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Williams to restart units at Wyoming natgas plant after blast

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April 28 (Reuters) - Williams Partners LP said Monday it plans to return to service the four undamaged units at its natural gas processing plant in Opal, Wyoming, which shut last week after an explosion and fire damaged one of the facility's five units.

The company did not say precisely when the four units would return to service but noted in a statement it was working with regulators and developing "preliminary plans" to bring the units back in a "timely manner."

Officials at the company were not immediately available for comment.

The April 23 incident at Opal was the second explosion and fire to shut a Williams gas facility in a month, leading some to worry that incidents like these will make it tougher for the industry to replenish stockpiles drained to critically low levels after a brutal winter.

The capacity of the four undamaged units totals 1.1 billion cubic feet of gas per day, which is sufficient to handle all of the gas currently available to the facility, Williams said.

At the time of the explosion, the damaged unit was one of four running to process about 1 bcf of gas. The fifth unit was idle, the company said.

The facility has remained shut since the April 23 incident. There were no reported injuries or damage to property outside the 160-acre facility, the company said.

The Opal plant has the capacity to process 1.5 billion cubic feet of gas daily when all five turbo-expander cryogenic gas-processing units are operating.

The company also said it is working to address the needs of customers whose business is affected by the temporary shutdown of operations at Opal.

Separately, Williams said it continues in investigate the cause of the March 31 explosion and fire that shut its liquefied natural gas storage facility in Plymouth, Washington.

The company said it is focusing on a failed pressure vessel that removes carbon dioxide from the gas prior to its being liquefied.

The explosion of the vessel sent shrapnel across the facility, including into one of the plant's two LNG tanks, damaging at least the outer shell of the tank. The company said it will confirm the integrity of the inner shell of the damaged tank after it transfers the LNG to the undamaged tank.

Each tank at Plymouth is capable of holding 1.2 bcf of gas.

The company could not say when the Plymouth facility will return to service noting the investigation "may continue for several months" while site materials are submitted for analysis.

Oil and gas company Williams Cos Inc, of Tulsa, Oklahoma, owns 66 percent of Williams Partners, including the general-partner interest, the company said.

(Reporting by Scott DiSavino; Editing by Sofina Mirza-Reid)