“Please remember, we have left nothing to chance,” said Hans Gruber (Alan Rickman), lead antagonist in the festive movie classic, Die Hard. Stern words issued to the group he has taken hostage during the Nakatomi Corporation’s Christmas party.
In fact, when you think about it, the whole movie plays out as something of a metaphor for process safety: Gruber (“the chain of events leading to an incident”), and his bid to steal US$640m in negotiable bearer bonds from Nakatomi’s almost impenetrable vault (“the plant”), thwarted by off-duty cop John McClane (“process safety”) who, by a stroke of blind luck, was in the Nakatomi building and on hand to save the day.
In much the same way, it is sometimes the result of blind luck that a major accident or incident is prevented from occurring.
To ensure the success of their mission, Gruber and his goons had devised a way to defeat every potential barrier to access the vault; from cutting the phone lines to convincing the emergency services to ignore a fire alarm – triggered by McClane on the 32nd floor – and abort a rescue effort.
Gruber had also ascertained that the main service doors to the office building would likely not be locked, enabling their entry, and that the security guards on duty that evening were unlikely paying as much attention as they needed to be. Human factors anyone?
Meanwhile, for reasons that only the scriptwriters are aware, the final vault security measure would be disabled if the local power grid was shut down. Gruber knew that, by having his gang pose as terrorists and not thieves, the FBI would kill the power to the building, thus eliminating this final barrier to opening the safe.
And finally, to emergency response, with the Nakatomi Plaza cordoned off and surrounded by police, by detonating an explosion on the roof and making it appear as if they had perished, Gruber’s remaining assailants planned to escape in an ambulance, driving past the police cordons, to enjoy their new lives “on the beach earning 20%”.
Barriers can and – as history has shown us – do fail. In fact, many process safety incidents are the result of multiple barrier failures.
HAZOP is a key part of effective process safety management and helps us to understand what could cause an incident, how it could be prevented and if we have appropriate barriers in place. When done correctly, HAZOP attendees actively look for sources of harm and the different ways in which barriers might fail.
Gruber very much had this mindset; that the barriers put in place by Nakatomi Corporation could be overcome. When facilitating HAZOPs, I always encourage the team to adopt a similar attitude, asking themselves: “what more could we do?” or “how could that barrier be overcome?”. That’s because the never-going-to-happen chain of events may be more likely than you think.
Of course, as effective as they are, HAZOPs can also be incredibly time consuming and costly. That’s why the following considerations are key in preparing for, and conducting, a successful HAZOP:
- Fail to prepare, prepare to fail. Gruber had more than done his homework. He had familiarised himself with the FBI’s terrorist playbook, knowledge he went on to use to his advantage. The same should be said for a successful HAZOP. The team should be provided with the correct drawings and documents, the nodes agreed beforehand, and the plant operating conditions understood.
- A HAZOP is crucial in teasing out major hazards and ensuring the appropriate barriers are in place. Re-HAZOPs, meanwhile, present a golden opportunity to make sure the barriers that were identified previously remain in situ, are still effective and will be available when needed.
- Having the right team is imperative. This was exemplified by computing expert, Theo, Gruber’s sole hacker who said: “You didn’t bring me along for my charming personality.” McClane had his own support network too – in the form of limo driver Argyl and Sergeant Powell, a source of moral support throughout, as McClane attempted to obstruct Gruber’s plans while evading capture and almost-certain death. During a HAZOP, the team should consist of experienced individuals who understand the design parameters of the equipment under scrutiny, or who have a thorough awareness of how the plant or facility in question is operated. They should be unafraid to challenge the status quo, always asking “what more can we do to prevent that?” and “how else could this go wrong?”
- Ensuring our barriers are independent is also critical. As Die Hard proves, despite multiple engineered barriers, almost all of them were easily breached under the right circumstances. It was only the result of a last-minute human intervention that ultimately meant Gruber failed to succeed.
- Barriers should continually be reviewed to ensure that they remain fit for purpose. Process safety and HAZOP is not an exercise in simply “jockeying papers across a desk”. Developed in the 1960s, it remains the first choice for identifying hazards in a process.
- Understand that human behaviour can influence barrier failure. The right competencies in the right place, at the right time, are vital. After all, nobody wants to be the out-of-his-depth Deputy Chief Robinson when Powell derisively asks if he wants a breath mint before meeting the FBI; a clear indication of the police officer’s lack of confidence in his colleague’s competence.
In short, a full understanding of the barriers to a potential incident and what could cause them to fail is an essential part of effective process safety; something everyone, at all levels of an organisation, can play their part in. Why does this matter? Well, as Gruber says to his hostages, the decisions we make could mean the difference between “walking out or being carried out”. And everyone should expect to go home safely at the end of their working day.
This article was originally published in the Chemical Engineer https://www.thechemicalengineer.com/features/the-greatest-teacher-accidents-are