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* Two CDUs, including newest, to remain in operation
* Coker last unit in refinery's $4-billion refit (Adds details, background)
HOUSTON, Sept 19 (Reuters) - BP Plc was readying a100,000 barrel per day (bpd) crude distillation unit, calledPipestill 11A, at its 405,000 bpd Whiting, Indiana, refinery toshut down in early October for an overhaul lasting at least fourweeks, said sources familiar with operations at the refinery onThursday.
BP was also on schedule to complete construction of a new102,000 bpd delayed coking unit in December, the sources said.
A BP spokesman declined to discuss operations at therefinery.
The refinery's new large CDU, the 260,000 bpd Pipestill 12,continues operating normally since completing startup in Julyand will remain in operation throughout Pipestill 11A'sshutdown. Another CDU, called Pipestill 11C, which completed anoverhaul in August, will continue operating while 11A is shut.
The coker is the last unit to be built as part of BP's$4-billion refit of the refinery to run up to 350,000 bpd ofcheaper crude oil from Canada's tar sands fields in Alberta.Before the project, the refinery could run only 80,000 bpd ofCanadian crude.
The Whiting refinery is BP's largest and at the heart of astrategic shift by the British energy giant to favor northernU.S. refineries. The company sold off refineries in Californiaand Texas earlier this year.
Crude distillation units are the primary refining units inan oil refinery. They do the initial refining of crude oilcoming into the plant and provide feedstock for all otherproduction units.
A delayed coking unit boosts the amount of refinablematerial obtained from barrel of oil and converts residual crudeoil into petroleum coke, a coal substitute. (Reporting by Erwin Seba; Editing by Gerald E. McCormick andMarguerita Choy)
