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Pipeline Design for Water Engineers – AMAC

Pipeline DESl6N fOR Water EN6 IMEERS THIRD REVISED AND UPDATED EDITION DEVELOPMENTS IN Water SCIENCE, 40 OTHER TITLES IN THIS SERIES VOLUMES 7-3 ARE OUT OIF PRINT 4 FRIED 5 N. RAJARATNAM 6 D. STEPHENSON GROUNDWATER POLLUTION TURBULENT JETS Pipeline Design FOR Water Engineers GROUNDWATER HYDRAULICS HYDROLOGY AND Water RESOURCES IN TROPICAL AFRICA RESERVOIR CAPACITY AND YIELD 10 G. KOVACS SEEPAGE HYDRAULICS HYDRODYNAMICS OF LAKES: PROCEEDINGS OF A SYMPOSIUM 12-13 OCTOBER 1978. LAUSANNE, SWITZERLAND 12 W. BACK AND STEPHENSON (EDITORS) CONTEMPORARY HYDROGEOLOGY: THE GEORGE BURKE MAXEY MEMORIAL VOLUME 13 MARlfJO AND LUTHIN SEEPAGE AND GROUNDWATER 14 D.

PREFACE TO SECOND EDITION The gratifying response to the first edition of this book resulted in small amendments to the second impression, and some major alter-

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Transcription of Pipeline Design for Water Engineers – AMAC

1 Pipeline DESl6N fOR Water EN6 IMEERS THIRD REVISED AND UPDATED EDITION DEVELOPMENTS IN Water SCIENCE, 40 OTHER TITLES IN THIS SERIES VOLUMES 7-3 ARE OUT OIF PRINT 4 FRIED 5 N. RAJARATNAM 6 D. STEPHENSON GROUNDWATER POLLUTION TURBULENT JETS Pipeline Design FOR Water Engineers GROUNDWATER HYDRAULICS HYDROLOGY AND Water RESOURCES IN TROPICAL AFRICA RESERVOIR CAPACITY AND YIELD 10 G. KOVACS SEEPAGE HYDRAULICS HYDRODYNAMICS OF LAKES: PROCEEDINGS OF A SYMPOSIUM 12-13 OCTOBER 1978. LAUSANNE, SWITZERLAND 12 W. BACK AND STEPHENSON (EDITORS) CONTEMPORARY HYDROGEOLOGY: THE GEORGE BURKE MAXEY MEMORIAL VOLUME 13 MARlfJO AND LUTHIN SEEPAGE AND GROUNDWATER 14 D.

2 STEPHENSON STORMWATER HYDROLOGY AND DRAINAGE 15 D. STEPHENSON Pipeline Design FOR Water Engineers (completely revised edition of Vol. 6 in the series) 16 W. BACK AND R. LETOLLE (EDITORS) SYMPOSlClM ON GEOCHEMISTRY OF GROUNDWATER 17 EL-SHAARAWI (EDITOR) IN COLLABORATION WITH ESTERBY TIME SERIES METHODS IN HYDROSCIENCES 18 HYDROLOGY AND Water RESOURCES IN TROPICAL REGIONS 19 D. STEPHENSON PIPEFLOW ANALYSIS 20 I. ZAVOIANU MORPHOMETRY OF DRAINAGE BASINS 21 SHAHIN HYDROLOGY OF THE NILE BASIN 22 STREAMFLOW CHARACTERISTICS 23 M. NEGULESCU MUNICIPAL WASTEWATER TREATMENT 24 GROUNDWATER MONITORING HANDBOOK FOR COAL AND OIL SHALE DEVELOPMENT 25 W.

3 KINZELBACH GROUNDWATER MODELLING: AN INTRODUCTION WITH SAMPLE PROGRAMS IN BASIC 26 D. STEPHENSON AND MEADOWS KINEMATIC HYDROLOGY AND MODELLING 27 EL-SHAARAWI AND KWIATKOWSKI (EDITORS) STATISTICAL ASPECTS OF Water CIUALITY MONITORING – PROCEEDINGS OF THE WORKSHOP HELD AT THE CANADIAN CENTRE FOR INLAND WATERS, OCTOBER 1985 28 Water RESOURCES AND Water MANAGEMENT 29 ANNANDALE RESERVOIR SEDIMENTATION 30 MICROCOMPUTER PROGRAMS IN GROUNDWATER 31 FRENCH HYDRAULIC PROCESSES IN ALLUVIAL FANS 32 L. VOTRUBA, 2. KOS. K. NACHAZEL, A. PATERA ANDV. ZEMAN ANALYSIS OF Water RESOURC_E SYSTEMS 33 L. VOTRUBA AND V. BROZA Water MANAGEMENT IN RESERVOIRS 34 D.

