I guess they bought them or had different standards on the rig in the gulf.
From:
http://investments-and-acquisitions.com/safety-violations-implicated-in-bp-oil-spill/
"Federal hearings last week revealed a number of safety violations that may have contributed to the Deepwater Horizon rig explosion. It appears that the maintenance and safety equipment on board the oilrig were out of date. Electronics technician, Michael Williams, testified that the emergency alarms were disabled several weeks prior to the explosion, which resulted in the death of eleven employees and an oil spill of more than 4 million barrels into the Gulf."
As for BP having such a great safety record, you might want to check sources other than BP's web site.
From:
http://abcnews.go.com/WN/bps-dismal-safety-record/story?id=10763042
"As the nation comes to grips with the worst oil disaster in its history,
there is evidence BP has one of the worst safety track records of any major oil company operating in the United States.
In two separate disasters prior to the Gulf oil rig explosion, 30 BP workers have been killed, and more than 200 seriously injured.
In the last five years, investigators found, BP has admitted to breaking U.S. environmental and safety laws and committing outright fraud. BP paid $373 million in fines to avoid prosecution."