Reducing pipe is also called large and small head, reducing pipe, different straight through. One of the chemical pipe fittings used for the connection between two different pipe diameters. According to the shape of the different, divided into concentric and eccentric size of the head two. Size head material includes stainless steel size head (304304L316316L), alloy steel, carbon steel size head, size head material has 20 steel, Q235, Q345, 16Mn and so on.