Lessons from Grenfell and Piper Alpha on risk assessing modifications
27th June 2018
A more significant factor these two landmark safety failures have in common is that they were both enabled by flawed alterations.
At Grenfell Tower, the building's concrete frame and block infill had contained domestic fires to the flats where they started for four decades. The rainscreen cladding panels and architectural crown feature fixed to it in 2015 added both fuel and a conduit for fire to race vertically and horizontally over the facades.
In Piper Alpha's conversion to pipe gas as well as oil in 1980, the principle that hazardous processes -- such as gas compression -- should be located as far away as possible from the control room and crew accommodation was ignored.
The risk this created was heightened by the failure to replace the fire walls between the modules with blast walls necessary to withstand explosions. That was a crucial oversight because not only did the fire walls fail to damp the blast, they blew apart like shrapnel, their shards rupturing oil and gas pipes, further fuelling the blaze.
As built, both structures would have curbed the loss of life in a catastrophe; as modified, they maximised it.
Both tragedies offer multiple lessons in fire safety and the changes that Piper Alpha prompted in regulation and management of high-hazard installations have prevented a re-occurrence so far in the UK's offshore facilities. But the point about risk assessing tweaks to a process or structure as rigorously as the initial design applies almost universally.
There is a reason the Management of Health and Safety at Work Regulations demand a review of any risk assessment when there is a "significant change in the matters to which it relates". But these reviews are often overlooked.
Modifications should trigger a re-examination of the parts and the whole, checking that old safeguards aren't compromised and whether new ones are needed.
Alterations to the hazard profile or controls must be recorded and broadcast to everyone who needs to know. You can't rely on individuals to carry the knowledge. Individuals move employers or retire. One generation forgets; a second never knows, said the critic Jonathan Meades.
Reliable transfer of information about systems and controls, as built and as altered, is what Dame Judith Hackitt's review of building regulations and fire safety triggered by the Grenfell disaster (p 9), calls a "golden thread" tying together all the dutyholders responsible for a building in construction or use.
That thread should be woven through all our processes as they are tailored to meet changing demands. Otherwise, we will be condemned to repeat others' mistakes, occasionally on a horrific scale.
As Hackitt said to a gathering of oil and gas executives on the 25th anniversary of Piper Alpha: "While the precise circumstances and contexts of major incidents differ in some respects, at heart I am left with the feeling that there are no new accidents. Rather there are old accidents repeated by new people."