4 STEPHENSON Water AND WASTEWATER SYSTEMS ANALYSIS 35 CELlA ET AL. COMPUTATIONAL METHODS IN Water RESOURCES, VOLUME 1 MODELING SURFACE AND SUB-SUR- FACE FLOWS. PROCEEDINGS OF THE VII INTERNATIONAL CONFERENCE, MIT. USA, JUNE 1988 36 CELIA ET AL. COMPUTATIONAL METHODS IN Water RESOURCES, VOLUME 2 NUMERICAL METHODS FOR TRANS- PORT AND HYDROLOGICAL PROCESSES. PROCEEDINGS OF THE V11 INTERNATIONAL CONFERENCE, MIT, USA, JUNE 1988 37 GROUNDWATER DISCHARGE TESTS: SIMULATION AND ANALYSIS 7 v. HANK AND J. SVEC 8 J. BALEK 9 McMAHON AND MElN 1 i GRAF AND MORTIMER (EDITORS) THIRD REVISED AND UPDATED EDITION DAVID STEPHENSON Department of Civil Engineering University of the Witwatersrand Johannesburg, South Africa ELSEVl ER Amsterdam – Oxford – New York – Tokyo 1989 ELSEYIER SCIENCE PUBLISHERS Sara Burgerhartstraat 25 Box 2 1 1, 1000 A Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC.

5 655, Avenue of the Americas New York, NY 10017, ISBN 0-444-87373-2 0 Elsevier Science Publishers , 1989 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science Publish- ers Physical Sciences & Engineering Division, Box 330, 1000 AH Amsterdam, The Netherlands. Special regulations for readers in the – This publication has been registered with the Copyright Clearance Center Inc. (CCC), Salem, Massachusetts.

6 Information can be obtained from the CCC about conditions under which photocopies of parts of this publication may be made in the USA. All other copyright questions, including photocopying outside of the USA, should be referred to the publisher. No responsibility is assumed by the Publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or opera- tion of any methods, products, instructions or ideas contained in the material herein. Printed in The Netherlands V PREFACE TO FIRST EDITION Pipelines are being constructed in ever-increasing diameters, lengths and working pressures.

7 Accurate and rational Design bases are essential to achieve economic and safe designs. Engineers have for years resorted to semi-empirical Design formulae. Much work has recently been done in an effort to rationalize the Design of pipelines. This book col lates pub1 ished material on rational Design methods as well as presenting some new techniques and data. Although retaining conventional approaches in many instances, the aim of the oook is to bring the most modern Design techniques to the civil or hydraulic engineer. It is suitable as an introduction to the subject but also contains data on the most advanced techniques in the field.

8 I3ecause of the sound theoretical background the book will al so be useful to under-graduate and post-graduate students. Many of the subjects, such as mathematical optimization, are still in their infancy and the book may provide leads for further research. The methods of solution proposed for many problems bear in mind the modern acceptance of computers and calculators and many of the graphs in the book were prepared with the assistance of computers. The first half of this book is concerned with hydraulics and planning of pipelines. In the second half, structural Design and ancillary features are discussed. The book does not deal in detail with manufacture, laying and operation, nor should it replace Design codes of practice from the engineer’s desk.

9 Emphasis is on the Design of large Pipelines as opposed to industrial and domestic piping which are covered in other pub1 ications. Although directed at the Water engineer, this book will be of use to Engineers involved in the piping of many other fluids as well as solids and gases. It should be noted that some of the designs and techniques described may be covered by patents. These include types of pre- stressed concrete pipes, methods of stiffening pipes and branches and various coatings. VI The system of metric units is preferred in the book although imperial units are given in brackets in many instances.

10 Most graphs and equations are represented in uni versa1 dimensionless form. Worked examples are given for many problems and the reader is advised to work through these as they often elaborate on ideas not highlighted in the text. The algebraic symbols used in each chapter are summarized at the end of that chapter together with specific and general references arranged in the order of the subject matter in the chapter. The appendix gives further references and standards and other useful data. PREFACE TO SECOND EDITION The gratifying response to the first edition of this book resulted in small amendments to the second impression, and some major alter- ations in this new edition.

