In rail transport, the U.S. DOT-111 tank car, also known as the TC-111 in Canada, is a type of unpressurized general service tank car in common use in North America. Tank cars built to this specification must be circular in cross section, with elliptical, formed heads set convex outward. They have a minimum plate thickness of 7⁄16 inch (11.1 mm) and a maximum capacity of 34,500 US gallons (131,000 L; 28,700 imp gal). Tanks may be constructed from carbon steel, aluminum alloy, high alloy steel or nickel plate steel by fusion welding. The black car carries petroleum products and has a capacity of 30,110 US gallons (113,979 L; 25,071.8 imp gal), a tare weight of 65,000 pounds (29,500 kg) and a load limit of 198,000 pounds (89,800 kg).   And the internals: