In oil & gas, petrochemical, refining, and other process industries, pumps are often required to handle high temperatures, high pressures, flammable or hazardous liquids, corrosive media, and continuous-duty operation.

Under these conditions, ordinary industrial pumps may not provide the mechanical robustness, sealing arrangements, reliability, and documentation required for critical process services.

This is where API 610 centrifugal pumps become important.

API 610 is a major industry standard developed for centrifugal pumps used in petroleum, petrochemical, and natural gas applications. The standard provides requirements that address pump design, construction, materials, mechanical integrity, testing, and related equipment considerations.

This guide explains what an API 610 pump is, the major API 610 pump configurations, how these pumps are selected, where they are used, and what engineers should consider when specifying an API 610 centrifugal pump.

 

 

1. What Does API 610 Mean?

API stands for the American Petroleum Institute.

API 610 is the API standard covering centrifugal pumps for petroleum, petrochemical, and natural gas industries. The American Petroleum Institute currently lists API Standard 610 in its standards catalog, and its standards plan records the 13th edition dated June 29, 2026.

Unlike a general-purpose pump specification, API 610 addresses the requirements associated with demanding process applications where pump reliability, mechanical integrity, maintainability, and controlled manufacturing and testing are especially important.

An API 610 pump is therefore best understood as a centrifugal pump engineered and specified to meet the applicable requirements of API 610 and the project's technical specification.

API 610 should not be confused with a particular hydraulic principle. Most API 610 pumps are still based on conventional centrifugal pump technology. What differentiates them is the engineering, mechanical design, materials, inspection, testing, and application requirements associated with the standard.

 

2. Why Are API 610 Pumps Important in Oil & Gas Applications?

Oil & gas and petrochemical plants contain many services where pump failure can lead to:

Production losses

Unplanned shutdowns

Product contamination

Hazardous fluid leakage

Fire or environmental risks

Expensive maintenance

Reduced plant availability

For this reason, process pumps used in critical services must be designed with reliability and maintainability in mind.

Typical fluids handled by process pumps may include:

Crude oil

Refined petroleum products

Hydrocarbons

Condensate

Hot process fluids

Chemical solutions

Cooling or process water

Corrosive liquids

Depending on the service, the pump may need to operate at elevated temperature, significant discharge pressure, or demanding suction conditions.

API 610 provides a structured technical basis for specifying and manufacturing these centrifugal pumps.

The goal is not simply to obtain higher pressure. The objective is to achieve reliable hydraulic and mechanical performance over the required operating range and service life.

 

3. API 610 Pump vs. Standard Industrial Centrifugal Pump

One of the most common misconceptions is that an API 610 pump is simply a "stronger centrifugal pump."

In reality, the difference is broader.

An API 610 project specification may place greater emphasis on:

Mechanical integrity

The shaft, casing, bearings, rotor, coupling, and other components must be designed appropriately for the specified operating conditions.

Rotor dynamics

High-speed or critical-service pumps require careful consideration of shaft stiffness, balance, natural frequencies, and overall rotor behavior.

Sealing

The sealing system must be suitable for the process fluid, operating temperature, pressure, and safety requirements.

Bearing and lubrication systems

Bearing arrangements and lubrication systems need to be appropriate for continuous process operation.

Maintainability

Pump construction should allow inspection, repair, and component replacement with minimum unnecessary downtime.

Inspection and testing

API 610 projects commonly involve detailed inspection, documentation, and performance testing requirements defined by the purchaser and applicable standard.

Therefore, selecting an API 610 pump is not simply a matter of matching flow and head.

 

4. Main API 610 Pump Configurations

API 610 includes several major centrifugal pump configurations. The appropriate configuration depends on the process conditions, flow rate, pressure, temperature, installation arrangement, and project requirements.

The major categories include:

4.1 OH - Overhung Pumps

In overhung pumps, the impeller is located on the overhung portion of the shaft relative to the bearing arrangement.

Common API 610 overhung configurations include:

OH1

OH2

OH3

OH4

OH5

OH6

OH7

The exact configuration depends on the mounting and drive arrangement.

Overhung pumps are widely considered for general process services where their hydraulic range and mechanical configuration are appropriate.

 

5. BB - Between-Bearings Pumps

Between-bearings pumps support the rotor between two bearings.

Typical API 610 configurations include:

BB1

BB2

BB3

BB4

BB5

These configurations are particularly relevant to demanding process services requiring high reliability, high head, large flow, or multistage hydraulic arrangements.

BB1 Pumps

BB1 pumps are typically associated with axially split, between-bearings, single-stage centrifugal pump designs.

They can be considered for applications requiring relatively high flow and process reliability.

BB2 Pumps

BB2 pumps are generally radially split, between-bearings, single-stage centrifugal pumps.

The radially split casing arrangement can be advantageous for certain high-temperature and high-pressure services.

