API 610, Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries.
API 610 is the American Petroleum Institute standard governing centrifugal pumps in petroleum, petrochemical, and natural gas service. It defines pump types by configuration, OH overhung, BB between-bearings, VS vertically-suspended, minimum design and construction requirements, allowable operating regions on the pump curve, materials of construction selection rules, vibration and bearing temperature limits, and the datasheet form used to specify pumps. The current edition is API 610 12th edition, 2021. ISO 13709 is the identical international version.
What API 610, Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries means.
API 610 emerged from the operating reality of refineries and petrochemical plants where pump failures dominated unplanned downtime through the 1960s and 1970s. The standard codified what major operators had learned individually. Minimum shaft stiffness, bearing housing rigidity, casing material selection per service, and the operating envelope inside which a centrifugal pump achieves the API-stated minimum mean time between repair of three years. The 12th edition expanded the seal-plan reference to API 682 4th edition, tightened vibration acceptance to ISO 10816-7, and added explicit requirements for variable-speed operation and condition monitoring instrumentation. Pumps purchased to API 610 are universally specified in oil and gas, refining, petrochemicals, and increasingly in hydrogen and renewable-fuels facilities. The datasheet form is the bid document and the lifetime asset record.
What pump types does API 610 cover.
API 610 defines five major pump-type families. OH, overhung pumps mount the impeller on an extended shaft with no support bearing between the impeller and the driver. OH1 is foot-mounted, OH2 is centerline-mounted, OH3 is vertical inline. BB, between-bearings pumps support the rotor between two radial bearings. BB1 is axially split single-stage, BB2 is radially split single-stage, BB3 and BB4 are multi-stage between-bearings, BB5 is barrel-cased multi-stage. VS, vertical-suspended pumps hang from a discharge head over a sump or in a barrel. VS1 through VS7 cover specific column, bowl, and bearing configurations. SP, submersible pumps mount the motor below the process liquid. The type selection drives casing pressure rating, materials availability, and the achievable head per stage.
What does an API 610 datasheet carry.
The API 610 datasheet is structured into operating conditions, capacity at rated, normal, minimum continuous stable flow, and BEP, site and utility conditions, pump construction, casing, impeller, shaft, wear-rings materials, bearing arrangement, seal arrangement, referencing an API 682 seal plan, driver coupling and baseplate, lubrication, instrumentation, inspection and testing requirements, and a list of vendor data documents. The form is structured so two vendors bidding the same service can be compared field by field. Vendor-supplied performance curves at the rated and BEP points back the bid. Site conditions, elevation, atmospheric pressure, ambient temperature drive the NPSHa calculation that pairs with the vendor's NPSHr.
What changed in the 12th edition.
The 12th edition, 2021 increased the minimum efficiency expectations through alignment with the ASME PTC 8.2 efficiency test code, expanded the seal-plan selection guidance to align with API 682 4th edition, made variable-speed-driven pumps a first-class case, rather than an exception, and tightened the acceptable vibration range under ISO 10816-7. Condition-monitoring instrumentation, bearing-temperature RTDs, seal-leakage detection, vibration probes on certain pump types moved from optional to standard. The datasheet form expanded by approximately 15% to accommodate the new fields.
Worked example, reading an API 610 type code.
A pump datasheet carries the type BB5. Break it into its two parts. BB places it in the between bearings category, so the impeller or impellers sit between two bearing housings rather than overhung from one. The 5 is the configuration within that category: radially split, multistage, double casing, which is the barrel pump. From those two facts the rest of the datasheet becomes predictable. A barrel pump is bought for high discharge pressure, so the casing rating, the seal plan and the baseplate will all be at the heavy end. It is radially split, so the inner assembly is withdrawn axially and the maintenance access required is the length of the pump rather than the width. It is multistage, so the datasheet should carry a stage count and the head per stage, and the minimum continuous stable flow will matter more than it does on a single stage pump. Compare that with OH2 on the same sheet set: overhung, single stage, centreline mounted, which is the standard refinery pump for hot hydrocarbon service, and a completely different item to install, foundation and maintain.
API 610 pump type codes, the full Table 1 set
API 610 12th edition, identical to ISO 13709, groups centrifugal pumps into three type categories. The code on a datasheet is the pump's configuration, not its duty.
| Code | Category | Configuration | Typical service |
|---|---|---|---|
| OH1 | Overhung | Foot mounted, single stage, flexible coupling | General service where the casing is not on the pump centreline |
| OH2 | Overhung | Centreline mounted, single stage, flexible coupling | The refinery workhorse; hot hydrocarbon service |
| OH3 | Overhung | Vertical in-line with a separate bearing bracket | In-line duty where floor space is tight |
| OH4 | Overhung | Vertical in-line, rigidly coupled | In-line duty, moderate conditions |
| OH5 | Overhung | Vertical in-line, close coupled | In-line duty, lighter conditions |
| OH6 | Overhung | High speed, integral gear driven | High head at low flow |
| BB1 | Between bearings | Axially split casing, one or two stages | High flow, moderate head; water and light hydrocarbon transfer |
| BB2 | Between bearings | Radially split casing, one or two stages | High pressure or high temperature duty |
| BB3 | Between bearings | Axially split casing, multistage | Pipeline and boiler feed at moderate pressure |
| BB4 | Between bearings | Radially split, multistage, single casing | Higher pressure multistage duty |
| BB5 | Between bearings | Radially split, multistage, double casing, the barrel pump | Boiler feed, injection, and the highest pressure duties |
| VS1 | Vertically suspended | Diffuser, wet pit, discharge through the column | Deep well and cooling water lift |
| VS2 | Vertically suspended | Volute, wet pit, discharge through the column | Wet pit service where a volute suits the duty |
| VS3 | Vertically suspended | Axial flow, wet pit, discharge through the column | Very high flow at very low head |
| VS4 | Vertically suspended | Line shaft driven sump pump | Sumps and drains |
| VS5 | Vertically suspended | Cantilever sump pump, no submerged bearing | Sumps carrying solids or intermittent liquid level |
| VS6 | Vertically suspended | Diffuser, double casing, the can pump | Low NPSH available duty, condensate and light hydrocarbon |
| VS7 | Vertically suspended | Volute, double casing | Low NPSH available duty where a volute suits the curve |
Operating region limits API 610 sets on the pump curve
These are the standard's own limits on where a pump may be selected to run, expressed against its best efficiency point (BEP).
| Term | Definition in the standard | Why it constrains the selection |
|---|---|---|
| Best efficiency point, BEP | The flow at which the pump is most efficient at the rated impeller diameter | Every other limit is defined relative to it |
| Preferred operating region, POR | 70 to 120 percent of BEP flow | The rated point is expected to sit inside this band |
| Allowable operating region, AOR | Set by the vendor, bounded by vibration, temperature rise, NPSH and thrust | The pump may run here, with higher vibration allowed than in the POR |
| Rated point | The duty the datasheet buys | The standard expects it between 80 and 110 percent of BEP |
| Head rise to shutoff | A continuously rising curve from rated flow back to zero flow | The standard asks for a rise of at least 10 percent for stable parallel operation |
| Minimum continuous stable flow | The lowest flow at which the pump runs without unacceptable vibration | Sets the size of the minimum flow recycle and its control valve |
Common questions
Is API 610 the same as ISO 13709.
What is the difference between API 610 and API 685.
Does API 610 apply to water-service pumps.
What is the typical lead time on an API 610 pump.
Get the equipment list template.
Vessels, pumps and exchangers with duty, service and the drawing each was read from. Plain .xlsx.