[en] In the aftermath of Enbridge's oil spill in Michigan from a pipe break, the company may face greater scrutiny in its Northern Gateway application for a pipeline crossing British Columbia to the coast, where tankers would ship Alberta bitumen to Asia. In addition, regulators in the United States are more likely to be more diligent regarding TransCanada's Keystone pipeline expansion and extension to the U.S. Gulf Coast, where refineries wait to process Canadian bitumen. The Enbridge spill has sparked a debate over the integrity of North America's aging pipelines. Operators claim that transmission pipelines can operate for an indefinite period of time, provided that the appropriate maintenance and inspection practices are used. Repairs can include outright replacement of corroded pipe sections or less demanding in-situ repairs to damaged pipe coatings or cathode replacement. Coatings and cathodic protection protects pipelines from the external environment. Pigging and chemicals prevent internal corrosion from water, carbon dioxide, hydrogen sulphide, chlorines and other residues. Despite these maintenance and repair efforts, many of the pipes currently in the ground were engineered for a useful life of 20 or 25 years. 6 figs.