BB3 Pumps

BB3 pumps are commonly associated with axially split, multistage, between-bearings centrifugal pumps.

They can be selected where several hydraulic stages are required to generate high head.

BB5 Pumps

BB5 pumps are radially split, multistage, between-bearings pumps, typically using a double-casing configuration.

This configuration is particularly relevant to high-pressure process services.

The exact pump configuration should always be selected against the API 610 edition, process data, and project specification rather than solely by pump type name.

 

6. VS - Vertically Suspended Pumps

VS pumps are designed with the pumping assembly vertically suspended.

Common categories include:

VS1

VS2

VS3

VS4

VS5

VS6

VS7

Vertical configurations may be considered when:

The pump must be installed in a tank or vessel

Available floor space is limited

The suction arrangement requires vertical installation

The process system requires a vertical suspended design

Different VS configurations have different hydraulic, structural, and installation arrangements.

The final selection depends heavily on the actual vessel, suction conditions, liquid properties, and required submergence.

 

7. Main Components of an API 610 Pump

Although API 610 pumps vary significantly by configuration, their main components generally include the following.

7.1 Pump Casing

The casing contains and guides the process fluid while withstanding the operating pressure and temperature.

Material selection depends on:

Fluid composition

Corrosiveness

Operating temperature

Design pressure

Mechanical requirements

For hazardous process fluids, casing integrity is a fundamental safety consideration.

7.2 Impeller

The impeller converts shaft power into hydraulic energy.

Its design determines major hydraulic performance parameters such as:

Flow rate

Head

Efficiency

NPSH characteristics

Power requirement

Depending on the pump configuration, the impeller may be:

Closed

Open

Single-stage

Multistage

7.3 Shaft

The shaft transmits torque from the driver to the impeller.

For process pumps, shaft design must consider:

Mechanical strength

Shaft deflection

Torsional loading

Critical speed

Corrosion

Fatigue

Seal requirements

A properly designed shaft contributes to stable operation and reduced vibration.

7.4 Bearings

Bearings support the rotating assembly and maintain proper rotor position.

Depending on the pump design, bearings may handle:

Radial loads

Axial loads

Combined loading

Lubrication arrangements must be selected according to operating speed, temperature, and service requirements.

7.5 Mechanical Seal

Mechanical seals are used to reduce leakage along the rotating shaft.

For oil & gas applications, seal selection is particularly important because the pumped medium may be:

Flammable

Toxic

Volatile

Corrosive

High-temperature

Seal arrangement and auxiliary systems should therefore be selected based on the actual process conditions and applicable project requirements.

7.6 Coupling and Baseplate

The coupling transfers power from the driver to the pump.

The baseplate supports the pump-driver assembly and helps maintain alignment.

Poor alignment can lead to:

Excessive vibration

Bearing damage

Coupling wear

Seal problems

Shaft damage

 

8. How Does an API 610 Centrifugal Pump Work?

The basic hydraulic principle remains the same as other centrifugal pumps.

Step 1: Fluid Enters the Pump

The process fluid enters through the suction nozzle.

The suction system must provide sufficient pressure to prevent undesirable cavitation.

Step 2: The Impeller Rotates

The driver rotates the shaft and impeller.

Mechanical energy is transferred to the process fluid.

Step 3: Fluid Gains Velocity and Energy

The rotating impeller accelerates the liquid and moves it toward the outer diameter.

Step 4: Velocity Is Converted Into Pressure

The hydraulic passage in the casing or diffuser converts part of the fluid velocity into pressure.

Step 5: Fluid Leaves the Pump

The pressurized fluid exits through the discharge nozzle and continues into the process system.

For a multistage pump, the process is repeated across multiple hydraulic stages, allowing significantly higher total head to be achieved.

 

9. Typical Applications of API 610 Pumps

API 610 centrifugal pumps can be applied to numerous services across the petroleum, petrochemical, and natural gas industries.

Typical applications include:

Refinery Processes

• Crude oil transfer
• Product transfer
• Hydrocarbon circulation
• Process feed
• Hot oil services

Petrochemical Plants

• Process liquid transfer
• Chemical circulation
• Intermediate product transfer
• Cooling and utility services

Oil & Gas Transportation

• Pipeline booster systems
• Terminal transfer
• Tank farm transfer
• Loading and unloading systems

LNG and Gas Processing

• Hydrocarbon liquid services
• Condensate handling
• Process circulation
• Utility systems

Offshore Applications

Vertical and horizontal process pump configurations may be used for:

• Produced water
• Process circulation
• Hydrocarbon transfer
• Utility services

The exact applicability depends on the fluid properties, operating conditions, pump configuration, and project specification.

 

10. Important Parameters for API 610 Pump Selection

Correct API 610 pump selection begins with accurate process data.

