RETROSPECTIVE HAZARD IDENTIFICATION AND ASSESSMENT OF AGEING PLANT

Just over a decade ago a catastrophic failure of a heat exchanger occurred at Esso's Longford gas plant in Australia killing two workers and injuring eight others. One of the contributory causes of the accident identified in the Royal Commission report was the failure to carry out a Hazard and Operability (HAZOP) study of the plant (built in 1969), a study which had been planned but not executed. Since then many companies have implemented programmes for retrospectively reviewing ageing plant to formally identify hazards and assess risk. This paper draws on experience from implementing programmes for the retrospective identification and assessment of major hazards within a UK-based, multi-national energy company. These programmes have entailed the application of two widely-used techniques (HAZOP and Process Hazard Review) to a variety of plant (offshore installations, gas terminals and gas-fired power stations), at a variety of levels (individual units and whole facilities) in both the UK and overseas. It also draws on the wider experience of the two consulting organisations which supported these programmes. The paper assesses the comparative benefits of the two hazard review techniques, the context in which they were applied and their success in achieving the desired outcomes. The paper then draws out the wider lessons for industry in terms of: the triggers for when to carry out a retrospective hazard study; the scope and timing for such studies; suitable methodologies; and linkage with other initiatives such as safety system obsolescence, decommissioning and performance standards review.