Tubes have circular, square, and rectangular sections and are used to transfer heat and high pressure. Their applications include oil furnaces and heat transmit. These products are usually made up to 12 inches and are seamless, while the pipes are made in two types, seamed and seamless. This is one of the differences between steel pipes and tubes. In addition to tubes, like pipes, it is available in different materials of steel and copper. One of the important characteristics of tubes is their thickness. Their thickness is the same as the tubes while the thickness varies in steel pipes. In tubes, the nominal diameter and the outer diameter are always equal. Also, their outer diameter is fixed like pipes and their thickness class is specified by BWG. The tubes do not have a specific length, while the pipes have a specific length.