FMC(BB4)

The API BB4(model FMC G/Z) pump is a horizontally mounted, radially split, multistage between-bearings centrifugal pump designed to API 610 / ISO 13709 standards. Unlike the axially split BB3, the BB4 features a radially split (barrel-type) casing with a removable inner cartridge, which permits the complete rotor assembly to be withdrawn without disturbing the suction and discharge piping. The multistage configuration utilizes either diffuser-type or volute-type stage casings, with axial thrust typically balanced by a balance drum or opposed impeller arrangement.

These pumps are engineered for high-head applications where containment integrity is paramount. They are widely used in refineries and petrochemical plants for heavy oil hydrocracking, residue hydrotreating, and high-pressure boiler feed water services. The BB4 design is also common in oil and gas production for high-pressure water injection, as well as in pipeline boosting and carbon capture applications. Its barrel casing provides superior resistance to thermal shock and pressure fluctuations, making it suitable for services with temperatures ranging from -40°C up to 250°C (482°F).

Technically, the BB4 pump features a heavy-duty rotor with short bearing spans to minimize deflection under extreme loads. Bearing arrangements typically include sleeve or tilting-pad journal bearings with thrust bearings sized for the high axial loads inherent in multistage operation, lubricated by pressurized oil systems. The pump is fully compliant with API 682 seal chambers, accommodating tandem or double cartridge mechanical seals with API 682 piping plans for maximum sealing integrity. Available in materials ranging from carbon steel to chrome steels and duplex stainless steels, the BB4 achieves flow capacities up to 900 m³/h and heads up to 1,800 meters, making it the standard choice for the most demanding high-energy pumping duties.