Standards
ANSI, ISO and API Process Pump Standards Compared
ANSI and ISO pump standards are different dimensional systems, so an ANSI pump does not replace an ISO pump size for size. ASME B73.1, B73.2 and B73.3 fix installation dimensions by size designation and also set design features; ISO 2858 (EN 22858) fixes the principal dimensions and nominal duty point for each designation. ISO 5199 and API 610 are technical specifications with no dimensional interchangeability statement in their published scopes. Interchangeability holds only for the same size and designation, confirmed against the nameplate and the installed pump drawing.
The Six Standards at a Glance
Three are ASME chemical-pump standards, two are ISO documents usually quoted together, and API 610 covers petroleum, petrochemical and gas services [1]–[3], [5], [7], [9].
| Standard | Pump type covered | What it specifies | When replacing a pump (same size and designation, confirmed against the nameplate and the installed pump drawing) |
|---|---|---|---|
| ASME B73.1-2026 | Metallic and solid polymer; horizontal end suction, single stage, centerline discharge | Dimensional interchangeability and design features | Standard’s intent: same designation, same mounting dimensions, nozzle size and location, input shaft, baseplate and foundation bolt holes; confirm on the nameplate and drawing. |
| ASME B73.2-2023 | Metallic; vertical shaft, single stage, nozzles in-line | Dimensional interchangeability and design features | Standard’s intent: same designation, same mounting dimensions and nozzle size and location; confirm on the nameplate and drawing. Not a like-for-like replacement for a B73.1 pump. |
| ASME B73.3-2022 | Metallic and plastic-lined sealless; horizontal end suction, single stage, centerline discharge | Dimensional interchangeability and design features | Standard’s intent, between B73.3 pumps of the same designation: the features listed for B73.1; confirm on the nameplate and drawing. |
| ISO 2858:1975 (EN 22858, now EN ISO 2858) | End-suction centrifugal pumps, maximum operating rating 16 bar | Three-number designation, nominal duty point and principal dimensions | Same designation, same principal dimensions; other forms and dimensions are the manufacturer’s choice, so confirm on the nameplate and drawing. |
| ISO 5199:2002 | Class II centrifugal pumps, single-stage or multistage, horizontal or vertical, any drive, general application; chemical process pumps (e.g. to ISO 2858) are typical | Design features for installation, maintenance and safety, including baseplate, couplings and auxiliary piping; driver requirements limited to rated power output | No dimensional interchangeability statement; fit follows the ISO 2858 designation, confirmed on the nameplate and drawing. |
| API 610, 12th ed. (January 2021); ISO 13709:2009 is a separate ISO document | Overhung, between-bearings and vertically suspended pumps for petroleum, petrochemical and gas industry process services; types designated e.g. OH2 | Requirements for centrifugal pumps, including hydraulic power recovery turbines | No dimensional interchangeability statement in its published scope; engineered against the installed pump’s API datasheet, drawing and nameplate. |
Dimensional Standards vs Technical Specifications
A dimensional standard fixes where a pump bolts down and where the pipes connect; a technical specification fixes how it is designed and built. A B73 committee presentation (Burkhardt and Wood) describes B73 interchangeability as “from an installation perspective (not individual parts!)” [4].
B73.1 does not fix head, efficiency, NPSHr, castings, power-end internals or materials, so parts follow the installed pump’s pattern; ISO 2858 fixes principal dimensions, with baseplate and installation dimensions in ISO 3661.
ASME B73.1, B73.2 and B73.3: The Three ANSI Chemical Pump Standards
All three are ASME chemical-process pump standards with a designation-based interchangeability intent, one per configuration [1]–[3].
ASME B73.1
B73.1 covers metallic and solid polymer horizontal end-suction pumps; the B73 committee presentation records that ASME B73.5M was withdrawn in 2012 and merged into B73.1 [4]. See What is an ANSI pump?, ASME B73.1 explained, ANSI pump size codes and the size tables for the G196 / Goulds 3196 pattern and the D Mark III.
ASME B73.2
B73.2 covers metallic, vertical shaft, single-stage pumps with the suction and discharge nozzles in-line; ASME’s description adds: “Maintenance and operation requirements are not included in this Standard.” [2]
ASME B73.3
B73.3 covers metallic and plastic-lined sealless pumps of horizontal end-suction, single-stage, centerline-discharge design [3]; the B73 committee presentation names both magnetic drive and canned motor pumps [4]. Its interchangeability list matches B73.1’s.
YSM supplies ANSI/ASME B73.1 chemical process pumps and has no published B73.2 in-line or B73.3 sealless range.
ISO 2858 vs ISO 5199
ISO 2858 fixes the designation, nominal duty point and principal dimensions of end-suction centrifugal pumps rated 16 bar; ISO 5199 is the Class II technical specification for centrifugal pumps in general application, and chemical process pumps to ISO 2858 are typical of those it covers [5], [7]. Per the iso.org abstract, the ISO 2858 table “covers flange sizes from 50 mm up to and including 200 mm”.
| ISO 2858:1975 | ISO 5199:2002 | |
|---|---|---|
| Pressure basis | Maximum operating rating 16 bar (clause 1) | For ISO 2858 pumps: basic design pressure at least 16 bar gauge at 20 °C in cast iron, ductile iron, carbon steel or stainless steel (clause 4.4.1) |
| Interchangeability | Same designation, same principal dimensions; confirm against the nameplate and the installed pump drawing | No dimensional interchangeability statement |
EN 22858 and EN ISO 2858
EN 22858:1993 was the European adoption of ISO 2858:1975. It has been superseded by EN ISO 2858:2010, which is identical to ISO 2858:1975, so a datasheet naming EN 22858 points to the ISO 2858 dimensional system [6].
