4/19/23,12:17 PM
FileOpen Web Viewer
ANSI/HI 9.6.6-2022
N
(ansi
American National Standard for
Rotodynamic
Pumps
for Pump Piping
@ E'
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
™ HYDRAULIC
L"INSTITUTE
FileOpen Web Viewer
4/19/23,12:17 PM
ANSV/HI 9.6.6-2022
American National Standard for
Rotodynamic Pumps
for Pump Piping
Sponsor
Hydraulic Institute
‘www.Pumps.org
Approved February 8, 2022
American National Standards Institute, Inc.
Hydrauic Institute Standards, Copyright© 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
2/72
4/19/23,12:17 PM
FileOpen Web Viewer
American Approval of an American National Standard requires verification by ANSI that the requirements
for due process, consensus and other criteria for approval have been met by the standards
National developer.
Standard
consensus is established when, in the judgement of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial
agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made
toward their resolution.
The use of American National Standards is completely voluntary: their existence does not in
any respect preclude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the
standards.
The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall
have the right or authority to issue an interpretation of an American National Standard in the
name of the American National Standards Institute. Requests for interpretations should be
addressed to the secretariat or sponsor whose name appears on the title page of this standard.
CAUTION NOTICE: This American National Standard may be revised or withdrawn at any
time. The procedures of the American National Standards Institute require that action be taken
periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National
Standards may receive current information on all standards by calling or writing the American
National Standards Institute.
Published By
Hydraulic Institute
300 Interpace Parkway, Bldg. A, 3rd Floor
Parsippany, NJ 07054
www.Pumps.org
Copyright © 2022 Hydraulic Institute
All rights reserved.
No part of this publication may be reproduced in any form,
in an electronic retrieval system or otherwise, without prior
written permission
of the publisher.
Printed in the United States of America
ISBN 978-1-954671-10-2
Hydrauic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
372
4/19/23,12:17 PM
FileOpen Web Viewer
Flowchart for use of standard (mechanical considerations) .
Flowchart for use of standard (hydraulic considerations) . . .
9.6.6
9.6.6.1
9.6.6.1.1
9.6.6.1.2
9.6.6.1.2.1
Rotodynamic pumps for pump piping .
A
Introduction
A
Purpose.
Scope ..
Piping
A
A
A
9.6.6.1.2.2
Viscosity considerations .
A
9.6.6.2
Pump Piping Design General .. .....uueeieeeieieneiaineeneenennasnaeneananns 2
9.6.6.3
Inlet (suction) piping reqUIFEMENtS . . .. oueie e
ei
et eieieeeneeeenaanaanaananns 3
9.6.6.3.2
Inlet (suction) pipe size/velocity requirements. . ......... ... ... ... i 4
9.6.6.3.3
Effect of piping-generated SWirl . . . ... ...................iiiiiiiii 5
96634
Required straight pipe 1engths. . .. ... .. ... ... 5
9.6.6.35
Need for physical hydraulic model Study . . .. .. ... ...........ooiieeeieaio.
.. 12
9.6.6.3.6
Use of computational fluid dynamics (CFD) .................. ..o, 13
9.6.6.3.6.1
Acceptable uses of CFD modeling in pump suction hydraulics . .................. 14
9.6.6.3.6.2
Unacceptable uses of CFD modeling in pump suction hydraulics ................. 14
9.6.6.3.7
Pump suction piping/wet-well connection .. ......... ... .. . .o 14
9.6.6.3.8
Pump suction @lbows. . . . ... .. 15
9.6.6.3.9
Pump station retrofit or modification ......... ... .. o 16
9.6.6.4
Outlet (discharge) piping requIremMents. . ... ..ueeeeeeeeieneeaeeaaaanaananaanns 16
9.6.6.4.1
Pipe size/velocity requirements. .. .......... ... 16
9.6.6.4.2
Outlet (discharge) straight pipe lengths. . . ..................................... 17
9.6.6.43
Recommendedvalves. . ....... ... .. iiiiiiiiiiiiiiiieiiaaaaa, 17
9.6.6.43.1
Shut-off/lsolation valves .. .......... ... ... ... 17
9.6.6.432
Check ValVes. . . ... .. o 17
9.6.6.433
Pumpcontrol valves . . ... ....... ... . 18
9.6.6.43.4
Trple-dUty VAIVES . . ... o 18
9.6.6.435
Airrelease VaIVeS . . . ... ...t 19
9.6.6.44
L
g
R
R
P e S
SRR
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
O ST
T 19
iii
472
4/19/23,12:17 PM
FileOpen Web Viewer
9.6.6.5
Inlet (suction) and outlet (discharge) general piping requirements.. .
9.6.6.5.1
Pipe nozzle alignment/pipe expansion load . .
9.6.6.5.1.1
9.6.6.5.2
Pump nozzle analysis
Pipe supports/anchors. .
9.6.6.5.2.2
9.6.6.5.2.3
9.6.65.2.4
Final installation .
9.6.6.5.2.5
Field adjustment . .
9.6.65.3
Parallel operation. . .
Appendices Introuction. .
Appendix A System curves .
A1
Calculation of the System curve . ... ... ... . i
A2
Pipe head loss calculationmethods. .. ... ... ...
Appendix B Water hammer .
B1
Water hammer .
Appendix C
ci
c2
Pipe supports for vertical loads
c3
Guides and restraints .
ca
cs
cé
s 27
Appendix D
D1
D2
Expansion joint types .
Expansion joint application.
B
... ...
oo 42
Appendix E Specialty piping components and applications. . ...............
3]
E2
E3
E4
ES
Check valves and strainers.
Devices to improve flow to the pump .
Piping for suction lift applications . . . .
Appendix F Pressure pulsation and acoustic resonance.
General. .
F1
Piping acoustics
F2
Appendix G
G
G2
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
572
4/19/23,12:17 PM
FileOpen Web Viewer
G3
Assessment
of Non-Compliant Piping . .
G4
Mitigation of Non-Compliant Piping . .
Appendix |
Sources of additional information. .
Appendix J
List of acronyms. .
Figures
9.6.6.3 — Suction pipe design for systems with suction lift. . . ............
... ... ... ol 4
9.6.6.3.4a — General example of requirement 9.6.6.3.4.5 with eccentric reducer downstream of the suction
pipefromabove . ... ... ... 6
9.6.6.3.4b — General example — pump suction with a required L, length for a flow-disturbing fitting . . . .. ...
. .8
9.6.6.3.4c — General example — pump suction with an allowed fitting connected directly and a required
L, length for a flow-disturbing fitting . . . . .......... ... 8
9.6.6.3.4d — Specific example — pump suction with a required L, length for a short-radius
reducing elbow (< 30% area reduction) . .
9.6.6.3.4e — Specific example — pump suction with a concentric reducer (1 pipe size reduction),
and a required L, length for a short-radius elbow. . . . ...........
... ..
i9
9.6.6.3.4f — Specific example - pump suction with a required L, length for a suction header
(teeorbranch flow) . . ... . ..
9
9.6.6.3.4g — Specific example — pump suction with an eccentric reducer (2 pipe size reduction),
arequired L, length for a concentric reducer (4 pipe size reduction),
and
ashort-radius elbow. . ... ... .. 9
9.6.6.3.4h — Specific example — pump suction with a required L, length for a concentric reducer
(4 pipe size reduction) and along-radius elbow. . . ............
... . oo 10
9.6.6.3.4i — Specific example —pump suction with a manufacturer-approved 90° elbow, an eccentric
reducer (1 pipe size reduction), and a required L, length for long-radius elbow . . ............. 10
9.6.6.3.4j — Specific example — pump suction with a manufacturer-approved 90° elbow and a required
L, length for an eccentric reducer (4 pipe size reduction) . . .. ..........
.. ... oo 10
9.6.6.3.4k — Specific example (top view) — between bearing split case (double suction) pump with
an eccentric reducer (1 pipe size reduction), a required L, length for a concentric
reducer
(4 pipe size reduction), and a short-radius elbow (*added one diameter for double suction
with elbow in plane with pump shaft) .. ... ... .. ... .. i n
9.6.6.3.41 — Undesirable effect of an elbow mounted directly on suction nozzle of double suction pump
with flow direction into the elbow inlet parallel to the shaft (applies to all double suction
applications with either horizontal or vertical shaft orientation on either side or bottom suction) . .11
9.6.6.3.4m — Examples of suction pipe fittings near the pump that require approval of the pump
OGS . . .. ie et iiaiicicaaietaacacaaiactasacasasastsasaaasasssasananans 12
9.6.6.4.3 — THIPIE-AUEY VAIVE . . ... .. ..o\ttt
et e
9.6.6.5.3a — Minimum required suction pipe length and spacing for parallel pumps . .
9.6.6.5.3b — Parallel pump installation L,
9.6.6.5.3c — Constant-velocity manifold design, parallel pumps. . . . ... ..............................
9.6.6.5.3d — Alternatives for suction header to suction lateral transition . .
C.1 — Pipe supports for vertical loads.
C.2 — Solid pipe hanger SUPPOMES. . . . . ... .. ..ttt 35
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
v
672
4/19/23,12:17 PM
FileOpen Web Viewer
C.3 — Constant-effort spring supports .
D.2 — Rubber expansion joints
D.3
— Metal bellows expansion joint . .
D.4 — Expansion joint bolting arrangement. . . ... ... ...
E.1 — FOOt VaIVe ANA SCIEN. . . .. ...ttt ittt et
E.2 — Foot valve (rubber flapper check valve without screen) .
E.3 — Foot valve installation .
E.4 — Typical temporary strainer
E.5 — Second upstream perpendicular lbow. . .. . ... ... 44
E.6 — Staightening Vanes . . .. .. ... ...ttt
s45
E.7 — Straightening vanes downstream from bend. . .
E.8 — Straightening vanes for solids-bearing liquids. .
E10—Grating
or flow grid . . . ... ... 48
E.11 — Self-priming piping amrangement. . . ... .. ... ...ttt 49
Tables
9.6.6.3.4 — Minimum required straight pipe length (L,) before pump suction nozzle .
B.1 — Magnitude
of pressure . .
i
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
7m2
4/19/23,12:17 PM
FileOpen Web Viewer
Foreword [Not part of American National Standard (ANSI)]
Purpose and aims of the Hydraulic Institute
The purpose and aims of the Hydraulic Institute are to drive all Pump System stakeholders towards a sustainable
future by:
a) Advancing Solutions for Pump System Performance and Efficiency
b) Developing Standards and Technical Resources
©) Educating the Global Marketplace
d) Advocating for the Industry
Purpose of Document:
Hydraulic Institute Standards and Guidelines may be published as American National Standards, and are adopted
in the public interest to help eliminate misunderstandings between the manufacturer, the purchaser, and/or the
user and to assist the purchaser in selecting and obtaining the proper product for a particular need. Use is completely voluntary and does not in any respect preclude a member from manufacturing or selling products which are
not conforming.
Definition of Hydraulic Institute Standard
Quoting from Article XV, Standards, of the By-Laws of the Institute, Section B:
“An Institute Standard defines the product, material, process or procedure with reference to one or more of the
following: nomenclature, composition, construction, dimensions, tolerances, safety, operating characteristics,
performance, quality, rating, testing and service for which designed.”
Definition of Hydraulic Institute Guideline
A Hydraulic Institute Guideline is not normative. The guideline is tutorial in nature, to help the reader better understand the subject matter.
Comments
from Users
Comments from users of this standard will be appreciated, to help the Hydraulic Institute prepare even more useful
future editions. Questions arising from the content of this standard may be directed to the Technical Director of the
Hydraulic Institute. If appropriate, the inquiry will then be directed to the appropriate technical committee for provision of a suitable answer.
Revisions
American National Standards of the Hydraulic Institute are subject to constant review, and revisions are undertaken whenever it is found necessary because of new developments and progress in the art. Errata or addenda
may be issued to address limited changes. If no revisions are made for five years, the standards are reaffirmed
using the ANSI canvass procedure.
Disclaimer
This document was prepared by a committee of the Hydraulic Institute and approved by following ANSI essential
requirements. Neither the Hydraulic Institute, Hydraulic Institute committees, nor any person acting on behalf
of the Hydraulic Institute: 1) makes any warranty, expressed or implied, with respect to the use of any information, apparatus, method, or process disclosed in this document or guarantees that such may not infringe privately
owned rights: 2) assumes any liabilities with respect to the use of, or for damages resulting from the use of, any
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
il
872
4/19/23,12:17 PM
FileOpen Web Viewer
information, apparatus, method, or process disclosed in this guideline. The Hydraulic Institute is in no way responsible for any consequences
to an owner, operator, user, or anyone
else resulting from reference
to the content of
this document, its application, or use.
This document does not contain a complete statement of all requirements, analyses, and procedures necessary
to ensure safe or appropriate selection, installation, testing, inspection, and operation of any pump or associated
products. Each application, service, and selection is unique with process requirements that shall be determined by
the owner, operator, or its designated representative.
Units of measurement
Metric units of measurement are used, and corresponding US customary units appear in parentheses. Charts, graphs,
and sample calculations are also shown in both metric and US customary units. Because values given in metric units
are not exact equivalents to values given in US customary units, it is important that the selected units of measure to
be applied
be stated in reference
to this standard. If no such statement
is provided, metric
units shall govern.
Consensus
Consensus for this American National Standard was achieved by use of the canvass method. The following organizations, recognized as having an interest in the standardization of pumps, were contacted prior to the approval
of this revision of the standard. Inclusion in this list does not necessarily imply that the organization concurred with
the submittal of the proposed standard to ANSI.
Universidad Tecnologica de Panama
TACO INC
Swiss Flow Solutions GmbH
Patterson Pump Company
Hydraulic, Measurement, and Inspection Consulting, LLC ~ Peerless Pump Company
Budris Consulting
Formally Sulzer
4B Engineering & Consulting, LLC
Summit Pump Inc
CDM Smith
Pentair
DynaTech Engineering, Inc.
Weir Minerals NA
Stantec
Xylem AWS
Parametrix, Inc.
Kirloskar Brothers Limited
AECOM
TRWD
Brown and Caldwell
Carollo Engineers
Trillium Pumps USA, Inc.
LAS VEGAS VALLEY WATER DIS
Irving Oil
Syncrude Canada
Kennedy Jenks
Westinghouse Electric Co.
Committee list
Although this standard was processed and approved for submittal to ANSI by the canvass method, a working committee met many times to facilitate its development. At the time it was developed, the committee had the following
members:
Chair — Dave Werth, Clemson Engineering Hydraulics, Inc.
Vice-chair — Steven Fehniger, CDM Smith, Water Services Group
Chair (Retired) — Mick Cropper, Sulzer (Retired)
Committee Member
Lloyd Aanonsen
Charlie Allaben
Paul Boyadijis
Jack Claxton
Company
General Rubber Corporation
HDR, Inc.
Mechanical Solutions, Inc.
Patterson Pump Company
Bob Hawboldt
AE - Associated Engineering
Kara Hurtig
Andrew Johansson
Northwest Hydraulic Consultants Ltd.
Alden Research Laboratory, Inc.
i
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
972
4/19/23,12:17 PM
FileOpen Web Viewer
Committee Member
Company
Daniel Boldt
Trillium Pumps USA
Mark Lawson
CIRCOR Pumping Technologies
Fangbiao Lin
Paul Moulton
Michael Mueller
Jeff Olsen
Maria Elena Rodriguez Hernandez
Stantec
AECOM
Flowserve Corporation
Aleks Roudnev
Weir Minerals North America
David Skinner
ITT - Industrial Process
Hazen and Sawyer, P.C.
Mark Supplee
Jerry Szofer
Rafiq Qutub
Applied Flow Tech
INGETEAM INDAR MACHINES
Grundfos Water Utility
Carollo Engineers, Inc.
Mike Zappone
Industry Partner
Committee Alternate
Mark Allen
Company
Jason Kerns
Joseph Orlins
Jeff Ruzicka
CDM Smith — Water Services Group
Flowserve Corporation
HDR Inc.
AECOM
AE - Associated Engineering
Constentino Senon
Stantec
George Tey
Trey Walters
Tyler Whitehouse
Ed Wicklein
Stantec
Eric Eylat
Applied Flow Technology
Carollo Engineers, Inc.
Corrollo Engineers, Inc.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
10172
4/19/23,12:17 PM
FileOpen Web Viewer
Flowchart for use of standard (mechanical considerations)
NOTE: This flowchart is intended as a guide to the use of this standard and can be used to locate the appropriate
sections in this standard. The chart is not a substitute for comprehension of the complete standard.
START
[
]
Atter conducting
piping analysis to
determine if pipe system induced forces f— Yes
on pump nozzles are loads within pump
allowable
loads? Section 9.6.6.5.1
x
END
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
172
4/19/23,12:17 PM
FileOpen Web Viewer
Flowchart for use of standard (hydraulic considerations)
NOTE: This flowchart is intended as a guide to the use of this standard and can be used to locate the appropriate
sections in this standard. The chart is not a substitute for comprehension of the complete standard.
Determine
pump outiet
START |
T
Outiet (dscharge) piing ———> (et Sacaenes 6a.4 and
9665
Inlet (suction) piping
-
r—p——
in pump outlet (discharge)
pipe: Section 9.6.6.4.3
No
Determine header
l
(manifold) design
Deter
pump pipe
mine
inlet (suction)
and pump inlet
design, size, and velocity: Sections
(suction) velocity:
966349665
Section 9.6.65.3
Design piping and
calculate system curve(s):
AppendixA
Determ
if required,
foot valves
ine,
and strainers: Appendix E
Calculate NPSHA
Make pump selection
Check NPSH Margin in accordance
with ANSUHI 9.6.1 Rotodynamic
Pumps - Guidel
for NPSHine
Margin
i
Review outlet
piping: Section 9.6.6.4
3
Deter
if pipingmine
changes are
needed to mitigate water
hammer: Appendix B
No
o
)
Study in accordance with
Determ
if physical
model
ine
Pumps for Pump Intake
96635
ANSI/
9.8 Rotodynamic
HI [¢—Yes— study is required: Section
Desig
and redesignn
as
required
Yes
—*No
l
END
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
12172
4/19/23,12:17 PM
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
FileOpen Web Viewer
1372
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.6.6
Rotodynamic pumps for pump piping
9.6.6.1 Introduction
This most recent revision of the standard has been divided into numbered requirements followed by guidance
(indicated by the word *Notes") for the user. Any lettered list within a numbered requirement are also requirements.
