1、I I i i l i l i I The Authoritative Resource for Safe Drinking Water SM Advocacy Communications Conferences Education and Trainin Sections Gcience and Technolmw,y PVC Pipe-Design and Installation AWWA MANUAL M23 Second Edition American Water Works Association Science and Technology AWWA unites the d
2、rinking water community by developing and distributing authoritative scientific and technological knowledge. Through its members, AWWA develops industry standards for products and processes that advance public health and safety. AWWA also provides quality improvement programs for water and wastewate
3、r utilities. MANUAL OF WATER SUPPLY PRACTICES-M23, Second Edition PVC Pipe-Design and Installation Copyright O 2002 American Water Works Association All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including phot
4、ocopy, recording, or any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publisher. Library of Congress Cataloging-in-Publication Data has been applied for. Printed in the United States of America American
5、 Water Works Association 6666 West Quincy Avenue Denver, CO 80235 ISBN 1-58321-171-3 Printed on recycled paper Contents List of Figures, v List of Tables, vii Foreword, ix Acknowledgments, xi Chapter 1 General Properties of Polyvinyl Chloride Pipe. . . . . . . 1 Background, 1 Material Properties of
6、PVC Pipe Compounds, 1 Corrosion, Permeation, and Chemical Resistance, 2 Environmental Effects, 5 Chapter 2 Testing and Inspection . . . . . . . . . . . . . . . . 9 Testing and Inspection, 9 Chapter 3 Hydraulics . . . . . . . . . . . . . . . . . . . . 13 Flow Formulas, 13 Chapter 4 Design Factors Rel
7、ated to External Forces and Conditions . . . . . . . . . . . . . . . . . . . . . 21 Superimposed Loads, 21 Flexible Pipe Theory, 24 Longitudinal Bending, 33 Expansion and Contraction, 40 Thrust Restraint-General, 42 Chapter 5 Pressure Capacity . . . . . . . . . . . . . . . . . 53 Internal Hydrostati
8、c Pressure, 53 Distribution Mains, 58 Transmission Mains, 59 Injection-Molded PVC Fittings, 62 Fabricated PVC Fittings, 63 Dynamic Surge Pressure, 63 Transmission Pipe Design Example, 67 Chapter 6 Receiving, Storage, and Handling . . . . . . . . . . . 73 Receiving, 73 Storage, 75 Chapter 7 Installat
9、ion. . . . . . . . . Scope, 77 Alignment and Grade, 77 Installation in Trenches, 77 Pipe Joints, 82 Pipe Cutting and Bending, 83 Pipe Embedment, 84 Casings, 86 . 77 . 111 Appurtenances, 88 Thrust Restraint, 91 Chapter 8 Testing and Maintenance . . . . . . . . . . . . . . 93 Initial Testing, 93 Timin
10、g of the Testing, 93 Initial Cleaning of the Pipeline, 94 Test Preparation, 94 Hydrostatic Testing and Leakage Testing, 94 Test Pressure, 95 Duration of Tests, 95 Allowable Leakage, 96 Disinfecting Water Mains, 96 System Maintenance, 96 Chapter 9 Service Connections . . . . . . . . . . . . . Direct
11、Tapping, 99 Saddle Tapping, 105 Tapping Sleeve and Valve, 107 Appendix A, Chemical Resistance Tables, 109 Appendix B, Flow Friction Loss Tables, 129 Bibliography, 157 Index, 163 List of AWWA Manuals, 167 . 99 iv Figures 1-1 1-2 3-1 3-2 3-3 3-4 4- 1 4-2 4-3 4-4 4-5 4-6 4-7 4-8 4-9 5-1 5-2 5-3 5-4 6-1
12、 7-1 7-2 7-3 7-4 7-5 7-6 Class 12454 requirements, 4 Approximate relationship for 12454 PVC for PVC pipe strength properties versus temperature, 6 Moody diagram-friction factor, 15 Moody diagram-relative roughness, 16 Friction loss characteristics of water flow through PVC pipe, 18 Resistance of val
13、ves and fitting to flow of fluids, 19 Distribution of HS-20 live load through fill, 23 Bedding angle, 28 Plasticity chart, 32 PVC pipe longitudinal bending, 36 PVC pipe joint offset, 37 Length variation of unrestrained PVC pipe as a result of temperature change, 41 Free-body diagram of forces on a p
