ExxonMobil fined £267k over five 'extremely flammable' gas leaks - including one lasting four months
The leaks at Fife Ethylene Plant were discovered between February 2018 and September 2019, and included one which lasted four months.
ExxonMobil been hit with a fine of over £267,000 for health a safety breaches after five leaks of extremely flammable hydrocarbons were uncovered during a routine inspection of it’s plant in Fife.
The Health and Safety Executive (HSE) said arrangements in place to detect and prevent corrosion were “woefully inadequate” and warned the consequences “could have been far more serious.”
The leaks at Fife Ethylene Plant - which closed in January 2026 after 40 years - were discovered between February 2018 and September 2019, and included one which lasted four months.
They were discovered after HSE inspectors detected strong smell of flammable gas on a routine inspection, and all five were were attributed to Corrosion Under Insulation (CUI).
The subsequent investigation launched by the executive concluded that the company did not have adequate arrangements for the inspection of insulated pipework.
The company pleaded guilty to breaching the Provision and Use of Work Equipment Regulations 1998, and the Health and Safety at Work etc Act 1974 and was handed the six-figure fine at Kirkcaldy Sheriff Court on Wednesday.
It said afterwards that “no workers, contractors or members of the public were put at risk, and the court held that no hazard was created and no actual harm was caused.”
Lindsey Stein, HSE inspectors, said: “At a site run by one of the biggest energy companies in the world, subject to the strictest controls, and processing high volumes of hazardous material, what our inspectors found beggars belief.
“The failure of ExxonMobil to properly inspect insulated pipework led to five separate leaks of highly flammable hydrocarbons, and while none of these leaks resulted in a catastrophic event, this was down to good fortune rather than good management. The arrangements in place to detect and prevent corrosion were woefully inadequate, and the consequences could have been far more serious.”
The inspector added: “Systematic risk management isn't just best practice, it's a legal duty, precisely because these are high-hazard operations where the margin for error is minimal. In its simplest terms, process safety is about keeping hazardous substances where they belong: inside the pipes, not in the atmosphere.
“Once we stepped in, the operator was able to identify and fix problems quickly and effectively. That tells you everything you need to know: the measures needed to prevent these leaks were reasonably practicable all along, and they should have been in place long before HSE was forced to intervene."
Inspectors’ initial investigations in 2019 was sparked after they noticed a strong smell of Dimethyl Sulphide (DMS), a highly flammable liquid that irritates eyes and skin and is harmful if . They discovered it was not a one-off.
An operator confirmed that DMS and ethane were leaking from an overhead pipe, and that the company had known about it for around four months but had kept operating without taking extra precautions.
HSE found there had been an earlier leak on the same pipe in February 2018, and another on a different pipe elsewhere on site in December 2018, both caused by CUI). Two further leaks were discovered, and the investigation was broadened to examine how the company managed the risk across the site.
The HSE said every leak released highly flammable hydrocarbons into the atmosphere, and, in all but one case, this happened while the plant was operating normally, with staff and contractors working on site.
Pipes on sites like this are often insulated to stop them freezing. Corrosion Under Insulation happens when water gets in under that insulation and corrodes the pipe underneath. Left unchecked, it weakens the pipes until they fail and leak. The industry accepts that CUI can't be prevented entirely where insulation is needed, but it must be properly monitored and managed.
HSE's investigation found the company's inspection system was not fit for purpose. Inspectors carried out visual "scoping" checks on each pipe, and the results were fed into a computer tool alongside data on the pipe and its operating conditions. This produced a risk score.
In said its visual inspections were “often inadequate” with overhead pipes were typically checked from ground level, sometimes several metres away, with limited visibility. Insulation was not always removed to allow a proper look underneath.
An ExxonMobil Chemical Limited spokesperson said: “We have accepted responsibility and resolved a matter relating to historical corrosion under insulation (CUI) issues at Fife Ethylene Plant between 2018 and 2019. No workers, contractors or members of the public were put at risk, and the court held that no hazard was created and no actual harm was caused.”
“We co-operated fully with the HSE throughout its investigation, including complying with all notices served, and commissioned an independent assessment. We accept full responsibility for the failures identified and have since made significant changes to how we inspect and manage corrosion risk across our operations.
“At the time of the incidents the Fife Ethylene Plant (FEP) organisation was moving to a revised and improved inspection methodology and this was successfully implemented together with a special program to address legacy challenges.”
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