API Cu / CB Type Casing Bushing Master Rotary Table Bushing and Insert Bowls For Oilfield Casing Bushings and Insert Bowls: CU, CUL, CB and etc. Casing Bushings can handle casings from 2.3/8 to 30inch O. D.. Type CU & CUL are solid bushings and Type CB are split bushings. They are designed and manufactured according to API Spec 7K. Specification for drilling and well servicing equipment. Master bushings and insert bowls sizing from 17.1/2 to 49.1/2inch. They are cast with