves. We recommend that you start with these two sections before exploring the different categories of damage mechanisms.

The damage mechanisms themselves (67 in total) are organized by category first, and then alphabetically. Each damage mechanism may contain one or more Important Concepts that provide information on why they occur in the first place.

And finally, each section may contain some Additional Resources that enable you to dig deeper into the topic.

What is a Damage Mechanism?

A damage mechanism is something that results in problems or failures with process equipment. Damage mechanisms can range from corrosion, to cracking, to heat damage, and everything in between.

API RP 571 (second edition) includes a variety of different damage mechanisms that are known to affect the refining industry. The damage mechanisms are grouped in the following categories:

  • Mechanical or Metallurgical Failure Mechanisms
  • Uniform or Localized Loss of Thickness
  • High Temperature Corrosion
  • Environment-Assisted Cracking
  • Other Mechanisms

Why Understanding Damage Mechanisms is Important

API RP 584 (Integrity Operating Windows) puts it best:

In today’s operating environment, it is not enough to base future inspection plans only on prior recorded/known history of equipment condition. A fundamental understanding of the process/operating conditions and resulting damage mechanisms are required in order to establish and maintain an inspection program that yields the highest probability of detecting potential damage. [API RP 584, 1st Edition, pp. vii]

Proper identification of damage mechanisms is important when:

  • Implementing the API Inspection Codes (510, 570, and 653)
  • Implementing API RP 584 (Integrity Operating Windows)
  • Conducting risk-based inspection per API RP 580 or similar frameworks
  • Performing fitness-for-service assessments

Damage mechanisms need to be understood and considered to determine corrosion rates, location (general or local), and opportunities for mitigation.

This project is a collaborative effort between Inspectioneering and The American Petroleum Institute. Click below to learn more about API's Individual Certification Programs.

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