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Ductile-Iron Pipe

and Fittings

AWWA MANUAL M41

Third Edition

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Copyright 2009 American Water Works Association. All Rights Reserved.

Contents

List of Figures, vii

List of Tables, xi

Preface, xiii

Acknowledgments, xv

General Information and History Chapter 1 ...................................................... 1

1.1 History, 11.2 Applications and Appurtenances, 31.3 Ductile Iron Pipe Research Association (DIPRA), 5

Applicable Standards Chapter 2 ............................................................................ 7

2.1 Related Standards, 72.2 Other Reference Standards and Special Products, 10References, 10

Manufacturing and Testing Chapter 3 ............................................................... 13

3.1 Manufacturing, 133.2 Testing, 173.3 Fittings Testing, 19References, 20

DesignChapter 4 ....................................................................................................... 21

4.1 Background, 214.2 Major Design Criteria and Formulas, 224.3 Truck Loads on Pipe Buried at Shallow Depths, 384.4 Thickness Design for Ductile-Iron Pipe Under Railroads, 434.5 Thickness Design for Ductile-Iron Pipe on Supports, 454.6 Special Use Considerations, 57References, 58

Pipe Joints Chapter 5 ............................................................................................. 59

5.1 Introduction, 595.2 Joints, 595.3 Gaskets, 645.4 Joint Accessories, 645.5 Permeation, 65References, 66

iii

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Copyright 2009 American Water Works Association. All Rights Reserved.

Ductile- and Gray-Iron Fittings Chapter 6 ........................................................ 67

6.1 Introduction, 676.2 Fittings, 676.3 Special Service Requirements, 70References, 71

Valves and Hydrants Chapter 7 ............................................................................ 73

7.1 Introduction, 737.2 Types of Valves and Hydrants, 737.3 Installation, 767.4 Operation, 767.5 Good Practice, 77References, 77

Thrust Restraint Design for Ductile-Iron Pipe Chapter 8 ............................. 79

8.1 Introduction, 798.2 The Thrust Force, 818.3 Thrust Blocks, 828.4 Restrained Joints, 858.5 Restraint Design for Vertical Bends, Tees, Reducers, and Dead Ends, 938.6 Encroaching Restrained Lengths, 978.7 Restrained Length, 998.8 Select Backfill Considerations, 998.9 Combining Thrust Blocks and Restrained Joints, 1018.10 Pipe in a Casing, 1018.11 Future Excavations, 1018.12 Deflected Unrestrained Ductile-Iron Pipe Joints, 1018.13 Computer Program, 1028.14 Restrained Length Calculation Procedure, 1028.15 Tabular Values for Fs, (Fs)b, and Rs, 1038.16 Restrained Joint Design Tables for Horizontal Bends, 104References, 147

Interior Linings and Hydraulics Chapter 9 .................................................... 149

9.1 CementMortar-Lined Ductile-Iron Pipe, 1499.2 Flow Characteristics of Ductile-Iron Pipe, 1539.3 Pumping Cost, 155References, 164

External Corrosion Protection Chapter 10 ..................................................... 165

10.1 Introduction, 16510.2 Basic Corrosion Theory, 16610.3 Corrosion Resistance of Ductile-Iron Pipe, 17210.4 Evaluation of Corrosive Soils, 173

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Copyright 2009 American Water Works Association. All Rights Reserved.

10.5 Buried ServiceCorrosion Control, 17510.6 Exposed Service Conditions, 18810.7 Submerged Service Conditions and Control, 192References, 193

Installation of Ductile-Iron Pipe Chapter 11 .................................................. 195

11.1 Introduction, 19511.2 Pipe Inspection, Storage, Handling, and Delivery, 19511.3 Trenching, Embedment, Pipe Installation, and Backfilling, 19711.4 Pipeline Accessories, 20911.5 Thrust Restraint, 21211.6 Flushing, Field Testing, and Disinfection, 21211.7 Service Taps, 21511.8 Highway and Railroad Crossings, 22011.9 Trenchless Applications, 22011.10 Subaqueous Installations, 22011.11 Other Installations, 222References, 225

Trenchless Installation Chapter 12 Horizontal Directional Drilling ......................................................... 227

