Pump Selection

COMPLETE REVISIONJanuary 2004

Process Industry PracticesMachinery

PIP RECP001Design of Pumping Systems That Use

Centrifugal Pumps

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice hasbeen prepared from the technical requirements in the existing standards of majorindustrial users, contractors, or standards organizations. By harmonizing thesetechnical requirements into a single set of Practices, administrative, application, andengineering costs to both the purchaser and the manufacturer should be reduced. Whilethis Practice is expected to incorporate the majority of requirements of most users,individual applications may involve requirements that will be appended to and takeprecedence over this Practice. Determinations concerning fitness for purpose andparticular matters or application of the Practice to particular project or engineeringsituations should not be made solely on information contained in these materials. Theuse of trade names from time to time should not be viewed as an expression ofpreference but rather recognized as normal usage in the trade. Other brands having thesame specifications are equally correct and may be substituted for those named. AllPractices or guidelines are intended to be consistent with applicable laws andregulations including OSHA requirements. To the extent these Practices or guidelinesshould conflict with OSHA or other applicable laws or regulations, such laws orregulations must be followed. Consult an appropriate professional before applying oracting on any material contained in or suggested by the Practice.

This Practice is subject to revision at any time by the responsible Function Team andwill be reviewed every 5 years. This Practice will be revised, reaffirmed, or withdrawn.Information on whether this Practice has been revised may be found at www.pip.org.

© Process Industry Practices (PIP), Construction Industry Institute, TheUniversity of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practicefor their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express writtenauthorization of PIP.

PIP will not consider requests for interpretations (inquiries) for this Practice.

Printing HistorySeptember 1995 IssuedJanuary 2004 Complete Revision

Not printed with State funds

COMPLETE REVISIONJanuary 2004

Process Industry Practices Page 1 of 16

Process Industry PracticesMachinery

PIP RECP001Design of Pumping Systems That Use

Centrifugal Pumps

Table of Contents

1. Introduction..................................21.1 Purpose ............................................. 21.2 Scope................................................. 2

2. References ...................................22.1 Process Industry Practices ................ 22.2 Industry Codes and Standards .......... 22.3 Other References .............................. 3

3. Definitions ....................................3

4. Requirements...............................44.1 General Design Principles ................. 44.2 Hydraulic Selection Criteria................ 54.3 Net Positive Suction Head

Considerations................................... 84.4. Heating/Cooling Jacket.................... 114.5. Driver ............................................... 124.6 Energy Evaluations .......................... 134.7. Application of

Specific Pump Types ....................... 14

Appendix – Figures ....................... 16A-1 Pump Operating Ranges as a

Function of Flow Rate and SuctionSpecific Speed, Nss

A-2 Pump Operating Ranges as aFunction of Flow Rate and SuctionSpecific Speed, nqs

A-3 Vertical Vessel Reference Levels forNPSHA Calculations

A-4 Horizontal Vessel Reference Level forNPSHA Calculations

A-5 NPSH vs. Flow Rate for VariousSpeeds at Nss = 9,000 and 11,000

A-6 NPSH vs. Flow Rate for VariousSpeeds at nqs = 175 and 215

PIP RECP001 COMPLETE REVISIONDesign of Pumping Systems That Use Centrifugal Pumps January 2004

Page 2 of 16 Process Industry Practices

1. Introduction

1.1 PurposeThis Practice provides designers with requirements for design of pumping systemsthat use centrifugal pumps.

1.2 ScopeThis Practice describes the requirements for general design principles, hydraulicselection criteria, net positive suction head considerations, jacket and driverconsiderations, and energy evaluations for design of pumping systems that usecentrifugal pumps.

Fire water pumps should be designed in accordance with the National Fire ProtectionAssociation (NFPA) codes and standards and are not covered by this Practice.

This document is a complete revision of PIP RESP001, and therefore, revisionmarkings are not provided.

2. References

Applicable parts of the following Practices, industry codes and standards, and referencesshall be considered an integral part of this Practice. The edition in effect on the date ofcontract award shall be used, except as otherwise noted. Short titles will be used hereinwhere appropriate.