PREFACE TO SECOND EDITION The gratifying response to the first edition of this book resulted in small amendments to the second impression, and some major alter-

Water

Water use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions.

System layout and pipework

The water supply system must be designed to achieve appropriate water pressure and flow, and to avoid contamination to potable water.

  • Water pressure
  • Water flow rate
  • Flow rate and pipe size Acceptable Solutions
  • System layout
  • Connection to the mains supply
  • Backflow
  • Mains connection
  • Pipe materials and specifications

As well as avoiding contamination and achieving the right pressure and flow, the system must be suitable for the temperature of water carried. A well-designed and installed system will also be durable, minimise noise from water flow and from problems such as water hammer, and support efficient use of water.

All water supply systems use a combination of pipes (of different dimensions and materials), valves and outlets to deliver water to building users. Some water supply systems also use storage tanks and pumps. Designing a water supply system involves getting all of these elements right so that clean water is delivered to the user at the appropriate rate and temperature.

Water pressure

If the aim is to provide for building users’ needs while also using water efficiently, the right water pressure is crucial. If water pressure is too low, this will be inconvenient for building users – for example, because showers have poor water flow, and baths take a long time to fill. If pressure is too high, this will lead to wastage of water, as well as high wear and tear on the system.

Typically, new buildings in areas with mains water supply will have mains pressure systems. Existing buildings, and buildings that are not connected to mains water, may have low pressure systems or unequal pressure systems (with different pressures for hot and cold water supply).

As an example of the difference in water usage, a low pressure hot water system shower flow may average about 7 litres per minute, while a mains pressure shower may average around 12–20 litres per minute.

Mains pressure systems require pressure limiting and pressure reducing valves to control water pressure and temperature. Typically, pressure limiting or pressure reducing valves will be used to control pressure in mains-supplied hot water systems or where high pressure may lead to problems such as burst pipes.

Low pressure systems require few valves or controls. In low or unequal pressure systems, pressure can be increased to adequate levels by storing water in a header tank (typically in the ceiling space) so that gravity can be used to create water pressure. If a tank is being used, see the BRANZ publications Water and Plumbing for details of installation requirements.

Pressure can also be raised to adequate levels using a pressurising pump, in which case it may be necessary to use pressure limiting and pressure reducing valves.

Water flow rate

The Building Code requires that sanitary fixtures and appliances have adequate water supply at an adequate flow rate.

As with water pressure, flow rates are crucial. A flow rate that is too high will result in water being wasted, whereas a flow rate that is too low will mean that sanitary fixtures and appliances don’t work properly.

Flow rate is affected by:

  • Water pressure
  • Pipe diameters – The smaller the internal diameter of the pipe, the lower the pressure and flow rate. (Note that pipes are generally referred to by their inside nominal diameter (DN), but it is actually the internal diameter that counts; a pipe rated as DN 15 may have an actual inside diameter ranging between 10–18 mm.)
  • Water temperature – higher temperatures will tend to raise pressure and flow rates (note: also see materials below).

A flow regulator can be used to maintain a constant flow, independent of water pressure. As an example, if someone is in the shower and the kitchen tap is turned on full, the temperature and flow are likely to remain more stable if a flow regulator is used.

Limiting the flow for a tap or appliance to a reasonable rate helps balance the available pressure throughout the system. Regulating flow allows a simpler design and minimum pipe sizes as peak flow rates can be specified accurately and can also reduce noise, splashing taps, and water hammer.

Manufacturers’ recommendations must be referred to for pressure and flow information when selecting tempering valves and outlets (taps, mixers and shower heads).

Flow rate can also be controlled by specifying low-flow outlets.

Flow rate and pipe size Acceptable Solutions

Building Code Acceptable Solution G12/AS1 sets out flow rates and pipe sizes. Pipes must be sized to achieve flow rates set out in accordance with Table 3 (see table below), or the pipes must be sized in accordance with Table 4.

When calculating pipe size, the speed of the water (velocity) moving through the pipes must not exceed 3.0 m/s.

Acceptable flow rates for fixtures and appliances

Flow rate (l/s) and temperature °C

Water Water use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions. System layout and pipework The water supply