12/17/2011
Q. I sometimes see reference to API pumps. What is special about an API pump?
A. API pumps are built to conform to specifications published by the American Petroleum Institute. There are several different specifications, but the most commonly used is ANSI/API 610 Centrifugal Pumps for Petroleum, Petrochemical, and Natural Gas Industries. Several different centrifugal pump types are described in this specification, but the overhung, end suction type is most commonly used.
The primary concern for such pumps is to safely handle hot oil at about 800 deg F. A few of the significant requirements of this specification are as follows:
- Basic design includes casing design and support. The casing is supported at its centerline so that there is minimal effect on pump/motor alignment by changes in operating temperature.
- Materials of the casing are selected to handle the liquid to be pumped. Cast iron is avoided because of the danger of failure due to external shock.
- Impeller wearing ring clearance is sufficient to avoid galling and seizure since steel or stainless steel wearing rings are commonly used.
- Impeller performance characteristics must show a steady increasing total head curve as rate of flow is decreased to shut off.
- Inspection and testing is also specified.
Other pump related standards published by API include the following:
- API 674 Positive Displacement Pumps—Reciprocating
- API 675 Positive Displacement Pumps—Controlled Volume
- API 676 Positive Displacement Pumps—Rotary
- API 682 Shaft Sealing Systems for Centrifugal and Rotary Pumps
- API 685 Sealless Centrifugal Pumps for Petroleum, Heavy Duty Chemical, and Gas Industry Service
