Every Layer of Protection Analysis (LOPA) and Hazard and Operability Study (HAZOP) in your document management system shares the same quiet flaw: It’s a set of assumptions frozen in time.
When the team originally sat down to review the plant and credited that relief valve as an independent protection layer, they assumed it was properly sourced, correctly sized, correctly installed and would lift at its set point. When they credited an operator’s response to an alarm, they assumed the alarm was audible everywhere it needed to be. They assumed procedures were current, operators were trained and maintenance personnel followed established practices. When they assigned a probability of failure, they assumed the maintenance program supporting that safeguard would still exist 10 years later, unaffected by staffing shortages, shifting capital priorities or operating expense reductions.
None of these are facts. They are assumptions. More importantly, they are assumptions about barrier conditions that may have been reasonable on the day of the assessment but begin degrading the moment the study is complete.
Here’s the problem: The study doesn’t age, but the plant does.
Over time, a facility develops an entirely different personality. It’s almost like a parent writing a story about their child’s future without knowing how the next decade will shape who they become. The story of how a plant is supposed to be protected slowly changes with time and circumstance. An experienced operator retires. An alarm setpoint is adjusted to eliminate nuisance trips. Maintenance backlogs continue to grow. Each change seems small and locally rational, but together they quietly turn green lines into red ones in a study sitting untouched in a folder.
To be fair, the industry recognizes this challenge. Revalidation programs exist for exactly this reason, and the risk teams responsible for them are among the busiest people in any facility. They’re constantly cycling through units, reviewing Management of Change (MOC) requests between studies and trying to keep up with plant changes using headcounts that haven’t grown alongside demand.
We’ve built a process where keeping risk assessments current depends on a small team chasing a plant that’s changing faster than it can be evaluated. At the same time, countless small changes made by operators and maintenance personnel slowly remove or weaken critical safeguards.
This exposure is especially evident in what I’d call Process Safety Management (PSM)-adjacent operations. These are facilities that fall below threshold quantities or outside covered processes but still manage real hazards. Because regulations don’t require formal revalidation, those activities often compete for limited resources or don’t happen at all. That’s how a five-year-old LOPA quietly becomes a 15-year-old one.
But don’t mistake this as only a non-PSM problem.
PSM-covered facilities complete revalidations on schedule and still lose barriers between review cycles. Incident investigations repeatedly identify safeguards that were credited in a current, compliant risk study but were degraded, bypassed or unavailable when they were actually needed.
Normal operations can continue without anyone realizing a protection layer has weakened. It’s only when something goes wrong that you discover whether a safeguard still performs as intended or whether it was unknowingly compromised by what seemed like a perfectly reasonable change weeks earlier.
So where do you start? Start by accepting what isn’t realistic.
No facility is going to monitor every credited safeguard every day. There are simply too many. Risk teams are already stretched thin, and operators already have more responsibilities than time allows. Any solution that begins with "monitor everything" ignores how industrial facilities actually operate.
Sort safeguards by the consequences of failure, and you’ll likely find that a relatively small number accounts for most of your facility’s risk reduction. Those are the safeguards that deserve the greatest attention.
For more information, email Justin Abshire at justin@novapathrisk.com.
