Are You Being Honest with Yourself Regarding IPL Integrity?

Are You Being Honest With Yourself Regarding IPL Integrity?

Mr. Andrew Madewell

Cognascents Consulting Group, Inc.

11777-A Katy Fwy Ste 438

Houston, TX 77079

andrew.madewell@cognascents.com

Keywords: Independent Protection Layer (IPL), Process Safety Management (PSM), Layer of Protection Analysis (LOPA), Process and Instrumentation Drawing (P&ID), Process Hazard Analysis (PHA), Process Safety Lifecycle.

Abstract

Independent Protection Layers (IPLs) are critical pieces of armor designed to protect against process upsets that may harm people, the environment, and/or commercial interests.  IPLs play a key role in any Process Safety Management (PSM) program.  They are often used to close the risk gap between elimination/mitigation measures and associated hazard scenario causes and consequences; hence, regulations exist that require companies to demonstrate IPL integrity and adequacy.

When conducting a Process Hazard Analysis (PHA) using the Layer of Protection Analysis (LOPA) methodology, IPLs are used to close the risk gap between elimination/mitigation measures for a given hazard scenario and its cause, consequence, and conditional modifiers.  In order for an IPL to be “available”, it must meet certain criteria defined by industry standards and company-specific guidance documents. 

Demonstrating IPL effectiveness, or adequacy, involves multiple pieces of information that are not always linked together and kept “evergreen”.  In addition, the various data repositories and tasks required to maintain the integrity of an IPL are “owned” by several functional roles.  Required data for IPL adequacy include the following: IPL design information, IPL integrity level analyses, maintenance and function testing data, and process safety time and IPL response time analyses. 

Companies do not approach IPL integrity the same way.  For example, companies perform IPL function testing and maintenance using different criteria; some employ a standard function testing methodology of confirmation that the IPL acts within the designated time window per regulatory requirements, while other companies actually measure the specific time it takes an IPL to respond to get to its process safe condition.  Either of these approaches provides compliance as to whether the IPL will act adequately given a process upset; however, vulnerabilities may exist depending on the approach employed.

The author posits that use of an evergreen IPL lifecycle reduces potential vulnerabilities in the design and function of an IPL.  In this paper, the author presents the advantages and disadvantages of using an evergreen lifecycle approach to establish and maintain the integrity and “availability” of IPLs.  The author also provides recommendations to enhance the robustness of maintaining IPL adequacy throughout the lifecycle of the protection layer.  Specifically, the author provides examples of IPL integrity successes through the use of an evergreen lifecycle methodology, enhanced operational insight, and potential pitfalls when not employing a holistic IPL lifecycle approach in maintaining IPL integrity and adequacy.

The target audience for this paper includes project managers, project or process engineers, EH&S managers, PSM coordinators, and operators; however, anyone involved with small or large capital projects may also benefit from this paper's content.