Moody's on Dec. 19 raised TC Energy Corp. subsidiary Columbia Pipeline Group Inc.'s senior unsecured rating to A3 from Baa1, with a stable outlook.

The rating agency based the upgrade on the pipeline company's "financial strength," benefiting from equity injections from parent TransCanada PipeLines Ltd., according to a news release. The equity injections have helped in funding the company's expansion program and debt maturities, with Columbia Pipeline paying down a $500 million debt in 2018.

Columbia Pipeline's cash flow is also expected to continue to increase after the company completed major projects during the year, including the $3.2 billion Mountaineer Xpress gas pipeline, $900 million WB Xpress gas pipeline, $600 million Gulf Xpress gas pipeline and pipe modernization programs.

In addition, Moody's said the upgrade reflects the strategic position of Columbia Pipeline's natural gas pipe network in the Appalachian Basin, which is expected to generate cash flow underpinned by long-term contracts.

Canada's TC Energy operates pipeline, power generation and energy storage facilities across Canada, the U.S. and Mexico.