Trans-Northern Pipelines Inc. A refined petroleum products pipeline serving southern Ontario and western Quebec. Trans-Northern Pipelines Inc. (TNPI) has been in operation since 1952 and delivers refined petroleum products to major cities and airports in southern Ontario and western Quebec. The company is a federally regulated firm under the jurisdiction of the National Energy Board, www.neb.gc.ca. TNPI is a member company of the Canadian Energy Pipeline Association, www.cepa.com.