In remembrance of times past and lessons learnt

Although we are not yet at the end of the millennium, an event no doubt to be marked by countless reviews, retrospectives and reminiscences, we could not let this month go by without turning our own thoughts to an event 25 years ago that has had a lasting impact on the safety practices of the process industries.

The detail of what happened at Flixborough on the afternoon of 1 June 1974 is recalled on page 27 by one of the chemical engineers involved in the investigations into a disaster that killed 28 operators, devastated a petrochemical complex and severely damaged over 2000 homes. Ralph King has long argued that the presence of water in one of the cyclohexane oxidation reactors may have contributed to the acknowledged failure of a temporary by-pass pipe between two reactors - officially attributed as the prime cause of the accident - and his perseverance has recently led to the HSE looking again at the underlying reasons behind that failure.

From an engineering perspective, the results of the HSE's investigations will be awaited with interest. But the impact of Flixborough goes far beyond the intricacies of the plant's process design and operation, important though they are (or perhaps were, since the design of such a plant, with its large inventories of flammable materials at high temperatures and pressures, would be unlikely today). Indeed, the speed at which the HSE itself was set up to implement and oversee the 1974 Health & Safety at Work Act owed much to the disaster and its aftermath.

On page 24 Phil Wright, chief engineer with a leading engineering insurance company, highlights the changes in industry's attitude towards risk assessment and management that have taken place since Flixborough. As he points out, the events of that June day have not stopped accidents happening - and other subsequent events such as Seveso may have had a larger say in changing legislation - but they marked the beginning of a cultural change in industry's, and society's, attitudes towards the risks involved in industrial processes.

Those changing attitudes were also recalled at last month's timely launch of the IChemE's excellent Accident Database (see page 25). Probably everyone in chemical engineering at the time can recall their surprise on hearing that the notorious `dog-leg' by-pass pipe had in effect been designed in chalk on the workshop floor by the plant's maintenance team, which did not include any process engineers. But, as speakers at the IChemE launch remembered, such was the industry culture of the day, before Hazops and Hazans and `permits to work' became the norm. And society's attitudes of the time, recalled by another senior chemical engineer involved in the investigations, were such that local residents complained more about the speed at which their local council boarded up broken windows than about the dangers of the plant in their midst.

We all change over the course of a generation, but what Flixborough really taught us is that there is no substitute for experience. If we fail to learn from our own and other's experience, we run the risk of repeating the mistakes of the past.