2.1 Process Industry Practices (PIP)– PIP REIE 686 - Recommended Practices for Machinery Installation and

Installation Design

2.2 Industry Codes and Standards

• American Petroleum Institute (API)– Std 611 - General Purpose Steam Turbines for Refinery Service– Std 610 - (ISO 13709) - Centrifugal Pumps for Petroleum, Petrochemical and

Natural Gas Industries

• American Society for Mechanical Engineers (ASME)– B73.1 M - Specification for Horizontal End Suction Centrifugal Pumps for

Chemical Process– B73.2 M - Specification for Vertical In-Line Centrifugal Pumps for Chemical

Process

• Hydraulic Institute– ANSI/HI 1.3 - Hydraulic Institute Centrifugal Pump Applications

COMPLETE REVISION PIP RECP001January 2004 Design of Pumping Systems That Use Centrifugal Pumps


2.3 Other References– Irving Taylor, What NPSH for Dissolved Gas?, Hydrocarbon Processing,

August 1967, Volume 46, Number 8, pages133-134– W. Roy Penny, Inert Gas in Liquid Mars Pump Performance, Chemical

Engineering, July 3, 1978– Mao J. Tsai, Accounting for Dissolved Gases in Pump Design, Chemical

Engineering, July 26, 1982– C. C. Chen, Cope with Dissolved Gases in Pump Calculations, Chemical

Engineering, October 1993– Jerry L. Hallam, Centrifugal Pumps: Which Suction Specific Speeds Are

Acceptable?, Hydrocarbon Processing, April 1982

3. Definitions

high stream factor plants: Plants in which the on-stream time must be 97.5% or greater atdesign capacity

intermediate life plants: Plants with an expected economic life of less than 20 years

long life plants: Plants with an expected economic life of 20 years or more

net positive suction head (NPSH): Total absolute suction head, in feet (meters) of liquid,determined at the suction nozzle and referred to the datum elevation, minus the vaporpressure of the liquid, in feet (meters) absolute. Datum elevation is the suction nozzlecenterline for vertical in-line pumps and the top of the foundation for other vertical pumps.

net positive suction head available (NPSHA): NPSH, in meters (feet) of liquid, determinedby the purchaser for the pumping system with the liquid at the rated flow and thecorresponding pumping temperature

net positive suction head required (NPSHR): NPSH, in feet (meters), determined by vendortesting with water. NPSHR is measured at the suction flange and corrected to the datumelevation. NPSHR is the minimum NPSH at rated capacity required to prevent a head drop ofmore than 3% (first-stage head in multistage pumps) caused by cavitation within the pump.

purchaser: The agency that issues the order and specifications to the manufacturer

relative density: Ratio of the density of one substance to that of a second referencesubstance, both at the same specified temperature

specific gravity: Dimensionless ratio of the density of a fluid to that of a reference fluid. Fordesign of pumping systems, the reference fluid is water at a temperature of 60ºF (15.5ºC).



4. Requirements

4.1 General Design Principles4.1.1 Pumping system curves shall be developed for all flow paths, piping

configurations, and process flow characteristics. Operation in each of thespecified flow paths shall be evaluated for viability. The off-design operatingcases and the amount of time in each operating case shall be identified.

4.1.2 Pump(s) selected for the system shall

a. Provide the head and flow required for all flow paths, pipingconfigurations, and process flow characteristics.

b. Be manufactured from materials acceptable to the process. Materialsshall be corrosion- and erosion-resistant.

4.1.3 Flow control systems shall ensure control of the flow within the acceptableoperating range of the selected pump(s).

4.1.4 Adequate protection shall be provided to prevent or minimize the impact ofoperating the pump dry or dead-headed. This may include re-circulation,power monitors, or other instrumentation to detect or prevent dry and dead-head operation.

4.1.5 Pump manufacturer shall determine the rated shaft power required by thepump assembly based on the operating conditions provided by the purchaser.Determination of the rated shaft power shall take into consideration thefollowing variables as a minimum:

a. Specific gravity

b Viscosity

c Mechanical seal(s)

d. Stuffing box pressure/suction pressure

e. Gear assembly

f. Couplings

g. Hydraulic tolerances

Other variables shall be taken into consideration as required. Motor drivershall be sized in accordance with Section 4.5.1.5, Table 1 (this Practice),unless the above-mentioned considerations require a larger driver.

4.1.6 Pump(s) shall have a shaft-sealing mechanism designed for all operatingconditions. Sealing mechanisms shall have adequate cooling, lubrication,and support systems consistent with process conditions and sealrequirements. Seal area / chamber (on the process side) shall be self-venting.

