The Difference Between Safe Operating Limits (SOL) and Integrity Operating Windows (IOW)

, Be the first to comment

Tags: Integrity Operating Windows Mechanical Integrity Safe Operating Limits


An AOC consultant, a process engineer, and a reliability engineer discuss the differences between Safe Operating Limits, Standard Limits, and Integrity Operating Windows.

Article

Is there any difference between Safe Operating Limits (SOL) and Integrity Operating Windows (IOW)?

Short answer is NO.

But let me tell you how all this started.

I was recently in a meeting where 2 engineers were talking about this topic. One of them was a process engineer, the other one was reliability engineer.

The process engineer was talking about the importance of defining a Technical Operating Envelope in their facility where they can easily identify the Safe Operating Limits (SOL) and standard limits. He indicated that the Technical Operating Envelope consists of the operating limits of a unit that specifies safe mechanical and process performance limits between minimum and maximum operating parameters.

He continued speaking and stated that a SOL is operating parameter, such as pressure, temperature or flow, that defines the limit to which equipment within the plant process can be safely operated. Deviating from the safe operating limit can result in immediate and severe consequences to health, safety and the environment.

On the other side of the table, the reliability engineer stated that from his point of view the most important items to be defined were the Integrity Operating Windows, both critical and standard. He clearly said that IOWs are derived from performing a corrosion hazard analysis. He also mentioned that IOWs are defined values for process variables that can affect the mechanical integrity of an asset if the operation deviates from the established limits for a predetermined length of time.

Both went back and forth on the validity and importance of the SOL and IOW critical. They both agreed on one fundamental topic: Process Engineering and Reliability Engineering personnel must report, investigate and take action on any SOL and IOW critical excursions.

At some point in the conversation, both looked at me and asked "What is your opinion on this matter?"

I said, "You both are correct on your statements."

They thought I was just joking and asked, "What do you mean?"

I replied that SOL and IOW critical are basically the same thing.

If you put an SOL chart and IOW critical chart together, they will look like this:

Safe Operating Limits (SOL) vs Integrity Operating Windows (IOW)

What most people consider "differences" between SOL and IOW critical is just the approach either Operations / Process Engineering / Reliability Engineering or Maintenance groups within an organization decide to manage.

In general, for Operations and Process Engineering, Safe Operating Limits (SOL) related to safety and asset performance. For Reliability Engineering and Maintenance, Integrity Operating Windows (IOW critical) are related to safety and asset life reduction.

Both looked at me and said, this is an Ah-Ha moment... They agreed that SOL and IOW critical are equivalents; what they initially viewed as differences were just a result of their different perspectives. The process engineer was looking at the overall function of the plant or unit and the reliability engineer was focused on the mechanical integrity of the asset or equipment. Same thing, just different perspectives!!


Be the first to comment

Comments

There are no comments for this article.

Add your comment

Related Services

Integrity Operating Window Development

Key parameters and mitigating actions for variables that may dramatically affect the intended design life of your asset

Development of Mechanical Integrity (MI) Procedures and Processes

A maintenance system designed in which elements work together as a quality system for maximum returns

RAM, RCM, FMEA, FMECA and Bad Actor Analysis

AOC delivers the policies, procedures, work processes, knowledge and actions such as preventive maintenance, predictive maintenance, and condition monitoring tasks.

Mechanical Integrity Assessments

An interdependent assessment of your people, process, and technologies for a confident path forward

End-of-Life, Remaining-Life, and Fitness-for-Service Assessments

When evaluation of inspection results suggest that an asset is near its end of useful life, Fitness for Service evaluations can determine if the asset us suitable for continued operation.

Corrosion Control Planning

Achieving zero corrosion-related loss of primary containment in the refining industry.

Related Training

RBI/MI Overview

What is Risk Based Inspection?

Equipment Data Collection

What information do we need to collect to support a Mechanical Integrity and/or RBI program?

Damage Mechanism Identification and Review

How do we identify and quantify the damage mechanisms that affect our equipment?

Estimate Risk

How do I estimate risk using the information that I have?

Activity Planning, Execution, and Evaluation

How do I plan and perform inspections and tests?

Manage Changes and Communicate Results

How do I ensure that my MI/RBI program is up to date and communicate to stakeholders?

Risk Based Inspection (RBI) - A Mechanical Integrity Best Practice

What are your goals for RBI? How will you measure your success? How will you sustain that success?

Related Knowledge

The MI Assessment - Understanding Your Mechanical Integrity Goals

Compliance? | Best Practice? | Risk Reduction? | One Step at a Time? | Capture Personnel Knowledge? | All Of The Above?

Production Loss Accounting - Heat Exchanger Bad Actor Analysis

Heat exchanger failures contribute to over $146M in losses for a large refining enterprise.

OSHA Compliance

What do you do when you are on the job for six weeks and you have a toxic leak twice the release of the recent DuPont event? Not to mention the fact that it is only 1992 and OSHA 1910.119 is just getting started...

From Fitness for Service to Reliability-Based Mechanical Integrity

An upgrader is brought safely back into production a year ahead of expectations, avoiding an opportunity cost exceeding $300 million.