20 Years on lessons learned from Piper Alpha. The evolution of concurrent and inherently safe design

It has now been well over 20 years since the North Sea Piper Alpha disaster in 1988. There have been many lessons learned; some documented others just etched in memory. The event chronicled many significant changes in the offshore industry. The emanating point for most sweeping changes has been the Cullen Report and the UK North Sea industry. This paper reviews some of the critical lessons and identifies many ‘secondary’ finer points that constitute important learnings. The paper looks at major changes instigated by step changes in safety criticality. It is argued that the ‘second tier’ modes of failure such as corrosion, materials degradation, environmental cracking, erosion, plant ergonomics, etc. need to be better examined. These mechanisms are dangerous threats to the integrity of deep subsea assets, and it is noted that such root causes of failure as witnessed or predicted have yet to be fully appraised. The authors’ use wide experiences and case histories to highlight such concerns, offering rational fit-for-purpose solutions. The industry disconnections between, urgency to build, knowledge transfer, and management of change, are refocused. Powerful advances in risk-based mechanical, process, materials, and corrosion engineering are emphasized and the use of key performance indicators (KPIs) are reasoned for best life-cycle integrity. To keep up with the pace of growth in the deepwater sector, methods of concurrent and inherently safe design have evolved in a world where the practicalities and costs of modification, repair and retrofit are extremely difficult. Hence getting it right at the outset is paramount. Thus the drive for purposeful investment, at design is more justifiable, than the traditional practice of postponing costs (and problems) to operations. In this way the ominous ‘gray’ zone between the two cost centers is better bridged for reasons of safety and commercial advantage.