(55n) A Digitalized, Cumulative Risk Management Approach to Maintenance Backlog Prioritization on High Hazard Installations

When an item of equipment on a plant is due for maintenance or if there is a fault, a work order is created either for preventive or corrective action. The work order outlines the activities to be undertaken to ensure ongoing suitability or to restore the equipment to its intended functional state and it includes a date when the work is expected to be completed. If the work is not done before the set completion date the equipment goes into maintenance backlog. Operating an equipment in backlog especially for a prolong period could compromise its safety and integrity, lead to a major accident, and potentially expose personnel and the environment to severe hazardous consequences.

Monitoring and eliminating or, at least reducing equipment in maintenance backlog to bare minimum is the goal of owners of high hazard installations but it remains a daunting task. Maintenance backlog management is also widely acknowledged in the high hazard industry as a challenge while concerted efforts are being made through knowledge sharing events and best practice publications to inform and advise on effective ways to manage equipment in backlog to protect against potential safety and operational risk exposure.

Organisations often expend considerable time and effort to reduce maintenance backlog and would generally prioritise Safety and Environmental Critical Equipment (SECE) based on company policies and/ or regulatory requirements. However, even with best endeavours the available resources may be too limited to address all critical equipment items in backlog leaving companies having to make the difficult decisions on which critical equipment to prioritise to sustain an acceptable level of safety while in operation. More pertinent are the questions of what criteria should be used for prioritisation, how would it be applied, and what impact does equipment left in backlog have on the installations cumulative risk exposure?

The process of prioritising equipment in backlog is typically done manually. A team of maintenance, safety and integrity personnel reviews all equipment in backlog periodically using their experience, knowledge, and judgment to assess parameters such as function and condition of each equipment, effect of failure on safety and operations, manhours required to clear the backlog etc. This approach can be time consuming, lead to inconsistencies, human errors such as underestimating the importance of a critical equipment, lack of understanding of the effect of the cumulative effect of multiple SECEs in backlog on major risk exposure etc.

This paper presents an alternative approach to prioritising equipment in backlog with focus on SECEs. Underpinned by the principle of cumulative risk management and the barrier management concept, the methodology entails assessment of the purpose and functionality of each SECE in backlog, simulate and rank the impact of different combinations of SECE failures and present the result in order of installation's vulnerability to major risk exposure. The output from this approach provides owners of high-hazard installations immediate vital insight on equipment items whose failure poses the biggest risk exposure, and a robust basis for prioritising and effectively reducing equipment in maintenance backlog.