Not all pumps are created equal.  Or at least that’s what they say about centrifugal pumps.  The American National Standards Institute (ANSI) has deemed a standard which is otherwise known as an ANSI process pump.


This type of pump was introduced for the first time in 1924 which was used exclusively for chemical processing.  Before ANSI pumps, the North American marketplace was dominated by Ingersoll Rand and Worthington, they were later credited with the development of the first modern pump. In fact, their pump serial #2 is in the Smithsonian museum for its historical significance.

Before ANSI pumps, each pump was uniquely plumbed.  Changing the piping was time-consuming and expensive.  Each company used their own specifications making pumps different every time they were made.  Replacement parts and delivery times were getting out of hand, they were nearly non-existent.

A standard needed to streamline piping across the board.  Manufacturers were turning into McGuyver in that they had to come up with creative ways to repair their pumps.  The replacement parts were not coming fast enough.  Pump companies resisted the effort to standardize pumps.  They did not want to monopolize the industry with one standard.  In the 1950’s, it was too late.  An early effort called the American Voluntary Standard took hold of standardizing the pump.  They were later named the American National Standards Institute.  They spearheaded the effort in what we know now as the ANSI process pump.

Across the board, manufacturers are required to follow certain specifications to call their product an ANSI process pump.  For the most part, the centrifugal pump has a horizontal, end suction, a single stage that is comparable in size.


The American Society of Mechanical Engineers (ASME) standard includes dimensional interchangeability requirements and certain design features to facilitate installation and maintenance and to enhance reliability and safety of B73.1 pumps.

The pumps are to have the same standard dimension designation from all sources of supply which are interchangeable with respect to mounting dimensions, size and location of suction and discharge nozzles, input shafts, baseplates, and foundation bolt holes.

ANSI process pumps are the exclusive choice for oil refinery applications since they meet the requirements of the American Petroleum Institute Standard 610 (API) for General Refinery Service.


ANSI process pumps are used across several industries.  They allow the buyers to switch pumps without having to change or redesign the motor attachment.  Since all ANSI pumps are built to the same specifications, fitting a new pump into your setup will not take a team of engineers.  They are all the same size.  The only difference is the manufacturer and brand.  Companies like Grunfos make great quality Peerless ANSI B73.1 Pumps that are durable.

Still, do your research before replacing a pump.  They are all the same size, however, the individual parts may not be interchangeable between brands.  The phrase “fits like a glove” does not apply 100% when it comes to ANSI process pumps.


ANSI process pumps are best for transferring water and other thin liquids.  Depending on their impeller, they can move heavier liquids.  Technology has improved over the years making it easier for oil companies to implement ANSI process pumps for other uses.

The most important feature of the pump is it is the only one that meets the standard.  Oil refineries are confined to this choice due to regulation along with other organizations who want to maintain a stringent protocol.   ANSI process pumps can handle higher temperatures and pressure applications that are more aggressive which is common in oil refineries.


One of the advantages of the ANSI process pump is also one of its disadvantages.  Because it is the standard especially in oil refineries, you are limited to your choices.  Put all of those cool, fancy pumps available at manufacturers like American-Marsh or Dickow on your wish list. There is a huge array of centrifugal pumps available but if you are restricted by regulation, you have to follow protocol.

Both companies do offer ANSI process pump solutions that are durable and available through a distributor like ESP.

Like any equipment at your facility, these pumps require some sort of maintenance.  ANSI process pumps require that you prime prior to start up.  The oil from your refinery is not enough to keep the impellers moving.  Performing the proper maintenance will keep your pump working for several years.

ANSI process pumps do get into trouble when they are mixed with saltwater.  It’s already a problem when it is mixed with the oil.  The saltwater needs to be removed before moving through the ANSI process pump.  It can cause corrosion.  This poses a challenge because oil refineries are known to have offshore drilling sites.

As mentioned before, ANSI process pumps have a hard time moving heavier liquids.  Check out the specifications before implementing the pump at your business.


Some manufacturers like EBARA are one of the leaders in offering only parts for the ANSI process pump.  They have learned that the whole pump does not generate profits as much as the parts.  Through wear and tear, it is inevitable that the part will go bad before the pump itself.

Over time, an ANSI Process pump is known to have parts from several manufacturers.  It is virtually unrecognizable in comparison to when it was originally purchased.  Some manufacturers even opt to buy all of the parts to the pump and put it together instead of getting the pump all at once.  Competition to sell the parts is extremely high thus making the prices lower than buying the pump at a premium.

The ANSI process pump is the standard in industries such as oil.  They are easy to repair because they do not need to be torn apart in order to access the motor.  The ANSI process pump started as a solution for manufacturers to benefit from buying custom piping for their businesses.  Their regulated size is both a pro and a con as it limits manufacturers in their choices.  In the end, ANSI process pumps provide a solution in standardizing sizing for easy replacement.

Contact ESP today for more information on adding ANSI process pumps to your business!