For guidance on the use of this standard for mechanical and hydraulic piping design, refer to the flow charts preceding this introduction.
9.6.6.1.1
Purpose
The objectives of this standard are to provide the requirements for rotodynamic pump piping and to educate users
about the effects and interactions of inlet (suction) and outlet (discharge) piping on rotodynamic pump performance
and service life.
9.6.6.1.2
Scope
This standard applies to inlet (suction) and outlet (discharge) piping for rotodynamic pumps of radial, mixed and
axial flow types, in all worldwide markets. It identifies and details the required and recommended practices for
pump piping that will serve to reduce the risk of the pump failure to perform due to system interaction.
9.6.6.1.21
Piping
This document is intended to complement ANSI/HI 9.8 Rotodynamic Pumps for Pump Intake Design. To eliminate
the possibility of overlap and conflict with other standards, this document is applicable as follows:
+
Al piping upstream from the pump, regardless of pump suction orientation (e.g. side-suction, bottom-suction,
etc.) and installation configuration (e.g. horizontal and vertical).
+
Al piping downstream from the pump, regardless of pump suction orientation (e.g. side-suction, bottom-suction,
etc.) and installation configuration (e.g. horizontal or vertical).
The standard excludes the following:
1) Any piping integral to the pump unit, such as auxiliary or lubricant piping.
2)
Requirements for suction piping when the pipe enters a tank, vessel, or other pump intake structure as described
in ANSI/HI 9.8 where specific suction piping requirements are provided.
The standard covers the following topics as they relate to rotodynamic pump suction and discharge piping:
-
Effects of piping on liquid suction conditions (such as the effect on net positive suction head available [NPSHA],
which influences cavitation).
+
Effects on pressure development of the pump, hydraulic and piping loads on the pump, piping system considerations (water hammer, parallel pump operation, valving, and pipe supports), pump noise, and pump vibration.
9.6.6.1.2.2 Viscosity considerations
The fundamental recommendations and requirements of this standard do not change with increases in liquid
viscosities for Reynolds numbers above 1 x 105
Effects
of changes in liquid viscosity
on pump performance are described in ANSI/HI 9.6.7 Rotodynamic Pumps —
Guideline for Effects of Liquid Viscosity on Performance.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
1
14172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
Head and rate of flow will normally decrease as viscosity increases. Power will increase, as will net positive suction
head required (NPSH3) in most circumstances. Starting torque may also be affected. Likewise, liquid flow within a
piping system will also be similarly affected by changes in liquid viscosity.
Friction in the pipe and fittings will be increased with higher viscosity. It is appropriate that these effects be taken
into consideration when determining the design of a piping system. For Reynolds numbers below 1 x 10° physical
modeling and CFD analysis studies may be considered as a means by which to simulate these effects. See sections 9.6.6.3.5 and 9.6.6.3.6.
9.6.6.2 Pump Piping Design General
In order to mitigate the risk of pump or system malfunction or failure, the piping system requirements shall be
identified and met. These requirements can be identified as the manifestation of the known best practices. This
standard presents known and accepted best practices based on information available to the Hydraulic Institute at
the date of publication.
9.6.6.21 In the application of this standard, the flow rate at pump rated condition point shall be used as the
design flow rate for the basis of the piping design. Refer to Notes 1 and 2.
Notes:
1.
Other considerations in the pump system design and contemplated modes of operation may require the pumps
to frequently function under higher rates of flow. In such instances, the maximum flow rate should be considered
for the purpose of piping design unless specified otherwise.
2.
Refer to ANSI/HI 9.8 appendix titled “Influence of pump selection on intake design* for discussion on this topic.
3.
Velocity to be interpreted as the average velocity
of the pipe calculated using the internal cross sectional area
unless otherwise indicated. Velocity of liquid inside the pipe should be determined using the pipe internal diameter rather than nominal pipe diameter.
4.
Reference pipe diameters relate to nominal pipe size (NPS), not the pipe inside diameter.
5.
Inthe case of existing pump installations, it is recognized that site conditions and constraints will often prevent
full compliance with the requirements of this standard. Refer to Appendix G for guidance in these circumstances.
6.
The function of pump piping is to provide a conduit for the flow of liquid to and from a pump, while not adversely
affecting the pump performance or reliability. Well-designed piping systems will normally be more energy efficient than a poorly designed system.
7. The function
of suction piping is to provide
a uniform velocity profile or symmetric approach flow to the pump
suction nozzle with sufficient pressure to avoid damaging cavitation in the pump. An uneven distribution of flow
is characterized by strong local currents and swirls. The ideal approach is a straight pipe, connected directly
to the pump, with no turns or flow-disturbing fittings close to the pump. Failure of the suction piping to deliver
the liquid to the pump in this condition can result in noisy operation, random axial load oscillations, premature
bearing or seal failure, cavitation damage to the impeller and suction portions of the casing, early onset of suction recirculation, and occasionally damage due to liquid separation on the discharge side. For additional intake
design recommendations
see references 1, 2, and 3 in Appendix H.
8.
Discharge piping flow characteristics normally will not affect the performance or reliability of a rotodynamic
pump, with a few exceptions.
a.
2
Sudden stopping and starting of pumps during emergency power failure, sudden valve closures can cause
water hammer and generate damaging high pressures to the pump and/or piping system components. To
evaluate the water hammer effect, a transient flow analysis may be required (see Section 9.6.6.4.4 and
Appendix B).
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
1572
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.
b.
Discharge piping can affect the starting, stopping, and priming of the pump.
c.
Thedischarge piping configuration can also influence any discharge flow recirculation that might extend into
the discharge piping at very low flow rates.
Itis a good practice to provide a pipe coupling or dismantling joint at the pump nozzles to facilitate maintenance
oor removal of the pump.
10. Common detrimental effects caused by poor pump piping and pipe support design include:
a.
Excessive piping loads on a pump because of pipe misalignment with the pump connections.
b.
Failure to properly restrain the pump to the foundation support. For example, when pump anchor fasteners
are loosened, modified, or removed to aid in alignment with piping, robust pump anchorage may be compromised and impact pump operation.
c. Excessive loads on piping resulting from unsupported or poorly supported valves, fittings, or vertical inline
pumps. Excessive pump nozzle loads are caused by thermal expansion of the pipe, unsupported piping and
equipment weight, axially unrestricted couplings, and misaligned piping. Excessive pump nozzle loads lead
to misalignment of the pump shaft with the driver shaft, mechanical seal failures, bearing failures, binding
or rubbing of the pump rotor, and in extreme cases, failure of pump nozzles or mounting feet.
9.6.6.3 Inlet (suction) piping requirements
Suction flow disturbances such as swirl, non-uniformity in the distribution of velocities and pressures, and sudden
variations in velocity can be harmful to the hydraulic performance of a pump, its mechanical behavior, and its reliability. Usually the higher the power, rotative speed, and specific speed of a pump, and the lower the NPSH margin, the more sensitive the pump's performance is to suction hydraulic conditions. This section provides requirements and guidance to minimize suction flow disturbances at the pump suction nozzle.
9.6.6.3.1 All suction fitting joints shall be tight, especially when the pressure in the piping is below atmospheric,
to preclude air leaking into the liquid.
Notes:
1.
Any valve in the suction pipe should be installed with stems oriented to minimize the possibility of air (gas)
accumulation unless this stem orientation creates an approach flow disturbance.
2.
For most pumping systems, an suction shut-off valve should be installed in the suction piping for system or
pump isolation. The shut-off valve should be selected with consideration of impact on NPSH margin.
3.
For pumps operating with a suction lift, suction pipe should slope constantly upwards toward the pump, with a
minimum slope of 1% (Figure 9.6.6.3). In general, as liquid travels through a piping network, entrained air tends
to rise to the highest point. If the pipe slopes upward toward the pump, then the velocity of the liquid will move
the air bubbles towards this high point at the pump. In contrast, if the pipe is fairly flat and the inside surface of
the pipe is very rough,
or the pipe slopes downward
toward the pump, then the fluid velocity may not be sufficient to keep the air bubbles moving. As a consequence, it is possible for a pocket of air to collect at localized
high points and gradually reduce the effective liquid flow area. This reduction in area can create a throttling
effect similar to a partially closed valve.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
3
16/72
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
RECOMMENDED
NOT RECOMMENDED
Figure 9.6.6.3 — Suction pipe design for systems with suction lift
Itis also possible that a slug of air may be swept into the pump during a restart or normal operation, causing a partial or complete loss of pump prime, especially in applications where the suction pipe is kept full by
a foot valve at its intake (see Appendix E).
4.
Any amount of entrained air in the liquid may adversely affect pump performance. Check with the pump manufacturer to determine allowable levels of entrained air, and review ANSI/HI 14.3 Rotodynamic Pumps for
Design and Application for more information on the topic.
9.6.6.3.2 Inlet (suction) pipe size/velocity requirements
This subsection provides guidance on velocity variation throughout the suction piping as well as guidance regarding maximum recommended suction velocity. The resultant suction piping size(s) can be determined based on this
guidance and recommendations at the design flow rate. For closed conduit flow applications in fully turbulent flow
regime, the magpnitude of the velocity does not measurably influence the flow distribution characteristics.
9.6.6.3.2.1
The velocity
in the suction piping shall be constant or increasing as the flow approaches the pump.
9.6.6.3.2.2
Transitions resulting
in flow deceleration at the pump shall not be used.
9.6.6.3.23
The suction pipe shall be at least as large as the pump suction nozzle. Refer to Note 1.
9.6.6.3.2.4
For liquids close to the vapor pressure, the velocity shall be kept low enough to avoid flashing of
the liquid in the piping, especially when fittings are present. Refer to Note 2.
Notes:
1.
The velocity at any point along the suction piping is recommended to be a maximum of 2.4 meters per second
(m/s)(8 feet per second [ft/s]), unless the liquid is a slurry. However, this velocity recommendation does not
apply to the straight run of pipe immediately upstream of the pump suction nozzle provided this pipe is the same
diameter as the pump suction nozzle and directly connected to the pump.
a.
See section 9.6.6.2 (Pump Piping Design General) for design flow rate guidance.
In all cases, especially for those with velocities in excess of 2.4 m/s (8 ft/s), suction velocities should be
evaluated with respect to noise, erosion, NPSH margin, water hammer, cavitation, pump and valve manufactuer's recommendations and pump system life cycle cost.
c. |If the liquid is a slurry, velocity may need to be higher to maintain solids in suspension (refer
to Appendix
E.4). Minimum velocity in range of 2 to 4 m/s (6.5 to 13 fi/s) typically recommended due to the high specific
gravity of solids for most slurries.
d.
For many common solids-bearing liquids (such as raw wastewater with primarily organic solids or primary
sludge), a minimum velocity
of 1.0 m/s (3 ft/s) is recommended to reduce sedimentation in horizontal piping.
e.
A velocity as low as 0.6 m/s (2 fi/s) is generally sufficient for organic solids (such as mixed liquor in an
activated sludge biological wastewater treatment process).
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
17172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
2.
Areduction in pressure and/or flashing can liberate dissolved air and vapor, which can be carried into the suction of the pump resulting in loss of performance and also potentially loss of prime.
3.
In some cases, smaller pipe sizes may be beneficial by allowing for more straight pipe length upstream of the
pump suction nozzle. Refer to requirement 9.6.6.3.2.3
4.
The suction piping should be designed with gradual transitions if changing pipe sizes.
5.
The suction piping should be designed to minimize changes in flow direction.
6.
Valves and other flow-disturbing fittings located in pump suction piping should be at least one pipe size larger
than the pump suction nozzle, with the exception of continuous-bore, 100% open valves (such as full-ported
ball valves and gate valves).
9.6.6.3.3 Effect of piping-generated swirl
The most disturbing flow patterns entering a pump are those that result from swirling liquid that has traversed
several changes of direction in various planes. When fittings, such as tees and elbows (especially two elbows
at right angles), are located too close to the pump suction, a spinning action, or swirl, is induced. This swirl may
adversely affect pump performance by reducing efficiency, head, NPSHA, and potentially causing noise, vibration,
and damage.
9.6.6.3.3.1
Liquid in the suction pipe shall approach the pump in a state of straight, steady (uniform) flow.
9.6.6.3.3.2 A straight and uninterrupted section of pipe be installed between the pump and the nearest flow-disturbing fitting. Refer to Notes 1-2.
Notes:
1.
See Figures 9.6.6.3.4a - k, which demonstrate the minimum required lengths specified in Table 9.6.6.3.4.
2.
If the minimum recommended pipe lengths cannot be provided, then conformance with the Standard may
be demonstrated with a physical model study. Modifications identified in the model study to address adverse
hydraulic conditions could include the use of flow-straightening devices (see Appendix E.2).
9.6.6.3.4 Required straight pipe lengths
The minimum
required suction pipe lengths stated in Table 9.6.6.3.4, the related requirements, and guidance are
provided to maximize the potential for uniform approach flow at the suction nozzle. Following the requirements
and guidance, will minimize the impact on pump hydraulic performance and improve the service life.
9.6.6.3.4.1 In general, pumps shall have an uninterrupted and unthrottled flow into the suction nozzle (no flowdisturbing fittings for the required minimum length identified with Table 9.6.6.3.4).
9.6.6.3.4.2 The use of flow-disturbing fittings on the suction of the pump shall be carefully evaluated.
9.6.6.3.4.3 Flow-disturbing fittings not specifically allowed by Table 9.6.6.3.4 shall not be connected directly to
the pump suction nozzle without approval from the pump manufacturer.
9.6.6.3.4.4 Isolation valves and other devices used on the suction side of the pump shall be sized andlocated
to
minimize disturbance of the flow into the pump (Table 9.6.6.3.4).
9.6.6.3.4.5 In horizontal suction piping, the flat side of the eccentric reducer shall be located on the top. In horizontal suction piping where flow approaches from above, either a concentric reducer or an eccentric reducer with
flat side on the bottom shall be used (Refer to Note 4 and figure 9.6.6.3.4a).
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
5
1872
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
DIRECTION
OF
£ccentAic Repucer |HAUIP FLOW
(FLAT SIDE ON BOTTOM)
Lo
¢
i
_____ R
PUMP SUCTION NOZZLE
N
g
'VERTICAL SUCTION
wTERaL
|
LONG RADIUS
ELBOW
Figure 9.6.6.3.4a - General example of requirement 9.6.6.3.4.5 with eccentric reducer downstream
of the vertical suction pipe from above
9.6.6.3.4.6 Table 9.6.6.3.4 shall be utilized to determine the minimum length
of straight pipe (L,) required immediately
upstream of the pump suction nozzle for a variety of commonly used fittings and valve types. Refer to Notes 5 - 7.
A.
Reference example Figures 9.6.6.3.4a - k.
B. The velocity recommendations of Section 9.6.6.3.2 do not apply to this section of pipe (i.e., the L/D,
section).
C. If several fittings are adjacent, the fitting with the greatest length requirement shall govern and that length
requirement shall be applied to the most downstream fitting (reference Figures 9.6.6.3.4g, h, and j).
Notes:
1.
Flow disturbances on the suction side of the pump can lead to deterioration in performance (lower head and/
or lower NPSHA), and damage leading to reduced impeller, mechanical seal, and bearing life due to cavitation,
pulsation surges, and excessive radial and axial forces.
2.
3.
4.
The effect of flow disturbances from fittings installed in the suction piping will diminish with increasing distance.
For example, short suction piping is less effective in moderating disturbances before the flow reaches the pump.
For VS6 and VS7 pump types, the straight run requirements summarized herein do not apply to suction can
piping which is covered in ANSI/HI 9.8.
Aconcentric reducer is typically applied in vertical suction pipes or horizontal pipe installations where there is no
potential for air or vapor accumulation. Eccentric reducers are normally used for horizontal installations where
there is potential for air or vapor accumulation. Eccentric reducers typically positioned with flat side up to avoid
trapping air or vapor. However, in vertical suction lateral which approaches from above eccentric reducer flat
side is positioned down as shown in Figure 9.6.6.3.4a to facilitate continuous removal of air or vapor through
the vertical lateral.
5.
Failure to provide the minimum pipe lengths specified in Table 9.6.6.3.4 can lead to the hydraulic and mechan-
ical issues described above.
6.
Double suction pumps are a sensitive application because an elbow in the plane of the pump shaft mounted on
the suction nozzle will direct more flow to one side of the impeller than the other (see Figure 9.6.6.3.4l).
7.
Figure 9.6.6.3.4m shows examples of flow-disturbing fittings attached directly to the pump that require approval
by the pump manufacturer.
6
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
1972
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
Table 9.6.6.3.4 — Minimum required straight pipe length (L,) before pump suction nozzle
(refer to Figures 9.6.6.3.4a - k)
Number of pipe diameters®®
Comments
Fiting
Long radius
Short radius
90° elbow
4
5
4
ek
it
Reducing elbow with 30% to < 50% area reduction
2
3
Area reduction
(%) =
Reducing elbow with > 50% area reduction
0
1
(AAIA,
Reducing elbow wilh < 30% area reduction
3
Reducers
Concentric
Eccentric
1 pipe size reduction
2 pipe size reductions
3 pipe size reductions
4 pipe size reductions
5 pipe size reductions
0(<10°F
0(<20°)
0(<207)
2(<20°)
3(<30°)
0(<20°)°
0 (<30%)
1 (<30%)
3 (<40°)
4 (<40°)
< 45° lateral
4
Tee, branch flow, > 45°
5
Continuous-bore valve (100% open)
0
Eccentric plug valve - rectangular 80% port
Eccentric plug valve - rectangular 100% port
4
3
Butlerfly valve®
2
For double suction pumps, add one
(Continuous-bore ball and
gate valves)
1)
an allowed fiting is connected directly 1o the pump, the next fitling upstream shall have a length L, between it and the pump at least
‘equal to the number of straight pipe diameters referenced in this table. The length of the allowed fiting ks not to be included as a part
of this distance. If several fitings are adjacent, longest L, governs. See Figure 9.6.6.3.4g. Allowed fitlings include a concentric reducer
of1- 3 pipe size reduction, an eccentric reducer of 1 - 2 pipe size reduction, a continuous bore valve or fiting approved by the pump
232
g 2
8
Notes:
Butterfly valves installed on the suction side of pumps with double suction impellers shall be oriented such that the valve operating shaft
s in a parallel plane to the pump shaft.