4.1.7 Suction and discharge piping shall be arranged to minimize turbulence thatmay reduce the pump’s performance or increase maintenance.

Comment: Refer to PIP REIE 686, Chapter 6, for more informationabout pump piping layout.



4.1.8 Arrangement of suction and discharge piping for pumps in wet pit sumpinstallations shall not permit gas entrainment and shall facilitate maintenanceof the pump.

Comment: Refer to Hydraulic Institute standards for more informationabout wet pit sump design.

4.1.9 Critical speeds shall fall at least 20% outside the operating speed range ofthe pump.

4.1.10 Suction and discharge piping on pumps used in parallel operation is criticalto proper operation. The same pipe size and line loss shall be maintainedbetween each pump and the point where the pumps tie together. Design ofthe piping shall provide equivalent suction and discharge pressures.

4.1.11 Pumps used in parallel shall be identical in design and size, shall be operatedat the same speed, and shall be installed with identical impellers.

4.1.12 If a flow orifice is used (to increase the slope of a pump curve as seen by thesystem), the orifice shall be installed downstream from the pump because itis a part that is subject to wear.

4.1.13 Pump suction line size is typically designed for fluid velocities from 3 to6 feet per second (1 to 2 meters per second). Acceptable velocities mayincrease or decrease depending on NPSH margin for the pump selected andsystem economic analysis.

4.1.14 Recommended pump discharge line size shall be designed for fluid velocitiesfrom 3.5 to 10 feet per second (1 to 3 meters per second).

4.1.15 Pump(s) shall use an impeller sized and designed to accommodate alloperating conditions. Semi-open or closed impellers shall be used in high-temperature applications to prevent the pump from locking up during warm-up and cool-down.

4.1.16 Design data verifying that the design of the pumping system conforms to thedesign principles as listed in the previous paragraphs of this section shall bedeveloped. Data shall be subject to a formal review by the purchaser beforerelease of the design for procurement/construction. Data and its formalreview shall become a permanent record for project, operations, andmaintenance purposes.

4.2 Hydraulic Selection Criteria4.2.1 Pump(s) selected for the pumping system shall have head capacity

characteristic curves that rise continuously as flow is reduced to shutoff.

4.2.2 If pumping system is designed for pumps to operate in parallel, the head riseto shutoff shall be at least 10% of the head at rated capacity.

Comment: Pumps without a substantial rise in characteristic curve, asflow is reduced, are more susceptible to operating at deadhead (shut-in) conditions if such pumps operate in parallel.



Comment: Achieving a continuously rising head characteristic curvewith low-flow high-head pumps is not always possible.Pumps with this characteristic rarely operate in parallel.

4.2.3 Pump impeller shall have a best efficiency point (BEP) that is between thenormal and rated operating points.

4.2.4 Normal operating point flow rate of the pump shall be greater than theminimum continuous flow rate specified by the pump vendor and less thanthe flow rate at the BEP for the selected pump impeller.

4.2.5 Pump shall be capable of at least a 5% head increase at rated condition withthe installation of a new impeller.

4.2.6 Minimum diameter of selected pump impeller shall be 105% of theminimum diameter impeller for the generic pump curve for the specificpump.

Comment: Suction recirculation increases as minimum diameterimpeller is approached. This can result in increased NPSHRat the same flow rate and in less predictable performance.

4.2.7 If the pumped fluid has a variable specific gravity, the head required to bedeveloped by the pump shall be based upon the lowest specific gravity andthe greatest system differential pressure for the required flow rate.

Comment: “Specific gravity” is used throughout this Practice in lieu of“relative density.” Some commonly used equations wouldotherwise be affected by the shifting temperature referenceused in relative density.

4.2.8 If viscosity corrections are required, head, capacity, and efficiencycorrections shall be the responsibility of the pump manufacturer. Thesecorrections shall be calculated in accordance with the “Centrifugal Pump”section of ANSI/HI 1.3.

4.2.9 Pumps with suction specific speeds of NSS greater than 11,000 (ηqs greaterthan 215) require specific approval by the purchaser. A quotation for such apump shall include minimum continuous flow rate, maximum operating flowrate, and operating experience.

