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(Updates with crude unit down at least a month)
HOUSTON, Aug 11 (Reuters) - Heavy damage to the largestcrude distillation unit at BP Plc's 413,500-barrel-per-day (bpd) Whiting, Indiana, refinery willrequire at least a month to repair, sources familiar with therefinery's plans said on Tuesday.
Piping inside the 240,000 bpd CDU, called Pipestill 12,which processes heavy sour oil crude, was damaged in amalfunction on Saturday.
BP spokesman Scott Dean declined to discuss operations atthe oil major's largest refinery in the United States.
The length of the unit's outage was being closely watched byrefined products and crude traders for the impact the loss ofproduction at the refinery could have on prices.
The sources stressed that the time frame for Pipestill 12'srestart was preliminary and may change.
"I would expect longer rather shorter," one of the sourcessaid.
Examination of the damaged crude unit was continuing onTuesday.
Pipestill 12 was the centerpiece of a $4 billion refit ofthe refinery to run more sour crude from Canada's tar sandsfields in Alberta. The rebuilt Pipestill 12 came on-line in July2013.
BP sold off refineries in Texas and California in 2013 tofocus its U.S. refining operations on plants with easy access toCanadian crude.
Crude distillation units do the initial refining of crudeoil coming into a refinery and produce feedstocks for all otherunits. (Reporting by Erwin Seba; Editing by Meredith Mazzilli,Jonathan Oatis and Marguerita Choy)
