(Adds update on FCC, details, background, paragraphs 2-9)
HOUSTON, May 1 (Reuters) - Motiva Enterprises wasreducing production levels on the second-largest crudedistillation unit at its 600,000 barrel per day (bpd) PortArthur, Texas, refinery ahead of the start of planned work onthe unit's heat exchangers, sources familiar with refineryoperations said on Thursday.
Instead of completely shutting the unit, Motiva plans toperform the work while the 200,000 bpd CDU, called VPS-4, isrunning at 50 percent capacity. If the work cannot be done whilethe unit remains in operation, Motiva will shut VPS-4 down asoriginally planned.
A Motiva spokeswoman declined to discuss maintenance at thePort Arthur refinery.
The restart of the refinery's 92,000 bpd fluidic catalyticcracking unit is expected to finish on Friday. The unit was shutto install a bypass line to a leaking boiler. The line is neededto prevent catalyst from being released into the air.
U.S. environmental rules require refiners to prevent therelease of catalyst into the atmosphere. The FCC was shut onMonday and began restarting on Wednesday.
Motiva has said a unit shut on Monday is restarting at therefinery. The company has declined to identify the unit.
The work on VPS-4 is expected to take about two weeks. VPS-4is one of three crude distillation units that do the initialrefining of crude oil coming into the refinery. The CDUs providefeedstock for all other units in the plant.
The other two CDUs will remain in operation while VPS-4 isat reduced production or shut.
Motiva is co-owned by Saudi Aramco and RoyalDutch Shell Plc {RDSa.L], which manages the refinery. Motiva'sPort Arthur refinery is the largest in the United States. (Reporting by Erwin Seba; Editing by David Gregorio)
