The tandem mill of cold strip steel usually consists of 3 stands, 4stands or 5 stands, therefore, it can complete the whole rolling process just in one pass. Pickled coils of the common carbon steel, low alloy steel coming from hot-rolling production are rolled into the coil strip with required thickness, flatness and finishing through one pass under normal ambient condition..

It is possible to keep production running continuously without stop when a welding machine and a looper are put into the line between the pay-off reel and the first stand. The tail of a coil is welded to the head of another coil when the coil is used up and in the meanwhile, the strip stored in the looper can keep the mill rolling at a certain speed without stop.