Comment: Suction specific speed, NSS (S), is an index of pump suctionoperating characteristics determined at the BEP with themaximum diameter impeller. Suction specific speed is anindicator of the NPSHR for given values of capacity androtating speed. NSS (S) provides an assessment ofsusceptibility of the pump to internal recirculation. NSS (S)is calculated by the following equation:

NSS (S) = (N)(Q)^1/2 / (NPSHR)^3/4

where NSS (S) = suction specific speed

N = rotating speed in revolutions per minute



Q = flow rate per impeller eye, in gallons perminute (cubic meters per second) at the BEPwith the maximum diameter impeller

= total flow rate for single suction impellers

= half of total flow for double suctionimpellers

NPSHR = net positive suction head required in feet(meters) at the BEP for the maximumdiameter impeller

Comment: Suction specific speed, Sderived using cubic meters persecond and meters, multiplied by 51.6, is equal to suctionspecific speed, NSS, derived using U.S. gallons per minuteand feet.

Comment: Industry has extensive published documentation indicatingthat pumps with high NSS (S), defined as 11,000 (215) andgreater, have reduced reliability.

Refer to Hallam (1982). At off-design (off-BEP) conditions,these pumps are susceptible to both suction and dischargerecirculation, which may result in high vibration and poorseal life. Pumps with high NSS (S) should not be acceptedfor services with widely varying operating flow rates. If noreasonable alternative to a high NSS (S) pump exists, stepsshould be taken to ensure pump operation at or very near theBEP. Consider a controlled bypass or a complete shutdownif the pump is used in a batch operation. Vibrationinstrumentation should be considered for proper monitoringof these steps.

Comment: Inducers have been applied successfully to as much as30,000 NSS (580 S), although the more common range is15,000 to 25,000 NSS (290 to 480 S) . When consideringinducers, particular attention should be devoted to theNPSHR curve shape and the pump manufacturer’sexperience. Care should be given when selecting inducersfor pumps that have a large range in flow rate because anarrow flow range is preferred for inducers.

4.2.10 Normal and rated flow rates of pumps shall be within the acceptable range inaccordance with Figures A-1 and A-2 (for SI and U.S. Customary units,respectively). Pumps with flow rates outside this range require specificapproval by the purchaser. Pumps with flow rates outside this range requireFigures A-1 and A-2 (for U.S. Customary and SI units, respectively),provided in the Appendix. Pumps with flow rates outside this range requirespecific approval by the purchaser.

Comment: Figures A-1 and A-2 may not apply to inducer designs.



Comment: As shown in Figures A-1 and A-2, the acceptable range offlow rates is reduced as higher suction specific speed pumpsare applied. It is recognized that the damage that may occurto a pump at high suction specific speeds is also a functionof the energy density level of the pump. Therefore,Figures A-1 and A-2 should be considered as a generalguide.

4.2.11 Pump manufacturer shall state the minimum continuous flow rate requiredby the pump and whether this flow rate is based on hydraulic stability orthermal limitations.

4.2.12 Determination of the minimum continuous flow rate of the process shall takeinto consideration normal, abnormal, start-up, and shutdown conditions.

Comment: Pump operation below the stated minimum continuousstable flow rate causes increased process fluid recirculationwithin the pump, which may result in increased noise, highvibration level, and bearing and/or seal failure. Pumpoperation below the stated minimum continuous thermalflow rate may result in gasket failure, seal failure, orflashing in the pump casing.

4.2.13 If process conditions or operating practice cannot ensure the minimumcontinuous flow rate required by the pump, a minimum flow bypass orinstrumentation to the alarm or to shut down the pump shall be provided.

4.2.14 Unless otherwise specified, minimum flow bypass shall be routed to thesuction vessel. If the system provides adequate cooling for the recirculatedfluid, consideration may be given to routing the minimum flow bypass to thepump suction line.

4.2.15 Bypass routed to the pump suction line shall be connected at a point that is aminimum distance of 10 pipe diameters upstream of the pump suctionflange.

Comment: Bypass control is often used on high specific speed pumps,such as axial flow pumps, because the power requirementdecreases with increased flow.

4.2.16 Size of the suction vessel, thermodynamic properties of the pumped fluid,and amount of fluid to be recirculated shall be taken into consideration todetermine whether a cooler is required in the bypass line.

4.3 Net Positive Suction Head Considerations4.3.1 Requirements for calculating NPSHA and for margins between NPSHA and

NPSHR shall be strictly applied. Additional margins shall not be appliedwithout specific approval of the purchaser.