14、ipe bend, 44 Resultant frictional and passive pressure forces on a pipe bend, 48 Suggested trench conditions for restrained joints on PVC pipelines, 50 Stress regression curve for PVC pressure pipe, 55 Stress regression line, 56 Strength and life lines of PVC 12454, 57 Pipeline profile, 67 Chock blo
15、ck, 75 Trench cross section showing terminology, 78 Examples of subditches, 79 Recommendations for installation and use of soils and aggregates for foundation, embedment, and backfill, 85 PVC pipe casing skids, 86 Casing spacer, 87 Fire hydrant foundation, 90 V 7-7 7-8 9- 1 9-2 9-3 9-4 9-5 9-6 9-7 9
16、-8 Types of thrust blocking, 91 Types of joint restraint, 92 Direct PVC pipe tap, 100 Tapping machine nomenclature, 100 Cuttinghapping tool, 101 Mounting the tapping machine, 103 Cutter feed, 103 Condition of coupon, 104 Tapping saddle, 106 PVC tapping saddle, 107 vi 1-1 4- 1 4-2 4-3 4-4 4-5 4-6 4-7
17、 4-8 4-9 4- 10 4-11 4-12 4-13 5-1 5-2 5-3 5-4 5-5 5-6 7- 1 7-2 8- 1 9-1 A- 1 A-2 Cell class requirements for rigid poly (vinyl chloride) compounds, 3 HS-20 and Coopers E-80 live loads, 24 PVC pipe stiffness, 26 Bedding constant values, 28 Values for the soil support combining factor, Sc, 29 Values f
18、or the modulus of soil reaction E b for the pipe-zone embedment, psi (MPa), 30 Soil classification chart (ASTM D24871, 31 Values for the modulus of soil reaction, E In, for the native soil at pipe-zone elevation, 32 Longitudinal bending stress and strain in PVC pipe at 73.4“F (23“C), 38 Coefficients
19、 of thermal expansion, 40 Length variation per 10F (5.60 AT for PVC pipe, 40 Estimated bearing strength (undisturbed soil), 45 Properties of soils used for bedding to calculate F, and R, 50 In situ values of soil properties for R, 52 Thermal de-rating factors for PVC pressure pipes and fittings, 54
20、Pressure classes of PVC pipe (C900), 59 Pressure ratings of PVC pipe (C905), 60 Short-term strengths of PVC pipe, 61 Short-term ratings of PVC pipe, 61 PVC pressure surge versus DR for 1 ftsec (0.3 ? AWWA C905, Polyvinyl Chloride (PVC) Pressure Pipe and Fabri- cated Fittings, 14 In. Through 48 In. (
21、350 mm Through 1,200 mm), for Water Trans- mission and Distribution;? and AWWA C909, Molecularly Oriented Polyvinyl Chloride (PVCO) Pressure Pipe, 4 In. Through 12 In. (100 mm Through 300 mm), for Water Dis- tribution. The material classification can be found on the pipe as part of its identifica- t
22、ion marking. Many of the important properties of PVC pipe are predetermined by the charac- teristics of the PVC compound from which the pipe is extruded. PVC pressure pipe manufactured in accordance with AWWA C900, C905, or C909 must be extruded from PVC compound with cell classification 12454-B or
23、better. Those compounds must also qualify for a hydrostatic design basis of 4,000 psi (27.58 MPa) for water at 73.4“F (23C) per the requirements of PPI? TR-3. The manner in which selected materials are identified by this classification sys- tem is illustrated by a Class 12454 rigid PVC compound havi
24、ng the requirements shown in Table 1-1 and Figure 1-1. CORROSION, PERMEATION, AND CHEMICAL RESISTANCE PVC and PVCO pipes are resistant to almost all types of corrosion-both chemical and electrochemical-that are experienced in underground piping systems. Because PVC is a nonconductor, galvanic and el
25、ectrochemical effects are nonexistent in PVC piping systems. PVC pipe cannot be damaged by aggressive waters or corrosive soils. Conse- quently, no lining, coating, cathodic protection, or plastic encasement is required when PVC and PVCO pipes are used. *NSF International, 789 N. Dixboro Rd., Ann Ar
26、bor, MI 48105. ?Plastics Pipe Institute, 1275 K St. N.W., Suite 400, Washington, D.C. 20005. GENERAL PROPERTIES OF POLYVINYL CHLORIDE PIPE 3 XI c1 in e m m rl O U 13 3 9 3 e o f; a m P a .3 U 13 i 4 PVC PIPE-DESIGN AND INSTALLATION Class 1 24 5 Propefly and Minimum Value: Impact strength (Izod) (34.
