Reference profile
- Designation
- API 610
- Title
- Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries
- Issuing body
- American Petroleum Institute (API)
- Current edition
- 12th Edition (January 2021 / ISO 13709 Equivalent)
- Status
- Active; premier global standard for heavy-duty centrifugal process pumps in petroleum industries.
- Category
- Centrifugal Process Pump Standard
Overview
API Standard 610 (ISO 13709) specifies requirements for centrifugal pumps, including pumps running in reverse as hydraulic power recovery turbines, for use in petroleum, petrochemical, and natural gas process industries.
API 610 pumps are engineered for maximum operational reliability, a minimum 3-year continuous uninterrupted service life, high tolerance to external nozzle loads, and zero-leakage safety when handling flammable or toxic hydrocarbons.
Scope & Applicability
Covers
- Pump classification & structural types: Overhung (OH1 to OH6), Between Bearings (BB1 to BB5), and Vertically Suspended (VS1 to VS7).
- Mechanical construction requirements: Centerline-mounted casings, heavy-duty cast steel bearing housings, shaft stiffness limits, and dynamic balancing (ISO 1940 Grade G2.5).
- Mechanical seal chamber dimensions & integration with API 682 seal systems and flush plans.
- Nozzle load allowances: Designed to withstand at least 2x the external piping forces and moments permitted by ANSI/ISO general industry pumps.
- Testing mandates: Hydrostatic testing (1.5x MAWP), hydrodynamic performance testing, NPSH margin testing, and vibration spectrum analysis.
Does NOT cover (exclusions)
- Positive displacement pumps (reciprocating or rotary)—covered by API 674, API 675, or API 676.
- General commercial water or non-hazardous chemical pumps—refer to ISO 5199 or ANSI/ASME B73.1.
- Detailed mechanical seal design and piping plan selection—refer to API 682.
- In-service pump repair and overhaul procedures—refer to API 687 and vendor manuals.
Key Requirements
Pump Type Selection (OH2, BB2, BB5, VS6)
- OH2 (Centerline-Mounted Overhung): Most widely used single-stage pump in refineries for temperatures > 177°C (350°F) or high nozzle loads. Centerline support maintains shaft alignment during thermal expansion.
- BB2 (Between Bearings 1 or 2 Stage): Ideal for high flow, medium pressure services where rotor is supported at both ends for maximum dynamic stability.
- BB5 (Double-Casing Barrel Pump): Designed for extreme high-pressure / high-temperature services (e.g., boiler feed, reactor charge) featuring an inner casing enclosed in a heavy outer forged pressure barrel.
- VS6 (Double-Casing Vertical Can): Used for low NPSHa or volatile liquid services (LPG, NGL, LNG) where the pump is submerged in a suction barrel.
Mechanical & Structural Features
- Bearing Housings: Steel or ductile iron construction required (cast iron prohibited for hydrocarbon service). Must include constant-level oilers, metallic labyrinth seals, and vibration probe taps.
- Shaft Stiffness & Deflection: Shaft diameter must limit maximum radial deflection at the primary seal faces to 0.05 mm (0.002 inches) under all operating conditions.
Hydraulic Performance & Operating Regions
- Operating Region Limits: The rated point must fall within the Preferred Operating Region (POR: 70% to 120% of BEP). Operation in the Allowable Operating Region (AOR) is permitted for transient conditions.
- NPSH Margin: NPSHA must exceed NPSH3 by at least 0.6 m (2.0 ft) or a 10% to 20% margin depending on operating temperature and hydrocarbon service.
Inspection & Hydrostatic Testing
- Hydrostatic Test: All pressure-retaining casings must undergo hydrostatic testing at a minimum of 1.5x MAWP for at least 30 minutes.
- Performance Testing: Certified shop performance test (head, flow, power, efficiency) and vibration FFT spectrum analysis are mandatory.
Technical Details
Shaft Deflection Formula Limit: Maximum dynamic shaft deflection under radial thrust load at the seal chamber faces is restricted to 0.05 mm (0.002 inches) to prevent mechanical seal face leakage.
Vibration Acceptance Criteria: Overall vibration velocity for OH2/OH3 pumps must not exceed 3.0 mm/s RMS (unfiltered) and 2.0 mm/s RMS (filtered at discrete frequencies).
Nozzle Load Magnification: API 610 pumps are specified to withstand 2x the standard Annex F allowable nozzle forces and moments transmitted from connected process piping.
Engineering Notes
- Always select API 610 over ANSI/ISO pumps when any of the following conditions are met: hydrocarbon fluid, operating temperature > 150°C (300°F), discharge pressure > 19 bar (275 psig), speed > 3600 rpm, or motor power > 110 kW (150 hp).
- Ensure mechanical seal chambers comply with API 682 dimensional envelopes and select the correct piping flush plan (e.g. Plan 11, Plan 21, Plan 53A/B) to guarantee seal reliability.
- Heavy-duty drain-rim baseplates must be 100% filled with non-shrink epoxy grout during field installation to damp dynamic vibration and preserve shaft alignment.
Related Standards
- API 682
Pumps—Shaft Sealing Systems for Centrifugal and Rotary Pumps (Mechanical Seals).
- API 686
Companion or referenced standard; verify its exact relationship in the adopted edition.
- ISO 9906
Companion or referenced standard; verify its exact relationship in the adopted edition.
- ISO 20816
Companion or referenced standard; verify its exact relationship in the adopted edition.
- ASME B73.1
Companion or referenced standard; verify its exact relationship in the adopted edition.
Source, Edition & Status
- Publisher
- API
- Edition Year
- 2021
- Industries
- Petrochemical, Refinery, Chemical, Power, Oil & Gas
- Content Status
- published
- Last Reviewed
- 2026-07-01
- Last Updated
- 2026-07-01
- Verified By
- Engineering Reviewer
- Official Link
- www.api.org
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