Evaluation, Visualisation and Monitoring of Cumulative Risk Exposure Resulting from SCB Deviation

The paper examines current industry cumulative risk management methodologies and presents a unique approach to cumulative risk evaluation, visualisation and dynamic monitoring.

Abstract

Identifying, understanding, and managing major risks is an integral part of operations within major hazard industries. In the UK and throughout Europe, this is typically achieved within a framework of goal-setting or prescriptive regulatory requirements. Safeguards required to protect against major risks or Major Accident Hazard (MAH) exposures are known as Safety Critical Barriers (SCBs) and comprises of human and hardware elements or a combination of both.

If an SCB is unable to operate as intended, it is deemed as an impairment from its functional requirement and is subject to an operational risk assessment. Impairments can include degraded hardware systems, maintenance backlogs, overrides, poor operating discipline, etc. SCB impairments can result in increased exposure to MAHs and undermine an organisation’s ability to demonstrate that operational risks remain as low as reasonably practicable.

Operational risk assessments often focus on individual SCBs, and the impact caused by deviation from their functional criteria, as opposed to the aggregate risk exposure from all recorded deviations. The outcome of these assessments typically leads to implementation of temporary safety measures that do not consider the cumulative effect of all existing interim safeguards associated with other SCB deviations. Risk assessment of SCB deviations also tend to primarily consider hardware systems with limited or no attention given to cumulative risk exposures created by impaired hardware and human-based SCBs.

The significance of managing cumulative risk exposure is further emphasized by the fact that major accidents seldom occur from the loss of a single SCB, but rather from combined hardware and human barrier failures. For example, in the Texas City refinery incident, the investigation uncovered a string of failures that included procedural breaches and equipment malfunction. Unofficial procedures were followed as the raffinate splitter tower was over-filled and the high-level alarm for the tower was non-functional and did not sound.

Although guidelines exist for cumulative risk management, current approaches can be cumbersome, labourious and provide limited or no comprehensive inclusion, visibility, and monitoring of all contributing hardware and human-related SCB deviations. To illustrate this for a typical MAH facility, multiple changes are regularly made to equipment functionality to mitigate the impacts arising from a protracted delay to start-up. These changes are risk assessed individually with implementation of temporary mitigations. However, there is often a lack of visibility or understanding of the cumulative effect of all the changes. Frequently, there is the perception that a cumulative risk assessment would be complex and time consuming, resulting in the acceptance of a risk exposure that is not fully understood.

Accounting for cumulative risks in operations and effectively demonstrating ALARP, even when temporary controls are put in place to mitigate SCB deviations, therefore remains a challenge. Operators of major hazard facilities openly recognise this challenge. It is widely accepted that a true understanding of cumulative risk is imperative and invaluable for successful major risk management and operational performance. To achieve this a methodology must provide robust and verifiable means of assessing cumulative risk exposure without being too onerous. The methodology must connect to a variety of data sources (i.e., SAP®, Synergi®, Permit to Work, Override logs etc.) and account for all hardware and human-based SCB deviations.

This paper discusses an alternative approach to assessing cumulative risk derived from hardware and human SCBs deviations. This approach takes SCB impairments into account, including sub-elements and tasks that are necessary for the barriers to function as intended, and the interactions and dependencies between the sub-elements and tasks. The approach is consistent with industry guidelines and good practice publications. It utilises a custom algorithm that enables determination of cumulative risk ratings based on dynamic status of all SCB elements, the hazard management hierarchy principle, and credible and foreseeable scenarios related to identified MAH at a facility.

The methodology has been developed into a digital tool. It enables monitoring and visualization of cumulative risk exposure. It also enables dynamic barrier management, while helping organisations to focus attention on those SCB deviations associated with cumulative risk exposures and the main contributors to major accident risk reduction. This methodology deepens understanding of major accident cumulative risks, helping to maintain it at or below their acceptable thresholds throughout the life of a facility. It also provides a robust, intelligent, and comprehensive means for effective and dynamic ALARP demonstration.

The cumulative risk digital tool has already been deployed on several MAH facilities where it has been proven to be an effective and reliable means to develop a representative cumulative risk profile. Ultimately, this has enabled organisations to achieve informed, risk-based decision-making related to resource planning, allocation, and deployment of measures to reduce their exposure and vulnerability to major risks.

REVaRS

The research paper describes the science underpinning the state of the art cumulative risk management and safety critical barrier visualisation solution – REVARS (Risk Exposure Visualization and Reporting Solution) which has been deployed across major producing facilities. REVARS provides an intelligent, comprehensive and robust platform that ensures organisations spend less time trawling through data and more time analysing and drawing vital intelligence that drive safety, resource optimisation and enhance operational efficiency.

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To learn more about REVARS and schedule a demo, visit revars.com