"When you make a complaint about it, rather than fix it right, they come up with another Band-Aid," said Kris Dye, a BP oil worker and United Steelworkers representative on the North Slope. "It's very frustrating."

One critical maintenance issue concerns the replacement of the warning systems used to alert workers to a gas leak that could lead to an explosion.

The need to replace the gas detectors was made a priority in 2001 in an internal BP report that said oil field technicians were "very concerned about continuing degradation of system reliability, and the ability of these systems to protect the workforce."

Nine years later, outdated systems to detect fire and leaked gas remain in place at some of BP's largest and most important plants, including the Central Power Station, several drill pads and two flow stations that route oil and gas into the pipeline system.

Many of the detection systems are obsolete - the manufacturers that made them are shuttered - so replacement parts are hard to come by, said Kovac, the mechanic. More important, the systems have to be shut down every time BP conducts maintenance on its facilities and pipelines, because the methods used to scan the equipment for flaws have been known to trigger the ultraviolet detectors that set off the fire and gas alarms.