The key parameters include:

Flow Rate

Normally specified in:

m³/h

L/s

US gpm

Differential Head

Specified in:

m

ft

Operating Pressure

Both suction and discharge pressure should be evaluated.

Temperature

Temperature affects:

Material selection

Mechanical seal selection

Bearing and lubrication requirements

Vapor pressure

NPSH conditions

Fluid Properties

The pump manufacturer needs to know:

Density

Viscosity

Vapor pressure

Corrosiveness

Solids content

Toxicity or hazardous characteristics

NPSHA

Available NPSH must be carefully evaluated, especially for hot or volatile hydrocarbons.

Speed

Pump speed influences:

Hydraulic performance

NPSH

Power

Vibration

Rotor dynamics

Duty and Operating Range

The pump should not be selected solely according to a single rated point.

Engineers should also consider:

Minimum continuous flow

Normal operating point

Maximum operating point

Start-up conditions

Turndown requirements

Transient conditions

 

11. Why NPSH Is Critical in API 610 Applications

Cavitation is one of the major risks in centrifugal pump operation.

When the local pressure in the pump falls below the liquid vapor pressure, vapor bubbles may form. Their subsequent collapse can damage hydraulic and mechanical components.

Possible consequences include:

Noise

Vibration

Head loss

Flow instability

Impeller erosion

Bearing damage

Seal failure

The basic relationship to consider is:

NPSHA > NPSHR

However, the required engineering margin depends on the application, pump design, fluid properties, and project requirements.

For hydrocarbon services, NPSH analysis is especially important because many process liquids have relatively high vapor pressure.

 

12. API 610 Pump Mechanical Design Considerations

One of the reasons API 610 is important is that the standard addresses much more than basic hydraulic performance.

For a demanding project, engineers may need to evaluate:

Rotor Dynamics

The rotating assembly must operate reliably within the required speed range.

Shaft Deflection

Excessive shaft deflection can negatively affect:

Mechanical seals

Bearings

Couplings

Rotor stability

Critical Speed

Operating speed and critical speeds must be properly evaluated for the selected pump.

Bearing Loading

Radial and axial forces must remain within acceptable design limits.

Thermal Expansion

High-temperature process conditions may cause significant dimensional changes.

Casing Design

The casing must be suitable for the specified pressure, temperature, and fluid.

These factors distinguish a properly engineered process pump from a basic general-purpose centrifugal pump.

 

13. API 610 Pump Sealing and Auxiliary Systems

For hazardous services, the seal system can be as important as the pump itself.

Depending on the process conditions, the system may require appropriate:

Mechanical seal arrangements

Seal flush systems

Cooling systems

Quench systems

Barrier or buffer fluid systems

The proper configuration depends on:

Fluid properties

Temperature

Pressure

Volatility

Toxicity

Leakage requirements

Seal selection should therefore be performed together with the pump selection rather than treated as an afterthought.

 

14. Materials for API 610 Process Pumps

Material selection should be based on the actual operating environment.

Common engineering considerations include:

Corrosion resistance

Temperature resistance

Mechanical strength

Erosion resistance

Compatibility with the pumped medium

Possible materials may include various grades of:

Carbon steel

Stainless steel

Duplex stainless steel

Alloy steel

Other corrosion-resistant alloys

The correct material cannot be selected solely from the pump model. It should be determined from the fluid composition, temperature, pressure, corrosion characteristics, and project material specification.

 

15. Common API 610 Pump Operating Problems

Even a properly designed pump can experience problems when system conditions or operating practices are incorrect.

Low Discharge Pressure

Possible causes include:

• Incorrect pump speed
• Wrong rotation direction
• Insufficient suction conditions
• Excessive internal wear
• Damaged impeller
• Operation outside the performance range

Excessive Vibration

Possible causes include:

• Misalignment
• Rotor imbalance
• Bearing problems
• Cavitation
• Pipe strain
• Foundation issues
• Hydraulic instability

Mechanical Seal Leakage

Possible causes include:

• Incorrect seal selection
• Seal damage
• Shaft runout
• Misalignment
• Improper seal auxiliary conditions
• Excessive vibration

High Bearing Temperature

Possible causes include:

• Poor lubrication
• Incorrect lubricant
• Bearing wear
• Misalignment
• Excessive mechanical load
• Abnormal operating conditions

Troubleshooting should focus on identifying the root cause rather than simply replacing individual components.

 

16. API 610 Pump Maintenance

Preventive maintenance is essential for maintaining process pump reliability.

A typical maintenance program may include:

Daily or Routine Monitoring

Check:

Pressure

Flow

Bearing temperature

Vibration

Seal leakage

Lubrication condition

Motor current

Periodic Inspection

Inspect:

Mechanical seals

Bearings

Coupling

Shaft condition

Impeller

Wear components

Alignment

Performance Monitoring

Compare actual operating data with the original pump performance.

