(Adds further units shut)
HOUSTON, Feb 17 (Reuters) - Motiva Enterprises shut its 195,000 barrel per day (bpd) crude distillation unit,the second largest at its Port Arthur, Texas, refinery, onTuesday morning due to a leak in a pipe, said sources familiarwith plant operations.
Traders said shutting of the VPS-4 CDU at the 600,250refinery, the largest in the United States, will be bearish forU.S. crude futures.
A Motiva spokesman said there was an operational upset on aunit at the Port Arthur refinery.
"There were no injuries associated with this situation,"said Motiva spokesman Ray Fisher. "All appropriate agencies werenotified. For reasons of commercial confidentiality, we do notprovide details about the operational status of individual unitsor information on supply."
Crews were trying to determine exactly which part of VPS-4'spiping was leaking and how long it might take to fix it, thesources said.
On Tuesday night, the Port Arthur refinery also shut a25,200 bpd heavy gas oil hydrotreater and lube oil production,said the sources.
The shutdown of the CDU will back out more crude in theHouston area, putting pressure on cash differentials because ofthe abundance of oil already available in the U.S. Gulf Coast,traders said.
That extra supply will likely slow down flows into theregion, including TransCanada Corp's Marketlinkpipeline and Enterprise Products Partners LP's Seawayand Seaway Twin pipeline.
Production has been slowed on several other units at therefinery due to the shutdown of VPS-4 on Tuesday, the sourcessaid.
The Port Arthur refinery's 60,000 bpd hydrocracking unitcalled HCU 2 was shut on Monday and remained shut on Tuesdaynight due to a leaking seal on the unit's compressor, sourcessaid.
Motiva is also performing a planned seven-week overhaul ofthe Port Arthur refinery's 92,000 gasoline-producing fluidiccatalytic cracking unit. Units associated with the FCCU,including an 18,000 bpd alkylation unit and a 49,000 bpdcatalytic reformer are also shut as part of the work, whichbegan on Jan. 13.
Motiva is a 50-50 joint venture between Royal Dutch ShellPlc and Saudi Aramco. (Reporting by Erwin Seba in Houston and Catherine Ngai in NewYork; Editing by Chizu Nomiyama, Marguerita Choy and CynthiaOsterman)