A Health and Safety Executive (HSE) investigation revealed that the two men – one aged just 17 and both untrained – were told to carry out work that could have led to an explosion and put them at risk of being overcome by fumes.
The two men were so worried they stopped work and sought advice from the harbour master. This resulted in the HSE launching an investigation and ordering their employer – C&L Marine of Plymouth – to halt repairs to the tank.
Plymouth Magistrates Court was told that the repair business had been commissioned to clean and repair a fuel leak in a tank on the fishing boat Margaret of Ladram in Sutton Harbour, Plymouth, in May 2011.
The fuel tank was accessed from a manhole below the vessel’s net store. The workers were required to use buckets to empty the tank of about 600 litres of residual seawater and diesel and use rags to clean the inside before welding.
The court heard the two men wore normal work overalls and had no face masks on the first day of work. They swapped roles regularly to provide a respite from fumes and the cramped working space in the tank – which was 4.5m long and 2.25m deep and curved in line with the vessel’s hull. One worker later recalled breathing difficulties when he was in the tank and complained of feeling dizzy and faint.
On the second day at work they sought advice after one man used a grinder, causing sparks to fall on his workmate who was holding a lamp to illuminate the work.
The harbour master ordered the men to stop work after the company failed to provide documentation and permits to show it was safe to work in the tank.
A HSE investigation found that there was no gas monitor to measure available oxygen in the tank and no gas-free certificate was obtained before beginning work.
An electric fan had been used to blow fumes out of the tank on the second day with another fan used in the net store. Neither proved effective because they were not fitted with an extraction hose.
The repair firm failed to conduct the gas monitoring needed to measure the available oxygen or for the presence of explosive gases in the tank. Also no gas-free or safe entry certificates were in place before beginning work.
“Both men were unsupervised, largely untrained and unfamiliar with the tank work they were undertaking,” according to the HSE.
C&L Marine had not provided rescue equipment, such as harnesses, lifelines or lifting equipment, or other appropriate emergency arrangements.
Speaking after the hearing, HSE inspector David Cory said: “C&L Marine’s lack of preparation for this work showed very significant failings which could have led to tragedy. It should have been well aware of the risks cleaning and then welding in the diesel fuel tank would have posed.
"The tank should have been thoroughly steam cleaned or jet-washed instead of being bucketed out and mopped with rags. There was no test for the presence of noxious or flammable gases or whether there was sufficient oxygen in the tank before the men began work.
"If the diesel fuel residues had been sufficiently heated, they would have created fumes which could have led to an explosion or fire. Ventilation was either absent or woefully inadequate.”
All employers whose staff work in a confined space must consider their activities properly, train and equip staff sufficiently, and reduce and control risks as much as possible, he added.
C&L Marine, of the Fish Quay, Sutton Harbour, Plymouth, pleaded guilty to breaching Regulation 3(1) of the Management of Health and Safety at Work Regulations 1999 and three breaches of the Confined Spaces Regulations 1997.
The company was fined a total of £20,000 and ordered to pay £23,000 in costs.