Risk-Based Inspection Technology – Continuous Improvement through Knowledge of API 581, 3rd Edition

By Valerie Magyari, Principal Engineer at The Equity Engineering Group, Inc. May 16, 2016

When was the last time you reviewed your Risk-Based Inspection (RBI) methodology?  Are you using calculation procedures for probability of failure, consequence of failure, and risk that haven’t had their basis reviewed in years?  Does everyone in your company who works with RBI understand the assumptions that the risk calculations are based on?  Are there aspects of your RBI program that could be improved with updated industry data and methodology?

Risk-Based Inspection (RBI) technology has had a major impact on managing plant equipment inspection throughout industry.  As with any worthwhile technology, improvements are the result of innovations that overcome existing weaknesses or limitations, and API RBI technology has seen many improvements in the past few years.  API RBI technology improvements have the benefit of careful consideration and vetting by a group of users representing many refining, petrochemical, and consulting companies.  No matter what RBI methodology your company uses, understanding the most current API RBI methods and models can help generate new ideas for improving any RBI program.

The newly-published 3rd Edition of API 581 Risk Based Inspection Technology includes significant improvements to the RBI methodology.  A few of the more noteworthy changes include…

  • The probability of failure calculation has been updated and enhanced—specifically, how damage is quantified for internal and external thinning.  This change results in a major update to the legendary Ar/t tables for characterizing wall loss due to thinning. 
  • The HTHA module was completely revised to produce a practical, high-level screening process that can be utilized with RBI. 
  • A prior limitation for consequence of failure methods has been removed.
  • Several updates to Part 2’s damage mechanism modules, including External/CUI corrosion, High Temperature Sulfidic and Naphthenic Acid Corrosion, and Carbonate Stress Corrosion Cracking.

API 581 is a lengthy and complex document, so attending a training course may be the most effective way to review RBI basics, learn about what has changed recently, and apply this knowledge to your facility’s RBI program. Click the button below to learn more about public RBI training courses as well as customizable private API RBI courses to assist you in understanding how to maximize the benefits of your RBI program and update it where applicable.

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