ANSI Pump Basics
What Is an ANSI Pump?
In most usage, an ANSI pump is a horizontal, end-suction, single-stage centrifugal process pump with a centreline discharge, built to the ASME B73.1 standard. ASME B73.1 is the Specification for Horizontal End Suction Centrifugal Pumps for Chemical Process. It requires pumps of the same dimension designation, from any supplier, to share mounting dimensions, nozzle sizes and locations, input shaft, baseplate and foundation bolt holes; hydraulics, materials and internal parts are each manufacturer’s own, so fit on a given installation is confirmed against the nameplate and the installed pump drawing.
Why It Is Called an “ANSI” Pump
The name refers to the American National Standards Institute: the forerunner standard was ANSI B123.1, and the ASME B73 pump standards, which ASME administers, are accredited by ANSI.
Strictly, the name covers more than one pump. An ASME B73 committee presentation by its chair, K. Burkhardt, gives “ASME B73 pumps” as also known as “ANSI pumps” and calls the idea of only one style of ANSI pump a myth: vertical in-line pumps to ASME B73.2 and sealless magnetic-drive and canned-motor pumps to ASME B73.3 belong to the same family. This page covers the horizontal end-suction pump the term usually means; the three standards are compared in process pump standards compared.
Design Features of an ANSI Pump
An ANSI centrifugal pump is recognised by an overhung end-suction layout, a centreline discharge, feet bolted to a baseplate, back pull-out construction and a dimension designation that fixes where it bolts down and connects.
| Feature | What it means on the pump |
|---|---|
| Horizontal, end-suction, single-stage, overhung | Liquid enters at the end of the casing along the shaft axis; a single impeller is mounted on the overhung end of the shaft. |
| Centreline discharge | The discharge nozzle sits on the casing centreline, at a size and location fixed for each designation. |
| Foot-mounted on a baseplate | The pump feet bolt to a baseplate; D, the shaft centreline height, is measured to the underside of the feet. |
| Back pull-out | For seal or bearing work the rotating assembly is withdrawn from the rear, and the casing and its piping stay in place. |
| Dimension designation, AA to A120 | Each designation, such as AA, A30 or A120, covers one or more hydraulic sizes with common installation dimensions; the numbers are not in size order. |
| Three CP lengths | CP, the length from the shaft coupling end to the suction flange face, takes one of three values across the designations: 17-1/2 in (445 mm), 23-1/2 in (597 mm) or 33-7/8 in (860 mm). |
The three CP values line up with the STX / Group 1, MTX-LTX / Group 2 and XLTX / Group 3 power ends of the 3196 and Mark 3 patterns; see the power frame cross-reference. Designation tables for each pattern are in the G196 vs Goulds 3196 and D Mark III vs Durco Mark 3 guides. The standard sets only a minimum seal-chamber envelope; seal options are in mechanical seals for process pumps.
What Is the Same on Every ANSI Pump, and What Differs
Two ANSI pumps of the same dimension designation are required to share their installation dimensions; the hydraulic design and the dimensions of internal parts are not standardised and remain each manufacturer’s own. What the standard fixes is set out in ANSI/ASME B73.1 explained.
| Part of the pump | Same for one designation? | Checked against |
|---|---|---|
| Feet, baseplate, foundation bolt holes, nozzles, input shaft | Required by the standard to match | Nameplate and installed pump drawing |
| Impeller, casing internals, bearing frame, shaft, sleeves, seal chamber design above the minimum, sealing arrangement | No: each manufacturer’s own pattern | Pattern of the installed pump |
| Curve, efficiency, NPSHr | No | The pump’s own curve for the duty |
Where ANSI Pumps Are Used
ASME B73.1 is written for chemical process duty, and the B73 committee presentation describes the pumps as broadly applicable beyond it, for liquids from benign to highly toxic. YSM’s range covers chemical, petrochemical, pulp and paper and utility duties in four hydraulic variants.
| Hydraulic variant | Typical service | YSM pumps |
|---|---|---|
| General purpose | Clean and lightly contaminated liquids | G196, D Mark III |
| Low flow at high head | Injection, dosing, reflux | G196 Low Flow, D Mark III Low Flow |
| Self-priming | Liquid source below the pump | G3796 Self-Priming, D Mark III Unitized Self-Priming |
| Non-clog | Large solids, fibres, entrained gas | G196 CV Non-Clog |
Application guides: chemical process liquid transfer, low-flow process pumps, wastewater chemical transfer and pulp and paper pumps.
Common Wetted Materials
Metal ANSI pumps have cast casings, impellers and covers, in grades from WCB carbon steel and CF8M stainless steel to titanium, with zirconium on request; the standard also covers solid polymer pumps.
| Material | Cast designation (ASTM) | Typical service |
|---|---|---|
| Carbon steel | WCB (A216) | Non-corrosive liquids, hydrocarbons, utility water |
| 316 stainless steel | CF8M (A743 / A744; A351 for pressure-containing castings) | General chemical service, mild acids, alkalis, solvents |
| Duplex stainless steel | CD4MCu (A890 Grade 1A) | Chlorides, brines, mildly abrasive corrosives |
| Alloy 20 | CN7M (A743 / A744; A351 for pressure-containing castings) | Sulphuric acid across a wide concentration range |
| Titanium | C-2, C-3 (B367) | Wet chlorine, hypochlorite, nitric acid, seawater |
Typical service is a starting point, not a corrosion rating. Nickel-alloy and zirconium grades are in the cast alloy reference; send liquid data in material selection inputs for a proposed material set.
