Contents
List of Figures, vii
List of Tables, ix
Foreword, xi
Acknowledgments, xiii
Introduction, xv
Definitions, xvi
AWWA Standards, xvi
Welded Tanks, xvii
Bolted Tanks, xvii
Part I Elements of Steel Water Tanks
Chapter 1 Typical Capacities and Configurations . . . . . . . . . 3
Reservoirs, 3
Standpipes, 3
Roof Designs for Reservoirs and Standpipes, 10
Elevated Tanks, 13
Multiple-Column Elevated Tanks, 13
Pedestal Elevated Tanks, 18
Chapter 2 Appurtenances . . . . . . . . . . . . . . . . . 25
Shell Manholes, 25
Pipe Connections, 26
Overflow, 28
Ladders and Safety Devices, 29
Roof Openings, 32
Vents, 33
Devices for Indicating Water Level, 35
Emergency Fill/Withdraw Connections, 36
Chapter 3 Cathodic Protection . . . . . . . . . . . . . . . 37
Nature of Corrosion, 37
Principles of Cathodic Protection, 39
Cathodic Protection Design, 40
Maintenance, 41
Chapter 4 Coating Systems . . . . . . . . . . . . . . . . . 45
Interior Coatings, 45
Exterior Coatings, 47
Inspection and Quality Control, 48
Removing Coating by Abrasive Blasting, 49
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Copyright (C) 1999 American Water Works Association All Rights Reserved
Part II The New Tank Project
Chapter 5 Selecting and Sizing Water Storage Tanks . . . . . . 53
Peak Demand, 53
Fire Flow, 54
Top and Bottom Capacity Levels, 54
Energy Costs, 55
Future Needs, 55
Environmental Impact, 56
Tank Costs, 56
Chapter 6 Construction Considerations . . . . . . . . . . . . 59
Design Standards, 59
Contract Documents, 60
Constructor Capabilities, 60
Guarantees, 60
Soil Investigations, 60
Reservoir and Standpipe Foundations, 63
Elevated Tank Foundations, 64
Tank Site, 65
Tank Coating—Welded Steel Tanks, 67
Tank Coating—Bolted Steel Tanks, 68
Tank Water Testing and Disinfection, 68
Engineer’s Role, 69
Bidding Documents, 70
Chapter 7 Inspecting New Tank Construction . . . . . . . . . 73
Responsibility for Quality, 73
The Foundation, 74
Fabrication, 76
Steel Delivery, 76
Tank Erection, 76
Field Cleaning and Coating, 79
Mechanical and Electrical Appurtenances, 81
Part III Existing Tanks
Chapter 8 Routine Operation and Maintenance . . . . . . . . . 85
Energy Management, 85
Controls, 86
Periodic Operator Inspection, 86
Tank Washouts, 88
Chapter 9 Professional Examination and Renovation . . . . . . 91
Tank Maintenance Engineer’s Functions
and Qualifications, 92
Pre-Bid Inspection, 94
Preparing Specifications, 99
Monitoring the Constructor’s Progress, 101
Periodic Reinspection, 104
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Copyright (C) 1999 American Water Works Association All Rights Reserved
Chapter 10 Cold-Weather Operation . . . . . . . . . . . . . 105
Causes and Results of Freezing, 105
Quantitative Data Related to Freezing, 108
Designing Tanks for Cold Weather, 108
Cold-Weather Operating Procedures, 113
Systems to Prevent Freezing, 114
Dealing With Frozen Tanks, 116
Appendix A Bibliography . . . . . . . . . . . . . . . . . 119
Appendix B Steel Water Tank Industry Standards
Organizations and Information Sources . . . . . . . . . . 121
Appendix C Inspecting and Repairing Steel Water Tanks,
Standpipes, Reservoirs, and Elevated Tanks for Water
Storage . . . . . . . . . . . . . . . . . . . . . . . 129
Index, 139
AWWA List of Manuals, 143
Copyright (C) 1999 American Water Works Association All Rights Reserved
Figures
F-1 A tank constructed in 1902 is still serving Wabash, Ind., with
practically no metal loss, xv
1-1 Welded steel reservoir, 4
1-2 Cross-sectional view of a welded steel reservoir, 4
1-3 Bolted steel reservoir, glass fused to steel, 5
1-4 Cross-sectional view of a bolted steel reservoir, 5
1-5 Welded steel standpipe with decorative pilasters, 8
1-6 Cross-sectional view of a typical welded steel standpipe, 8
1-7 Bolted steel reservoir, 9
1-8 Cross-sectional view of a bolted steel standpipe, 9
1-9 Column- and rafter-supported cone roof tank, 11
1-10 Column- and rafter-supported roof with knuckle, 11
1-11 Self-supporting dome roof or umbrella roof, 12
1-12 Self-supporting ellipsoidal roof, 12
