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History is the best lesson in safety

“They adopted a superficial attitude to the assessment of risk of major hazard…The safety policies and procedures were in place: the practice was deficient.”

The 30th anniversary of the Piper Alpha explosion has just past, serving as a good reminder to us all about the importance of safety in our line of work. The devastating explosion occurred on the North Sea oil rig on July 6, 1988, killing 167 people. Thirty bodies were never recovered.

Piper Alpha Explosion



The disaster began with a routine maintenance procedure. A backup propane condensate pump in the processing area was due for a routine pressure safety valve inspection. The valve was removed and blind flanges were installed, but the flanges leaked when the system was at full pressure.

As a standard rule, maintenance work in operations areas such as these are controlled, first by a work order specifying the equipment to be worked on, and then by the nature of the work to be done (in this case a specific repair on a specific valve). The work order must be authorized by a designated supervisor before any maintenance work can start.

Control of the actual equipment is then typically monitored by a permit system. A safe work permit is created by operating personnel and signed by a designated person, certifying that the equipment has been made safe for maintenance (e.g. by closing necessary valves, de-pressuring the equipment to be worked on, and removing any hazardous material, etc.). Maintenance personnel will sign, accepting the equipment. At the end of the job the process is reversed, with the equipment being formally transferred back from maintenance to operations personnel.

In the Piper Alpha case, the valve was removed during the day shift by maintenance personnel who expected to have it repaired and available for service by the end of the shift. Because the workers could not get all the equipment they needed by 6 PM, they asked for (and received) permission to leave the rest of the work until the next day. In the handover to the new shift, this information was somehow not properly communicated to the incoming shift. The confusion was possibly the result of a large number of other jobs also in progress at the time.

Later in the evening during the next work shift, the primary condensate pump failed. The people in the control room who were in charge of operating the platform decided to start the backup pump, not knowing that it was under maintenance.

Gas products escaped from the blind flanges (where the pressure safety valve was located) with such force that survivors described it as sounding like the scream of a banshee. The leak was picked up by gas detection equipment and an alarm sounded showing a gas leak. But just a few moments later, the leak ignited and exploded.

Rigs such as this are protected by deluge systems that spray large quantities of sea water over everything in case of a fire or major gas leak. However, it was the rig’s practice to lock out the deluge system whenever divers were working nearby to avoid the hazard of sucking a diver up against the inlet grating to the deluge pumps and drowning him as his air supply ran out.

Divers had been working on the rig for several weeks continually in the period leading up to the incident. The deluge system had therefore been left locked out all the time as a shortcut to avoid have to lock it out every day.

The force of the explosion blew down the firewall separating different parts of the processing facility, and soon large quantities of stored oil were burning out of control. And because of these shortcuts and mistakes, 167 people lost their lives.

Today, tomorrow and everyday thereafter, we should follow our policies, procedures, and Lock Out Tag Out every time we hand something over to maintenance. Let us learn from the mistakes of the past and always remember: THE LESSON OF SAFETY IS WRITTEN IN BLOOD.


Lord Cullen

According to an official report commissioned by Lord Cullen, a Scottish judge who conducted a 13-month inquiry into the tragedy, all these failings should have been obvious to the owners and managers. The findings, detailed in the Cullen Report, went on to say that the refinery managers were too easily satisfied with the permit process.

”All these failings should have been obvious to Occidental’s managers,” Lord Cullen said in his report. “They were too easily satisfied that the permit to work system was being operated correctly, relying on the absence of any feedback of problems as indicating that all was well.”

The managers “failed to provide the training required to ensure that an effective permit to work system was operated in practice. In the face of a known problem with the deluge system they did not become personally involved in probing the extent of the problem and what should be done to resolve it as soon as possible,” Lord Cullen said in his report. “They adopted a superficial attitude to the assessment of risk of major hazard. They failed to ensure that emergency training was being provided as they intended. The platform personnel and management were not prepared for a major emergency as they should have been. The safety policies and procedures were in place: the practice was deficient.”

The recommendations in the Cullen Report were ultimately adopted by refineries and have helped to pave a safety process for us as an industry (PSM). However, in order to avoid tragic mistakes like the Piper Alpha explosion, one must actually practice safety, following protocols to a T.

For more information on the Piper Alpha explosion and the Cullen Report, visit these sites:   

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Posted by: Gary Pitman