Metal tubing serves many purposes in modern infrastructure. As such, it must be versatile, strong and affordable. Two main tube manufacturing processes have developed to meet society’s needs, drawn over mandrel (DOM) and seamless. Both processes produce tubing made from several metals, including; copper, steel and aluminum.
Metal piping, such as DOM and seamless, tubing are used for a range of purposes. They serve as structural scaffolding, pipelines for gas and water, delivery of fluids or bulk solids, steamrollers, conveyor belt rollers, bearing casings, casings for concrete pilings and oil well casings. Seamless tubing withstands pressure better than DOM and is more easily available.
DOM tubing is made with metal sheets. It is drawn over a mandrel in a cold-formed method, to form a tube shape. The edges of the metal are then welded with an electrical resistance welder to secure the tube.
Seamless tubing is created via two methods: extrusion and rotary piercing. In extrusion, a hot metal ingot is pressed through a die to form the pipe. In rotary piercing, a solid billet is drawn over a rotary cutting tool via two external rollers. The rough tube from this process is drawn through an elongator to lengthen it and thin the walls. A reducing mill further thins the walls of the tube externally. A rotary sizer finishes off the round shape of the seamless tube.