1-13 Double-ellipsoidal tank, 14
1-14 Cross-sectional view of double-ellipsoidal tank, 14
1-15 Medium-capacity welded elevated tank, 15
1-16 Cross-sectional view of medium-capacity, torus-bottom welded elevated tank, 16
1-17 Large-capacity elevated tank, 17
1-18 Cross-sectional view of large-capacity, multi-column elevated tank, 17
1-19 Spherical single-pedestal tanks give pleasant silhouette, 18
1-20 Cross-sectional view of small-capacity spherical single-pedestal tank, 19
1-21 Alternative single-pedestal tank design, 20
1-22 Large-capacity single-pedestal elevated tank, 20
1-23 Cross-sectional view of large-capacity single-pedestal elevated tank, 21
1-24 Folded-plate design of a modified single-pedestal tank support, 22
1-25 Cross-sectional view of modified single-pedestal tank, 22
2-1 Inward-opening shell manhole detail, 26
2-2 Outward-opening shell manhole detail, 27
2-3 Recessed inlet–outlet pipe bottom connection detail, 27
2-4 Nonrecessed inlet–outlet pipe bottom connection details, 28
2-5 Overflow air break with flap valve, 29
2-6 Exterior caged ladder details, 30
2-7 Safe-climbing rail for an outside ladder, 31
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Copyright (C) 1999 American Water Works Association All Rights Reserved
2-8 Roof guardrail details, 32
2-9 Roof manhole assembly details, 33
2-10 Double 90° elbow roof vent detail, 34
2-11 Pan deck vent detail, 34
2-12 Typical clog-resistant vent detail, 35
3-1 Schematic diagram of a battery, 38
3-2 Corrosion of steel in water, 39
3-3 Tank corrosion protection—vertically suspended anodes, 42
3-4 Tank corrosion protection—horizontally suspended anodes, 43
5-1 Typical daily flow at constant pumping rate, 54
5-2 Typical daily flow with variable-rate pumping, 55
5-3 Relative cost by type of steel tank for 500,000-gal (1.9-ML) tanks, 56
5-4 Relative cost by type of elevated steel tank, 57
6-1 Soil-testing operations, 62
6-2 Example of tank supported on granular berm foundation, 64
7-1 Tank foundation construction, 75
7-2 Typical welding operation in the field, 77
7-3 Reviewing a weld radiograph, 78
7-4 Newly erected elevated tank, 79
9-1 Experienced riggers evaluate hard-to-reach areas on tower tanks, 93
9-2 Active corrosion penetrated this 1 4 -in. (6-mm) steel tank bottom in 9 years.
Periodic inspections and washouts would have revealed and prevented this
problem well in advance of failure, 95
9-3 Measuring shell thickness with ultrasonic equipment, 96
9-4 Washing out tanks allows easier inspection and keeps tanks sanitary, 97
9-5 Inspection of the degree of abrasive blast cleaning, 102
9-6 An abrasive blast-cleaning operation, 102
10-1 A frozen water tank, 106
10-2 Isothermal lines for lowest one-day mean temperatures and normal daily
minimum 30°F (–1°C) temperature line for January, United States and
Southern Canada, 110
10-3 Double-seating, internal-closing drain valve, 112
10-4 Tank riser bubbler system, 115
10-5 Pumped circulation system for small riser pipes, 116
10-6 Tank-thawing operation, 118
viii
Copyright (C) 1999 American Water Works Association All Rights Reserved
Tables
1-1 Typical welded steel water-storage reservoir sizes, 6
1-2 Glass-coated, bolted steel reservoirs and standpipes (capacity in thousand
gallons), 7
1-3 Typical welded steel water storage standpipe sizes, 10
1-4 Typical double-ellipsoidal steel elevated tank sizes, 15
1-5 Typical medium-capacity welded steel elevated tank sizes, 16
1-6 Typical large-capacity welded steel elevated tank sizes, 18
1-7 Typical small-capacity single-pedestal steel elevated tank sizes, 19
1-8 Typical large-capacity single-pedestal steel elevated tank sizes, 21
1-9 Typical modified single-pedestal steel elevated tank sizes, 23
6-1 Typical soil investigation requirements, 61
6-2 Tank site selection considerations, 65
10-1 Thousands of British thermal units (Btu) lost per hour from elevated steel
tanks, 109
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Copyright (C) 1999 American Water Works Association All Rights Reserved
