Analysis of a loss of containment incident dataset for major hazards intelligence using storybuilder

A dataset of 975 incidents investigated by the Health and Safety Executive (HSE) from 1991 has been analysed using a loss of containment (LOC) model in Storybuilder, a software tool for incident analysis developed as part of the Occupational Risk Model (ORM) project, sponsored and developed by the Dutch Ministry of Social Affairs and Employment (Ale et al., 2008) to identify patterns of occurrence. The LOC model breaks down main and underlying causes of incidents in terms of barriers, tasks and safety management systems that failed in the course of an incident.Failure of containment due to substandard condition/material, with a significant contribution to structural failures including corrosion was the most frequent cause of incidents. The number of failures during indication, detection, diagnosis and response of a substandard containment was high which suggests that inspection and maintenance of pipework and process equipment focused on detection of mechanical damage and its precursors could significantly reduce incident occurrence. Failures to provide adequate means of measuring and indicating process parameters such as temperature, level or pressure was next in frequency of occurrence. Level detection had the largest share in the failure of the barrier. Direct intervention by operators failed in a large number of incidents thus discouraging reliance on this barrier as an effective means to stop a LOC incident.It is recommended that an analysis of barrier failures, task failures and the underlying management delivery failures of all incidents, including dangerous occurrences, investigated by HSE would provide quantitative evidence on the evolution of underlying causes of incidents and their associated safety management delivery failures. This evidence would allow prioritisation of preventative intervention policies, and could help develop metrics that would quantitatively show the effect of HSE’s work on patterns of incident occurrence, the barriers that commonly fail and their associated tasks and management delivery failures.

► 975 loss of containment incidents and dangerous occurrences have been analysed.
► Failure of containment due to substandard condition was the most frequent cause.
► Plans and procedures had the largest contribution to the failure of barriers.
► Competence of operators was the second most frequent failure of management delivery.