ExxonMobil Chemical Limited has been fined £267,000 after health and safety inspectors uncovered five separate leaks of extremely flammable hydrocarbons at its Fife Ethylene Plant. The serious incidents, which occurred between February 2018 and September 2019, were attributed to the company’s inadequate arrangements for inspecting insulated pipework. The fine underscores the critical importance of robust safety protocols, particularly at sites handling hazardous substances.
Inadequate pipe inspection arrangements led to five hydrocarbon releases
The Fife Ethylene Plant, located at Mossmorran near Kirkcaldy, operates as an Upper Tier COMAH (Control of Major Accident Hazards) establishment. This designation signifies that the plant manages substantial volumes of hazardous substances, necessitating the strictest controls due to the potential for catastrophic consequences should health and safety failings occur. The leaks, caused by Corrosion Under Insulation (CUI), presented a significant risk to both personnel and the environment.
The issues at the plant first came to light during a routine inspection by Health and Safety Executive (HSE) inspectors on 21 May 2019. During their visit, inspectors detected a strong smell of Dimethyl Sulphide (DMS), a highly flammable liquid. An operator confirmed that DMS and ethane were actively leaking from an overhead pipe, a problem the company had been aware of for approximately four months without implementing additional safety precautions or ceasing operations in the affected area.
This discovery prompted a investigation by the HSE, which quickly revealed that the May 2019 incident was not isolated. The investigation uncovered an earlier leak on the same pipe in February 2018, and another on a different pipe elsewhere on the site in December 2018. Both of these previous incidents were also caused by CUI. As the inquiry progressed, two further leaks were identified, bringing the total to five, all stemming from the same underlying issue of corroded pipework concealed by insulation.
The first recorded leak occurred on 23 February 2018, involving a pinhole leak of DMS and ethane from a high-pressure steel pipe operating at 115 degrees Celsius. This leak persisted for around four months before being rectified. A subsequent leak on 15 December 2018, involving ethane gas, was only spotted by chance when a worker noticed a haze through the insulation during unrelated duties. This particular leak lasted approximately six weeks, resulting in an estimated 82 tonnes of hydrocarbons escaping into the atmosphere.
The leak discovered by HSE inspectors on 21 May 2019, on the same DMS line but at a different point, had been active since 29 January 2019, leaking a mixture of 20% DMS and 80% ethane for about four and a half months. In response, the HSE issued a Prohibition Notice on 24 May 2019, banning access to the hazardous area, followed by an Improvement Notice on 28 May 2019, mandating repairs. The company eventually addressed this specific problem on 13 June 2019 by installing a bypass.
Even as the HSE’s investigation continued, another pinhole leak was found on 26 June 2019, this time on the inlet line to the acetylene converter. This further discovery underscored the pervasive nature of the CUI problem across the plant’s infrastructure. The investigation concluded that ExxonMobil Chemical Limited had failed to implement adequate systems for the inspection and maintenance of its insulated pipework, directly leading to these preventable releases of highly flammable substances.
The prosecution and subsequent fine serve as a stark reminder to all industrial operators, especially those managing COMAH sites, of their fundamental duty to ensure the integrity of their plant and equipment. Proactive inspection and maintenance programmes are crucial for preventing CUI and other forms of degradation that can lead to hazardous leaks, protecting both workers and the wider community from major accident risks.
This story was originally published by HSE Media Centre.