‘manufacturer.
Globe valves and diaphragm valves shall not be used on the suction side of the pumps.
For vertical In-ine pumps, elbows may be installed on the suction side with an orientation paraliel to the pump shaft a distance L, a
minimum of two pipe diameters for long radius elbows and three pipe diameters for short radius elbows.
Length of straight pipe between fiting and pump may be reduced from that presented in the above table with approval of the pump
manufacturer.
Alternative values may be used if substantiated by a physical model study. See Section 9.6.6.3.5
The data in this table are based on commercially available fitings.
Flow-straightening devices do not serve as a substitute for the L, requirements in this table unless validated by a physical model study.
Refer to Appendix E.2 for information on flow straightening devices, and section 9.6.6.3.5 for information on physical model studies.
9) _Refer to the information provided in subsection 9.6.6.3.4 for further guidance
* For fittings that require less than two pipe diameters of straight pipe length, space shall be sufficlent for ease of pump installation and removal.
* The pump manufacturer is responsible for guaranteeing pump performance when providing designs for fitings (or furnishing fittings) that are
nmwmmmmammmmmmWMMsmm
10 by both the purchaser and pump manufacturer, the pump manufacturer shall guarantee pump performance including the furnished fiting(s) at the guarantee pol
as tested in accordance with ANSUHI 14.6 Rotodynamic
for Hydraulic Performance TesL. f the
connected
are supplied
by
« The angles given are the maximum per side for standard commercial fittings. Nonstandard fittings having a greater angle per side shall use the
number of pipe diameters corresponding to that angle, regardiess of the number of pipe size reductions.
# Care must be taken when placing a butterfly valve downsiream from a fitting such as an elbow o tee. The valve operating shaft and disk shall be
orlented in the same plane as an elbow or lee. In cases where this is in conflict with table 9.6.6.3.4 Note 2, then Note 2 governs and additional
distance (1-3 pipe diameters) between the tee or elbow and valve should be considered to avokd more adverse hydraulic conditions and loading
on the valve.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
7
2072
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
DIRECTION OF
LIQUID FLOW
/
N
FLOW-DISTURBING
g
FITTING
REDUCER
Figure 9.6.6.3.4b — General example — pump suction with a required L, length for a flow-disturbing fitting
DIRECTION OF
LIQUID FLOW
i
I
4
N
Q
PUMP SUCTION NOZZLE
FLOW-DISTURBING
FITTING
ALLOWED FITTING FROM
TABLE96.6.34
Figure 9.6.6.3.4c — General example — pump suction with an allowed fitting connected directly and a
required L, length for a flow-disturbing fitting
DIRECTION OF
LIQUID FLOW
/
PUMP SUCTION NOZZLE
Figure 9.6.6.3.4d — Specific example — pump suction with a required L, length
for a short-radius reducing elbow (< 30% area reduction)
8
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
2172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
Figure 9.6.6.3.4e — Specific example — pump suction with a concentric reducer (1 pipe size reduction),
and a required L, length for a short-radius elbow
PUMP SUCTION NOZZLE
Figure 9.6.6.3.4f — Specific example — pump suction with a required L, length for a suction
header (tee or branch flow)
NOTE THAT THE L; LENGTH OF 5 x PIPE DIAMETER IS DRIVEN DIRECTION OF
BY THE LONGEST GOVERNING LENGTH OF THE 90 DEGREE
'SHORT-RADIUS ELBOW (THE CONCENTRIC REDUCER ONLY [ LIQUID FLOW
REQUIRES AN L, OF 2 x PIPE DIAMETER)
L,=5xD,
/
PUMP SUCTION NOZZLE
He—p g A
&
!
ECCENTRIC REDUCER,
2 PIPE SIZE REDUCTION
SHORT RADIUS
ELBOW
'CONCENTRIC REDUCER,
4 PIPE SIZE REDUCTION
Figure 9.6.6.3.4g — Specific example — pump suction with an eccentric reducer (2 pipe size reduction),
arequired L, length for a concentric reducer (4 pipe size reduction), and a short-radius elbow
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
9
22172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
NOTE THAT THE L, LENGTH OF 4 x PIPE DIAMETER IS DRIVEN |\ o0
e
oc
BY THE LONGEST GOVERNING LENGTH OF THE 90 DEGREE
LONG-RADIUS ELBOW (THE CONCENTRIC REDUCER ONLY
LIQUID FLOW
REQUIRES
L, OF 2 x PIPE DIAMETER)
LONG RADIUS
ELBOW
'CONCENTRIC REDUCER,
4 PIPE SIZE REDUCTION
Figure 9.6.6.3.4h — Specific example — pump suction with a required L, length for a concentric
reducer (4 pipe size reduction) and a long-radius elbow
DIRECTION OF
LIQUID FLOW
LONG RADIUS ELBOW
Figure 9.6.6.3.4i — Specific example ~pump suction with a manufacturer-approved 90° elbow, an eccentric
reducer (1 pipe size reduction), and a required L, length for long-radius elbow
PUMP SUCTION NOZZLE
/ L,=3xD,
)
DIRECTION
OF
LIQUID FLOW
PUMP MANUFACTURER
APPROVED 90° ELBOW
ECCENTRIC REDUCER,
4 PIPE SIZE REDUCTION
Figure 9.6.6.3.4] — Specific example — pump suction with a manufacturer-approved 90° elbow and a
required L, length for an eccentric reducer (4 pipe size reduction)
10
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
23172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
DIRECTION OF
LIQUID FLOW
ECCENTRIC REDUCER,
1 PIPE SIZE REDUCTION
'CONCENTRIC REDUCER,
4 PIPE SIZE REDUCTION
Figure 9.6.6.3.4k — Specific example (top view) — between bearing split case (double suction)
pump with an eccentric reducer
(1 pipe size reduction),a required L, length for a concentric reducer
(4 pipe size reduction), and a short-radius elbow (*added one diameter for double suction with elbow in
plane with pump shaft)
FLOW DIRECTION
ELBOW INLET
Figure 9.6.6.3.41 — Undesirable effect of an elbow mounted directly on suction nozzle of double
suction pump with flow direction into the elbow inlet parallel to the shaft (applies to all double suction
applications with either horizontal or vertical shaft orientation on either side or bottom suction)
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
1
24772
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
SUPPLIED BY PUMP
MANUFACTURER
‘ORIENTATION REQUIRES
PUMP MANUFACTURER's
APPROVAL
Figure 9.6.6.3.4m — Examples of suction pipe fittings near the pump that require
approval of the pump manufacturer
9.6.6.3.5 Need for physical hydraulic model study
A properly conducted physical model studyis a reliable method to identify unacceptable flow patterns at the pump
suction for given sump or suction piping design and to derive acceptable intake sump or piping designs. Considering the cost for a physical model study, an evaluation of the list of conditionsin requirement 9.6.6.3.5.1 is needed
to determine if one is required.
9.6.6.3.5.1 A physical hydraulic model study shall be conducted for pump suction piping with one or more of the
following conditions listed below. Refer to Note 1.
A.
Piping geometry that deviates from this standard such as the requirements outlined in Table 9.6.6.3.4.
B. Ininstances
where the piping may draw
from a free surface intake and sump geometry (such as bay width, bell
clearances, sidewall angles, bottom slopes, distance from obstructions, the bell diameter, submergence etc.)
that deviates from ANSI/HI 9.8.
C. Nonuniform or nonsymmetric approach flow to the pump suction piping exists (e.g., significant crossflow or a
short-radius pipe bend near the pump suction, etc.).
D. The pump suction piping intake submergence is below the ANSI/HI 9.8 recommended minimum to reduce the
probability that strong free surface air core vortices will occur.
12
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
2572
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
E. Proper pump operation of a critical service or application as defined by the owner, operator
or user (such as a
safety-related system).
F.
The diameter of the suction piping (L, designated pipe) is greater than 600 millimeters (mm) (24 inches [in]) or
flows greater than 630 liters per second (L/s) (10,000 gallons per minute [gpm]) per pump.
G. When suction piping is supplied from a free surface intake, refer to ANSI/HI 9.8 for physical modeling total station flow rate criteria. In cases where ANSI/HI 9.8 and this standard conflict, the more restrictive criteria shall
govern.
H. When the cost of improper pump operation, pump repair, remediation of poor piping design, impacts of inadequate performance, or pump failure would be significantly more than the cost of a physical model study.
9.6.6.3.5.2 The physical model study shall be conducted by a hydraulic laboratory using personnel that have
experience in modeling pump intakes and pump suction piping. Refer to Note 2.
Notes:
1. The requirement for a physical model study assumes that there is no prior physical model study for the intake
and/or piping design considered in terms
of physical features and flow rates.
2.
Refer to ANSI/HI 9.8 for recommendations and requirements regarding physical model study objectives,
scale selection, scope, instrumentation and measuring techniques, test plan, acceptance criteria, and report
preparation.
9.6.6.3.6
Use of computational fluid dynamics (CFD)'
Computational Fluid Dynamics (CFD) is an analysis method used in fluid mechanics that deals with numerical
solutions of the general flow equations for mass, momentum, and heat transfer. Its origin can be traced to the
1930s, but its rapid development followed the advancements in computing power combined with the needs of the
aerospace industry in the 1950s and 1960s. Today, CFD is used within many sciences and industries that involve
fluid flow and transport phenomena, including the pump industry.
CFD encompasses
a range of methods using very simple meshes and algorithms that can be run on an ordinary
personal computer (PC) to the most advanced methods that require high performance computing. Most generalpurpose, commercial CFD codes use the Reynolds Averaged Navier-Stokes equations — an approach that offers a
reasonable combination of accuracy and computational efforts that is suitable for many industrial applications. For
a given code, there are options for establishing boundary conditions, meshing of the flow domain, model selection,
and solution schemes. These factors can influence computational
speed and accuracy.
When simulating pump stations, (including approach geometry, sump, and pump suction piping) steady-state CFD
models are often selected due to their computational efficiency. Steady-state models cannot predict fluctuating
phenomena or short-term extreme values such as transient vortex activity and fluctuations in swirl or point velocities. Advanced techniques to simulate time-dependent phenomena are available; however, there are practical
limitations in predicting time-dependent and highly curvilinear flow patterns, such as swirls and vortices.
CFD modeling poses many limitations that require skilled and experienced modelers to properly select methods
and parameter settings to produce results that correctly represent the behavior of a full-scale prototype, even when
using an otherwise well-proven CFD code. Validation of simulations against experimental data is absolutely necessary for a given class of problems. To aid CFD modelers and to eliminate most common pitfalls, some industries
have developed best practice guidelines suitable for their specific field.
' The Intake Design and Pump Piping committees met to discuss the application of CFD modeling with regards to the approach
flow to a pump. Experts nationally and internationally (academic, HI partners, and nonmembers)
were invited to discuss the
latest in modeling of intake structures, including current state of the art simulation, post processing methods, and case studies.
The outcome of the meeting was used by the committee to revise this section (June 27, 2016, Indianapolis, IN).
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
13
26/72
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.6.6.3.6.1
Acceptable uses of CFD modeling in pump suction hydraulics
CFD simulations may be used to determine the extent of the physical model and the velocity distribution needed at
the physical model boundary. CFD simulations may also be used to compare designs, to aid in the initial selection
of a design (or design development option) for testing using a physical model, and to better define the range of
variables to be tested.
Notes:
1.
CFD is useful in determining general approach flow patterns such as those to a sump and pump suction piping.
2.
CFD simulations may practically cover a much larger area upstream from the pump than would be possible or
practical for a physical model of the scale required to satisfy the minimum Reynolds number given in ANSI/HI
9.8.
3.
Useful applications of CFD would include determining whether or not physically modeling a single suction pipe
‘would be adequate.
4.
The advances in CFD indicate that further uses of these computational simulations may be possible in the future
and the Hydraulic Institute may consider additional applications of CFD in future revisions of this standard.
9.6.6.3.6.2
Unacceptable uses of CFD modeling in pump suction hydraulics
9.6.6.3.6.2.1 CFD modeling shall not be used to demonstrate compliance with this standard (see ANSI/HI
9.8 physical model study acceptance criteria subsection.)
Notes:
1.
There is a lack of generally available correlations of CFD simulations to experimental results for the complex
flow patterns near pumps.
2. Thereis lack of satisfactory
evidence that an appropriate
acceptance criteria for CFD modeling
of pump intakes
and/or piping has been developed
and verified.
3.
There have been no best practice guidelines established for CFD modeling of pump intakes and pump suction
piping.
9.6.6.3.7
Pump suction piping/wet-well connection
In cases where pump suction piping connects to a supply source with a free liquid surface (e.g., wet wells, sumps,
or tanks), it is important to consider the influence of the vessel's geometry on the flow pattern to the pipe suction,
submergence of the pipe inlet, and crossflow velocity at the pipe inlet. Typically these connections include a flared
fitting flush with the vessel wall or a turned-down elbow (with or without flare) extending into the liquid.
This subsection is provided to alert the user of special considerations and provide general guidance for interface
of the suction piping with connection to supply source with a free liquid surface. The requirements associated with
the wet well for various wet well/pipe interface configurations with a free liquid surface are included in ANSI/HI 9.8.
9.6.6.3.7.1 Requirements for wet-well design, wet well outlet fittings (i.e. connection to wet well), flow guiding
elements, and submergence shall be as provided in ANSI/HI 9.8.
1
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
27172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
Notes:
When turned-down elbows are used, a floor cone or floor splitter may be installed under the suction elbow inlet
to reduce submerged vortices from the floor. However, their potential negative influence on other hydraulic conditions should be carefully considered.
a.
Turned-down elbows are susceptible to adverse submerged vortices forming from the vessel floor or walls,
which can travel significant distances along the suction piping.
b.
Turned-down elbows typically provide better pump suction nozzle conditions when they are long versus
short radius and when they incorporate a flare or bell mouth end.
c. A floor cone or floor splitter can reduce circulation within the suction piping and flow preswirl at the pump
suction.
Suction piping that connects straight through a wall may incorporate a flare or bell mouth fitting to reduce headloss.
a.
Horizontal flush-mounted inlets are susceptible to submerged vortices from the walls and midflow in shear
zones, which can travel significant distances along the suction piping.
Minimum submergence calculations should be based on the diameter of the plain end, flare or bell mouth
fitting per ANSI/HI 9.8.
Inadequate submergence can result in adverse and/or air entraining surface vortices, which can negatively
impact pump performance. Vortices may not be of concern if there is no air entrainment and the vortex core and
associated swirling flow dissipate before reaching the pump suction nozzle.
The extent of vortices and swirling flow in the pump suction piping can only be evaluated using physical hydraulic modeling per ANSI/HI 9.8.
9.6.6.3.8
Pump suction elbows
Pump suction elbows are often used to turn the flow direction into pumps, and may be attached directly to the
pump suction nozzle or be located upstream of the pump in the suction piping. Elbows that are not designed specifically for attachment to the pump suction can create flow separation and secondary currents when flow travels
through the elbow resulting in nonuniform velocity profile entering the pump, which can result in reduced performance, increased maintenance, and shortened pump service life.
9.6.6.3.8.1 For pump suction elbows of varying types, the minimum required straight pipe length (L,) before pump
suction nozzle shall be provided in accordance with Table 9.6.6.3.4. See Note 1.
9.6.6.3.8.2 When pump suction elbows are designed or supplied by the pump manufacturer, the pump manufacturer shall be responsible for guaranteeing pump performance in accordance with the requirements identified in
Table 9.6.6.3.4.
Notes:
1.
Table 9.6.6.3.4 provides minimum requirements for the length of the straight pipe between the end of the elbow
and pump suction nozzle. Because constant-diameter elbows (either short radius or long radius) have a pronounced effect on the velocity profile, additional lengths of straight pipe are required to provide uniform velocity
profile into the pump. Alternatively, reducing elbows accelerate the flow through the bend, which evens out the
velocity profile and reduces harmful secondary currents.
2.
Refer to ANSI/HI 14.6 regarding pumps tested with fittings.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
15
28172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.6.6.3.9
Pump station retrofit or modification
Proper piping and pump station layout as outlined in this standard are recommended to be followed in all pump stations that are being retrofitted or modified with similar, smaller, or larger capacity pumps. If the physical dimensions of
the existing pump station are insufficient to accommodate the requirements of this standard, then the layout should
maximize inclusion
of the requirements in combination
with the additional improvements/procedures listed below.
Notes:
1.
Retrofits in space-constrained pump stations could improve the piping layout through modifications that enhance
suction side hydraulic conditions, while striving to meet the requirements of this standard with shorter pipe
lengths as demonstrated with the following examples:
a.
Valve replacement with alternate valve type that results in less flow disturbance and associated straight
pipe length required.
b. Pipe size reduction
so that the number
of straight pipe lengths over an existing length of pipe is increased,
assuming the NPSH margin and other design criteria can be met at the higher velocity.
c.
2.
If pump type is changed as part of the retrofit, reconfigure the piping to minimize flow-disturbing fittings and/
or valves to minimize pipe length required to meet straight run requirements.
Failure to evaluate the impact of existing flow-disturbing fittings or other existing adverse hydraulic phenomena
may lead to adverse pump performance
even if the previously
installed pumps did not experience
any adverse
performance issues. If the existing pump station suction piping cannot be modified to comply with this standard,
then the designer should consider the following approaches to optimize suction piping:
a.
The use of flow conditioning devices coordinated with the pump manufacturer
b.
Physical hydraulic model testing
c.
|If practical, use a similar configuration to one with a proven, successful operation
3.
Appendix G can be consulted to provide additional guidance for improving the hydraulics of piping configurations. The discussion in Appendix G is intended to outline several approaches that have been successful for
improving pump intake hydraulics.
4.
