Philadelphia Energy Solutions LLC, the owner of the largest U.S. East Coast oil refining complex, has hired an investment bank to help tackle its debt burden, as it struggles with low profit margins, people familiar with the matter said on Tuesday. The move underscores the challenges facing some East Coast refineries, which used to enjoy a competitive advantage when oil prices were high because they were able to secure supplies cheaply by rail. The crash in oil prices has changed that. Philadelphia Energy Solutions’ latest woes come five years after private equity firm Carlyle Group LP and Energy Transfer Partners LP’s Sunoco Inc rescued the refinery owner from bankruptcy, in a deal supported by tax breaks and grants that saved thousands of jobs. The refinery complex is still one of the region’s largest employers, and U.S. energy officials have warned that its closure could lead to price […]