API610 BB4 Multistage Pump

API610 BB4 Multistage Pump

What is an API610 BB4 multistage pump?

An API610 BB4 multistage pump is a centrifugal Pump designed according to BB4 pump specification in API610 10th edition. The API 610 refers to standards relating specifically to centrifugal Pumps and centrifugal pumping systems. These standards specify the pump design and testing criteria, focusing mainly on pump reliability instead of dimensional interchangeability. The BB4 means that the pump has a “between-bearing” type 4 design where the shaft is supported on bearings at both ends, and the impeller is mounted between bearings. All BB pumps have an impeller mounted horizontally, in the same orientation as bearings, and are high-pressure centrifugal pumps.

As its name implies, the pump is multistage because it contains two liquid chambers connected in series. Fluid enters the first chamber at the suction line pressure and exits from the second chamber at elevated pressure. The first-stage and second-stage impellers have different designs to achieve better pump performance. The first-stage impeller is designed to resist pump cavitation, while the second-stage impeller is designed for maximum pump efficiency. API610 BB4 multistage pump manufacturers also sometimes refer to this pump as a segmental-ring pump or ring-section pump because it contains separate, sectional pieces that are all held together by large, threaded rods.

Configuration of an AP1610 BB4 multistage pump

Figure: Configuration of an AP1610 BB4 multistage pump

Pump manufacturers configure an API610 BB4 multistage pump for high-performance metrics such as a high flow capacity of up to 500 cubic meters per hour, a lift range of about 1500M, a wide working temperature range between -20 and 200o Celsius, and a design pressure exceeding 10 Mpa. The pump seal system is designed per the API610 sorts of seals, such as packing, and mechanical seals, which are tailored for various working conditions. An API610 BB4 multistage pump is suitable for a wide range of applications, including the transfer of clean water (impurity less than 1%) and corrosive liquids whose physical features are similar to clean water according to different raw materials

Components of an AP1610 BB4 multistage pump


Name of component




-The purpose of the axle is to transmit the drive torque to the impellers to centrifugal pumps

– It is usually made of stainless steel


Bearing body (part a)

-It supports the pump axle and the impeller on one end.


Adjust the shalt sleeve

For adjusting the shalt sleeve


Shaft sleeves

– They are usually mounted over the shaft and shaft assembly to protect it in a corrosive environment

-They protect the shaft from packing wear at the stuffing box

– They also protect the running surface of the shaft seal or in-contact surfaces from damage or abrasive wear


Suction segment

-Allows in the fluid through when the first stage impeller rotates, creating a vacuum inside the suction casing


Seal flush piping

-Allows for the circulation of fluid to or from the seal chamber to maintain efficient lubrication and adequate temperature, pressure, temperature, and solids management

-it thus creates an ideal working environment for the seals that eliminate tear and wear and prolongs the service life.


Primary guide vane

They guide the liquid out of the first stage chamber by centrifugal force.



-To impart kinetic energy to the fluid, leading to an increase in fluid flow rate and pressure for displacement through the Pump


Spit out section

-To allow easy access to the internal component of the Pump


Balance disc component

-To offset the unbalanced axial thrust of the fluid pushing on portions of the shaft


Pump casing

-Includes the suction, discharge and stage casings

-Can be cast or forged; the Forged type has better quality than the casting type of casing for a high-pressure pump like this one

-The pump casing houses the first-stage and second-stage impellers

-It converts the kinetic energy or velocity head from the impeller into the pressure head

-It guides the flow to the outlet

-It creates a pressure boundary for the pumped liquid


Padding/ mechanical seal

-Acts as a check valve and a slider bearing

Preventing the fluid under pressure from leaking out of the pump or air from being drawn into the pump when under vacuum conditions.


Packing gland/seal

-Packing seals use rope-like materials that wrap around the shaft of a pump

-They are used for filling the dead space and minimizing fluid loss

-They are replaced more often than mechanical seals

-However, packing seals are the most economical choice of sealing solutions


Bearing body parts (b)

It supports the pump axle and the impeller on one end.


Jilt hydrosphere

How does an AP1610 BB4 multistage pump work?

The pump is run using an electric motor via a flexible coupling. When the pump is powered, torque is transferred from the motor shaft to the pump shaft via a flexible coupling, thereby setting the impellers installed on the pump shaft into rotary motion. The pump has two stages, each with a different impeller design. As the impellers rotate, a vacuum is created, allowing the fluid to draw into the pump. The transfer fluid is first drawn from the sump into the eye of the first-stage impeller.

When the fluid strikes the impeller’s vanes, some kinetic energy is imparted, leading to an increase in fluid velocity. The centrifugal force acting on the impeller discharges the fluid from the impeller’s vanes into the diffuser. In the diffuser, the pressure of the fluid increases due to a reduction in speed and the guide vanes then directs the liquid out of the first-stage chamber into the second-stage chamber by centrifugal force. In the second stage chamber, the impeller imparts more kinetic energy to the fluid, further elevating the fluid pressure before it exits the pump and transfers to the desired location via the delivery pipe network.