Implementation of recommendations within this subsection, Appendix E.2 or Appendix G are not to be interpreted as compliance with the minimum length of pipe L,.
9.6.6.4 Outlet (discharge) piping requirements
9.6.6.4.1 Pipe size/velocity requirements
See section 9.6.6.2 (Pump Piping Design General) for design flow rate requirement.
9.6.6.4.1.1 The maximum velocity (average of cross section) at any point along the discharge piping shall be
4.5 m/s (15 ft/s). Refer to Notes 1 and 2.
Notes:
1.
16
The pump discharge nozzle velocity may exceed this value. Therefore, the pipe that is directly connected to the
pump discharge nozzle, which is often the same diameter as the discharge nozzle itself, is not subject to this
velocity limit. In instances where this nozzle velocities exceed the velocity limit, increase pipe size as required
to reduce velocity with consideration of the system items listed in Note 3.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
29772
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
2.
If the liquid is a slurry, then the velocity in the discharge piping may be higher in order to keep solids in suspension. See Appendix E.4 for slurry pumping recommendations.
3.
System pipe friction losses and minor losses (see Appendix A.1), life-cycle costs, and process considerations
normally dictate the size of the discharge piping and fittings.
4.
Note that the adverse effects of hydraulic transients due to events like check valve slam typically increase with
flow velocity and should be considered. Refer to 9.6.6.4.4 Water Hammer.
9.6.6.42 Outlet (discharge) straight pipe lengths
The required straight pipe lengths immediately downstream of the pump discharge are not as critical as the suction
piping.
Notes:
1. Pipe fittings mounted close
to the pump discharge nozzle will normally have minimal effect
on the performance
or reliability of rotodynamic pumps. If in doubt whether a fitting will negatively affect the pump, check with the
pump manufacturer.
2.
Some pumps can be sensitive to flow-disturbing fittings mounted close to the pump discharge. This can result
in increased noise, vibration, and hydraulic loads. If in doubt whether a fitting will negatively affect the pump,
check with the pump manufacturer.
9.6.6.4.3
Recommended valves
Valves commonly provided in a pump discharge piping are isolation, check, pump control, and air release valves.
The following sections briefly discuss these valve types and functions (See Appendix E for details of valve types).
The pumping system and associated operation and maintenance cost for each valve type should be evaluated as
part of a life-cycle cost (LCC) analysis recognizing that the valve headloss impact will vary by system (greatest
impact to the lower head systems). Refer to Pump Life Cycle Cost: A Guide to LCC Analysis for Pumping Systems
for LCC details.
9.6.6.4.3.1
Shut-off/lsolation valves
Shut-off/Isolation valves are typically used in normally open or normally closed valve positions.
Notes:
1.
For most pumping systems, a shut-off valve should be installed in the pump suction piping for system isolation.
Likewise, a shut-off valve should be installed in the pump discharge piping for system isolation.
2.
If a pump is to be isolated for maintenance or other specific function, the valves are closed. Otherwise the
valves are normally open during pumping operation.
3.
Where practical, isolation valves should be selected to maximize the open cross sectional area to provide a
minimum restriction of the pipe in full open position.
4.
The discharge shut-off valves can be used for pump control. Refer to Pump control valves subsection 9.6.6.4.3.3.
9.6.6.4.3.2
Check valves
A check valve is typically necessary between the pump discharge nozzle and the discharge shut-off valve to
protect the pump from reverse flow and excessive backpressure.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
17
3072
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.6.6.4.3.2.1 When there is no air/vacuum valve included upstream of the check valve for applications with a
sump or wet well with water at sea level and ambient temperature, any check valve installed in the pump discharge
pipe shall be no more than 7.6 m (25 feet) above the lowest liquid level (pumping level). Refer to note 1 and requirement 9.6.6.4.35.1.
9.6.6.4.3.2.2 At higher elevations, higher temperatures, and for liquids with different vapor pressures, this distance shall be evaluated
and will be less than the specified 7.6 m (25 ft). Refer to Note 1.
Notes:
1.
The distance limits given in 9.6.6.4.3.2.1 and 9.6.6.4.3.2.2 are based on the vapor pressure of water at sea
level and at ambient temperature. Greater distance may allow vapor to form upstream of the check valve.
Such an accumulation of vapor can cause hydraulic shock or water hammer the next time the pump starts (see
9.6.6.4.4), unless other protections are provided for the pump system.
2.
Check valve selection should consider water hammer potential. Rapid valve closure after reverse flow has been
established can lead to high transient pressures. Refer to Appendix B for details.
3.
If expansion joints are used on pump discharge piping, they should be placed on the pump side of the check
valve since it can dampen, but not transfer, closure slam. However, expansion joints should not be considered
a water hammer mitigation strategy.
9.6.6.4.3.3
Pump control valves
Control valves are capable to perform preset functions (pressure or flow adjusting /balancing).
Notes:
1.
Pump control valves are automated valves typically used for a flow or pressure control of a pumping system, or
to regulate opening and closing time of a valve during pump stopping or starting. Refer to ANSI/HI 14.3 Rotodynamic Pumps for Design and Application and ANSI/HI 14.4 Rotodynamic Pumps for Installation, Operation,
and Maintenance for valve start-up and shut down operation recommendations for axial flow and mixed flow
pumps.
2.
Pump control valves are actuated by pump discharge liquid pressure or with an external powered actuator
(electric motor, pneumatic and hydraulic system).
9.6.6.4.3.4 Triple-duty valves
A triple duty valve is a combination valve that provides several functions including isolation, circuit balance and
check valve into one valve body (see Figure 9.6.6.4.3).
Triple-duty valves allow shorter installed pipe lengths at reduced costs compared to separate single function
valves. These valves are also useful in other applications where space limitations exist.
Note that triple-duty valves (refer to Figure 9.6.6.4.3) will have a high head loss and result in higher energy cost
associated with their use.
18
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
3172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
Figure 9.6.6.4.3 — Triple-duty valve
9.6.6.4.3.5 Airrelease valves
Air release valves are normally provided at high points in the discharge piping. These valves allow the release of air
trapped in the piping, enabling the full volume of the piping to be used for conveying liquid.
9.6.6.4.3.5.1 Pump applications which start up with a large volume of air in the system upstream of a check valve
or in the suction piping shall be vented before the liquid flow contacts the check valve disc to minimize
air trapped
in downstream piping. Refer to Note 1.
Note:
1.
For pumps or discharge piping that are located high and above the suction water level, for example a vertical
turbine pump or self-priming pump, an air release valve is generally located upstream of the check valve sized
for large volume of air to be vented during pump start up since the pump column and discharge head or portion
of suction piping is typically full of air.
9.6.6.4.4 Water hammer
Water hammer, (hydraulic transient), is a condition that exists when a column of liquid changes velocity quickly. This
condition can occur in any of the following instances: the power to the driver is lost suddenly, air is finally expelled
from the system piping, a valve is closed too quickly, or a check valve closes too slowly and allows backflow to
ooccur before it fully closes. When this occurs, the kinetic energy is rapidly transformed into pressure energy, which
will cause a sharp rise above or fall below normal system pressure. This transformation produces an acoustic pressure wave that propagates within the pipe. See Appendix B for more detail.
9.6.6.4.4.1 A fast closing valve, e.g. check valve or other controlled valve in the discharge piping will create some
amount of water hammer which shall be considered in order to avoid damage to the pump and system. Refer to
Notes 1 and 1a.
1.
Fast closing valves have a variety of closing characteristics which influence the amount of water hammer the
system experiences. Consideration of valve type, liquid velocity, pipe material properties and configuration of
system may identify that modeling should be used to determine the effects of valve closure characteristics on
the pump and system.
a.
Many check valves rely on some reverse flow to achieve closure. However, rapid check valve closure after
a high reverse flow velocity has been established, can lead to more severe water hammer. This can be
reduced by limiting the reverse
flow velocity, the check
valve closure rate, or both. (See Appendix B and
A Methodology for Predicting Check Valve Slam and Surge Transients Due to Check Valve Closure in a
Municipal Water Pumping Station Proceedings
for more information.)
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
19
3272
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.6.6.5 Inlet (suction) and outlet (discharge) general piping requirements
9.6.6.5.1 Pipe nozzle alignment/pipe expansion load
Proper design and analysis of the pump and piping layout prior to installation of the system are absolutely essential
to the service life and reliability of a pump. This can ensure that nozzle loads remain below acceptable limits for
installed pumps by providing a properly supported piping system, which minimizes field adjustments during installation, saving both time and money.
This subsection presents a general overview on pipe load analysis at the interface with a rotodynamic pump. Addi-
tional details can be found in references 6, 7, 8, 9, 10, and 11.
Notes:
1.
Nozzle loads affect pump operation in various ways. At low levels, the effects may be insignificant. At high levels,
nozzle loads can contribute to the following:
a.
Coupling misalignment, which leads to
Heat buildup in bearings, which decreases bearing life
In severe instances, fractures within the pump case
Decreased coupling life
Increased noise and vibration levels
Pump shaft failure
b.
Shaft movement, which leads to reduced service life of packing, shaft sleeves, and mechanical seals
c.
Fatigue or failure of the shaft
d.
Excessive deformation or catastrophic structural failure of
Pump hold-down bolts or support structure
Pump nozzles
e.
Pump casing gasket leaks
.
Pipe to pump flange leaks.
g. Decreased mean time between repair or failure.
9.6.6.5.1.1 Pump nozzle analysis
Analysis of the thermal and static loads on the pump nozzles are done at both the working and ambient conditions,
and the effects of supports and braces must also be considered (see Appendix C).
9.6.6.5.1.1.1 Couplings on the pump piping shall be restrained. Such restraints shall be designed to accommodate the expected misalignment. See Notes 1 and 3.
Notes:
1.
For additional information refer to Appendix D.
2.
Incorrectly selected and designed piping supports which are included to reduce the nozzle loads at operating
temperature can cause an increase in the magnitude of pump nozzle loads at ambient temperature.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
3372
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
a.
As the pipe attached to the pump increases or decreases in temperature, it results in thermal expansion or
contraction of the pipe, which causes it to deform from its original ambient condition. These deformations
will produce a strain in the pipe. If the pipe meets any resistance to this strain, such as a pump flange connection, the strain will be translated into a force on the pump in the direction of the deformation. The thermal
growth of the pump nozzles (working and ambient) should therefore be considered in the analysis.
3
Nozzle loads can be profoundly affected by the degree of misalignment between the pump nozzle and the
connected piping. Misalignment can be either at an angle to the centerline of the nozzle and/or a lateral offset
to the centerline of the nozzle. Thermal expansion and contraction, acting on the piping, pump, or both can
often exacerbate misalignment present under ambient conditions at the time of installation. Frequently both
misalignment conditions can be present. Piping may be configured to accommodate both by providing a pair of
restrained flexible couplings, spaced appropriately to accommodate the potential angular misalignment, at each
‘connection.
The analysis of the suction and discharge piping needs to be completed before the forces and moments on the
pump can be calculated. The analysis should be done in conjunction with the pump manufacturer when the
predicted nozzle loads approach or exceed the maximum allowable, and include the following:
a.
Suction and discharge nozzle stresses.
b.
Hold-down bolt stress.
c.
Pump slippage on the baseplate.
d. Internal clearances and distortion.
e.
Movement of pump shaft.
The Hydraulic Institute, American Petroleum Institute (API), and the European Committee for Standardization
(CEN) have provided methods for evaluating
the loads applied to the nozzles of pumps. Care must be taken
to
verify the nozzle loads allowed by the pump manufacturer since the allowable loads as recommended by the
pump manufacturer could be less than what is allowed by these standards.
9.6.6.5.2 Pipe supports/anchors
Proper installation of piping, supports, and restraint fixtures is imperative to obtain optimum performance and reliability from connected pumps and rotating equipment. Pumps require precise shaft alignment to operate properly.
9.6.6.5.2.1
Note 1.
The installed piping shall be supported by the surrounding structure, not by the pump itself. Refer to
Notes:
1.
Pipe supports are used to hold the weight of the pipe and liquid off the pump nozzles, while restraints and
qguides are used to redirect
the forces generated by thermal and pressure thrust effects away from the pump
nozzle.
Some new installations may have a flexibility analysis performed (discussed later in this subsection) to determine size and placement of supports and guides. Design should include an evaluation of the forces from
fast-acting, shock-inducing check valves or other fast closing valves (see Section 9.6.6.4.4 Water hammer), if
applicable.
a. Since the pipe installation
will take place while the pipe is in its ambient condition with no liquid in the pipes,
the loads and displacement experienced will not correspond to the analysis. Careful installation and field
checks of all support fixture settings and placements is essential to ensure the piping system will perform
under working conditions,
as the analysis predicted.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
21
34/72
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
3.
Pipe supports may be designed to handle vertical, horizontal, axial, thermal, and seismic forces. Refer to
Appendix C for more information.
9.6.6.5.2.2
Design considerations
System flexibility is the ability of the piping to absorb the thermal loads and displacements.
9.6.6.5.2.2.1
The piping system shall have provisions to reduce the forces to allowable levels. Refer to Note 1.
Note:
1. All piping systems include terminal connections
of some kind, such as pumps, vessel connections,
or anchors,
which are to be considered as fixed points in the system. These terminal connections, particularly in the case of
pumps, are sensitive to the forces generated by the attached pipe. Supports and restraints will aid in transferring
or redirecting the load.
9.6.6.5.2.3
Cold spring
Cold spring is the practice of purposely fabricating certain sections of pipe too short or too long to compensate for
thermal movements at system operating conditions.
9.6.6.5.2.3.1
Cold spring installation practice shall not be interpreted to comply with this standard.
Notes:
1.
If properly designed, the cold spring will effectively relieve loads on the pump nozzles and terminal connections at operating temperature, but can easily overload attached equipment in the ambient condition.
2.
Flange mating and alignment during installation can be extremely difficult when pipes are intentionally made too
short.
3.
Cold spring adjustment could be forgotten or unknown when making future modifications to the existing piping
system.
9.6.6.5.2.4
Final installation
After the piping has been completely installed and all terminal and equipment connections are made, perform final
adjustment of restraints and anchors with consideration of the requirements and guidance outlined in this subsection in absence of pump manufacturer's guidance to the contrary. Provisions for a final piping field weld close to the
pump may be used to ensure the piping system will be near a zero load condition.
9.6.6.5.2.4.1
Flanges of connecting piping shall not be sprung (forced) into position. Refer to Note 1.
9.6.6.5.2.4.2 Pipe flange bolt holes shall be lined up with nozzle bolt holes, within the limits of the flange bolt-hole
manufacturing clearance, to permit insertion of bolts without applying any external force to the piping. Refer to Note 1.
Notes:
1. The use of come-alongs or other means of providing a large amount of force to align the piping with the pump
flanges is not allowed. This helps ensure that the installed piping system will be within allowable pump nozzle
loads.
2.
22
Couplings (restrained as noted in subsection 9.6.6.5.1.1) can be used to ease gasket assembly. Utilize couplings to correct misalignment within the limits defined by the coupling and/or pump manufacturer.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
3572
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
9.6.6.5.2.5
Field adjustment
In order for successful pump operation, assess and adjust the piping connections to the pump as well as any
spring supports as outlined in this subsection.
9.6.6.5.2.5.1 For field adjustment to proceed, all restraints and guides shall be installed, and terminal and pump
cconnections shall be aligned and tight.
9.6.6.5.2.5.2 Nozzle loads at pumps and other critical terminal connections shall be checked to ensure that overloading will not occur.
9.6.6.5.2.5.3
Pump to motor alignment shall be rechecked when system reaches operating temperature.
9.6.6.5.2.5.4 Spring supports shall not bottom out under normal operating loads and temperatures (refer to the
spring support section in Appendix C). Refer to Note 3.
9.6.6.5.2.5.5 Pump alignments shall be checked to ensure that the attached spring support is indeed keeping the
pump nozzles within allowable loads. Refer to Note 3.
Notes:
1.
The shipping stops should be removed after hydrotesting of the system is complete and just prior to start-up
with the pipe full of liquid.
2. Thermal movements in the piping should be measured and compared to the displacements used in the piping
analysis.
3.
Periodic inspection of the spring supports with indicator (indicator provides a scale utilized to determine pipe
position), if so equipped, should be performed
to ensure that the loads in the system have not changed over
time. Also, the supports themselves should be included in a regular preventive maintenance program.
4.
Proper installation and alignment is crucial to the performance and reliability of both the pump and the expansion joint. Improper installation can result in overloaded pump nozzles and expansion joint fatigue and failure.
See Appendices C and D for types and application guidelines.
9.6.6.5.3
Parallel operation
Hydraulic piping design for parallel pump systems are similar to those required for single pump installations, but
include additional considerations discussed in this subsection.
9.6.6.5.3.1 The liquid velocity in the suction manifold shall not exceed the velocity in the suction lateral for all
‘operating scenarios.
9.6.6.5.3.2 There shall be minimum interaction between the suction flow of one pump with another. Figure
9.6.6.5.3a illustrates the minimum recommended spacing and length of pump suction pipe, based on the ratio of
the suction lateral diameter to header diameter.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
23
36172
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
HEADER—
501 T | T,
203220, |SEE TABLE
<03|23D0,| 96634
Figure 9.6.6.5.3a — Minimum required suction pipe length and spacing for parallel pumps
9.6.6.5.3.3
Suction laterals directly opposite each other shall not be used. Refer to Note 4.
Notes:
1. Varying suction or discharge pressures along a common header can impact the performance of pumps operating
in parallel. It is important to carefully analyze the pressure drop along each header segment and through each
suction and discharge lateral to achieve a low pressure variation (between laterals) relative to the total head produced by each pump. Minimizing
the pressure variation between laterals will promote balanced NPSHA
and flow
through each pump. The pressure on the suction side of the pumps should be nearly equal: likewise the pressure
on the discharge side of the pumps should be nearly equal (see Figure 9.6.6.5.3b).
Figure 9.6.6.5.3b
— Parallel pump installation L,
a. The maximum velocity in the suction header (also referred
to as a suction manifold) should
not exceed the
value stated and explained in subsection 9.6.6.3.2. Keeping the velocity below this value will help to minimize
the difference in the suction pressures at each pump. In addition, the velocities in the discharge manifold
should be low enough so that there are no significant discharge pressure differences.
