On the morning of the 25th of September 2019, a heat exchanger on the Esso Longford Gas Plant near Melbourne in Australia, experienced brittle fracture and discharged around 10 tonnes of flammable hydrocarbon vapour to the environment. When the resulting cloud reached a nearby heat source, it ignited, burned back to the exchanger causing a jet fire which lasted 2 days.

2 workers – Peter Wilson and John Lowery – were killed (8 others injured) and Melbourne was deprived of its gas supply for 2 weeks in early spring.

The subsequent investigation by the Australian Royal Commission determined that a periodic HAZOP study would likely have identified the cause of the accident as credible (operator error during start up, leading to low temperature brittle fracture and loss of containment). It also uncovered that Esso had planned and budgeted for a HAZOP for 1995 but failed to carry it out.

There is an economic tenet - negative externality – for an activity that imposes a negative effect on an unrelated third party. An example would be pollution. Party A builds a factory to make a product, which is subsequently bought by party B. As they agree on the price of the exchange, they are both deemed to have benefited. However, one by-product (externality) of this exchange is pollution from the factory, which impacts party C living nearby, for whom the externality becomes negative.

Taking the analogy further, past and present carbon emissions are a negative externality for future generations.

In the same way, Esso’s decision not to instigate a periodic HAZOP on their Longford facility in the late 90s became a negative externality for the killed / injured workers and, to a lesser extent, the public in Melbourne who were deprived of hot water for several weeks. Interestingly, it seems that the latter (less negative but many more people) was the key driver for the Royal Commission, which ultimately imposed fines totalling A$2m on Esso in 2001.

In my time as a HAZOP chair, I haven’t been aware of a negative externality as egregious as Longford. However, I have occasionally been subject to pressure to extend the working day to protect an optimistic schedule, to which I have succumbed. However, when this happened again recently, I refused. I explained that HAZOP is an intense and rigorous exercise. Accordingly, continuing to work beyond sensible norms (max 6 hours plus breaks), significantly increases the risk of overlooking key hazards and their potential to lead to operator fatalities in subsequent decades.

Parties A and B here are the HAZOP chair and the client. Party C is the future operator.

If you want your HAZOP to save future lives, stand firm.

Saving Future Lives