How an ANSI Pump Differs from ISO and API Process Pumps
An ANSI pump follows the ASME B73.1 envelope; an ISO process pump follows the ISO 2858 envelope and the ISO 5199 Class II specification, and an API 610 pump is specified for petroleum, petrochemical and natural gas industry services. The ANSI and ISO envelopes differ, so the pumps do not interchange directly; see process pump standards compared.
| Aspect | ANSI pump | ISO process pump | API 610 pump |
|---|---|---|---|
| Standard | ASME B73.1, chemical process | ISO 2858 (rating 16 bar; designation, nominal duty point and dimensions) with ISO 5199 (technical specification, Class II) | API 610, 12th edition (2021) |
| Pump types covered | Horizontal end-suction, single-stage, centreline discharge | End-suction, rated 16 bar (ISO 2858); Class II centrifugal pumps in general application (ISO 5199) | Overhung, between-bearings and vertically suspended |
| YSM range | G196, D Mark III | AC (EN ISO 5199 / EN 22858 pattern) | KZ (API 610 type OH2 conventions) |
Reading an ANSI Pump Size Code
An ANSI size code gives the two nozzle sizes and the nominal impeller diameter in inches, and the nozzle order depends on the pattern: the Goulds 3196 pattern writes 2x3-13, discharge first, for the pump that the Durco Mark 3 pattern writes suction first after a group number and K, as in 2K3x2-13. Both are designation A30, so pumps are compared by designation rather than by the string; each format is decoded in ANSI pump size codes.
ANSI Pumps from YSM
YSM makes two B73.1 families, as complete non-OEM pumps and as replacement parts, and builds them at its Zibo works, in operation since 2010.
- G196 series: Goulds 3196 pattern, open impeller, STX / MTX / LTX / XLTX power ends, 24 general-purpose sizes plus Low Flow, G3796 Self-Priming and CV Non-Clog. Series maximums: 7,000 US gpm (1,590 m³/h), 730 ft (223 m), 700 °F (371 °C), 375 psig (2,586 kPa).
- D Mark III series: Durco Mark 3 pattern, reverse-vane impeller, Group 1 / 2 / 3 power ends, 26 general-purpose sizes plus Low Flow and Unitized Self-Priming. Series maximums: 7,500 US gpm (1,700 m³/h), 990 ft (300 m), 400 psi (27 bar), −100 °F to 700 °F (−73 °C to 370 °C).
Size, impeller diameter, material and seal arrangement set the limits of a given pump. A YSM pump or part is interchangeable with an installed pump only for the same size and designation, confirmed against the nameplate and the installed pump drawing (reading a nameplate and drawing). Both families are compared on the ANSI process pumps page; selection questions are in the ANSI process pump FAQ.
ANSI Pump FAQ
Why is it called an ANSI pump if the standard is ASME B73.1?
The name refers to the American National Standards Institute (ANSI): the ASME B73 pump standards are accredited by ANSI, and their forerunner was ANSI B123.1. An ASME B73 committee presentation gives ASME B73 pumps as also known as ANSI pumps.
Are all ANSI pumps interchangeable?
Only at installation level, and only for the same size and designation: ASME B73.1 requires matching mounting dimensions, nozzles, input shaft, baseplate and bolt holes, while curves, impellers and parts differ by manufacturer. Interchange is confirmed against the nameplate and the installed pump drawing.
Is every chemical process pump an ANSI pump?
No. ISO 5199 pumps and API 610 pumps also serve as process pumps. In everyday use, “ANSI pump” means the ASME B73.1 horizontal end-suction pump; strictly, pumps to ASME B73.2 (vertical in-line) and B73.3 (sealless) are also called ANSI pumps.
What is the difference between an ANSI and a non-ANSI pump?
An ANSI pump is built to the ASME B73.1 dimensions and design features for its designation. A non-ANSI pump follows its maker’s own envelope or another standard’s, for example ISO 2858, so it does not fit an ANSI baseplate and piping without a selection and installation review.
Does an ANSI pump have to be metal?
No. ASME B73.1 covers metallic and solid polymer centrifugal pumps. YSM supplies its ANSI pumps in cast metals, from WCB carbon steel to titanium, with zirconium on request.
Sources: ASME B73.1 (asme.org); ASME B73 committee presentation by K. Burkhardt and D. Wood (about 2015–16); ISO 2858 and ISO 5199 (iso.org); API Std 610, 12th edition (API 2025 Refining catalogue). Confirm requirements against the current edition.
Send Your Duty or Installed Pump Data
Send the duty point and liquid data, or the installed pump’s nameplate and drawing, for a reviewed G196 or D Mark III proposal.
Goulds, 3196, 3796, CV 3196, STX, MTX, LTX, XLTX, ITT, Durco, Mark 3, Mark III and Flowserve are trademarks or product designations of their respective owners, used only to identify dimensional patterns. YSM Pumps (Jinan Yingsiman Machinery Co., Ltd.) is an independent non-OEM manufacturer, not affiliated with, sponsored by or endorsed by ITT Goulds Pumps or Flowserve.