2.
To allow for future expansion, manifolds should be terminated at full diameter with blank flanges.
3.
An alternative design concept is shown in Figure 9.6.6.5.3c that maintains suction and discharge header
velocities identical for each pump. Typically pumps in this arrangement are the same capacity. This type of
24
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
3772
4/19/23,12:17 PM
FileOpen Web Viewer
Rotodynamic Pumps for Pump Piping — 2022
construction may be considered for settling slurry applications when a minimum velocity is required to maintain
solids in suspension.
]
B
Figure 9.6.6.5.3c — Constant-velocity manifold design, parallel pumps
4. Thereason for the prohibition of suction laterals directly opposite each other is that the prerotation inherent in the
suction pipe of one pump can cause significant turbulence in the suction pipe of the second pump.
5.
Figure 9.6.6.5.3d provides two alternatives for the transition from suction header to lateral. The figure on the
left shows a reducing tee with an associated sudden transition from header to the lateral diameter. This configuration requires the isolation valve be the same size as the lateral. The figure on the right shows an alternative
which includes a tee with one or two pipe size reduction to an isolation valve followed by a reducer to lateral
diameter to minimize the flow disturbance from the change of direction and acceleration.
/—mmmuomz
PUMP SUCTION
NOZZLE
AN
SUCTION
Dx
I
ot
LATERAL————= | |
L
1soLATIoN vALVE | |
REDUCING
TEE
T
4 | sucrion LateRaL
[ : e
T
REDUCER
:
=
D
REDUCING
TEE
(ONE TO TWO PIPE SIZE REDUCTION)
8_. e[
o
‘SUCTION
HEADER
Figure 9.6.6.5.3d — Alternatives
for suction header
to suction lateral transition
6.
Fabricated connections which create excessive flow disturbances should be avoided, (ex. lateral pipe projection
into header).
7.
Like single pumps (see Section 9.6.6.4.3), pumps operated in parallel should have isolation valves to allow any
individual pump to be taken out of service. Additionally, each pump operated in parallel should have a check
valve installed in its discharge pipe, between the pump and the header, to prevent backflow when not operating.
When one of the pumps is to be used as an installed spare, a pressure-relief device may be required between
the suction isolation valve and the pump suction nozzle. This would ensure that, in the case of discharge isolation and check valve leakage, the suction side of isolated pump would not be subjected to full discharge header
pressure.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
25
38/72
4/19/23, 12:17 PM
FileOpen Web Viewer
Appendices - Introduction — 2022
Appendices (Informative)
Introduction
These appendices are not part of this standard and are included for informative purposes only. They discuss a
number of technical items and calculation methods that relate to the application of rotodynamic pumps in piping
systems. Their purpose is to provide the reader with the knowledge that there are various analytical methods,
hardware, components, and references for pumping systems that can help the specifier and user minimize problems and maximize efficiency. The calculations and procedures shown herein are meant to be illustrative only. The
reader should refer to the many published textbooks, standards, and guidelines that cover these subjects in depth.
26
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
39772
4/19/23, 12:17 PM
FileOpen Web Viewer
Appendix A - System Curves — 2022
Appendix A (Informative)
System curves
Refer to Appendices Introduction located immediately preceding the Appendix A.
A.1
Calculation of the system curve
The performance of the pump is usually represented in a diagram format by the so-called pump H-Q curve (head
capacity curve). The corresponding curve for the piping system is called the system curve. The flow rate at which
the pump and system curves intersect each other is the flow that will pass through the piping system Refer to
ANSI/HI 14.3 figure 14.3.3.2 titled *pump and system curve interaction® for graphical representation. To correctly
determine the sizes of the pump and piping system, knowledge of the characteristics of their respective curves is
necessary.
System curves can be very simple, such as when the pump is connected to a single piping system with no control
valves and a fixed static head on both the suction and discharge side. On the other hand they can be extremely
complex, such as when multiple pumps are connected to a system having several control valves, numerous
branches, and varying static heads. In the first instance, the system curve can be calculated
by taking into account
the static heads and figuring the friction losses within the piping system. In the second case, the static heads and
friction losses will vary and a branch analysis must be performed.
The pump total head is at the heart of developing the requirements
for any pumping system.
The operating head
imposed on the pump is composed of two principal components, the fixed, or static, head that varies over a defined
range and the dynamic head losses that vary with the liquid velocity in the piping system. Other factors that will
affect these values include liquid viscosity and specific gravity. These losses will vary by the number of pumps in
operation and the pumps' speed of operation if variable speed drives are provided. The value associated with the
dynamic head losses in a pumping system (commonly called friction) can be approximated by the use of empirical
formulae developed from experimental results conducted by researchers in the last century. Each method requires
the estimation of the roughness of the pipe or conduit wall and the flow regime in the pipe. Calculation of loss
values (commonly identified as minor losses) through fittings and valves suffer from the same level of uncertainty
because the absolute value will depend a great deal on the nature of the turbulence in the stream approaching a
fitting or valve. It can be appreciated, therefore, that any calculation of dynamic head losses must be viewed as an
approximation and that the actual conditions affecting dynamic head losses will never be known specifically. It follows, then, that the requirements to be used for selecting pumping equipment must be based on a combination of
assumptions that define the most optimistic and most pessimistic estimates for pipe roughness and fitting and valve
losses. Designers should be aware that overconservatism in the evaluation of hydraulic losses has been found to
be the root cause of many poorly designed pumping systems. A more detailed discussion of the uncertainty of the
calculations and the shortcomings and advantages of various methods may be found in Chapter 3, Pumping Station Design, Revised 3rd ed., Jones, et al, Elsevier Butterworth-Heinemann, 2006. Because of the uncertainties as
described above, whenever possible the system curve calculations should be verified by field measurements.
The following subsections provide a discussion of factors influencing head losses and commonly used methods for
calculating liquid flow losses in piping systems. In addition to below subsections a friction loss calculator is available in the Hydraulic Institute Engineering Data Library located at edl.pumps.org.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
27
4072
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix
A - System Curves
— 2022
A.1.1
Factors
that affect head loss
The calculation of friction loss is based on empirical coefficients and as such contains uncertainties that may lead
to errors in sizing the pump. The range of friction factors should be carefully evaluated before making a decision as
to what to use.
a) Flow rate: When the flow rate increases, the flow velocity increases and so does the friction or resistance to flow
caused by viscosity. The head loss is approximately related to the square of the velocity under turbulent flow
conditions.
b) Pipe inside diameter: When the inside diameter is made larger, the flow area increases and the liquid velocity for a
given rate of flow is reduced. When the liquid velocity is reduced, there is lower head loss in the pipe. Conversely,
if the pipe diameter is reduced, the flow area decreases, the liquid velocity increases, and the head loss increases.
€)
Roughness
of pipe wall: As the roughness
of the inside of a pipe increases, so does the thickness of the slow
or nonmoving boundary layer. The resultant reduction in flow area increases the liquid velocity and along with it
the head loss in the pipe.
d) Corrosion and scale deposits: Scale buildup and corrosion both serve to increase the pipe roughness, which will
increase
the head loss
in the pipe. Scale buildup has the added disadvantage of reducing the inside diameter
of the pipe.
e) Liquid viscosity: The higher the viscosity, the higher the friction between two moving streams of liquid. It requires
more energy to move a high viscosity liquid than it does for a low viscosity
liquid.
f)
Length of pipe: Head loss is constant along a unit length of pipe. In many tables this head loss is given as a
gradient in *per 100 meters (m)" or *per 100 feet (ft)* of pipe. To calculate the head loss, the gradient must be
multiplied by the actual length
of the pipe.
g)
Fittings: There are two basic methods to predict the head loss in valves and fittings. One method assigns a K
factor to each type or size of fitting, which is applied to the velocity head (KV#/2g) to calculate the loss. Fittings
such as elbows,
tees, valves, strainers, etc. have all been tested and assigned K factors based on the velocity
head and head loss measured through them. The other method assigns an equivalent length of straight pipe to
each type or size of fitting. There are charts and tablesin various handbooks, including the Hydraulic Institute
Engineering Data Book that provide these values. The Engineering
Data Book defines the procedure
and lists
the data necessary for predicting head loss for viscous liquids and paper stock.
A.1.2 Friction loss calculations
/A number of experimental studies were conducted many years ago to confirm the predicted head loss in pipes. The
results
have been published as both formulas and tables for different size pipes, and different flow rates. The two
methods most used are by Darcy and Weisbach, and by Hazen-Williams. The Hazen-Williams relationship, however, has limitations on the scope of its use and the user should determine its applicability for any given application.
The following section illustrates the basic mathematics behind each of these two methods. It should be noted that
these two methods are not acceptable
for use with non-Newtonian fluids. For non-Newtonian fluids, such as paper
stock or slurries, specialty algorithms are available from various sources for calculating friction losses.
A2 Pipe head loss calculation
methods
A.2.1
Darcy-Weisbach equation
The Darcy-Weisbach equation is an empirical equation with a dimensionless friction factor. The equation was
developed to calculate head loss in a pipe with incompressible liquid flow. Pipe head loss tables based on the
Darcy- Weisbach equation may be found in the Hydraulic Institute Engineering Data Book and the Hydraulic Institute Engineering Data Library (https://edl.pumps.org/). The equation has the following basic form:
o~
b=t
28
v
2-g
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
4172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix A - System Curves — 2022
Where:
= Total head loss, in m (ft)
f
= Darcy friction factor related to the pipe roughness
L
= Lengthof pipe,inm (i)
D
=
Diameter
of pipe, in m (ft)
V= Average liquid velocity in the pipe, in m/s (ft/s)
g
=
Acceleration
due to gravity, 9.81 m/s? (32.2 ft/s?)
Friction factors (f) for the Darcy-Weisbach equation may be taken from the “Moody Diagram,” which may be found
in the Hydraulic Institute Engineering Data Book and the Hydraulic Institute Engineering Data Library (https://edI.
pumps.org/), as well as in many other publications. In the Moody Diagram the friction factor is a function of Reynolds number Re. In the laminar
regime (Re < 2000) the friction factor is based on Poiseuille’s
law and is a direct
function
of Reynolds number
(f = 64/Re). In the turbulent
regime (Re > 4000) the friction factors are based on the
C.F. Colebrook equation that includes the influence of Reynolds number, pipe hydraulic diameter and internal surface roughness.
A.2.2 Hazen-Williams equation
The Hazen-Williams equation takes a different approach. The equation (Hazen-Williams formula) is based on testing of actual pipes of various sizes with differing degrees of roughness. The tests were conducted
in the first part
of the last century and the results presented in the reference book titled Hydraulic Tables, by Gardner S. Williams
and Allen Hazen. The tests demonstrated applicability of use for a broader range of pipe diameters. The research
indicated pipe sizes down to 25 mm (1 in) and up to approximately 4.3 m (14 ft) in diameter. The C or roughness
values must be adjusted for pipe age and materials, through the use of correction factors. Caution should be used
in selecting appropriate C values for different types and sizes of pipes and velocity ranges. The Hazen-Williams formula was strictly designed for water at ambient temperatures and is not applicable to other liquids. The tables are
based on the following formula:
Vs
hy = Cos L+ rmpr
Where:
h,
= head loss, inm (ft)
V= Average liquid velocity in the pipe, in m/s (ft/sec)
C
= Hazen-Williams coefficient
L
= pipe length, in m (ft)
D
= pipe diameter, in m (ft)
C,.s = units correction factor, 6.824 (3.002)
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
29
42172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix B - Water Hammer — 2022
Appendix B (Informative)
Water hammer
Refer to Appendices Introduction located immediately preceding the Appendix A.
It is not the intent of this material to provide detailed means
to analyze the magnitude and duration of surge waves.
This analysis is covered in many hydraulics texts and can be performed with available computer software. This
material
is provided to inform designers and users of pump piping systems when a surge analysis may be necessary. In most cases, the peak pressure of this surge may be below the pressure that may cause damage, but one
cannot determine this solely by any simple rules.
When pumps start or stop or the momentum of the fluid in the piping is changed by any other means (like opening
or closing a valve rapidly), a pressure wave is formed. The pressure wave can be either above or below the normal
pressure in the piping with the pumps operating depending on the configuration of the piping and pump system.
These pressure waves are called surge pressures or water hammer and their magnitude can be sufficient to burst
or collapse piping, valves, machinery casings, and other devices.
The magnitude of the pressure wave can be calculated with reasonable precision if the configuration of the piping
is known, the size of the pipes, the materials of the piping, the properties of the fluid, and how quickly the pump
and/or fluid accelerates or decelerates. When the column of fluid in the piping is either started or stopped, the
energy
of the system is transformed from velocity energy to head or pressure energy. Since the liquid and piping
material are not completely incompressible, they will absorb a fraction of the energy.
Often the Instantaneous Water Hammer equation, or the Joukowsky equation, can be helpful for a quick estimation, but it has limitations'. This equation will predict that the maximum surge pressure will occur whenever
the fluid
is stopped in less time than it takes for a pressure wave to travel from the equipment that stopped the flow to the
other end of the piping system and back. This may be better illustrated by an example. If a piping system is 2680
m (8800 ft) long and the fluid is water, the highest surge pressure would occur if the water is stopped faster than it
takes the pressure wave to travel 2680 m (8800 ft) and then reflect back to the source, a total of 5360 m (17,600
ft). A pressure
wave in water travels at the velocity
of sound in the liquid. For water in rigid piping materials (such
as carbon steel), the velocity
of sound is about 1340 m/s (4400 ft/s) so a pressure wave in 2680 m (8800 ft) of pipe
will take about four seconds to travel down the pipe and return back to the origin. If a valve at the end of the pipe is
closed
in less than four seconds, the pressure of the surge wave will be maximized. The calculation of this value is
discussed in Appendix B.1.3.
B.1 Water hammer
Transient forces resulting from water hammer can produce large displacements in the piping system, which can
cause severe damage to the piping system and any attached equipment, and should be evaluated.
B.1.1
Momentum
Water has mass.
One cubic meter
of water at 4 °C (39 °F) hasa mass of 1000
kg (1 ft* of water has a mass
of 62.4
Ibm). Moving water has momentum, which is directly related to both the mass and the velocity
of the liquid.
* This concept is only strictly correct for: 1) frictionless systems, 2) are well above vapor pressure and thus do not experience
fransient cavitation anywhere at any time, and 3) for uniform, straight pipes with no reflections of any kind. Consult other more
specialized references for more details such as “When the Joukowsky Equation Does Not Predict Maximum Water Hammer
Pressures®, Wallers T, Leishear, R., Journal of Pressure Viessel Technology, Vol 141, December 2019.
30
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
43772
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix
B - Water Hammer
— 2022
Liquid momentum = mass of the liquid in the piping system x velocity of the liquid
The faster the liquid is flowing, the greater its momentum. The greater the momentum, the more damage that can
‘occur due to water hammer if the liquid is suddenly stopped.
This sudden change in momentum creates a force (Newton's second law of motion) as follows:
Fn =C_»p-A»L-(('I/::z‘))
Where:
F,
= Momentum force, in N (Ib)
p
= Fluid density, in kg/m* (Ib_ /ft?)
A
= Cross-sectional area of pipe, in m? (ft?)
L
= Total length of pipe, in m (ft)
V,
= Initial velocity, in m/s (ft/s)
V,
= Final velocity, in m/s (ft/s)
[
= Initial time, in s
t,
= Finaltime,ins
C,s = units correction factor, 1.000 for metric (0.031 for US customary)
The above equation assumes rigid pipe walls and incompressible liquid, and only applies to relatively
slow valve
closures [about (t, - t,) > L/305, where L is in meters; or (t, - t) > L/1000, where L is in fee].
B.1.2 Acoustic shock wave
‘When the flow of liquid is suddenly stopped, the liquid tries to continue in the same direction. In the area where the
velocity change occurs, the liquid pressure increases dramatically due to the momentum force. As it rebounds, it
increases the pressure along the pipe near it and a shock wave or acoustic pressure wave is formed. This is analogous to the waves on a pond after a stone is dropped in. The waves radiate outward in all directions. As the wave
travels further from the center, its energy is spread over a larger and larger area and it will dissipate and eventually
die out. In a pipe the acoustic pressure wave can only travel along the pipe. It will travel at the wave speed, and
if we assume very rigid steel pipe and ambient temperature, it will be roughly 1341 m/s (4400 ft/s) (see Appendix
F.1). Since it is contained, it cannot dissipate its energy very quickly. As with the wave in the pond that will reflect
when it encounters an obstruction, so will the shock wave.
The same series of events that caused the pressure wave in the first place will occur every time the wave encounters an obstruction. This obstruction could be another valve, a fitting, or the pump. If nothing breaks, as with the
ripples in a pond, the pressure wave will strike and reflect off any rigid surface. It will continue to travel up and
down the pipe until it eventually dissipates
its energy through stressing parts and piping. When the pressure wave
reaches a component that will not bend to resist it, two things can happen. The pressure wave will be reflected or
the part will break.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
31
44772
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix B - Water Hammer — 2022
B.1.3
Magnitude
The potential increase in pressure due to the sudden deceleration of flow can be large. Based on elastic column theory, the maximum pressure produced by an instantaneous flow deceleration can be estimated using the
Joukowsky equation.
AP=C,, -p-a-(-AV)
Where:
AP
= Change in pressure
in Pa (psi)
p
= Liquid density, in kg/m? (Ibm /ft?)
a
= Wave speed in pipe section (includes effects of liquid and pipe stiffness), in m/s (ft/s)
AV
= Change in flow velocity, in m/s (ft/s)
Cys = units correction factor, 1.00 for metric (2.16 x 10+ for US customary)
For example, the sudden closure of valve at the downstream end of a pipe section results in a sudden flow deceleration (AV is negative) that generates a positive pressure wave (AP is positive) that travels upstream from the valve.
