Boardwalk Pipeline Partners LP (NYSE: BWP) said Thursday it has priced its public offering of 10.5 million units at $27.80 per unit. Houston-based Boardwalk expects to receive $287.7 million from the offering and plans to use the proceeds to repay debt and for general purposes. Boardwalk expects the offering to close on Aug. 7, and underwriters likely will have a 30-day option to purchase up to 1.575 million additional units. Barclays, Citigroup, Deutsche Bank Securities, J.P. Morgan, Morgan Stanley,…