4.3.2 NPSHA shall be calculated assuming the following:

a. 110% of rated pump capacity

b. Lowest liquid level in the suction vessel



c. Operating condition with the lowest NPSHA

Comment: The operating condition with the lowest NPSHA typicallyhas the highest temperature, vapor pressure, and viscosityand typically has the lowest liquid level.

4.3.3 On vertical vessels, lowest liquid level shall be defined as the bottom tangentline with pump inlet piping connected at the bottom of the vessel or at thetakeoff level if the inlet line to the pump is not connected to the bottom ofthe vessel (see Appendix Figure A-3). On horizontal vessels, lowest liquidlevel shall be defined as the bottom inside level (see Appendix Figure A-4).

4.3.4 For existing vessels, and if selection of pumps is limited, the liquid levelmay be taken as one of the following:

a. Elevation of the minimum operating liquid level if vessels have levelcontrol

b. Elevation of the low alarm setting if vessels have level control

c. Elevation of the automatic shutdown level if vessels have a levelcontroller, low-level alarm, and automatic shutdown device

4.3.5 NPSHA shall exceed NPSHR by a minimum of 3 feet (1 meter) fromminimum continuous flow to 110% of rated operating point. Use of aninducer to meet this requirement shall require approval of the purchaser.

Comment: 3-feet (1-meter) minimum margin is desirable becauseNPSHR of individual impellers may vary significantly.NPSHR is determined under ideal pump operatingconditions, and at the stated NPSHR, the pump is already incavitation with a 3% head loss. Cavitation damage can resultin high-energy density impellers at head losses less than thenormal 3% used in standardized testing.

Comment: Using the equation in Section 4.2.9 of this Practice and the3-feet (1-meter) margin specified in Section 4.3.5 above, theminimum acceptable NPSHA can be estimated with thefollowing expression:

NPSHA ≥ [(N/ Nss)^4/3 * Q^2/3 ] + 3 (U.S. Customaryunits)

NPSHA ≥ [(N/ S)^4/3 * Q^2/3 ] + 1 (SI units)

With an assumed pump speed, the minimum NPSHA can beestimated and used to determine the preliminary elevation ofthe suction vessel.

4.3.6 If the margin between NPSHA and NPSHR at 110% of rated operating pointis less than 5 feet (1.5 meters) or if an inducer is used, NPSHR testing shallbe performed.

4.3.7 If the pumped liquid has dissolved or entrained gas, the NPSHA used toselect the pump shall be half of the calculated NPSHA.



Comment: Some common liquids in which the NPSHA may beadversely affected by dissolved gases include carbondioxide, hydrogen sulfide, amine, etc.

Comment: Published articles related to this topic are as follows: Taylor(1967), Penny (1978), Tsai (1982), and Chen (1993).

4.3.8 NPSHA used to select the pump shall be indicated on the data sheet.

4.3.9 For uncontrolled applications, i.e., cooling tower pumps, in which the pumpscan run out to the end of the curve, NPSHA shall exceed NPSHR by aminimum of 3 feet (1 meter) from minimum continuous flow to the end ofthe curve.

Comment: Uncontrolled pumps typically operate at the end of the curvebecause of overly conservative system design factors. Thisresults in a pump with a greater head requirement thanactually exists in the installed system. This head requirementcan be a significant source of unreliable operation.

4.3.10 NPSHR reductions or corrections for hydrocarbon liquids and hot water areunacceptable.

4.3.11 Elevation of suction vessel shall be set to meet the requirements for marginbetween NPSHA and NPSHR specified in Sections 4.3.5 through 4.3.9above.

Comment: Figures A-5 and A-6 provided in the Appendix give to theengineer establishing suction vessel elevation anappreciation of the NPSHA that must be provided at variousflow rates and pump speeds to meet NSS (S) limitations. Forplanning purposes, the preliminary vessel elevation shouldbe based on the NPSH requirements shown in Figures A-5and A-6, with NSS of 9,000 (S of 175) as a reasonableapproach. This allows the selection of a pump withoutexceeding the NSS ≤ 11,000 (S = 215) limit (seeSection 4.2.9). Raising the suction vessel may be moreeconomical than using a larger, slower speed or a doublesuction pump. For example, for pumps with identicalprocess conditions, a pump that operates at 1,770 RPMversus 3,560 RPM increases cost from 40% to 100%. Apump that operates at 1,180 RPM versus 3,560 RPMincreases cost from 100% to 300%. Drive motors thatoperate at 1,180 RPM are also significantly more expensivecompared with motors that operate at 1,770 RPM or3,560 RPM. Some suction vessels can be raised to provideadequate NPSHA at a reasonable cost. By adequatelyaddressing these issues, the overall cost effectiveness andreliability of the pump will be enhanced.