As an example, assume a pump is working at 345 kPa (50 psi) and the liquid is traveling 1.5 m/s (5 ft/s). Table B.1
shows the increase in pressure at the crest of the shock wave, which is the increase in pressure over the pressure
as measured in the pump casing. If the flow was suddenly stopped, the instantaneous pressure inside the casing
will jump to 2503 kPa (368 psi), or 345 kPa (50 psi) static + 2158 kPa (318 psi) as indicated in Table B.1 at 1.5 m/s
(5 fi/s). If the liquid velocity was instead 2.4 m/ s (8 fi/s), the instantaneous pressure will hit 3797 kPa (558 psi).
Pump casings are not usually designed for this magnitude of pressure increase.
Table B.1 — Magnitude
of pressure
[density, p =1000 kg/m? (62.4 Ibm/ft’) and wavespeed, a = 1,438 m/s (4,717 ft/s)]
Velocity m/s | Apressure kPa
Velocity ft/s
Apressure psi
432
1
64
0.6
863
2
127
09
1295
3
191
12
1726
4
254
15
2158
5
318
18
2589
6
381
21
3021
7
445
24
3452
8
508
27
3884
9
572
30
4316
10
635
34
4891
n
699
37
5323
12
762
40
5754
13
826
43
6186
14
889
4.6
6617
15
953
03
32
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
45/72
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix
B - Water Hammer
— 2022
This equation ignores any dampening effect of the fluid compressibility and the piping material elasticity and so this
equation slightly overpredicts the maximum surge pressure?.
The initial pressure
wave will propagate from the source
of the wave (the closed valve) back towards
the other end
(and up any branches) of the piping system (back to the pump). Depending on the configuration at the other end,
a pressure wave will reflect back to the original source (the closed valve). Because of the damping in the system,
the magnitude of this reflected wave is usually smaller than the initial pressure wave. The wave will be reflected
back again to other end (back to the pump) and this cycle will repeat. This reflection of the pressure waves from
each will continue with the magnitude decaying each time until the pressure reaches steady state. The time for this
decay depends on the initial pressure magnitude, the length of the piping system, and liquid and piping properties.
In water systems with steel piping, there will be multiple cycles of reflected waves, even with pressure-dampening
surge control vessels on the pump discharge.
The aforementioned example is just one of many types and causes of water hammer. In any case, the actual value
of the high- or low-pressure reflected wave should be evaluated using more robust methods
and tools than the
Joukowsky equation or other simplified approaches.
B.1.4 Damage
Water hammer and the associated high-pressure spikes can exceed the pressure rating for pump casing, valves
and associated piping. While these high pressures each may be experienced for a short time, over time they can
cause the components to fail. Different materials used in the system can react differently based on their properties.
Observing a point of failure may not be the actual cause of the failure. Valve closure speeds, system operation and
the use of surge suppression devices can reduce the pressure spikes and, therefore, the risk of a failure.
Cast iron is a rather brittle material and in most cases will not be able to withstand the sudden impact of a pressure wave well above its normal internal pressure, traveling at the speed of sound. The face
of the pump casing is
the largest open area of the pump. Therefore, it will experience the highest forces due the pressure change. In a
typical volute design, the tongue or cutwater is placed relatively close to the impeller at a given point to direct the
flow leaving
the impeller as efficiently as possible. This also makes the casing very rigid in this location.
The face of
the casing tries to bulge outward but is held firmly
by the tongue. This causes extremely high stresses in this area
and is usually the point where the failure begins. Experience has shown that strengthening this area has little or no
effect on the casing's ability to survive water hammer.
Other materials that are more ductile may absorb the shock waves without cracking, but still risk permanent deformation and ultimate failure. The pump is not the only component that is affected by this phenomenon. Valves,
sprinkler heads, and pipe fittings are also at risk of catastrophic damage. Pipe hangers and pump foundations can
also be adversely affected by water hammer.
‘Water hammer can be controlled through proper valve closure rates (with slow closing valves), the addition of diaphragm tanks to absorb
the pressure surge, and relief valves to release the pressure, as well as other methods
found in literature. Careful modeling can help to verify that a proposed solution for relieving water hammer will
result in the desired reduction in pressures.
2 This concept is only strictly correct for: 1) frictionless systems, 2) are well above vapor pressure and thus do not experience transient cavitation anywhere al any time, and 3) for uniform, straight pipes with no reflections of any kind. Consult other more specialized references for more details such as “When the Joukowsky Equation Does Not Predict Maximum Water Hammer Pressures”,
Wallers
T., Leishear, R., Journal of Pressure Vessel Technology, Vol 141, December 2019.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
33
46172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix C - Selecting and Locating Pipe Supports and Restraints — 2022
Appendix C (Informative)
Selecting and locating pipe supports and restraints
Refer to Appendices Introduction located immediately preceding Appendix A.
This appendix is meant to give the user a brief overview of the subject of pipe supports. There are a number of
books and articles that go into this subject in considerable depth. There are also many organizations and individuals who specialize in this area who can assist the user when designing the system if required.
Selecting and locating pipe supports and restraints in a piping system, particularly when connecting to rotating equipment such as pumps, turbines, or compressors, can be a difficult task. There are many factors that the designer must
take into consideration.
These include system flexibility, which will change
as supports and restraints
are added; nozzle
load limits of attached equipment; and the general layout of the structure by which the piping must be supported. In
addition, natural frequencies of piping that can be excited by typical pump excitations such as vane pass can result in
elevated vibration of not only the piping, but the pump itself. Care must be taken to ensure that the piping has proper
supports so that the natural frequencies of the piping directly connected to the pump has sufficient separation margins
from potential excitation sources so as to not become excited and result in excessive vibration. Internal fluid mass in
the piping must also be accounted for in the frequency calculation. Refer to ANSUHI 9.6.8 Guideline for Dynamics of
Pumping Machinery to properly account for piping directly connected to the pumping unit when calculating natural frequencies of the pump and piping system. All these combine to create a dynamic problem that is difficult to generalize.
For the pipe support around pumps and other rotating equipment, the following design guidelines are recommended.
C.1 Restraint and anchors
Restraints should be placed in a position that will force the pipe to thermally grow in a direction away from the
pump nozzle and into the piping system, where the displacement and associated expansion load can be absorbed
Refer
to ANSI/HI 9.6.2 Rotodynamic Pumps for Assessment of Applied Nozzle Loads for allowable nozzle loads for
several pump types and ANSI/HI 12.1-12.6 Rotodynamic Centrifugal Slurry Pumps for Nomenclature, Definitions,
Application, and Operation.
Anchors and restraints placed near pumps should correspond to planes of zero growth, relative to the pump. The
piping system restraint should limit pipe forces acting on the pump.
C.2 Pipe supports
for vertical loads
Pipe supports for vertical loads (Figure C.1) are designed specifically to carry the weight of the pipe, along with
associated vertical loads, such as insulation, process liquid, fittings, valves, etc. The supports will not restrict the
thermal expansion of the piping in any direction. Rigid resting-type supports are widely used for horizontal piping
runs. The support is affixed to the pipe, providing vertical support while allowing the pipe to slide laterally along the
structure. These supports prove to be satisfactory in most applications where the friction load due to the weight is
relatively small compared to the thermal expansion forces.
When adequate overhead space and structure is present, solid hanger supports (Figure C.2) should be used. The solid
hanger will carry the vertical load of the pipe, while eliminating the frictional effects of the resting-type fixtures. In piping systems that exhibit considerable vertical movement due to thermal effects, spring-type
supports should be used.
Hangers should be sized so that there are minimal vertical loads on the equipment nozzles in the ambient condition.
Constant-effort spring supports (Figure C.3), when placed properly, can alleviate many problems faced when connecting to rotating equipment. Using a constant-effort device, which will support the vertical piping load similarly in
hot and ambient conditions, can greatly reduce loads carried by equipment nozzles.
34
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
47072
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix C - Selecting and Locating Pipe Supports and Restraints — 2022
Figure C.1 — Pipe supports for vertical loads
Figure C.2 — Solid pipe hanger supports
‘SMALL CHANGE IN EFFECTIVE LEVER ARM
CONSTANT
LOAD
Figure C.3 — Constant-effort spring supports
C.3
Guides and restraints
Pipe restraints are used to introduce a fixed point and control the direction in which a pipe system is permitted to
move. When used to control movement due to thermal expansion/contraction, the restraint is designed to limit the
movement of the pipe in the axial direction and provide some restraint to bending or rotation. Restraints can be
beneficial when connecting to rotating equipment by directing pipe displacements away from the equipment connections and into more flexible areas of the pipe system that have been verified to include the ability to absorb the
movement. Tie rods and jointed struts can be used on horizontal or vertical pipe runs, or in transition areas at pipe
elbows or vertical drops that require the movement of the pipe to be restricted in the horizontal direction.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
35
48172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix C - Selecting and Locating Pipe Supports and Restraints — 2022
Pipe guides (Figure C.4) are used to restrict the effects of rotation and/or bending on the pipe, while allowing unrestricted axial movement of the pipe.
MAY BE
INCLUDED FOR
TWO AXIS
YP\
RESTRAINT
o B
FLOOR, DECK, OR ROOF
Figure C.4 — Pipe guides
C.4 True anchors
True anchors are seldom used as fixtures, which combine the characteristics of the support and restraint devices,
to limit
pipe movement in the three linear planes and the rotation about the three axes. They can be used to isolate
vibration and displacements from different segments of the system.
The devices can also be used to raise the natural frequency of the system to reduce amplitude and avoid resonance.
The effects of piping need to be considered
in the structural modal analysis of the pump and piping system, refer to ANSI/HI 9.6.8.
C.5 Spring supports
Spring supports (Figure C.5) are an important part of most pump piping systems. They are designed to support the
deadweight load of the pipe, process liquid, and associated attached equipment, such as insulation, valves, and
fittings, while at the same time absorbing the effects of thermal expansion on the pipe. Spring supports are often
placed directly above or below a pump nozzle connection. The following guidelines are provided for the proper
installation of spring supports:
a) Spring support height should be adjusted to allow adequate flange alignment and seating at the pump nozzle.
Proper alignment should be accomplished without adjusting the spring load or removing the shipping stops from
the support.
b) With the piping empty, the shipping stops will prevent the spring load from deflecting the pipe, which can
‘cause misalignment with pumps, terminal connections, and other support fixtures. If the flange connections are
made before removing the stops, the spring will exert a force at least equal to the weight of the fluid that it was
designed to support. The stops should remain in place until after the hydrotest of the piping system is complete
and be removed prior to system start-up.
36
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
49772
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix
C - Selecting and Locating Pipe Supports
and Restraints
— 2022
'CAGE WHICH PRECOMPRESSES THE SPRING
vMESTABLISESITSI‘AMM EXTENSION
\;
s 1] SN—
CONNECTING
ROD
peellllberey
TYPICAL SWAY BRACE MECHANISM
iy
LIMIT RODS WHICH PRECOMPRESS
THE SPRING AND ESTABLISH ITS
Il
MAXIMUM EXTENSION
ANOTHER MECHANISM
USING TWO SPRINGS
SWAY BRACE EMPLOYING
PRECOMPRESSED AND
LIMITED ACTION SPRING
PLAIN SPRING WITHOUT
LIMITED ACTION
RESISTANCE
'OFFERED BY
SPRING
CONNECTING ROD IS USUALLY —
'ADJUSTED SO THAT OPERATING
POSITION IS AT THIS POINT
+DEFLECTION
ZERO
DEFLECTION
Figure C.5 — Spring supports
€)
When spring supports are used at pump attachments, they should be placed directly above, below, or adjacent
to the pump nozzle.
d) Supports
should be placed on the attached piping to achieve a near zero dead load on the pump nozzle. Allowances must be made, however,
for angular offsets at hanger supports that are necessary
when the piping is in
an ambient condition.
C.6
Friction
from supports
Friction should not be ignored when determining the overall flexibility of the piping in systems that connect to
pumps or other rotating equipment. The analysis should be performed with and without friction included, determining the worst-case situation with regard to piping stresses and nozzle loads.
Two common methods for lowering the frictional effects within the system are low-friction bearing plates and rollers.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.
pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
37
50172
4/19/23, 12:17 PM
FileOpen Web Viewer
Appendix D - Expansion
Joints — 2022
Appendix D (Informative)
Expansion joints
Refer to Appendices Introduction located immediately preceding the Appendix A.
Expansion Joints are commonly used to reduce pipe stresses and nozzle loads in a pump piping system. They typically accomplish this by absorbing otherwise damaging forces and displacements and replacing them with the low
stiffness (spring rate) and high movement capability of the expansion joint. Primary sources of pipe stresses and
nozzle loads include thermal expansion and contraction reaction forces, installation misalignment, ground settlement and other external displacement forces, as well as loads related to shock and vibration.
It is most desirable to direct potentially damaging pump piping loads and displacements away from the pump. To
do this the pump piping should be supported and un-anchored to allow the free movement away, and in addition
each component of the pump piping should be restrained, in order to continuously hold the pressure thrust force in
tension. It is less desirable to locate an anchor close to the pump as this will direct potentially damaging loads and
displacements from that section of piping toward the pump. Whether the piping between the pump and anchor is
considered restrained or un-restrained, considerations should be made for anticipated loads and displacements. If
the piping between the pump and anchor has an un-restrained expansion joint or coupling, there will be a potentially damaging compressive pressure thrust force acting on the pump. If the piping between the pump and anchor
has a restrained expansion joint or coupling, there will be potentially damaging pipe strain from thermal expansion
and contraction reaction forces and other forces mentioned above.
DA
Expansion joint types
Slip (axial) joints or packed joints are common in smaller-diameter applications, where misalignments and nozzle
loads are not as critical. The slip joint is essentially a pair of telescoping cylinders, one inside the other. A compression sleeve is mounted at the end of the outer cylinder. Sealing between the cylinders is accomplished using either
packing or an elastomer O-ring. The design is simple and reliable, but its use is limited to applications where pipe
movements are in the axial direction (Figure D.1).
BUILT-IN LIMIT STOP
— PACKING
.
[
SUP PIPE
STUFFING BOX
B
B
LUBRICATION FITTINGS
DRAIN MAY BE PROVIDED TO ELIMINATE
POCKETING IN HORIZONTAL LINES
X
CONNECT
THE FLANGE
ON THIS
SIDE OF THE EXPANSION
JOINT
TO THE PUMP
Figure D.1 — Slip/packing expansion joint
38
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
5172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix D - Expansion Joints
— 2022
Elastomer (rubber) expansion joints (Figure D.2) are commonly used for relatively low-pressure (<300 psi), lowtemperature (<400°F) applications. Their use is widespread in hotels, institutions, and large office buildings: on
condenser and circulating water pipes: and as an isolation device guarding against transmission of vibrations due
to pump vibration and pressure pulsations. Rubber expansion joints, due to their flexibility, provide protection from
slight misalignments in piping and pump nozzle connections.
When rubber expansion joints are used on the suction
cconnection of a pump, consideration should be given to filling the internal convolutions with a softer material or utilize an optional removable sleeve to minimize flow disturbance to the pump.
Metal (bellows) expansion joints are typically used for relatively high-pressure (>300 psi), high-temperature
(> 1,000°F) applications, where nonmetallic components are not suitable (see Figure D.3).
FLOW
FLOW
BLEED
CCONNECTION —~
1
1
SIMPLE WELDED-IN SLEEVE
SPLIT RETAINING RING \‘,/
RUBBER COVER
HEINFORCEMENT
(FABRIC & STEEL)
Z
RECESSED SLEEVE
WITH BLEED
CONNECTION
FLow
(PERMITS COCKING
(OR OFFSET MOVEMENT)
v
FLOW
Z
o5
i
RUBBER mss/
\
OPTIONAL REMOVABLE
SIEEVE
FLOW
Figure D.2 — Rubber expansion joints
TWO-PIECE OVERLAPPING
SLEEVE (PERMITS SMALL
GAP FOR COCKING
MOVEMENT)
REMOVABLE SLEEVE
FOR FLANGED JOINT
Figure D.3 — Metal bellows expansion joint
Both elastomer and metal expansion joints come in a wide range of standard designs and can be custom built to
serve a specific task. These expansion joints are generally more versatile than packed slip joints because they
‘combine axial movement, angular rotation cocking, and a certain amount of lateral movement offset. For increased
lateral movement, two expansion joints can be joined by a nipple and limit rods. These are known as universalor
Caution must be used when including expansion joints in the piping design. The piping on both sides of the expansion joint must be self-supported to operate as intended: the joint cannot be used to support the weight load of the
piping system. Proper pipe support fixtures should be chosen (see Appendix C) to allow for the free axial movement of the joint. In pump applications where expansion joints are used in vertical pipes, spring hangers may be
required to support the weight of the piping directly over the pump nozzle. Some industries do not allow the use of
flexible connections on pump suction and discharge flanges. In those cases, the flexibility to accommodate thermal growth must be built into the piping. This requires pipe strain analysis to avoid overloading either the pump or
the piping.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
39
52172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix D - Expansion Joints — 2022
High vibration, cyclic flow, or pump pulsations can quickly fatigue metallic bellows causing failure of the joint. External sleeves are often used to protect the fragile bellows and to provide protection for personnel and equipment
should the joint fail. Internal sleeves will reduce the pressure drop across the joint and protect the bellows from flow
erosion and turbulence (see Figures D.2 and D.3).
Once installed, the expansion joint will require periodic inspection for corrosion on metal joints and delamination on
elastomer joints, but little maintenance is required to keep an expansion joint operating. If the joint is found to be
defective or damaged, it should be replaced.
D.2
Expansion joint application
Consideration must be given to pressure effects when expansion joints are used in pump applications. When an
expansion joint is mounted close to a pump nozzle, the pressure exerted by the liquid on the joint will generate a
force equal to the pressure across the inside surface area of the expansion joint, times that projected area. Ideally the pump end of the expansion joint is anchored or restrained to absorb this force, and prevent it from acting
on the pump. If the attached piping is, instead, anchored on the other side of the expansion joint, this force will
be directed back towards the pump nozzle, where possible overloading can take place. Self-equalized expansion
Jjoints, which are equipped with tie rods on the exterior of the expansion joints, should then be used between the
mounting flanges (Figure D.4). As shown in Figure D.4, tie rods should be used with double nuts to prevent movement in either direction. Tie rod nuts should be installed finger tight against the expansion joint lugs and then the
double nuts tightened against each other. Tightening each set of double nuts against each other will lock them in
place and prevent unwanted adjustment or loosening. It is good practice to install double nuts against both sides of
the expansion joint lugs, because pressure effects can act in both axial directions as a result of positive or negative
pressures. It is important to not over-tighten the tie rods as this can create undue stress in the system.
