Tetra Technologies UK Limited has been fined £350,000 following the catastrophic collapse of a 700-tonne chemical storage tank at its Peterhead premises on 21 June 2023. The incident left a 62-year-old self-employed worker with multiple life-changing injuries, including spinal fractures and severe chemical burns. The Health and Safety Executive (HSE) investigation found the failure was entirely foreseeable and preventable due to long-standing corrosion and a lack of adequate maintenance.
Corroded 700-tonne chemical tank ruptured, causing extensive, life-changing injuries
The incident occurred at Tetra Technologies UK Limited’s offshore supply base in Peterhead, a facility crucial for supplying North Sea oil and gas installations and handling thousands of ship movements annually. Philip Moir, a 62-year-old self-employed rope access technician, was on site conducting routine surveys of storage tanks when Tank 7, a bolted steel tank containing approximately 480,776 litres of calcium chloride solution, ruptured without warning. Mr Moir was almost immediately immersed to chest height in the escaping fluid, a dense solution weighing around 700 tonnes. He was subsequently discovered slumped over the wheel of a nearby cherry picker, which, along with a Ford Transit pickup and a small skip, had been displaced by the sheer force of the released chemicals.
Mr Moir sustained a horrific array of injuries, including a double fracture of his spine and pelvis, a lacerated liver, a punctured lung, multiple rib fractures, a fractured sternum, and a fractured wrist. He also suffered extensive chemical burns requiring multiple skin grafts. The severity of these injuries has prevented him from working since the incident, rendering him unable to climb ladders or perform tasks at height, fundamentally altering his professional and personal life.
The HSE’s comprehensive investigation, conducted by both regulatory and specialist inspectors, meticulously uncovered the root causes of the structural failure. It was determined that the rupture occurred around halfway up the tank shell, where the third row of plates split vertically along a bolted seam. Crucially, investigators found that approximately 4.5mm of the original 5.5mm steel plate had been lost through corrosion over time, leaving a dangerously thin 1mm of steel unable to withstand the immense outward forces exerted by the fluid within. The loss of any protective coating had left the steel surfaces exposed to aggressive coastal air, significantly accelerating external degradation. The inherent density of calcium chloride, which is more than one-third denser than water, further exacerbated the forces applied to the already compromised structure.
Evidence gathered by the HSE revealed a severe lapse in maintenance and inspection protocols. Tank 7 was over 30 years old, and its manufacturer’s maintenance manual explicitly required six-monthly checks of seams and bolts, alongside annual external inspections for corrosion. Disturbingly, an inspection conducted as far back as 2013 had already identified extensive outer surface corrosion over the lower section of the tank and corrosion at bolted connections. Despite these clear warnings, no remedial work was carried out on Tank 7. Furthermore, the company was unable to provide any evidence of a regular inspection regime being followed in the years leading up to the catastrophic failure. On the morning of the incident, Tank 7 had been filled to capacity – a decision made to create space at the company’s Aberdeen premises – and failed less than thirty minutes after the final load was pumped in.
The HSE concluded that the failure of the tank was not only foreseeable but entirely preventable, stemming from a systemic failure to manage the risks associated with ageing infrastructure and hazardous substances. Following the incident, Tetra Technologies UK Limited took steps to remove all similar bolted tanks from its sites and closed its Peterhead operation, relocating its activities to its Aberdeen premises.
Tetra Technologies UK Limited, with its registered address at One Fleet Place, London, pleaded guilty to breaches under sections 3(1) and 33(1)(a) of the Health and Safety at Work Act etc. 1974. The company was fined £350,000 at Peterhead Sheriff Court. This prosecution underscores the critical importance of diligent maintenance, thorough inspections, and robust risk management to prevent serious injuries in industrial settings.
Originally published by the Health and Safety Executive.
