The roundness of the reducing elbow should not exceed 1% of the corresponding outer diameter of the end, with an allowable deviation of ±3mm. The material of the reducing elbow complies 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. Reducing elbows ( reducers) are a type of pipe fitting used at pipe diameter changes. The commonly used forming processes are reduction and extrusion pressing, expansion and reduction pressing, or reduction and expansion pressing, and stamping forming can also be used for certain specifications of reducing elbows.