What is Line 5 made of?
Line 5 was built by the Bechtel Corporation, which also built the Hoover Dam, and was over-engineered from the get-go.
The Line 5 Straits of Mackinac crossing in northern Michigan is made from specially manufactured steel, formed from a molten billet, to produce seamless piping, and is a minimum of 0.812 inches thick—the heaviest-walled pipe in our North American network.
The twin 20-inch-diameter lines that run along the bottom of the Straits are not exposed to the water. They’re covered with an external coating of fiber-reinforced enamel, recognized as one of the most robust pipeline protection materials.