Tube bending and pipe bending services produce finished parts from tubes and pipes. Tubes are hollow, usually cylindrical objects that are used as flow lines for fluids and gases in pneumatic, hydraulic, process, medical, and food processing applications. Tubes are generally smaller and less rigid than pipes, larger devices that are used in transport systems for fluids and solids in a variety of applications and industries. Tube bending and pipe bending services specify tube size by outside diameter and pipe size by inside diameter. Typically, diameter is measured in inches (in). Although most tubes and pipes are cylindrical, products with oval, round, square, and rectangular cross sections are available. Bendable tubes and pipes are made from materials such as aluminum, brass, carbon steel, stainless steel, copper, nickel alloys, polyvinyl chloride (PVC), plastics, titanium, and superalloys. Some tube bending and pipe bending services produce finished parts from products that are made of Inconel^® , a nickel-based alloy that contains chromium and iron. Inconel is a registered trademark of Special Metals Corporation.