Marathon Petroleum Corp plans to finish a multi-unit overhaul in late July at its 585,000-barrel-per-day (bpd) Galveston Bay Refinery in Texas City, Texas, said sources familiar with plant operations.

Marathon shut the 225,000-bpd Pipestill 3B crude distillation unit (CDU) on Monday to begin connecting to it the units shut for the overhaul, the sources said.

Marathon spokesman Sid Barth declined to comment on Tuesday.

The company began the overhaul on May 23 with the shutdown of a 65,000-bpd reformer, a 60,000-bpd residual oil hydrotreater and an aromatics unit, the sources said.

Five days later, the 60,000-bpd hydrocracker, the 31,500-bpd alkylation unit and a 47,500-bpd aromatics recovery unit were shut along with a sulfur recovery unit.

The overhaul was originally scheduled to begin in March, but was pushed back twice to reduce the risk that large numbers of contract workers at the refinery would spread novel coronavirus, according to the sources.

(Reporting by Erwin Seba; Editing by Sandra Maler and Subhranshu Sahu)