BP is shutting a fluid catalytic cracker (FCC) at its Whiting, Indiana, refinery for six weeks of planned work that starts today, a person familiar with operations said.

The maintenance is being conducted on the No. 600 catalytic cracker, said the person, who asked not to be identified because the information isn’t public.

The unit has a capacity of 80,000 bpd and is the smaller of two catalytic crackers at the refinery, according to a filing with state regulators.

Scott Dean, a spokesman for BP in Warrenville, Illinois, declined to comment.

The 420,000-bpd Whiting refinery is the largest serving the Midwest market. Gasoline for prompt delivery in the Chicago spot market rose 3.5 cents to a 3.5-cent discount to New York Mercantile Exchange futures on Monday, the strongest level since October.