ANSI vs ISO Pump Standards: Can One Replace the Other?
No, not size for size. ASME B73.1 and ISO 2858 are different dimensional systems, so an ANSI pump does not fit an ISO pump’s baseplate and piping, and parts do not cross over.
| ANSI (ASME B73.1) | ISO (ISO 2858 with ISO 5199) | |
|---|---|---|
| Dimensional basis | Installation dimensions by dimension designation | Principal dimensions by three-number designation |
| Design and construction | Design features within B73.1 | ISO 5199 Class II |
ISO 2858 designations read inlet – outlet – nominal impeller diameter in millimetres (80-50-250 = 80 mm inlet, 50 mm outlet, 250 mm impeller; ISO 2858:1975, clause 3), suction first, whereas the G196 code puts the discharge first and is in inches (see ANSI pump size codes). The choice normally follows the installed base or the project specification.
API 610: How It Differs from ASME B73 and ISO 5199
API 610 covers centrifugal pumps for petroleum, petrochemical and gas industry process services, including overhung, between-bearings and vertically suspended types [9]. Unlike ASME B73 it has no dimensional interchangeability statement in its published scope, and unlike ISO 5199, written for general application, it names specific industries and assigns type designations such as OH2.
The B73 committee presentation describes B73 as having a “narrow pump type scope compared to API 610” [4].
API 610 and ISO 13709
API’s 2020 catalogue lists the 11th edition (September 2010) as the identical national adoption of ISO 13709:2009 [10]; its 2025 catalogue lists the 12th edition (January 2021) as Std 610, with no ISO 13709 reference [9]. ISO 13709:2009 has the same title and opening scope sentence [8], so the document and edition named on the project datasheet govern.
YSM’s KZ range is an end-suction process pump family to ISO 13709 / API 610 type OH2 conventions, selected against the project’s API 610 datasheet (API 610 type OH2 end-suction pumps).
Which Standard Applies to My Pump?
Read the standard from the pump’s datasheet or purchase specification, then match the installed pump’s size and designation. Without a datasheet, the nameplate and drawing identification guide lists the data to collect.
| Document names… | Start here |
|---|---|
| ASME B73.1 | G196 series (Goulds 3196 pattern) or D Mark III series (Durco Mark 3 pattern) |
| ISO 5199 with ISO 2858 / EN 22858 | AC single-stage process pump; range: ISO 5199 / ISO 2858 process pumps |
| API 610 type OH2 | KZ end-suction pump |
| API 610, vertical VS1 or VS6 | KVT vertical turbine pump, API 610 version on request |
| ASME B73.2 or B73.3 | Not in YSM’s published ranges; send the datasheet for review |
Process Pump Standards FAQ
What is the difference between ASME B73.1 and B73.2?
B73.1 covers horizontal end-suction pumps and B73.2 covers vertical in-line pumps. Each fixes installation dimensions by designation for its own configuration, so neither replaces the other like for like.
What does ASME B73.3 cover?
Sealless horizontal end-suction, single-stage, centerline-discharge centrifugal pumps in metallic and plastic-lined construction. Its interchangeability statement lists the same features as B73.1, for B73.3 pumps of the same designation.
What is the difference between ISO 2858 and ISO 5199?
ISO 2858 sets the designation, nominal duty point and principal dimensions of end-suction pumps rated 16 bar. ISO 5199 is the Class II technical specification for centrifugal pumps in general application; chemical process pumps to ISO 2858 are typical of those it covers.
Is EN 22858 the same as ISO 2858?
Yes. EN 22858:1993 was the European adoption of ISO 2858:1975; it has been superseded by EN ISO 2858:2010, which is identical to ISO 2858:1975.
Can an ANSI pump replace an ISO pump?
Not size for size: ASME B73.1 and ISO 2858 are different dimensional systems, and parts do not cross over. The choice normally follows the installed base or the project specification.
Is API 610 the same as ISO 13709?
Not in API’s current edition. API’s catalogues list the 11th edition (2010) as the identical national adoption of ISO 13709:2009 and the 12th edition (January 2021) as Std 610 alone. The edition named on the project datasheet governs.
Sources
- ASME B73.1-2026, asme.org.
- ASME B73.2-2023, asme.org.
- ASME B73.3-2022, asme.org.
- K. Burkhardt and D. Wood, ASME B73 Pump Standards, B73 committee presentation, ASME C&S Connect; its edition dates predate [1]–[3].
- ISO 2858:1975, iso.org; clauses 1 and 3.
- BS EN ISO 2858:2010, BSI listing.
- ISO 5199:2002, iso.org; clauses 1.1, 1.2 and 4.4.1.
- ISO 13709:2009, iso.org.
- API Publications Catalog 2025, Refining: Std 610, 12th Edition, January 2021, product C61012.
- API Publications Catalog 2020, Refining: Std 610/ISO 13709:2009, 11th Edition.
Send the Datasheet
Send the pump datasheet, or a nameplate photo with the duty, and we review which standard and YSM range fit.
General guidance only; the current edition of each standard and the project datasheet govern. Goulds, 3196, ITT, Durco, Mark 3 and Flowserve are trademarks of their respective owners, used only to identify a pump pattern; YSM Pumps is an independent manufacturer, not affiliated with ITT or Flowserve.