12.1 Introduction, 22712.2 Predesign Investigation, 22912.3 HDD Assembly Methods for Flexible Restrained-Joint

Ductile-Iron Pipe, 23012.4 Survey, 23212.5 Subsurface Analysis, 23212.6 Borepath Design, 23412.7 Pipe Design: Introduction, 23512.8 Testing and Service Pressure/Loads, 23812.9 Thermal Expansion/Contraction and Pulling Load Recoil, 239References, 239

Guidelines for Purchase of Pipe and Fittings Chapter 13 ............................ 241

13.1 General, 24113.2 Ductile-Iron Pipe, 24313.3 Ductile-Iron and Gray-Iron Fittings and Specials, 24413.4 Polyethylene Encasement, 244References, 245

Appendix A Illustrations of Proprietary Joints for Ductile-Iron Pipe and Fittings ...................................................................................... 247

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

AWWA Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

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Copyright 2009 American Water Works Association. All Rights Reserved.

1

AWWA MANUAL M41

Chapter 1

General Information and History

This manual provides the user with both technical and general information to aid in the design, specification, procurement, installation, and understanding of ductile-iron pipe.

The manual describes ductile-iron pipe and fitting products, appurtenances, and their application to practical installations, whether of a standard or special nature.

1.1 HIsTory ___________________________________________________________________________1.1.1 GeneralThe history of pipe parallels that of civilization. The earliest communities were estab-lished near water sources that later became inadequate as populations increased. Hy-draulic engineering was born of the necessity to transport water closer to the point of use. From ancient Babylons clay pipes, to the underground tunnels of ancient Greece, to the aqueducts of the Roman Empire, to the cast-iron mains of Versailles, France, to todays modern pipe, the search for an affordable piping material with reliable strength and durability evolved. Cast-iron pipe rapidly became the standard material for wa-ter distribution mains. Today, in the United States and Canada alone, there are more than 622 utilities that have had cast-iron distribution mains with continuous service records of more than 100 years, and 23 for 150 years or more.

The production of iron pipe most likely developed from or coincided with the man-ufacture of cannons as early as the year 1313. There is an official record of cast-iron pipe being manufactured at Siegerland, Germany, in 1455 for installation at the Dil-lenberg Castle.

In 1664, King Louis XIV of France ordered the construction of a cast-iron pipe main to extend 15 mi (24 km) from a pumping station at Marly-on-Seine to Versailles to supply water for the fountains and town. This cast-iron pipe provided continuous service for more than 330 years. When the line was originated, the production of iron required the use of expensive charcoal for the reduction of the iron ore. By 1738, success

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Copyright 2009 American Water Works Association. All Rights Reserved.

2 DUCTILE-IRON PIPE AND FITTINGS

had been achieved in producing lower-cost iron by using coke instead of charcoal. Fol-lowing this success, the more progressive cities began to install cast-iron mains.

The use of cast-iron pipe was introduced in the United States in the early 1800s. Since that time, various other piping materials have been offered for water distribu-tion. However, waterworks engineers continued to use cast iron until ductile iron, a stronger and equally durable piping material, became available.

1.1.2 Development of JointsFlanged . Originally, cast-iron pipe was made with flanged joints, using lead

gaskets. Improved joints of this type are still used for many aboveground plant instal-lations and other specialized applications.

Bell and spigot . The bell and spigot joint was developed in 1785 and was used extensively until the 1950s. This joint was assembled by caulking yarn or braided hemp into the base of the annular bell cavity and then pouring molten lead into the remaining space inside the bell. On solidification, the lead was compacted by caulk-ing, thus effecting a watertight seal. Materials other than lead have also been used to confine yarn or hemp in the base of the bell cavity.

Mechanical joint . The mechanical joint was developed for gas industry use in the late 1920s but has since been used extensively in the water industry. This joint has standardized dimensions and uses the basic principle of the stuffing box and gland, with a rubber gasket being compressed by the gland.

Roll-on joint . The roll-on joint was developed in 1937 and was used for approxi-mately 20 years before its manufacture was discontinued. Assembly of this joint involved a compressed rubber gasket rolled under