Inspectioneering Journal

Establishing Integrity Operating Windows (IOWs) for Refinery Fired Heaters

By Tim Hill, Principal Consulting Engineer at Quest Integrity Group. This article appears in the November/December 2018 issue of Inspectioneering Journal.


Understanding and establishing effective Integrity Operating Windows (IOWs) is critical in the operation of refinery fired heaters. IOWs, as described by API 584, are a specific subset of operating limits focused on maintaining the integrity and reliability of process equipment. IOWs address issues involving process parameters that, when not adequately monitored or controlled, can impact the likelihood and rates of damage mechanisms, potentially leading to loss of containment.

The establishment, implementation, and maintenance of IOWs require a multidisciplinary approach and should be considered an essential part of a facility’s operation and maintenance strategies. This article provides an overview of the key components in establishing IOWs, the levels of IOW limits, and the basic principles and application of API Recommended Practice 584 to achieve reliable fired heater performance.

IOWs – What's the Big Deal?

IOWs are the limits within which fired heaters should operate to maintain safe and productive operation. According to API 584, IOWs are “a vital component of integrity management,” and should be implemented “for the express purpose of avoiding unexpected equipment degradation that could lead to loss of containment.” [1] Essentially, IOWs offer an operator considerable peace of mind in the condition of their assets, as long as they are operating within determined parameters.

This content is available to registered users and subscribers

Register today to unlock this article for free.

Create your free account and get access to:

  • Unlock one premium article of your choosing per month
  • Exclusive online content, videos, and downloads
  • Insightful and actionable webinars
Interested in unlimited access? VIEW OUR SUBSCRIPTION OPTIONS

Current subscribers and registered users can log in now.

Comments and Discussion

Posted by UDAYAN PATEL on January 30, 2019
This article is very informative. All the... Log in or register to read the rest of this comment.

Add a Comment

Please log in or register to participate in comments and discussions.

Inspectioneering Journal

Explore over 20 years of articles written by our team of subject matter experts.

Company Directory

Find relevant products, services, and technologies.

Training Solutions

Improve your skills in key mechanical integrity subjects.

Case Studies

Learn from the experience of others in the industry.


Inspectioneering's index of mechanical integrity topics – built by you.

Industry News

Stay up-to-date with the latest inspection and asset integrity management news.


Read short articles and insights authored by industry experts.

Expert Interviews

Inspectioneering's archive of interviews with industry subject matter experts.

Event Calendar

Find upcoming conferences, training sessions, online events, and more.


Downloadable eBooks, Asset Intelligence Reports, checklists, white papers, and more.

Videos & Webinars

Watch educational and informative videos directly related to your profession.


Commonly used asset integrity management and inspection acronyms.