Accidents
See some examples of major accidents illustrating the importance of adequate maintenance.
Accident in DUBLIN PORT
On an early autumn evening in 2007, in Dublin port, an accident happened which affected families, workers and businesses in three European Union member states.
As the stern line on a ship about to leave Dublin port was being let out, it snapped and whipped across the deck, hitting the ship’s second officer. Both his legs were broken. He was taken to hospital where one leg was amputated but he died six days later. An official enquiry into the cause of the accident found that the accident had a number of causes, including failure to maintain the stern line. Analysis of the mooring line after the accident showed that it had deteriorated, largely due to exposure to ultraviolet (UV) radiation from sunlight. Inspection procedures onboard were informal and no records were kept. The maintenance failure cost the second officer his life.
The lesson to be drawn from the Dublin accident which applies to all types of vessels is that mooring lines have to be regularly inspected and replaced as necessary. Their condition inevitably deteriorates because they are constantly exposed to every kind of weather from frost to intense sunlight.
In all workplaces employers should ensure that ropes, winches, chains and all types of lifting equipment are checked regularly and are properly maintained and, if they are worn or defective they are replaced.
EXPLOSION AT THE FLIXBOROUGH CHEMICAL PLANT
Thirty years on, debate still rages over the cause of the explosion at the Flixborough chemical plant in the English midlands. One factor, however, became clear during the official investigation into the incident: there were failures in maintenance procedures.
More than 30 years after the explosion at the Flixborough chemical plant in England, debate about what caused it continues. However, one thing is certain from the official report - there were concerns about poor maintenance procedures.
When a large quantity of cyclohexane escaped after a bypass system in a reactor ruptured, it formed a flammable mixture in the air, found a source of ignition and exploded. Twenty-eight workers were killed and 36 more injured. Fire took hold and there was extensive damage to property.
An official enquiry found that plant modification occurred without a full assessment of the potential consequences. Only limited calculations were undertaken on the integrity of the bypass line and no pressure testing had been carried out on pipework which had been installed three months earlier when part of the plant was being modified. This was a contributory cause of the accident.
Good industry practice requires that process and plant modifications should not be carried out without having undertaken a safety, engineering and technical review. A risk assessment should identify what hazards have been created by the change that may affect plant or personnel safety, and what action can be implemented to reduce or eliminate risks.
FIRE AT HAMLET CHICKEN PROCESSING PLANT
The owner of a chicken processing factory in the US state of North Carolina was jailed for 20 years following a fire in which 25 people were killed and 54 injured. All had found themselves trapped behind locked fire doors when the fire began.
An improvised repair was the root cause of what has been described as the second worst industrial accident in the history of the United States of America. In the fire that swept through the Chicken Processing Plant in Hamlet, North Carolina, on September 3, 1991, 25 workers were killed and 54 injured, all of them trapped behind locked fire doors.
After a maintenance worker discovered a leak on a hydraulic line driving a conveyor belt, the line was switched off and the leaking section was replaced by a factory-prepared line. This line was shortened because it was too long and posed a tripping hazard, and a new connector was installed. Shortly after the line was brought back into use, it separated at the connection point. It is thought that the pressurised hydraulic fluid atomised and exploded when it was exposed to heat from the processing plant fryers.
The owner was given a 20-year jail sentence and the business declared itself bankrupt. The official inquiry recommended that high-pressure maintenance and repair work should only be carried out by personnel trained by suppliers of the equipment.
Employers have to ensure appropriate training and competence of the workers carrying out the maintenance activities. Workers mustn’t go beyond their level of competence (i.e. beyond their training and experience). Employers have to ensure that there are procedures to follow by workers when confronted with a situation beyond their competence.
EXPLOSION AND FIRE AT THE PHILLIPS COMPANY HOUSTON CHEMICAL COMPLEX
Shortly after 1pm on October 23, 1989, a massive explosion demolished the Phillips 66 Company polyethylene plant at Pasadena, Texas, killing 23 people and injuring 314.
In October 1989, 23 people died and 314 were injured in an explosion at the Phillips 66 Company chemical plant in Pasadena, Texas.
The economic loss totalled $1.4bn. The primary cause of the explosion and fire was the release of flammable gases. The official enquiry into the accident found that Phillips’ own corporate safety procedures and industry standard practice required back up protection in the form of a double valve or blind flange during maintenance work on pipes. However, at local plant level the company had a special procedure which did not incorporate the required backup. The Phillips Company was charged by the OSHA with failing to inform and train maintenance employees how to work safely with hazardous chemicals. The company agreed to pay a fine of $4m.
The lessons learnt from the accident are that safe systems of work for maintenance operations have to be in place and they have to be followed. Employers also have to ensure that maintenance workers are informed about risks and trained to work safely with hazardous chemicals.
