THE OIL companies guilty of a series of safety breaches on North Sea rigs have been named and shamed by the government's health and safety watchdog - but only after a freedom of information request by the Sunday Herald.

In the past three years, Shell, Total, BP, Chevron, Maersk and other companies have all faced legal action from the Health and Safety Executive (HSE), forcing them to fix flaws in their crucial safety and maintenance systems.

Numerous rules designed to reduce the risk of accidents, fires and explosions and prevent workers from being injured or killed have been broken. Fire doors, valves, and other critical safety equipment have been found to be faulty, and maintenance regimes inadequate.

Twenty years ago, the Piper Alpha oil platform operated by Occidental in the North Sea exploded and caught fire, killing 167 men. It was the world's worst offshore oil disaster.

Anxious to prevent a repeat, the HSE has since been attempting to regulate the safety of the 250 manned and unmanned facilities on the UK continental shelf. Last November it published the results of an intensive three-year inspection of 100 installations.

Known as the KP3 report, it uncovered safety problems on nearly one-third of the rigs inspected. But the HSE refused to name any of the companies or installations at fault, provoking furious criticism from trade unionists.

The Sunday Herald submitted a request under freedom of information legislation, asking the HSE to lift the veil on the companies. At first it refused, but after an internal review, officials agreed to identify the installations served with improvement or prohibition notices as a result of the inspections.

Late on Friday, the HSE released a list of 18 instances between March 2005 and October 2007 when legal notices had been served. The most frequent offender was the biggest and richest oil company in the North Sea, Shell, which received six notices covering five installations.

At Brent Bravo in July 2006, Shell was told that it had "failed to ensure the health and safety of your employees and others" by not ensuring that oil pipework was maintained in good repair. In February last year the HSE said the company had an "excessive backlog of maintenance activities for safety critical equipment" at Clipper 48/19A.

BP was charged with failing to take "appropriate measures to prevent the uncontrolled release of flammable substances" at its Schiehallion platform in December 2006. A corroded wrap plugging a two-year-old pipe leak wasn't properly tested or replaced.

Attempts are still being made to rectify two breaches of safety rules discovered at Maersk's Janice A rig on October 30 last year. The company's deadline for complying with one breach has been extended from March 1 to April 30, while the other is due to be met by June 1.

HSE told Maersk: "You have not ensured the safety of your employees and other persons in that you have failed to provide and maintain plant and systems of work that are, so far as is reasonably practicable, safe."

Independent health and safety experts point out that there are "enormous dangers" associated with the offshore oil industry. And they are concerned that the crackdown by the HSE might fail to achieve the necessary changes.

"The appeals to oil companies to accept the case that good health and safety is good business appear to be falling on deaf ears," said Professor Andrew Watterson, head of the occupational and environmental health research group at the University of Stirling.

"A more punitive legal and financial approach is needed to ensure offending oil companies do put their houses properly in order. The consequences of not doing so is likely to be more injuries, deaths and major emergencies."

The industry's record, however, is defended by the oil companies.

Shell pointed out that the number of enforcement notices it had received was in direct proportion to the percentage of platforms it operated.

"Obviously we are not satisfied with this position. However, over the past three years we have been running a $1.2 billion upgrade project to prepare our assets for the next phase of the North Sea," a Shell spokeswoman said.

"Reliability trends, hydrocarbon release trends, and spill trends have improved year on year since 2004, reflecting the increased levels of investment," she added. "Our goal is 100% compliance on planned corrective safety-critical maintenance on all our platforms."

The UK offshore industry association, Oil and Gas UK, insisted that the problems were being managed. The safety of installations was key to the long-term sustainability of the industry and the security of UK energy supplies, it said.

The association's spokeswoman added: "The industry has therefore been working in close co-operation with the HSE on the KP3 asset integrity programme for several years, and is collectively spending more than £1bn a year on maintaining its installations."