4.3.12 If significant changes are made to the piping layout, the NPSH calculationsshall be repeated with the actual layout.



Comment: Generally, this recalculation is not required unless the pipingdiameter or equivalent length is changed significantly toincrease pressure drop.

4.4. Heating/Cooling Jacket4.4.1 The pump shall have a heating/cooling jacket if conditions require it as

stated in Section 4.4.2.

Comment: The following are the types of jackets typically used oncentrifugal pumps:

a. Stuffing box jacket

b. Seal chamber jacket (fully jacketed only)

c. Pump casing jacket

d. Bolt-on or external steam jacket (casing)

e. Bearing housing cooling jacket (Oil sump fin tube is preferred. Castbearing housing jackets are acceptable only with purchaser’s approval.)

Comment: Jackets are used to remove or add heat to the local area towhich they are applied. High-temperature liquids that flashif heat is added, such as through rubbing friction ormechanical seals, require cooling. High-temperature liquidsthat solidify if the temperature decreases require the additionof heat, especially during startup when piping and pumps areat ambient temperature. Jackets must be hydrostaticallytested before the pump is shipped. Leakage to theatmosphere could be hazardous in some processes.

4.4.2 A heating/cooling jacket shall be used in the followingconditions/applications:

a. Temperature of pumped fluid is above 300ºF (150ºC) unless metalbellow-type seals are used.

b. Temperature of pumped fluid is above 572ºF (300ºC).

c. Boiler feedwater pumps

d. Dead-ended seal chambers

e. Liquids with low flash points

f. Products with high melting points

4.4.3 Cooling/heating jackets or inserts for seal chambers shall be provided by thepump vendor if specified by the purchaser.

4.4.4 If the temperature of the pumped fluid is greater than 350ºF (175ºC), thepump and seal vendors shall be jointly consulted about using cooled flush orrunning the seal chamber dead-ended with jacket cooling.



4.4.5 Cooling/heating jackets for seal chambers shall have connections arrangedso that the entire passageway can be mechanically cleaned, flushed, anddrained.

4.5. Driver4.5.1 Electric Motor

4.5.1.1 For applications in which the pumped fluid has a variable specificgravity, the rated power of the motor shall be based on the greatestspecific gravity.

4.5.1.2 If viscosity corrections for the pumped fluid are required, the powerrequirements specified in Sections 4.5.1.4, 4.5.1.5, and 4.5.1.6 shallbe increased an appropriate amount by the pump manufacturer.Start-up at cold temperature when the viscosity of the pumped fluidis higher than viscosity under operating conditions shall be takeninto consideration.

4.5.1.3 Use of a variable speed motor may be considered under one or moreof the following circumstances:

a. If the process operating conditions have a large range inoperating flow rates or if a significant portion of the flow isrecirculated

b. In slurry service if reduction in pump speed reduces erosionand eliminates throttling valves

c. If the process does not require a constant head, which istypically controlled by throttling

d. If routine operation of the pump results in operating powerof less than 50% of rated power, which will result in excessheat and inefficient operation of the motor

Comment: The primary benefit of variable speed pumps isthe reduction of energy requirements because ofthe elimination of throttling and minimizederosion in slurry pumps. Variable speed pumpsmay also provide benefits in systems requiring awide range in flow. Variable speed pumps inconstant flow and head system service have noadvantage.

4.5.1.4 If the end-of-curve power is less than 5 hp (4 kW), the next standardsize larger motor shall be used.

Comment: The purpose of this requirement is to overcomestartup problems caused by slow acceleration ofsmall motors overcoming inertia and drag of seals.Seal drag increases as suction pressures increase.Failure to consider these factors can result in



tripping the driver before operating speed isreached.

4.5.1.5 Driver power shall, as a minimum, be equal to the rated shaft powerat the rated point multiplied by the percentage listed in Table 1.