27、7 Jlrn 0.65 fi-lbhn.) Tensile strength (48.3 MPa 7,000 psi) Modulus of elasticity in tension (2,758 MPa 400,000 psi) Deflection ternoerature under load 170C i1 58“Fl o 4 Source: ASTM D1784, American Society for Testing and Materials, 100 Barr Harbor Dr., West Conshohocken, PA 19428-2959. Note: The c
28、ell-type format provides the means for identification and close characterization and specification of material proper- ties, alone or in combination, for a broad range of materials. This type format, however, is subject to possible misapplication since unobtainable property combinations can be selec
29、ted if the user is not familiar with commercially available materials. The manufacturer should be consulted. Figure 1-1 Class 12454 requirements Permeation The selection of materials is critical for water service and distribution piping in loca- tions where the pipe may be exposed to significant con
30、centrations of pollutants com- prised of low molecular weight petroleum products or organic solvents or their vapors. Research has documented that pipe materials, such as polyethylene, polybutylene, polyvinyl chloride, and asbestos cement, and elastomers, such as those used in jointing gaskets and p
31、acking glands, may be subject to permeation by lower molecular weight organic solvents or petroleum products. If a water pipe must pass through an area sub- ject to contamination, the manufacturer should be consulted regarding permeation of pipe walls, jointing materials, etc., before selecting mate
32、rials for use in that area. Chemical Resistance Pipe. Response of PVC pipe under normal conditions to commonly anticipated chemical exposures is shown in Table A-1 in Appendix A. Resistance of PVC pipe to reaction with or attack by the chemical substances listed has been determined by research and i
33、nvestigation. The information is primarily based on the immersion of unstressed strips into the chemicals and, to a lesser degree, on field experience. In most cases, the detailed test conditions, such as stress, exposure time, change in weight, change in volume, and change in strength, were not rep
34、orted. Because of the complexity of some organochemical reactions, additional long-term testing should be performed for critical applications. Data provided are intended only as a guide and should not necessarily be regarded as applicable to all exposure durations, concentra- tions, or working condi
35、tions. This chemical resistance data is similar for PVCO pipe. Gaskets. A check of the chemical resistance of the gasket should be completed independently of that for the pipe. Because gasket and pipe materials are different, so too are their abilities to resist chemical attack. Similarly, charts fo
36、r resistance of gas- ket materials to chemical attack are based on manufacturers testing and experience. The use of these charts is complicated by the fact that more than one elastomer may be present in a rubber compound. Chemical resistance information for commonly used gasket materials is provided
37、 in Table A-2 in Appendix A. GENERAL PROPERTIES OF POLYVINYL CHLORIDE PIPE 5 Table A-2 is a general guide to the suitability of various elastomers currently used in these chemicals and services. The ratings are primarily based on literature published by various polymer suppliers and rubber manufactu
38、rers, as well as the opinions of experienced compounders. Several factors must be considered in using a rubber or polymer part. The most important of these factors include the following: Temperature of service. Higher temperatures increase the effect of all chemi- cals on polymers. The increase vari
39、es with the polymer and the chemical. A compound quite suitable at room temperature may perform poorly at elevated temperatures. Conditions of service. A compound that swells considerably might still func- tion well as a static seal yet fail in any dynamic application. Grade of the polymer. Many typ
40、es of polymers are available in different grades that vary greatly in chemical resistance. Compound itself. Compounds designed for other outstanding properties may be poorer in performance in a chemical than one designed especially for fluid resistance. Availability. Consult the elastomer manufactur
41、ers for availability of a com- pound for use as a PVC pipe gasket material. If it is anticipated that gasket elastomers will be exposed to aggressive chemicals, it is advisable to test the elastomers. ENVIRONMENTAL EFFECTS The following paragraphs discuss the effects of environmental factors on PVC
42、pipe, including temperature, biological attack, weather, abrasion, and tuberculation. Thermal Effects The performance of PVC pipe is significantly related to its operating temperature. Because it is a thermoplastic material, PVC will display variations in its physical properties as temperature chang
43、es (Figure 1-2). PVC pipe can be installed properly over the ambient temperature range in which construction crews can work. PVC pipe is rated for performance properties at a temperature of 73.4“F (23C); however, it is recognized that operating temperatures of 33-90F (1-32C) do exist in water sys- t
44、ems. As the operating temperature decreases, the pipes stiffness and tensile strength increase, thereby increasing the pipes pressure capacity and its ability to resist earth- loading deflection. At the same time, PVC pipe loses impact strength and becomes less ductile as temperature decreases, nece
45、ssitating greater handling care in sub-zero weather. As the operating temperature increases, the impact strength and flexibility of PVC pipe increases. However, with the increase in temperature, PVC pipe loses ten- sile strength and stiffness; consequently, the pressure capacity of the pipe will be
46、reduced and more care will be needed during installation to avoid excessive deflection. Most municipal water systems operate at temperatures at or below 73.4“F (23C). In these applications, the actual pressure capacity of PVC pipe will be equal to or greater than the products rated pressure. Intermi
47、ttent water system temperatures above 73.4“F (23C) do not warrant derating of pipe or fitting pressure designations. New users and installers of PVC pipe should be aware of the pipes capacity to expand and contract in response to changes in temperature. The PVC coefficient of thermal expansion is ro
48、ughly five times the normal value for cast iron or steel. Provi- sions must be made in design and installation to accommodate expansion and contrac- tion if the pipeline is to provide service over a broad range of operating temperatures. In general, allowance must be made for 3/s in. of expansion or
49、 contraction for every 6 PVC PIPE-DESIGN AND INSTALLATION 140 120 1 O0 !+ e! 9 3 al 4- 80 io! 73.4 60 40 20 120 1 O0 80 60 40 % of 73.4“F Pipe Strength Property Figure 1-2 Approximate relationship for 12454 PVC for PVC pipe strength properties versus temperature 100 ft (30.5 m of pipe for each 10F 66C) change in temperature. Gasketed joints provide excellent allowance for thermal expansion and contraction of PVC pipelines. The coefficient of thermal expansion for PVCO is the same as for PVC. Resistance to Biological Attack PVC pipe is nearly totally resistant