Changes in:

Flow

Head

Power consumption

Vibration

may indicate internal wear or changing system conditions.

Maintenance Records

Maintain records of:

Operating hours

Vibration trends

Seal replacement

Bearing replacement

Overhaul history

Performance data

Trend-based maintenance can identify developing problems before they cause a major shutdown.

 

17. How to Choose an API 610 Pump Manufacturer

Selecting the right manufacturer is as important as selecting the pump type.

When evaluating a supplier, consider:

Engineering Capability

Does the manufacturer understand:

Process pump design?

Hydraulic selection?

High-temperature services?

High-pressure applications?

NPSH analysis?

Material selection?

Manufacturing Capability

Evaluate:

Casting quality

Machining accuracy

Rotor balancing

Assembly control

Quality inspection

Testing Capability

Ask what testing and inspection documentation can be provided for the project.

Depending on the purchase specification, this may include:

Performance testing

Material documentation

Dimensional inspection

Balancing records

Pressure testing

Non-destructive examination

Inspection and test plans

After-Sales Support

For long-term industrial operation, spare parts, technical support, troubleshooting, and maintenance assistance are also important.

 

18. API 610 Does Not Mean Every Pump Is Automatically "API Certified"

This point is important for pump buyers.

There is a difference between:

"Designed / manufactured to meet API 610 requirements"

and

"API-certified product or manufacturer."

The actual certification status depends on the manufacturer, product, project, and applicable API certification program.

Therefore, purchasing teams should ask for specific supporting documentation rather than relying only on the phrase "API 610 pump."

Depending on the project, buyers may request:

API documentation

Technical datasheets

Inspection and test plans

Material certificates

Test reports

Quality documentation

Drawings

Performance curves

Manufacturing records

The applicable requirements should always be confirmed against the purchaser's technical specification.

 

19. API 610 Pump Selection Checklist

Before requesting a quotation, prepare the following information:

Parameter	Recommended Information
Pump Service	Process description
Fluid	Fluid name and composition
Flow Rate	Normal / Rated / Maximum
Differential Head	Normal / Rated
Suction Pressure	Operating value
Discharge Pressure	Operating value
Temperature	Normal / Maximum
Density	kg/m³
Viscosity	cP
Vapor Pressure	At operating temperature
NPSHA	Available NPSH
Pump Speed	rpm
Driver	Motor / Turbine
Power Supply	Voltage / Frequency
Installation	Horizontal / Vertical
Pump Configuration	OH / BB / VS
Seal Arrangement	Project requirement
Materials	Process-specific
Standards	API 610 edition / project specification
Duty	Continuous / intermittent
Area Classification	Hazardous area requirements

Providing complete information allows the pump manufacturer to recommend the correct hydraulic and mechanical configuration.

 

20. HNYB PUMPS: Industrial Centrifugal Pump Solutions for Process Applications

HNYB PUMPS is a professional Chinese manufacturer of industrial centrifugal pumps, serving water supply, petrochemical, oil & gas, chemical, mining, power, and other industrial applications.

Our product portfolio includes various centrifugal pump configurations, including:

Petrochemical process pumps

Horizontal centrifugal pumps

Horizontal multistage centrifugal pumps

High-pressure multistage pumps

Split case centrifugal pumps

Chemical centrifugal pumps

Vertical centrifugal pumps

Customized industrial pump systems

For demanding oil & gas and petrochemical applications, pump selection can be customized according to:

Flow

Head

Temperature

Pressure

Fluid properties

Materials

Sealing requirements

Installation configuration

Driver requirements

Project specifications

HNYB PUMPS focuses on combining hydraulic performance, mechanical reliability, material compatibility, and application-specific engineering to provide dependable pumping solutions for industrial projects.

For projects that specify API 610, customers should provide the applicable API 610 edition and project technical specification so that the pump design, inspection, testing, materials, and documentation can be evaluated against the actual purchasing requirements.

 

API 610 centrifugal pumps are designed for demanding process applications where reliability, mechanical integrity, maintainability, and controlled testing are important.

For oil & gas, refining, petrochemical, LNG, and other process industries, choosing the correct pump requires much more than selecting a pump based only on flow and head.

Engineers should evaluate:

Flow + Head + Temperature + Pressure + Fluid Properties + NPSH + Pump Configuration + Materials + Sealing + Driver + Project Specification

The correct combination of these factors helps ensure stable operation, reduced maintenance requirements, and improved plant availability.

HNYB PUMPS provides a range of industrial centrifugal pump solutions for demanding process applications. For API 610-related projects, we recommend evaluating the pump against the specific API 610 edition and purchaser's technical specification before finalizing the design or procurement.

Contact HNYB PUMPS with your process data and project requirements for a customized centrifugal pump recommendation.