The roundness of the reducer should not exceed 1% of the corresponding end outer diameter, with an allowable deviation of ±3mm. The material for reducers follows SY/T5037, GB/T9711, GB/T8163, ASME ASTM A106/A53 GRB, API 5L, APT5CT, ASTM A105, ASTM A234, ASTM A106, DIN German standards, and customer-specified standards.Reducers (transition pieces) are a type of fitting used at pipe transition sections. Common forming processes include diameter reduction and expansion pressing, diameter reduction with expansion pressing, or for certain specifications, stamping.