UPDATE 1-Valero combining overhaul with Tx refinery repair

HOUSTON, Feb 21 (Reuters) - Leading U.S. refiner Valero Energy Corp. (VLO.N) said on Wednesday it will combine a previously planned hydrocracker overhaul with repairs to its 170,000 barrel per day Sunray, Texas, refinery, shut since a Friday fire.

The company also has not established an exact restart date for the refinery, which supplies gasoline and other motor fuels to Texas, Colorado, New Mexico and Arizona, according to a statement from spokeswoman Mary Rose Brown.

The hydrocracker work was originally set to run for 40 days, beginning in April and finishing in May.

Workers at the refinery on Wednesday inspected piping and performed work to restore essential safety flare, fuel gas and steam systems at the refinery located 60 miles north of Amarillo, Texas, Brown said.

"Given the complexity of this work, we have yet to establish an exact restart date, but it will be weeks before a partial start-up can be anticipated," she said.

The workers were also isolating pipes damaged by a blaze in a propane deasphalting unit, which uses propane to squeeze the last gasoline out of gunky residual crude oil, Brown said.

One worker is in critical but stable condition with burns at a Lubbock, Texas, hospital. Two other workers were released from the hospital on Monday.