NEW YORK -(Dow Jones)- A hydrocracking unit shut by severe thunderstorms on Friday at BP PLC's (BP) Texas City, Texas, refinery is expected to return to service by the end of the week, a person familiar with operations said on Monday. The storm caused a compressor at the unit to trip off line which resulted in a small fire that was brought under control within 30 minutes, the person added. BP on Sunday said feed would be removed from the ultracracker unit, another name for a hydrocracking unit, to facilitate maintenance that was expected to last until April 26, according to a filing to the Texas Commission on Environmental Quality. Company spokesman Scott Dean said BP doesn't comment on day-to-day refining operations. Maintenance at the key gasoline-making Fluid Catalytic Cracking Unit No. 3 and an alkylation unit at the Texas City refinery has been underway since early January. The Texas City refinery is able to process up to 406,507 barrels of crude oil a day. -By Rose Marton-Vitale, Dow Jones Newswires; 201-264-4185; rose.marton@dowjones.com