The ovality of the reducers should not exceed 1% of the corresponding end outer diameter, and the allowable deviation is ±3mm. The materials for reducers are in compliance with SY/T5037, GB/T9711, GB/T8163, ASTM A106/A53 GRB, API 5L, APT5CT, ASTM A105, ASTM A234, ASTM A106, DIN German standards, and customer-specified standards for reducers (transition pieces). Reducers are a type of piping fitting used in pipe diameter changes. The commonly used forming processes include diameter reduction pressing, diameter expansion pressing, or a combination of both. For certain specifications, stamping forming can also be applied.