Reducers, also known as size heads, are used to connect pipes of different sizes; Generally, it is divided into concentric reducer and eccentric reducer. When the projection of the two ports of the reducer is concentric, it is called concentric reducer, and the projection of the eccentric reducer is a small circle cut in the outer circle. The roundness of the reducer shall not be greater than 1% of the outer diameter of the corresponding end, and the allowable deviation is �±3mm. The material of the reducer is made of SY/T5037, GB/T9711, GB/T8163, ASTM A106/A53 GRB, API 5L, APT5CT, ASTM A105, ASTM A234, ASTM A106, DIN German standards and customer requirements.