UPDATE 1-Sunoco, Phila. refinery workers in tentative deal

* Sunoco, USW ink tentative labor deal for Philly refinery

* Labor union to vote on deal Monday

By Janet McGurty

NEW YORK, June 27 (Reuters) - Sunoco Inc reached a tentative labor agreement with members of the United Steelworkers union at its Philadelphia refinery late Tuesday, sources familiar with the situation said, moving a joint venture with Carlyle Group to keep the refinery operating one step closer to fruition.

Details of the agreement between the USW and the company were not released. A union ratification vote on the deal is planned for Monday. A Sunoco spokesman was not immediately available for comment.

The 335,000-barrel-per-day (bpd) refinery is the largest on the U.S. East Coast. A deal between Sunoco and Carlyle is aimed at saving the refinery -- the nation's longest continuously operating plant -- from closing, easing fears of a potential fuel shortage this summer.

The labor deal affects about 650 hourly workers at the plant, which employs 1,000 other workers. The refinery also can employ as many as 1,000 independent contractors during times of peak maintenance.

Sunoco, which was poised to shut the plant in July if it did not find a buyer, extended the deadline until August. If one cannot be reached by then, it will idle the main processing units.

Under a deal with Carlyle, Sunoco would put the refinery assets into the joint venture in exchange for a non-operating minority interest in the venture.

Carlyle would contribute cash, hold the majority interest and oversee day-to-day operations.

Sunoco has not disclosed financial terms, and officials suggested they were still counting on support from the national, state and local governments before sealing a deal.

Sources familiar with the situation have said environmental issues regarding the sale have been worked out.

They said that the parties are still waiting to see what kind of aid the joint venture would receive from the state.

Recently, Shell was offered up to $1.7 billion in tax breaks to build an ethane cracker in the center of the state to process local Marcellus shale oil and natural gas.

Oil markets are closely watching the fate of the refinery, one of three in a 12-mile radius near Philadelphia that are threatened with closure. One has already been saved and one is unlikely to be.

Last week, Delta Air Lines Inc inked a deal with Phillips 66 to buy the shuttered 185,000-bpd Trainer refinery in a bid to keep a lid on fuel costs. The deal received $30 million from local lawmakers.

Planned maintenance at Trainer and an expansion of jet fuel making capabilities will begin next week, with fuel production expected in September.

The third regional refinery -- Sunoco's 178,000-bpd shuttered plant in Marcus Hook -- is not expected to be sold as a refinery. A study on use of the site by a regional planning group is expected to be released later on Wednesday.