Table 1. Electric Driver SizingRated Pump

PowerRated Pump

Power MultiplierBhp kW % of Rated Shaft Power< 30 < 22 125

30-100 22-75 115> 100 > 75 110

4.5.1.6 If the end-of-curve power is greater than 100 hp (75 kW), the motorshall be sized to cover the end-of-curve power or 110% of ratedpower, whichever is less. For applications that are expected tooperate at the end-of-curve, such as cooling-water circulating pumps,motors shall be sized to operate at the end-of-curve.

4.5.1.7 The motor and coupling shall be sized to meet any specified futureincrease in power or head requirement.

4.5.1.8 The motor shall have adequate power for initial run-in on water withthe pump throttled to 50% of rated capacity. If this requirementresults in an increase in motor size, the larger motor shall be quotedas an alternate.

Comment: The purpose of this requirement is to verify that themotor is adequately sized for water runs. However,if a larger motor must be furnished solely for waterruns, it should first be verified that a water run isplanned, and if so, alternate methods ofaccomplishing the water run should be investigatedbefore deciding to use the larger motor. If waterruns are not planned for startup, other methods ofensuring cleanliness of the system must be usedsuch as a blowdown with compressed air.

4.5.2 Steam Turbine4.5.2.1 Steam turbine drivers shall conform to API Std. 611.

4.5.2.2 Steam turbine power rating shall be 110% of the greatest calculatedpower requirement of the pump at any operating condition.

4.6 Energy Evaluations4.6.1 Selection of pumps and drivers shall take into consideration cost of energy in

the plant in which they are to be installed along with a payout periodconsistent with the design life defined in the project premises.

4.6.2 Efficiency of pump/driver used for the selection described in Section 4.6.1shall be the efficiency that occurs at the normal operating flow rate and at



the resulting head for the diameter of the impeller selected. Hours per year ofpump operation shall reflect the design stream factor.

4.7. Application of Specific Pump Types4.7.1 ASME B73.1M and B73.2M Pumps

Unless otherwise specified, application of ASME B73.1M andASME B73.2M pumps shall be limited in accordance with Tables 2, 3, and 4:

Table 2. ASME Pump LimitationsCharacteristic Limitation

Maximum Temperature - °F (°C) 300 (150)Maximum Discharge Pressure - psig (kPa) 275 (1,900)Maximum Suction Pressure - psig (kPa) 75 (500)Maximum Rotative Speed - RPM 3,600

Table 3. ASME Vertical in-Line Pump Limitations

Type of Pump:Horizontal ASME AA through A-70

Vertical in-Line ASMEIntermediateLife Plants

Long Life, HighStream Factor

Plants

Flow - Max., GPM (Cubic Meters/Hour ) ASME Standard 600 (135)Head - Max., Feet (Meters) ASME Standard 400 (120)

Table 4. ASME Horizontal Pump Limitations

Type of Pump:Horizontal ASME A-80 through A-120

IntermediateLife Plants

Long Life, HighStream Factor

Plants

Flow - Max., GPM (Cubic Meters/Hour ) ASME Standard 2,000 (450)Head - Max., Feet (Meters) ASME Standard 200 (60)

4.7.2 API 610 Single Stage PumpsUnless otherwise specified, application of API 610 single stage pumps shallbe limited in accordance with Tables 5 and 6.

Table 5. API Overhung Pump LimitationsType of Pump:Overhung API

Horizontal or VerticalIntermediate Life

Plants

Long Life,High StreamFactor Plants

Flow - Max., GPM (Cubic Meters/Hour) 5,000 (1,140) 3,000 (680 )Head - Max., Feet (Meters) 1,000 (300) 700 (215)



Table 6. API High-Speed, Integrally Geared Pump Limitations

Type of Pump:High-Speed, Single Stage,

Integrally Geared, API

IntermittentService or

Intermediate LifePlants

Long Life,High StreamFactor Plants

Flow - Max., GPM (Cubic Meters/Hour) 350 (80) 250 (57)Head - Max., Feet (Meters) 5,000 (1,525) 4,500 (1,370)



Appendix – Figures

PIP RECP001 STEERING TEAM BALLOT – COMPLETE REVISIONDesign of Pumping Systems That Use Centrifugal Pumps 11/20/03


Appendix – Figures

Documents

Pump Selection