Working of API610 BB4 multistage pump

Figure: Working of API610 BB4 multistage pump

Applications of an AP1610 BB4 multistage pump

AP1610 BB4 multistage pumps are extensively used in thermal Power plants, refineries, petrochemical engineering, coal chemical industries, cooling or heating System, wastewater treatment plants, cement plant etc. Typical uses of this pump include:

  • AP1610 BB4 multistage pumps are used for Low pressure (LP) and high-pressure (HP) boiler feed.
  • They used for reverse osmosis.
  • They are used as MP boiler feed pump.
  • They are used for domestic and industrial water supply.
  • They are used as feed water pump.
  • They are also used as water supply pumps in commercial buildings.
  • API 1610 BB4 multistage pumps are also used to transfer all kinds of corrosive and neutral liquid mediums with physical features similar to clean water.
  • They are also perfect for the transfer of clean water with impurities of less than one percent
  • They are also suitable for Hydrofining & hydro treatment units.
  • API 1610 BB4 multistage pumps also applied in pipeline transportation and water injection in oil field.

Advantages of API610 BB4 multistage pump

  • API610 BB4 multistage pumps have a long service life of up to 20 years.
  • They can present interrupted operations for more than three years if used as instructed by API610 BB4 multistage pump manufacturers.
  • Their flexible coupling accommodates minor angular and parallel misalignment and also reduces pump vibration.
  • API610 BB4 multistage pumps have replaceable wear rings to reduce wear of casing and axial running clearances
  • They are also highly reliable due to the use of standardized baseplates, which help to ensure maximal alignment of the pump and drive shafts.
  • They can pump liquids over long distances.
  • They have High-performance stability.
  • API610 BB4 multistage pumps also have high-pressure capabilities.
  • They also have high hydraulic efficiency.
  • They also have low running costs because they require little maintenance.
  • They are Suitable for a wide range of temperature applications (ranging from -20 to 200oC).
  • They require smaller cast impeller size because the head per stage is small.

Disadvantages of API610 BB4 multistage Pump

  • API610 BB4 multistage pumps have high initial installation and maintenance cost.
  • They are also complex to design and costly to acquire.
  • They are hard to maintain when they break down. The maintenance operation is quite difficult because the pump contains many parts inside the casing that need maintenance and service.
  • The components inside the pump casing can be difficult to access.

Troubleshooting API610 BB4 multistage pump

Zero flow after Pump start-up

  • The suction lift is too high. Make sure there is no obstruction at the pump inlet. Raise the level of liquid in the suction tank or lower the pump.
  • There is air in the Pump or Suction Pipework. Make sure that the pump and pipe network are filled with the liquid to be transported.
  • The pump is operating in reverse. Check that the motor rotates in the direction indicated by the pump manufacturer. If not reverse the motor polarities.
  • Either Pump impellers, filter or check valve, is clogged with impurities. Inspect the pump impeller filter or check valve and clean them if it is necessary.

The pump is vibrating excessively

  • Some parts of the pump are unbalanced. Inspect and rebalance pump parts.
  • Large misalignment between the pump shaft and the motor shaft. Inspect and realign the shafts.
  • Worn out bearing or impeller. Inspect the bearing and impeller for wear and replace them if it is necessary.
  • The suction or discharge pipe is not supported. Ensure the suction and discharge pipe are adequately supported and tightened according to the pump manufacturer’s installation guide.

Pump noise level is very high

  • The pump is working in cavitation. Fully open the inlet valve and correct suction line.
  • Pump working outside duty range. Ensure that the pump operating within duty point.
  • There is air in the liquid. Submerge suction pipe to ensure vortexes are not created on the surface of the liquid.

The pump overheats during the operation

  • Poor coupling alignment. Ensure the pump is properly aligned and coupling rubber is in place.
  • The pump grease is contaminated grease. Clean oil or use the type of grease specified by the API610 BB4 multistage pump manufacturer.
  • Excess grease. Drain the excess grease.
  • The bearing covers are too tight. Loosen the bearing covers following the pump manufacturer’s guide on the required bolt torque.


An API610 BB4 multistage pump is a type of centrifugal pump with a “between-bearing” type 4 design, two chambers, and configured to meet the standards provided in API 610 10th edition. It can also be described as a radially split single casing, multistage pump with bearings at either end of the rotating assembly. The pump is mounted to a baseplate and driven by a motor via a flexible coupling. It is sometimes also referred to as a segmental-ring pump or ring-section pump.

Pump manufacturers configure the pump with two Impellers of different designs, which are installed and rotated on the same shaft but in separate chambers. When the motor is started, the impellers rotate and create a vacuum inside the pump. The transfer fluid is first drawn into the first chamber, where a first-stage impeller imparts it with some kinetic energy by accelerating its speed and directing it into the diffuser. In the diffuser, the kinetic energy is converted into pressure energy. The fluid is then directed into the second chamber by guide vanes, where the second-stage impeller further increases the fluid pressure and pumps it to the required destination via the piping network. API 610 BB4 multistage pump manufacturers design the pump to fit various applications in many industries, including thermal Power plants, Refineries, Petrochemical engineering, Coal and chemical industries, Cooling or Heating Systems, wastewater treatment, cement plant etc. Advantages of these pumps are high strength, highly durable, versatile, high total head, high pressure energy, highly resistant to high temperatures, and high hydraulic efficiency.