UPDATE 1-Control room work may delay Texas refinery return

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By Erwin Seba

HOUSTON Nov 21 (Reuters) - Repairs to a control room heavily damaged in Thursday's explosion at Delek US Holding's (DK.N) 58,000-barrel-per-day (bpd) Tyler, Texas, refinery may delay the plant's return to production, sources familiar with refinery operations said on Friday.

One worker died in a Dallas hospital from burns sustained in the Thursday blast and fire at the refinery's saturated gas plant, Delek said on Friday.

Another worker remained in critical condition at Parkland Hospital in Dallas from burns sustained in the fire, according to the sources. Two other workers were treated at hospitals near Tyler.

A Delek spokesman declined to discuss damage to specific parts of the refinery, located 104 miles (167 kilometers) east of Dallas.

The company did say an initial assessment showed most of the refinery's processing units were not damaged by the fire. Delek said the refinery would not be producing until the cause of the explosion was known.

Parts of the refinery will be shut in the coming days for damage assessment and to help the investigation, the company said.

According to the sources, the control room for the saturated gas plant also serves the refinery's crude oil distillation unit, which does the initial refining of oil coming into the refinery.

"It's pretty much burnt up on the inside," one of the sources said about the control room.

The blast was likely the ignition of highly explosive naphtha gas, source said. A saturated gas plant separates out substances like methane, propane and hydrogen from gases generated in refining.

The U.S. Occupational Safety and Health Administration began interviewing workers at the plant on Friday, but were unable to get to the site of the explosion because of small fires still burning near the sat gas plant.

The U.S. Chemical Safety Board does not expect to launch its own investigation, Chairman John Bresland said in a telephone interview.

"We're concerned about any accident in the refining industry, unfortunately with our limited resources we can't go to every refinery accident," Bresland said.

The CSB has a 35-member staff currently conducting eight investigations, he said.

The board will continue to monitor investigations at the refinery and could start its own probe if new information develops, Bresland said.

Three workers at the refinery were injured in April when they were sprayed by hot oil while working on the refinery's coking unit.

Delek US Holdings bought the refinery in May 2005 from Crown Central Petroleum LLC for $74 million. (Editing by Christian Wiessner)