Sunoco Inc reached a tentative labor agreement with the members of the United Steel Workers union at its Philadelphia refinery late Tuesday, sources familiar with the situation said, moving a joint-venture deal with Carlyle Group to keep the refinery operating one step closer to fruition.

The 335,000 barrel per day refinery is the largest plant on the East Coast.

It was one of two Sunoco plants in the region scheduled for closure, as Sunoco exits the refinery business.

In April, private equity group Carlyle Group entered into exclusive talks with Sunoco to operate the plant.

A union ratification vote on the deal is planned for Monday.

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