This is not the same thing. There are two concepts in molding: First, it is made by burning the original tube with a mold. Second, that kind of relatively large elbow, produced with the middle plate. The middle plate was pressed into two pieces by a mold. They are then welded together using electrodes to produce large elbows. And the introduction of the system is similar to the drawing. For example, the elbow of 500, the raw material is 300 or other steel pipes with a smaller diameter than 500. Then burn it red on the machine and walk on a mold that slowly becomes thicker at 90 degrees. The elbow of 500 is produced. This production is fast and the surface of the product is smooth.