Close-coupled pump motors have a long shaft to enable the pump impeller to be directly mounted on the motor shaft. Close-coupling results in a compact pumping solution with a smaller footprint. The lack of a gearbox or other coupling eliminates many mechanical issues and avoids the need for alignment during installation.
In recent years demand for CCP motors has been increasing rapidly. ABB has supplied hundreds of these motors for OH5 pumps for chemical, oil and gas applications. OH5 pumps are specified in American Petroleum Institute standard API 610, which defines them as centrifugal overhung pumps that are close-coupled and vertically inline mounted. Their major advantage is that they require only about one-third of the floor area needed for an equivalent horizontally mounted pump.
Special focus on tolerances and bearings
As the pump impeller is mounted on the motor shaft, it is vital that all mechanical tolerances are correct. During manufacturing special attention is paid to ensuring that run-outs, concentricities and perpendicularities are within the tolerances.
The pump does not have its own bearing assembly, and the motor’s bearings have to withstand all the forces generated during operation. ABB CCP motors are fitted with deep groove ball bearings at the D-end and double angular ball bearings at the N-end.
The N-end bearing assembly is axially locked, with the angular contact bearings mounted face-to-face in an ‘X’ arrangement. The downwards axial load is handled by the larger inner bearing, with the outer bearing handling the upwards load. The axial float of the shaft (including the axial float of the bearings) is very low. To make regreasing easier, either grease pipes or an outlet grease collector are provided, depending on the frame size.
Close cooperation with pump manufacturers
The motor is an integral part of the overall pump, and close coordination between ABB and the pump manufacturer is essential to ensure optimal results. One of ABB’s longstanding partners in the close-coupled pump segment is Flowserve Corporation. Flowserve is headquartered in Irving, Texas and Flowserve Desio, the unit responsible for OH5 pumps, is located near Milan, Italy. Flowserve Desio has around 450 employees, with facilities that include a foundry and main workshop.
“Our collaboration with ABB goes back decades, and over the last few years alone we’ve sourced hundreds of ABB motors for our close-coupled pumps,” says Vincenzo Savoca, API 1&2 stg. Product Manager, Flowserve. “We work together with our colleagues at ABB and share information. Our engineers are in close contact with ABB’s technical department throughout every project.”
In 2010 ABB and Flowserve entered into a global frame agreement. This covers a number of business divisions within ABB and lays down how the two organizations work together. It provides a set of terms and conditions, avoiding the need to renegotiate basic matters each time an order is placed. The two companies are in contact on an almost daily basis, and cooperation extends to joint product development projects and collaboration to resolve end user issues.
Recently ABB and Flowserve have worked together to supply OH5 pumps for a US$ 4 billion oil refinery upgrade project in Southeast Asia. Flowserve will supply around 20 close-coupled pumps incorporating ABB motors.
Wide range of outputs
All ABB CCP motors are produced to order. They deliver IE3 premium efficiency, and IE4 will be available in the near future. Frame sizes are 132 to 355, with even larger sizes possible. Power outputs range from 5.5 to 450 kW. ABB designs the bearing systems to allow rotational speeds up to 3600 rpm in all frame sizes. The motors are for direct-on-line (DOL) connection. Flameproof and increased safety protection types are available for hazardous areas, as well as regular versions for non-hazardous areas.
“The main benefit of close-coupled pumps is that they offer a much smaller footprint than other designs. They are the ideal choice where space is limited. This has led to a surge in orders for CCP motors over the last few years,” says Marco van der Mast, Global Key Account Manager, ABB. “We’ve already supplied a lot of CCP motors for the chemical, oil and gas industries, and we also have designs ready for water and wastewater pumps.”
Vincenzo Savoca, API 1&2 stg. Product Manager, Flowserve