The reducer is also called a big or small head, a reducer, or a reducer. One of the chemical pipe fittings, used to connect two pipes with different diameters. According to the different shapes, they are divided into two types: concentric large and small heads and eccentric large and small heads. The materials of the big and small heads include stainless steel big and small heads (alloy steel, carbon steel big and small heads). The materials of the big and small heads include No. 20 steel, Q235, Q345, 16Mn, etc.