ExxonMobil Fine Exposes The High Cost Of Delayed Process Safety Action

On August 26, the UK Health and Safety Executive (HSE) announced it was fining ExxonMobil £267,000 for hazardous releases at its Mossmoran facility in Fife. The prosecution followed five releases of highly flammable dimethyl sulphide and ethane from corroded pipework between February 2018 and September 2019. Organizations with similar risks should take this as a stark reminder that identifying equipment degradation is not enough, and operators must act before a warning becomes an incident.

The investigation revealed a repeated failure to respond decisively when action could have mitigated the incident. A pinhole leak releasing dimethyl sulphide was detected in February 2018, yet repairs took around four months while the site continued to operate. Later that year, an employee discovered an ethane leak by chance. Caused by corrosion beneath the cladding, it persisted for about six weeks and released an estimated 82 tonnes of hydrocarbons into the atmosphere.

Subsequent X-ray inspections found sections of pipework below the minimum safe thickness. HSE inspector Lindsey Stein said only “good fortune” had prevented a catastrophic event and called the site’s systems for detecting and preventing corrosion “woefully inadequate”. In an environment handling petrochemicals, weaknesses of this kind can rapidly escalate into fire, explosion or toxic release.

The central issue for ExxonMobil is not simply that physical barriers degraded, but that the organization failed to convert warning signs into timely action. Effective process safety management (PSM) depends on a clear view of barrier health across equipment, systems and procedures. Modern PSM platforms can bring together corrosion readings, inspection schedules, leak detection data and outstanding actions, then flag deviations and escalate unresolved risks before containment fails.

Management of Change (MoC) provides another critical line of defence. Evidence of corrosion should be treated as a material change in asset condition, triggering a structured impact assessment, named ownership and formal approval for any decision to continue operating. This creates an auditable route from detection to resolution and makes it harder for known risks to remain unaddressed without adequate control.

PSM tools can help to mitigate risk exposure

Technology providers are increasingly supporting this approach. Suppliers assessed in the Verdantix Green Quadrant: Process Safety Management Software (2026) – including Prometheus Group, Sphera and Wolters Kluwer Enablon – offer bowtie visualizations that show how risk exposure changes as barriers weaken or recover. Used well, these tools give operational teams and senior leaders a shared, current view of where intervention is required.

ExxonMobil’s Mossmorran incident shows that process safety failures rarely begin with a single dramatic event. They develop when degradation is visible but tolerated, actions remain unresolved and accountability is unclear. Software cannot replace sound engineering judgement or a strong safety culture, but it can make weak barriers harder to overlook and corrective action easier to govern. Explore our research on barrier risk management and related process safety processes on the Verdantix research portal.