PIPER ALPHA DISASTER
Two decades after an explosion and fire ripped through the Piper Alpha oil production platform in the North Sea off the coast of Scotland, killing 167 of its 226 crew members, the horror of the disaster remains fresh in the mind
The horror of the Piper Alpha disaster, in which 167 workers died on a North Sea oil platform off the coast of Scotland, is still fresh in the memory more than 20 years after the terrible events of June 1988.
On the day the disaster occurred, the day shift maintenance crew was working on the the condensate pumps which compressed gas. One of the pumps was removed for routine maintenance and the condensate pipe was temporarily sealed with a flat metal disk. Because the work could not be completed before the next shift change-over, the metal disc was left in place as the day shift went off duty. The shift coming on duty was unaware of this. Later in the evening, when the other condensate pump stopped working, the pump under maintenance was started up. A permit-to-work document was found for it, but not one which stated that the pump must not be started. The pump failed and gas leaked out at high pressure and then ignited.
The lessons to be learned from the Piper Alpha tragedy are that the quality of safety management is critical and permit-to-work system has to be followed to ensure effective communication between all parties affected by any maintenance procedure. The plant for maintenance where work is being done has to be properly isolated and there is a need for safety training for workers and managers.
SULPHUR DICHLORIDE LEAK - CATENOY
On Wednesday morning, on April 26, 2006, the sulphur dichloride plant at Catenoy, in Oise, France was working normally. By lunchtime the plant had been evacuated and three employees were in hospital recovering from burns.
In the early morning a sulphur dichloride plant at Catenoy, in Oise, France was working normally. By lunchtime the plant had been evacuated and three employees were in hospital being treated for burns. During the morning excessive pressure had been detected in a boiler and the installation switched automatically to standby.
A sensor was found to be faulty and while it was being replaced the maintenance technician removed the entire assembly because it was impossible to remove only the sensor. While this was being done, a release of hydrogen was observed. Just after midday the alarm sounded and the decision was taken to evacuate the plant. Three workers were hospitalized for burns and irritations and production was disrupted for 18 days at a cost of €270,000.
The key lesson to be learned is that all maintenance operations, whether routine, unusual or exceptional, must be subject to complete prior risk assessment in order to avoid creating conditions which could lead to an accident or aggravate the initial consequences of an incident.
STOCKLINE Plastics factory explosion
On May 11, 2004, the peace of the Woodside district of Glasgow was shattered by an explosion which razed a factory to the ground. Workers from nearby shops, offices and factories rushed to rescue those who were trapped in the rubble and within minutes of the blast firefighters, ambulance staff and police were on the scene.
A gas explosion at the Stockline Plastics factory in Glasgow razed the building to the ground killing nine workers and injuring 40 people, one of whom was a passer-by.
An official investigation into the accident concluded that an ageing underground LPG pipe was inadequately protected when buried, it was subject to corrosion and ultimately it failed, leaking gas into the factory basement.
The UK Health & Safety Executive prosecuted the owners and operators of the plastics factory. Serious weaknesses were found in the health and safety procedures at the factory. During the trial the court heard that if the companies operating the factory had dug up, inspected and replaced the corroded, leaking LPG pipe, the explosion could have been prevented.
The lessons to be learned are that lack of inspection and maintenance can have catastrophic consequences. Safety and health management including suitable and sufficient risk assessments is crucial. Pipes carrying hazardous gas have to be regularly inspected and properly maintained.
GAS OVEN EXPLOSION - GELEEN
The DSM chemical plant at Geleen, in the province of Limburg in the Netherlands, produces melamine. On the morning of April 1st 2003, as a maintenance crew was restarting a gas oven, an explosion caused the top cover of the oven to collapse and topple over. Three workers, not involved in the maintenance of the oven, who were standing on the cover fell into the oven and were killed.
In April 2003, three maintenance workers were killed when a gas oven in a melamine plant exploded and the three workers who were standing on the cover of the oven fell into it. The accident occurred in the DSM plant at Geleen, in Limburg in the Netherlands.
The gas oven was fuelled by natural gas and residual gasses from neighbouring plants. The residual gases were contaminated and had to be filtered before use. The filters had to be cleaned regularly, which meant shutting down the plant.
Restarting it could be a time consuming process and so the workers, who were experienced and responsible, devised a fast-track procedure. This created a combustible mixture of gas and air in the oven which was ignited by a stray spark. Although this was the immediate cause of the explosion, investigations concluded that the underlying cause was a company culture which had allowed the untested fast-track procedure to be used.
The lesson is to follow safe procedures and not to take short cuts even under time pressure. The accident also highlights the importance of the safety culture.