There’s an acronym for just about everything. Whether it’s ASME, ANSI or API, you should know the difference. In this post, we’ll describe what API pump standard is, and how it differs from the ANSI pump standard.
API Pump Standard – Defined
American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industries. API focuses on developing petroleum and petrochemical equipment and operating standards. API maintains more than 500 standards and recommended practices related to everything from drill bits to environmental protection in this industry.
In terms of pumping equipment, centrifugal and rotary positive displacement pumps used in petrochemical, gas, and petroleum industries must satisfy the requirements of the American Petroleum Institute Standard 610 for General Refinery Service.
Whereas ANSI standards refer to dimensional standards, API’s standard refers to the pump’s construction, design, and ability to handle high temperatures and pressures.
API pumps are considered to be heavier duty than ANSI pumps. Differences in casings, bearing housings, mounting feet, and back cover arrangements allow API pumps to control emissions, and be more efficient and reliable in the recommended applications.
Casings - API pump casings are sometimes built in the single volute design, but more commonly built in the double volute design to reduce thrust loads around the impeller and shaft. They are also built to withstand higher temperatures and pressures, and more capable of handling fluids that are prone to cause environmental damage.
Mounting Feet – Since API pumps can be intended for high temperature applications, the mounting feet must accommodate the expected expansion. An ANSI pump will have mounting feet projecting from the underside of the casing, and bolted to the baseplate. Conversely, an API centrifugal pump will be mounted on the horizontal centerline of the casing, not the bottom. The feet project from the sides of the casing, and bolt to pedestals that rise from the baseplate. When expansion occurs, the mounting feet exert minimal amounts of stress on the casing above and below the pump’s centerline.
Bearing Housing – Bearing housings for API pumps must be of more robust construction. They also must house a means of cooling the bearings, typically done with a cooling jackets that deliver a greater amount of cooling water.
Back Cover Arrangement – In the petrochemical, gas, and petroleum industries, the EPA demands that emissions are controlled. The ANSI back cover arrangement has a gap between the mating faces of the frame adaptor and the pump casing, allowing for dangerous emissions to escape. The API design however, forms a tighter seal with a compression gasket with metal to metal fits. This helps to better manage emissions.
Not being clear on the benefits of API vs. ANSI can cause people to select the less expensive ANSI when the application demands API. Be sure that you do your research and talk to an engineer about the details of your process. They will be able to ensure you select the pump you need for long lasting reliability.
Not sure which pump you need for your process? Ask us about it! We gladly provide technical assistance to businesses and municipalities in Wisconsin and upper Michigan.