ANCHORAGE, ALASKA ? Oil giant BP searched for skilled workers and steel pipe Tuesday to replace badly corroded transit lines that this week forced the shutdown of operations at the largest oil field in the U.S.

The world’s second-largest oil company announced Sunday it was shutting down the Prudhoe Bay oil field after a small leak was found in one of its three lines that bring oil to the 800-mile trans-Alaska pipeline. BP has 22 miles of transit lines and will be replacing two of the lines, or 16 miles.

“We have taken all nonessential persons off the slope,” Steve Marshall, president of BP Alaska Exploration Inc., told analysts Tuesday. More than 100 workers will be going up in the next few days to remove insulation and get a better look at the corroded pipes, he said.

The company also said it would recruit workers from across North America to complete the inspections and do other work required, including replacing the corroded pipes.

“We need to touch more of the pipe to see where these things are,” said Bill Hedges, BP’s corrosion expert. “We clearly know we weren’t finding the worst spots.”

The Prudhoe Bay field produces about 400,000 barrels a day – about half of all North Slope production – with production divided equally between the eastern and western sides.

The phased shutdown began Sunday on the east side, where the leak was discovered. It will likely move to the west side, where in March corrosion in another transit line caused a spill of up to 270,000 gallons – the biggest spill in the history of the North Slope or portion of Alaska north of the Brooks Range mountains.

Bob Malone, chairman of BP North America who took over July 1, defended the company Tuesday.

“I’m not able to see a systemic issue,” Malone told analysts. “These are very, very unfortunate incidents. I can say with comfort I’m seeing a high level of focus on safety and operation integrity.”

Thomas J. Barrett, administrator of the Department of Transportation’s Pipeline and Hazardous Materials Safety Administration, said his office has issued BP several compliance orders since the March 2 spill and will issue several more when the current onsite investigations are complete.