The design, construction and placement of oil and natural gas pipelines is essentially similar, using the same materials and welding techniques. As a result, conversion of a pipeline to carry one product versus another is safe when properly executed. Indeed, TransCanada has done similar conversions in the past: most recently, it converted a section of the Canadian Mainline pipeline from gas to oil for delivery to the Keystone Pipeline in the U.S. Since July 2010, this converted pipeline has safely delivered nearly one billion barrels of oil into the United States.
Some differences do exist between gas and oil pipelines—in particular the location of shut-off valves and pump stations. If the Energy East pipeline proposal is approved, TransCanada will install new valves and pump stations as necessary, while also performing a check of the structural integrity of the entire existing pipeline.