The American Petroleum Institute (API) maintains equipment standards for the oil, gas, and petrochemical industries. Centrifugal and rotary positive displacement pumps in these industries must comply with API 610.

While the latest edition of API 610 provides clear guidelines, new customers often over-spec their pumps. With a little knowledge, this can be avoided.


Whether installing a new pump or replacing an old one, it is important to follow the instructions. These will help ensure the system is installed properly and can operate safely. A quality concrete pump foundation is also a good idea, as this will help ensure the API pumps are not moving during operation.

API pumps are typically used in oil production and pipeline applications but can also be found in other industries. They are designed to handle much higher temperatures and pressures than ANSI process pumps, which makes them perfect for the petrochemical industry. Additionally, they can take flammable, toxic, hazardous, or explosive fluids.

These pumps are centrifugal and come in different forms and configurations, depending on their application. For example, they can be overhung or between bearings (BB). Generally, a centrifugal API process pump has a standardized casing based on the 610 standards set by the American Petroleum Institute. This standard defines how a pump should be constructed and designed to operate under critical working conditions. It also includes guidelines for controlling emissions and safely treating liquids that could cause environmental damage. This makes API process pumps the right choice for more challenging applications in oil refineries.



API pumps are used in applications with higher pressures and temperatures than those allowed by ANSI standards. They are commonly utilized in classified locations requiring extra safety to prevent toxic or explosive vapors from escaping into the air.

Centrifugal API pumps are often found in oil and gas industries, as well as other types of industrial processing. They are used to handle hydrocarbons like crude oil, refined fuels, and aromatic hydrocarbons, and non-hydrocarbon fluids like sulfuric and hydrofluoric acids, caustics, and solvents. They can also be used for power generation.

The most common API pump standard is the API 610 for general refinery service. The 610 specifications recommend that API process pumps be overhung, between-bearing units with an end suction design. They are typically equipped with an electric motor rated to a Class 1, Division 2 (explosive vapors might be present) or better.

API 610 / ISO 13709 pumps include several styles and configurations, including API OH1 centerline mounted units, which feature a spacer coupling that keeps misalignment angles low and an integral bearing housing to absorb the forces imposed on the shaft. Other models include a horizontal end suction API OH2 unit with a separate bearing bracket. All of these can be supplied with a full range of options and features to suit the requirements of any industry or application.



Unlike ANSI pumps, API Pumps are specifically designed for oil refinery service. They meet a higher performance standard and can handle more rigorous working conditions and environmental issues. This makes them superior for the most demanding applications, including high-pressure, high-temperature, or chemically aggressive services.

These centrifugal pumps are characterized by their construction and design. While ANSI pumps are dimensionally-based, the API standards center on the pump’s construction and ability to handle high temperatures and pressures. They are available in several different styles and sizes to meet the demands of your plant.

Depending on the application, the API pump can be categorized into three types: Overhung, Between Bearing, and Vertically Suspended. Overhung API pumps have a foot-mounted base plate design that a flexible coupling can drive. This type of pump is most common for petrochemical, petroleum, and natural gas applications.

Between-bearing API pumps are a multistage, axially split casing design that can be driven by a single bearing or multiple. This is a great option for applications where space is limited, and power output is important. These pumps are often used in classified locations where explosive vapors may be present and can also use explosion-proof motors. They can be a more expensive option than Overhung API pumps but offer a wide range of performance features to meet the unique needs of your refinery.


The American Petroleum Institute (API) maintains over 500 standards and recommended practices for equipment in the Oil and gas industry. Unlike ANSI process pumps, API Pumps are designed with specific applications in mind. They are often heavier in construction to withstand the temperatures and pressures required for their application. Differences in casings, bearing housings, mounting feet, and back cover arrangements also allow them to control emissions, be more efficient, and handle fluids prone to environmental damage.

Generally speaking, API pumps are used in oil refineries and petrochemical industries. While API 610 specifies the general requirements for centrifugal pumps in these types of services, many manufacturers and engineering firms create overlaid specifications to fit the particular application better.

When repairing an API pump, the first step is to shut down the unit. Then, open the suction valve to empty the liquid from the pump. Once the pump has reached capacity, close the vent valve and remove the drain plug. Next, relubricate the bearings and replace the volute seal.