Careful attention should be given to the design of the tie rods, also known as control rods or thrust rods, in piping
systems capable of inducing a hydraulic pressure reaction force on the pump (most systems).
Figure D.4 — Expansion joint bolting arrangement
40
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
5372
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix D - Expansion Joints
— 2022
In such systems, tie rods [if properly designed, installed, and hand tightened (do not apply torque) with no gap
between
tie rod nuts and gusset plates or flanges and in accordance with the expansion joint manufacturer's
rec‘ommendations] will restrain the axial internal pressure force sufficiently so as to prevent an excessive reaction
force on the pump. It is critical that the tie rods are finger tight with no gap between nuts and supporting brackets
and/or gussets. If a gap is present, the full pressure reaction force will act on the pump until the gap is consumed by
the deflection of the adjacent piping and/or pump. As a cautionary note, any expansion joint or coupling that cannot
be installed with its restraint finger tight, such as with many grooved couplings, cable restrained expansion joints
and braided hose, will impose the full pressure reaction force on the pump and will require additional consideration.
‘When an inadequate design is used, the magnitude of reaction force on the pump can easily exceed acceptable
nozzle loads and have harmful effects on the pump.
The design criterion for tie rods should not be limited to maximum allowable stress calculations, but should also
include considerations for axial deflection, or stretch, of the tie rods due to the pressure in the pipe. This is particularly important when using high-strength tie rods as the stress can be within allowable but the deflection can also
be relatively high. ASTM B31.3 and other similar codes address this by reducing the maximum allowable design
stress for rods with a resulting increased safety factor.
The following design recommendations apply:
a)
A supported and un-anchored piping system utilizing expansion joints should be equipped with tie rods to
restrain the force caused by the pipe internal pressure.
b)
Tie rods should be evaluated and designed to ensure allowable rod stress is not exceeded. This evaluation may
use ASME B31.3 or a similar
code or method.
€)
Anchored piping systems, in most cases, will induce unbalanced hydraulic pressure reaction force on the pump
since the piping cannot freely stretch away from the pump. Tie rods, used in the vicinity of the pump, should be
evaluated for axial stiffness and stretch. As a rule of thumb, tie rod stretch under maximum system working pressure is recommended to be limited to the stretch of an equivalent length of pipe plus 0.010" (including stretch of
any supporting brackets). In these cases, the system and pump should be evaluated to ensure the rod deflection
is acceptable for all components.
d)
The maximum
allowable nozzle loads of the pump should not be exceeded (including any deflection resulting
from stretch of the tie rods).
e)
The weight of the pipe and contents shall be supported on the opposite side of the expansion joint from the
pump.
f)
Tie
rods
should be used with double
nuts to prevent movement in either direction. Tie rod nuts should be
installed with no gap between the nuts and expansion joint gusset plates in accordance with expansion joint
manufacturer's recommendations and then the double nuts tightened against each other. It is important to not
oover-tighten the tie rods as this can create undue stress in the system.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
a1
54172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
Appendix E (Informative)
Specialty piping components and applications
Refer to Appendices Introduction located immediately preceding Appendix A.
E.1
Check valves and strainers
E.1.1
Check valves
Check valves are normally installed in the discharge (not suction) pipe to automatically prevent reverse flow when
the pump is stopped.
When using a check valve in the suction pipe, consideration should be given to the increased pressure drop to
the suction of the pump, the possibility of exposing the entire pump casing to discharge pressure, and to potential
water hammer shock to the piping (see Section 9.6.6.4.4 Water hammer).
For requirement associated with check valve installation elevation relative to lowest well/sump level, see Section 9.6.6.4.3.2. The check valve is installed to reduce backspin on shut-down, to reduce pump rotor upthrust on
start-up, and to prevent water hammer.
Check valves are typically used in parallel and series pumping systems to allow automated stop/ start and change
of operating conditions of pumps without the need of operating isolation valves.
There are many types of check valves and the type must be carefully selected for the application. Some check
valves are designed specifically for clean water applications such as nozzle type check valves and double door
check valves and not suitable for solids bearing liquids while others like swing check valves and rubber flapper
check valves are designed specifically for both clean water and solids bearing liquids.
E.1.2
Foot valves
Foot valves are specially designed check valves used at the inlet of the suction lift pipe to maintain pump prime,
by maintaining liquid over the first-stage impeller (see Figure E.1) and/or to protect the pump from reverse rotation.
Foot valves are designed to open fully with very little pressure differential across the valve. The difference between
a check valve and a foot valve is that the foot valves are typically equipped with a screen at the inlet of the valve
whereas a check valve is not designed with an inlet screen. Other check valves types can also be used as foot
valves including rubber flapper (see Figure E.2 shown without a screen) and double door. These can be used with
or without a screen based on the service. They should be installed in a vertical orientation (see Figure E.3) (or
they may not work), below the top of the water level with the foot or the end of the suction pipe at least four pipe
diameters below the top of the water level. This will maintain a primed condition in the suction pipe. The foot valve
and pipe should be sized to minimize suction pipe losses maximizing the NPSH available to the pump and carefully
reviewed due to risk of water hammer.
Foot valves are not designed or recommended for use with solids bearing fluids. Potential problems with leakage
and failure to close may be encountered when solids are present in the liquid. Therefore, foot valves should be
limited to pump installations where pump nonperformance due to foot valve failure does not place the user at high
risk. It must be remembered that, unless a suction pressure relief is provided, pumps must have the suction side
designed to contain the maximum allowable working pressure of the pump, plus any hydraulic shock loading or
water hammer due to sudden foot valve closing.
42
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
5572
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
Figure E.1 — Foot valve and screen
Figure E.3 — Foot valve installation
Figure E.2 — Foot valve (rubber flapper
check valve without screen)
Foot valves may be used with caution at the inlet of bowl assemblies for vertical well pumps to keep the column
pipe filled, to prevent backspin and to prevent well disturbances caused by rapidly draining water. Note that this
practice is normally limited to use on small pumps [less than 3.7 kW (5 HP), less than 30m (100 ft) setting, and less
than 345 kPa (50 psi) surface pressure]. The pump manufacturer should be consulted for advice, warranty considerations and approval.
E.1.3
Strainers
Strainers may be installed in the pump suction piping to keep unwanted material out of the pump. The strainer may
be installed at the suction bell in vertical turbine pumps. The strainer usually introduces only a moderate pressure
drop. However, as it accumulates debris, the pressure drop will increase. It is, therefore, recommended that in-pipe
strainers be installed with upstream and downstream pressure taps. The pressure drop should be monitored to
prevent excessive headloss and possible cavitation. In-pipe strainers can be manually or automatically cleaned
type. A rule of thumb for strainer application is that the open area be three times the area of the upstream pipe. For
a cone-type strainer, the point of the strainer should face upstream or as directed by the strainer manufacturer (see
Figure E.4). In a suction lift application or low positive suction pressure in an open system, the strainer should be
sized for a minimum pressure drop. The strainer should not be installed on the pump suction nozzle. See Section
9.6.6.3.4, for the recommended safe distance.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
43
56172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
Figure E.4 — Typical temporary strainer
A temporary strainer may be installed (in the pump suction pipe) during system shakedown, prior to initial startup,
when a permanent strainer is not being installed. This is especially important and customary on critical pump services, such as nuclear, power, and refinery. However, the pressure drop must be low enough to provide the pump
with adequate NPSH to preclude damaging cavitation. The strainer should remain in the system until periodic
inspection shows the system to be clean. A typical temporary strainer installation is shown in Figure E.4. (Note that
in some applications it is required that temporary strainers be removed as soon as they are no longer needed.)
For all applications the Pipes should be thoroughly flushed before installing a suction strainer.
E.2
Devicesto improve
flow to the pump
In certain cases, compliance
with the minimum length of pipe L, (see Section 9.6.6.3.4, Table 9.6.6.3.4, and Figure
9.6.6.3.4a) at the suction of the pump, may result in large installations whose cost and overall dimensions may be
prohibitive.
It may be possible to reduce length L, (Figure 9.6.6.3.4a) by using a flow straightening device upstream of the
pump suction and after flow-disturbing fittings and valves. Where vanes are installed in a pipe section the design,
number, shape and spacing of the vanes must be suitable for the application be it clean water or solids bearing.
Other devices, such as vaned elbows, also improve suction flow to the pump. When the suction piping includes a
second perpendicular elbow near the pump (see Figure E.5), the flow straightener (vertical splitter) should be positioned in the straight run of pipe leading to the pump, at least five pipe diameters away from the pump.
Figure E.5 — Second upstream perpendicular elbow
In cases where an suction strainer is required and the suction pipe length is insufficient to ensure proper flow to the
pump suction, a combination fitting with both a flow strainer and straightening vanes can be used.
44
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
5772
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
Flow improvement devices and the resulting allowable L, length should only be used with mutual consent of the
pump manufacturer and installer, or after evaluation with applicable and acceptable flow analysis tools.
The material presented below is provided for the convenience of designers in correcting adverse hydraulic conditions of systems with non-compliant piping. None of the flow conditioning devices described herein are part of
the standard design recommendations provided in this standard. The remedial measures described are based on
general experience and knowledge gained over many years of improving the hydraulics of pumping systems. Corrections described herein have been effective in the past but may or may not result in a significant improvement in
performance characteristics for a given set of site-specific conditions. Other remedial fixes not provided herein may
also be effective, and a physical model study (as described in ANSI/HI 9.8) is needed to verify that a given remedial
design feature results in acceptable flow conditions.
It is critical that any flow conditioning device installed in piping is adequately secured to prevent it from breaking
loose and damaging the pump. Consideration should be made to the hydraulic forces and/or flow induced vibration
imposed on the flow conditioning
devices. Experience has shown that such phenomena may be higher than
expected close to the pump suction. Engineering analysis can better inform those designing and manufacturing
the flow conditioning device regarding the means and methods for fabricating and installing/securing such devices.
Corrosion and erosion should be considered when using a flow conditioning device. When selecting materials, the
characteristics of the pumped liquid should be considered. The flow conditioning device should be constructed of
‘compatible materials and of equivalent corrosion and erosion resistance to the pump and interconnecting piping.
Another important consideration for flow conditioning devices is the ability to pass solids. Certain flow condition
devices may not be suitable for solids-bearing liquids and can be susceptible to collection of fibrous rags and other
debris. Considerations to reduce the potential to accumulate material on flow conditioning devices are included in
Section E.2.1. The accumulation of materials on a flow conditioning device has the potential to disturb and restrict
flow, which can reduce pump performance and service life.
The user should coordinate the location of any flow conditioning device with both the device and pump manufacturer.
Following are some examples of commonly implemented flow conditioning devices:
E.2.1
Straightening vanes
Flow straightening vanes can be an effective method of controlling swirling flow in piping and can mitigate vortices
that extend into pump inlet (suction) piping. A common dimensional configuration for flow straightening vanes provides
for a vane length that is 3 times the spacing between the vanes. When configured in a cross type arrangement,
the length of the straightening vanes is often 1 pipe diameter. Typical flow straightening vane configurations are
presented in Figure E.6.
VS
—D—
PROFILE &'
D
SECTION
B-8"
Figure E.6 — Straightening vanes
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
45
58172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
If not carefully implemented, flow straightening vanes can cause detrimental effects to pump intake hydraulics by
exacerbating a flow distribution problem. For example, use of improperly oriented flow straightening vanes near an
outlet of a bend can accentuate unbalanced flow distribution downstream of the vanes. To prevent this occurrence,
the vanes should be oriented parallel to the plane of a bend, thereby using the pipe length to encourage flow distribution. Figure E.7 demonstrates the proper orientation of flow straightening vanes downstream from a bend.
4c
PROFILE
|
c
SECTION C-C'
'
FLOW
VANES ORIENTED PARALLEL TO
"THE PLANE OF THE UPSTREAM
PIPING TO ALLOW RECOVERY OF
FLOW SEPARATION DOWNSTREAM
FROM THE BEND
DIRECTION
Figure E.7 — Straightening vanes downstream from bend
Straightening vanes are most commonly used in clear liquids and hydrocarbon applications. Vanes specifically
designed to pass stringy/fibrous materials have been demonstrated to be effective in raw wastewater applications.
Solids-passing straightening vanes do not span across the entire flow field in the pipe and are designed to shed
entrained rags and debris with a sloped leading edge at an angle of 45 degrees or less. Vanes are often designed
to extend across approximately 2/3 of the pipe diameter to allow sufficient room for debris to pass and generally
do not reduce clearances to less than sphere size of the pump. Common solids-passing vane configurations are
shown in Figure E.8.
46
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
50172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
ij
213D
D
<4mm
—
GREATER THAN
PROFILE
SPHERE SIZE OF
THE PUMP
s
FLOW
DIRECTION
o
o
SECTION D-D'
'VANES ORIENTED
WITH ANGLED
LEADING
EDGE THAT DOES NOT
EXTEND
ACROSS THE ENTIRE
A
—TD—=
[
GREATER THAN
SPHERE SIZE OF
THE PUMP
<4 FLOW
DIRECTION
SECTION E-E'
E
120 DEGREES TYP
g
A
P
~H
=
=
ALTERNATE
'STRAIGHTENING VANE
CONFIGURATION
Figure E.8 — Straightening vanes for solids-bearing liquids
E.2.2 Turning Vanes
Turning vanes can be an effective method for mitigating non-uniform flow that invariably occurs downstream from
an elbow not meeting the area reduction requirements presented in Table 9.6.6.3.4. A common design guideline
for turning vanes is the use of one (1) or more vanes oriented perpendicular to the plane of the bend. Figure E.9
presents a typical turning vane configuration.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
47
60/72
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
Caution must be used when using turning vanes in fluids with stringy/fibrous materials. Solid vanes may not be
appropriate in these applications. Turning vanes can be effective for liquids with small particulates.
Figure E.9 —Turning vanes
E.2.3
Grating
or flow grids
Grating or Flow Grids can be used in the piping or flow field approaching a pump to stabilize flow for clean water
applications. These may have a depth-to-opening ratio that varies from 1:1 to 3:1, depending on application. Provided the bar material thickness is small relative to the opening size, and the flow path is generally normal to the
opening, head losses through the grating should be minimal. However, it is important to evaluate head loss, especially for systems with limited NPSH margin. To ensure that pump performance is not detrimentally affected by
captured debris, monitoring of either differential pressure or pressure on the pump side of the grating should be
considered. Figure E.10 presents a typical grating configuration.
-3
o
(T
{
)
=
|
—
NS4
Hoens
'CONFIGURATION
Figure E.10— Grating or flow grid
E.2.4
Proprietary Flow Conditioning Devices
There are many proprietary flow conditioning devices that may be suitable to deliver well-distributed flow downstream from flow-disturbing fittings. The Hydraulic Institute does not have data from application of these devices to
confirm hydraulic performance in pump applications and therefore cannot comment on their effectiveness.
48
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
6172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
E.3
Piping for suction lift applications
Self-priming systems require special piping considerations for proper operation. Design recommendations
listed below:
a)
Install the suction piping the same
manufacturer.
b)
)
Slope horizontal runs upward toward the pump.
size as the pump suction, unless otherwise approved
are
by the pump
The static lift must not exceed the pump rating. Depending on the manufacturer, static lift may be defined as:
suction lift rating, maximum lift or lift capability, or static priming lift.
d)
Minimize the static lift, number of fittings and total length of suction piping to keep priming time to a minimum.
Excessive priming time will result in an increased fluid temperature that can cause liquid in the priming chamber
to vaporize before prime is achieved.
e)
All connections in the suction piping must be leak-free to avoid air being drawn in (see Section 9.6.6.3), which
will extend and possibly compromise the priming of the pump.
Install a priming bypass pipe to allow evacuation of the suction pipe air volume to facilitate priming. It is mandatory if a check valve is installed in the pump discharge pipe (Figure E.11).
Design the layout of the suction piping such that no high points are created, where air or vapor can be trapped
or accumulate, which can prevent priming.
h)
The effects of dissolved gases and altitude should be carefully considered.
Figure E.11 — Self-priming piping arrangement
E.4
Solids/slurry
Systems intended to carry solids-bearing liquids need special attention. In addition to general piping design guidelines, care is needed to avoid excess energy consumption, settling/blockage, and wear. Factors to consider include
pipe velocity especially in vertical runs, valve selection, piping arrangement, and piping materials.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
49
6272
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
E.4.1
General
Solids/slurry characteristics are beyond the scope of this standard. Refer to ANSI/HI 12.1-12.6.
E.4.2
Piping arrangement
Piping should be arranged to avoid sudden changes in direction and areas where solids can accumulate, which
could result in rapid wear and blockages. General guidelines include the following:
a)
Avoid low spots.
b)
Use long-radius elbows wherever turns are needed.
c) If piping inclines are used on heavy slurries, keep the angle slightly less than the angle that would allow gravity
to move the solids when the pump is not operating.
d) Provide means to flush the piping in sections where blockage may occur.
€)
Keep valves to a minimum.
f)
Maintain accessibility to potential wear areas (joints, elbows, and geometry changes).
E.4.3
Materials
Slurries can be very abrasive and corrosive. Piping materials must be chosen properly to achieve acceptable
service life. The pipe material
must be resistant to corrosion by the liquid in the slurry and resistant to erosion by
the solids. Slurries can be handled by carbon steel if the resulting corrosion and erosive rate is acceptable. More
ccommonly slurries are handled by rubber-lined, duplex stainless-steel, urethane-lined or high-density polyethylene
pipe. The choice is typically governed by particle size, carrier characteristics and economic considerations. In high
wear areas such as elbows, tees and size transitions, piping may be lined with white cast iron inserts, ceramic tiles
or replaced with rubber hose.
Rubber-lined pipe is often a good choice for small particles like sand. Metal pipes are required if there are larger
solids present but the liquid carrier must be compatible with the pipe material. Urethane-lined and rubber-lined
pipes can accommodate larger solids in a mixture that includes smaller solids.
