Fusion Welding
One process for producing pipe is fusion welding, sometimes called "continuous welding", in sizes from 1/8" to 4-1/2". Fusion-welded pipe begins with coils of steel of the width and thickness required to meet the size and weight of the pipe to be manufactured. Successive coils of steel are joined end to end to form a continuous strip. The steel strip is fed into a straightening machine and then into a gas-fired furnace where it is heated to the temperature required for forming and melting. Forming rollers at the end of the furnace shape the heated skeleton into an oval shape.
The rolls are then used to press the edges of the skeleton firmly together to obtain a forge weld. The heat of the skeleton combines with the pressure exerted by the rolls to form the weld. No metal is added to the operation. The final sizing rolls bring the pipe to the desired size.