E.5 Air valves
Air valves comprise a general category of valves including air release valves, airfvacuum valves, vacuum breakers
and combination air valves. An air valve is an essential component in the design of system piping
Air release valves are hydromechanical devices
that automatically vent pockets of air and gas as they accumulate
in a pressurized piping system. In general, as the liquid is being pumped, entrained air will bubble up to the high
points in the system piping. If the pipe slopes upward, the velocity
of the liquid will move the air bubbles
to stagnate at a high point. In contrast, if the pipe is fairly flat and the inside surface of the pipe is very rough, or the pipe
slopes downward,
then the fluid velocity may not be sufficient to keep the air bubbles moving.
As a consequence,
it is possible for a pocket of air to collect at these high points, and to gradually reduce the
effective liquid flow area, which may create a throttling effect similar to a partially closed valve. Additionally, sudden compression of these air pockets can set up severe shock waves when released with the potential for serious
equipment
and piping damage.
Air/lvacuum valves are typically float actuated hydromechanical devices used to automatically vent large volume of
air or gas or allow air/gas into the pipe during filling and draining operations of a piping system.
Vacuum breakers are similar to air/vacuum valves except their function is to only allow air inflow.
50
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
63/72
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix E - Specialty Piping Components and Applications — 2022
Combination air valves are used to perform the same function as the air/vacuum valves and also perform the air
release function of smaller volume of air or gas.
All of the above valves have specific design characteristics for either solids-free liquid or solids bearing liquid
systems.
For vertical wet pit pumps on clean water or solids bearing liquid service, it is usually appropriate to use an air/
'vacuum valve or a combination air valve. Install this type of valve at the high point of the pump discharge nozzle
and between the pump discharge and the discharge check valve. It is important to size and adjust the air release
valve to evacuate most of the air on start-up. A small volume of air is desirable to cushion the liquid
as it slams
against the check valve on pump start-up. A vacuum valve is used to release the vacuum accumulated during
pump shutdown, when the liquid in the column pipe returns by gravity to the wet well. If the vacuum in the column is
not released to atmospheric pressure when the pump is shut-down, it may result in a damaging water slam against
the check valve.
On initial filling of piping systems or after a shut-down that results in draining of the system, caution is required to
prevent possible damage to air release valves. During filling of the piping with liquid there can be a sudden change
in momentum forces on the air release valves when the fluid flowing in the pipe changes from all low-density gas to
the higher density liquid. When this interface passes a high point with an air release valve, the valve can undergo the
same sudden change in momentum. The resulting forces may exceed the strength of the air release valve housing.
For horizontal pumps that are not self-venting (trap air at the top of the volute), install a valve located at the highest
point on the volute case.
Additionally, air valves may be installed on piping high points, changes in grade, and at periodic intervals on long
horizontal runs that lack a defined high point.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
51
64172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix F - Pressure Pulsation and Acoustic Resonance — 2022
Appendix F (Informative)
Pressure pulsation and acoustic resonance
Refer to Appendices Introduction located immediately preceding Appendix A.
F.1
General
In addition to producing steady pressure to move liquid, all pumps generate pressure pulses or fluctuations. In the
majority of cases with rotodynamic pumps, these pulsations are inconsequential because they are very small in
magnitude.
In certain installations, pressure pulsations of significant magnitude can be amplified 5 to 20 times by acoustical
resonance in the piping system. These amplified pulses can in turn cause pump vibration and fatigue failure of
internal pump components and piping supports. For these pumping applications, the pump system designer should
ensure that sufficient separation margin exists between the dominant pump-pressure pulsation frequency and the
suction or discharge piping arrangement corresponding acoustic resonant frequencies. The piping arrangement
should be altered to eliminate sympathetic conditions.
The purpose of this section is to inform pump system designers of this phenomenon and to provide basic calcula-
tion methods.
F.2
Piping acoustics
suction and discharge piping systems have acoustical resonance just as pipe organs have acoustical resonance.
If the pipe length, or the distance from the pump to a reflection point, results in multiple half-wave or quarter-wave
resonance equivalent to the vane passing frequency, the potential exists for the pressure pulsations to be reflected
back to the pump and thereby amplified. A quarter-wave can exist if the outlet piping discharges to an open well
(considered open end condition). Piping resonance may be calculated using basic wave theory, and reflection
points can be listed based on actual field experience.
The half-wave and quarter-wave resonance frequency of a pipe may be calculated as follows:
itz
Frequency, f, k-2 —-——- For half wave (both ends open or both ends closed)
Frequency, I1
7
k
%———-
For quarter wave (one end closed)
= harmonic multiples (1,2,3...n)
acoustical velocity of sound in the discharge pipe, in m/s (ft/s)
L
distance from the pump's last volute vane (cutwater) to any reflection point in the piping, in m (ft)
NOTE: Typically, only the first and second harmonic multiples need be considered, however, it is possible for resonance to occur at higher harmonics.
52
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
65/72
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix F - Pressure Pulsation
and Acoustic Resonance
— 2022
The acoustical velocity of sound within the pipe (also known as the wave speed) may be calculated as follows:
Veocily, 2 = C (u)" 1
P
T
ey
(1+2~R~E]
e-E,
Where:
= acoustical velocity of sound, in m/s (ft/s)
C,is = units correction factor, 1 if metric units are used and 12 in/ft is US customary
units are used
g
= Acceleration
due to gravity, 9.81 m/s? (32.2 ft/s?)
E
= fluid bulk modulus
of the liquid (see below)
y
= fluid specific weight, 9.8 kN/m?
at 4 °C (62.4 Ibffft*
at 39 °F) for water
R
= inner radius of the pipe, in mm (in)
e
= thickness of the pipe wall, in mm (in)
E,
= elastic modulus
of the wall material (see below)
The bulk/elastic modulus (E1) for typical materials is
Carbon steel = 21 x 107 kPa (30 x 10* psi)
Cast iron = 10 x 107 kPa (15 x 10° psi)
Ductile Iron = 166 GPa (24.0 x 10 psi)
Prestressed concrete = 1.0 x 107 kPa (1.5 x 10* psi)
Polyethylene = 0.12 x 107 kPa (0.18 x 10* psi)
The bulk/elastic modulus (E) of a typical liquid is
Water at ordinary conditions = 0.20 x 107 kPa (0.30 x 10* psi)
Forrigid pipe and ambient temperature water, the acoustical velocity is 1440 m/s (4720ft/s);
with 100-mm (4-in) schedule
40 carbon steel pipe, the velocity is 1330 m/s (4365 ft/s); while for polyethylene plastic 100-mm (4-in) schedule
40 pipe, the value drops to 266 m/s (872 ft/s).
Reflection points are discontinuities in the discharge piping that can reflect the pressure wave back to the source.
Theoretically, if there is a change in the impedance, then a portion of the wave will be reflected.
Typical reflection
points include plate orifices, reducers, or increasers with 50% or more area change, tees at headers, and partially
closed valves. Long-radius elbows do not reflect acoustical waves, but transmit them similarly to straight pipe.
Short-radius elbows and vaned elbows, on the other hand, may reflect acoustical waves.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
53
66/72
4/19/23, 12:17 PM
FileOpen Web Viewer
Appendix G - Modifications or Improvements to Non-conforming Existing Systems — 2022
Appendix G (Informative)
Modifications or improvements to non-conforming
existing systems
Refer to Appendices Introduction located immediately preceding Appendix A.
Existing Systems
This appendix provides guidance to pump piping system designers, owners, and operators for situations where
existing site conditions prevent compliance with the minimum length of pipe (L,) as required in this Standard.
G.1
Introduction
Many existing pump installations operate successfully for the end user despite not meeting the parameters established in the this standard. Generally, it is neither practical nor advised to make wholesale changes to an existing
pump installation solely to achieve compliance with this standard.
It is common for owners and designers to be confronted with a situation in an existing installation where intuition
suggests that a pump replacement should be a straight-forward process, but the desire for compliance with the
Hydraulic Institute Standards results in a significant impact on project costs and schedule. The information presented in this Appendix provides guidance for navigating replacement of equipment in existing systems where the
equipment is operating satisfactorily, but does not comply with this Standard. Physical inspection of pump internal
ccomponents and review of pump repair & maintenance records is recommended to confirm no apparent damage
as a result of adverse intake hydraulics. Any findings will help the designer modify, upgrade, or replace the suction
piping as necessary to provide efficient, economical, and reliable long term operation of the pump system.
Existing systems with suspected suction related problems should be brought into compliance with the this standard
and ANSI/HI 9.8
G2 In-kind replacement
Upgrades, modifications and rehabilitation of existing pump stations can be categorized as in-kind pump replacement or modified capacity replacement as defined herein:
G.2.1
In-kind pump replacement: These projects typically include replacement of pumping equipment for maintenance purposes without the intent of changing the hydraulic operating characteristics, approach flow, intake or
suction piping configuration. An in-kind pump is defined as a machine matching the pump type, suction nozzle
diameter, rotating speed, head and flow as required to match the original performance of the unit being replaced.
In-kind pump replacements are expected to provide the same performance curves (i.e. head-flow, efficiency,
NPSH3, and power), reliability, and equipment longevity as the pump being replaced.
If the historical performance of the pump being replaced is unacceptable to the user, making improvements to the
piping approaching the pump should be carefully evaluated to determine if adverse intake hydraulic conditions are
the source of the deficiency. With acceptable historical performance, an in-kind replacement is often a reasonable
approach, even in situations where the piping does not comply with this standard. The designer
should be cautioned, however, that subtle differences in pump hydraulic or mechanical characteristics could result in an undesirable response to suction hydraulics not compliant with this standard.
54
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
67172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix G - Modifications or Improvements to Non-conforming Existing Systems — 2022
G.2.2 Modified capacity replacement: These projects are usually a result of required changes in flow or total
head that alter the hydraulic operating conditions such that the existing hydraulic performance characteristics
are no longer suited for the application. In this circumstance, historical performance may not be an indication of
anticipated future performance after the replacement pumps have been installed. Therefore, for modified capacity
pump replacement projects, it is recommended that necessary modifications be implemented to improve the flow
approaching the pump to achieve compliance with the Hydraulic Institute standards.
Where it is not practical to meet the requirements of this Standard, recommendations to improve the pump
approach flow are provided in Appendix E. While it is recognized that the modifications will not bring the installation
into compliance with this standard, these modifications may improve suction hydraulics in an effort to achieve the
greatest extent of compliance possible given the constraints imposed by existing conditions.
G.3
Assessment of non-compliant piping
A standard approach to achieving the desired pump suction hydraulics is to provide a sufficient length of straight
pipe downstream from a flow disturbing fitting. For determination of required straight pipe lengths, the designer
should refer to Table 9.6.6.3.4 of this standard.
In situations where there is not a practical or economical way to meet the Standard(s), there are multiple methods
that may be used to assess pump suction hydraulics and validate improvements.
G.3.4 Pump sensitivity
Certain pump types are less sensitive to adverse hydraulic conditions resulting from suction piping configurations
not compliant with the standard. Many pumpsof low to mid specific speed design [n,<40 (Ns < 2000)] and suction
specific speed [S<180 (Nss<9500)] may operate successfully with piping configurations that are out of compliance
with the standard with limited adverse effects on pump performance and reliability. This is especially true for equipment that exhibits very low NPSH3 characteristics relative to NPSHA. Please note that piping non-compliance can
have more severe effects on pumps operating outside the Preferred Operating Region (POR) and often can result
in elevated hydraulic noise levels. Consult with the pump manufacturer
when considering the sensitivity of a pump
in a certain application.
Another item for consideration when evaluating the sensitivity to pump suction piping configurations are the consequences of reduced hydraulic performance or pump failure.
G.3.2 Physical hydraulic model study
A physical model study can be used to evaluate hydraulic conditions in pump piping systems and to develop mitigation measures. Details of the physical hydraulic modeling process are presented in ANSI/HI 9.8. If such a model
study shows compliance with the ANSI/HI 9.8 acceptance criteria, then the system is deemed to be compliant with
the Standard.
G.3.3
Computational Fluid Dynamics (CFD)
Computational Fluid Dynamics (CFD) is a useful tool for evaluating hydraulic conditions in pump piping systems
and to develop mitigation measures. As noted in Section 9.6.6.3.6 in this standard, CFD currently is not a tool used
for demonstrating compliance with this Standard. If used to evaluate an existing piping configuration, it should be
noted that the precise flow metrics and acceptance criteria have not been established for pump intake analysis as
of this edition.
G.4
Mitigation of Non-Compliant Piping
Correction of adverse pump intake hydraulics can be accomplished through implementation of piping modifications. Appendix E - Specialty Piping Components and Applications presents some correction measures that are
‘commonly
used in pump suction piping.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
55
68/72
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix H - References — 2022
Appendix H
References
Hydraulic Institute. ANSI/HI 9.8 Rotodynamic Pumps for Pump Intake Design.
Committee European for Normalization (CEN). Rotodynamic Pumps — Design of Pumps Intakes — Recommendations for Installation of Pumps (CR 13930).
Committee European
for Normalization (CEN). Rotodynamic Pumps
Outlet
on Piping (CR 13932).
— Recommendations
for Fitting of Inlet and
Process Industry Practices. Recommended Practices for Machinery
(API Recommended Practice 686/PIP REIE 686).
Installation and
Installation Design
Process Industry Practices. Typical Piping Arrangements for Centrifugal Pumps (PIP REEP004).
Hydraulic Institute. ANSI/HI 9.6.2 Rotodynamic Pumps for Assessment of Applied Nozzle Loads.
Commitiee European for Normalization. Rotodynamic Pumps — Forces and Moments on Flanges (CR 13931).
International Organization for Standardization. SO 9905, Technical Specification for Centrifugal Pumps, Class I.
International Organization for Standardization. ISO 5199, Technical Specifications for Centrifugal Pumps, Class .
. American Petroleum Institute. API-610 — Centrifugal Pumps for Petroleum, Heavy Duty Chemical, and Gas
Industry Services.
. Process Industry Practices (PIP). Allowable Piping Loads on Rotating Machinery Nozzles (PIP RESE002).
. Hydraulic Institute. Engineering Data Book.
. Hydraulic Institute. Engineering Data Library, edl.pumps.org.
. Mark's Standard Handbook for Mechanical Engineers, 8th ed., New York: McGraw Hill.
. American Societyof Mechanical Engineers (ASME). Code for Pressure Piping B31. New York: ASME.
. Europump and Hydraulic Institute. Pump Life Cycle Cost: A Guide to LCC Analysis for Pumping Systems,
Second Edition
. Hydraulic Institute. ANSI/HI 12.1-12.6 Rotodynamic Centrifugal Slurry Pumps for Nomenclature, Definitions,
. Hydraulic Institute. ANSI/HI 14.1-14.2 Rotodynamic Pumps for Nomenclature and Definitions.
. Hydraulic Institute. ANSI/HI 14.3 Rotodynamic Pumps for Design and Application.
Hydraulic Institute. ANSI/HI 14.4 Rotodynamic Pumps for Installation, Operaion, and Maintenance.
. Hydraulic Institute. ANSI/HI 14.6 Rotodynamic Pumps for Hydraulic Performance Acceptance Tests
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions.pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
69/72
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix
H - References
— 2022
22. Hydraulic Institute. ANSI/HI 9.6.1 Rotodynamic Pumps - Guideline for NPSH Margin.
23. Hydraulic Institute. ANSI/HI 9.6.3 Rotodynamic Pumps - Guideline for Allowable Operating Region.
24. Hydraulic Institute. ANSUHI 9.6.7 Rotodynamic Pumps - Guideline for Effects of Liquid Viscosityon Performance
25. Hydraulic Institute. ANSI/HI 9.6.8 Rotodynamic Pumps - Guideline for Dynamics of Pumping Machinery.
26. Mechanical Contractors Association. Guidelines for Quality Piping Installation.
27. American Water Works Association (AWWA) M11. Steel Water Pipe: A Guide for Design and Installation.
28. Jones, et al. Pumping Station Design, 3rd ed. Elsevier Butterworth-Heinemann, 2006.
29. Ballon,A Methodology
for Predicting Check Valve Slam.
30. Solé, Segara,
and Walters, Surge Transients Due to Check Valve Closure in a Municipal Water Pumping Station
Proceedings.
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
57
7072
4/19/23, 12:17 PM
FileOpen Web Viewer
Appendix | - Sources of Additional Information — 2022
Appendix |
Sources of additional information
Pullman Power Products. Design of Piping Systems. New York: John Wiley & Sons, 1956. p. 210-254.
James R. Payne and Vincent A. Carucci. Guidelines for the Design and Installation of Pump Piping Systems. PVRC
Project, January 1993.
National Valve and Manufacturing Company. NAVCO Piping Datalog. Pittsburgh: NAVCO, 1974. p.130-135.
Michael Bussler and Tony Paulin. Pipe Design for Robust Systems, Chemical Engineering. June 1997. p. 84.
Crocker and King. Piping Handbook. New York: McGraw Hill, 1973.
Gardner S. Williams and Allen Hazen. Hydraulic Tables.
58
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
7172
4/19/23,12:17 PM
FileOpen Web Viewer
Appendix J - List of Acronyms
— 2022
Appendix J
List of acronyms
ANSI - American National Standards Institute, www.ANSI.org
API - American Petroleum Institute, www.APl.org
ASME - American Society of Mechanical Engineers, www.ASME
.org
AWWA - American Water Works Association, www.AWWA.org
CEN - Committee European of Normalization (the European Committee for Standardization), www.CEN.eu
CFD - Computational fluid dynamics
HI - Hydraulic Institute, www.Pumps.org
ISO - The International Organization for Standardization, www.ISO.org
NPSH - Net positive suction head (in absolute head terms, above vapor pressure)
NPSHA - Net positive suction head available (available to pump)
PIP - Process Industry Practices, www.PIPorg
c127
Hydraulic Institute Standards, Copyright © 1997-2022, All Rights Reserved
https://subscriptions. pumps.org/index htmi?PDF=9-6-6¢.pdf&CUSTNAME=
59
7272