WELDED STEEL TANKS FOR WATER STORAGE
ANSI/AWWA D100-96
(Revision of AWWA D100-84)
AWWA STANDARD FOR WELDED STEEL TANKS FOR WATER STORAGE
American Water Works Association New England Water Works Association
Effective date: Mar. 1, 1997. First edition approved by AWWA Board of Directors June 26, 1941; by AWS July 23, 1941; and by NEWWA Sept. 24, 1942. This edition approved by AWWA June 23, 1996. Approved by American National Standards Institute Nov. 27, 1996.
AMERICAN WATER WORKS ASSOCIATION
6666 West Quincy Avenue, Denver, Colorado 80235
AWWA Standard
This document is an American Water Works Association (AWWA) standard. It is not a specification. AWWA standards describe minimum requirements and do not contain all of the engineering and administrative information normally contained in specifications. The AWWA standards usually contain options that must be evaluated by the user of the standard. Until each optional feature is specified by the user, the product or service is not fully defined. AWWA publication of a standard does not constitute endorsement of any product or product type, nor does AWWA test, certify, or approve any product. The use of AWWA standards is entirely voluntary. AWWA standards are intended to represent a consensus of the water supply industry that the product described will provide satisfactory service. When AWWA revises or withdraws this standard, an official notice of action will be placed on the first page of the classified advertising section of Journal AWWA. The action becomes effective on the first day of the month following the month of Journal AWWA publication of the official notice.
American National Standard
An American National Standard implies a consensus of those substantially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether that person has approved the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standard. American National Standards are subject to periodic review, and users are cautioned to obtain the latest editions. Producers of goods made in conformity with an American National Standard are encouraged to state on their own responsibility in advertising and promotional materials or on tags or labels that the goods are produced in conformity with particular American National Standards.
C AUTION N OTICE: The American National Standards Institute (ANSI) approval date on the front cover of this standard indicates completion of the ANSI approval process. This American National Standard may be revised or withdrawn at any time. ANSI procedures require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of publication. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute, 11 W. 42nd St., New York, NY 10036; (212) 642-4900.
Copyright © 1997 by American Water Works Association
Printed in USA
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Committee Personnel
The D100 Revision Task Force that developed this standard had the following personnel at that time:
Robert S. Wozniak, Chair K.A. Alms
A.M. DeVaul R.G. Biale
R.P. Kennedy Richard Blaisdell
Ron Kern
L.E. Bower
E.C. Knoy
B.E. Kromer F.M. Couch
J.R. Buzek
Y.T. Lin
Ray Crosno
S.W. Meier
Chris Sundberg R.J. Davis
D.G. Cull
L.R. Todd
The Standards Committee on Steel Elevated Tanks, Standpipes, and Reservoirs that reviewed and approved this standard had the following personnel at the time of approval:
Forrest M. Couch, Chair Consumer Members
S.F. Crumb, Ft. Worth Water Department, Ft. Worth, Texas (AWWA) R.D. Davis, American Water Works Service Company, Voorhees, N.J.
(AWWA) Walter Harris, City of Houston, Houston, Texas
(AWWA) J.W. Houlihan, East Bay Municipal Utility District, Oakland, Calif.
(AWWA) K.W. Kells, * Connecticut Water Company, Clinton, Conn.
(NEWWA) K.A. Nadeau, Connecticut Water Company, Clinton, Conn.
(NEWWA) A.R. Terrell Jr., Little Rock Municipal Water Works, Little Rock, Ark.
(AWWA)
G.A. Weeks, St. Louis County Water Company, Chesterfield, Mo. (AWWA)
General Interest Members
J.R. Buzek, AEC Engineers & Designers, Minneapolis, Minn. (AWWA) B.R. Conklin, Camp Dresser & McKee Inc., Cambridge, Mass.
(NEWWA) F.M. Couch, Black & Veatch Engineers, Kansas City, Mo.
(AWWA) Ed Darrimon, Bay Area Coating Consultants, Valley Springs, Calif.
(AWWA) W.J. Dixon, Dixon Engineering Inc., Lake Odessa, Mich.
(AWWA) M.E. Gilliland, US Army Corps of Engineers, Huntsville, Ala.
(AWWA)
E.C. Knoy, Tank Industry Consultants Inc., Indianapolis, Ind. (AWWA) H.J. Miedema, Robert Bein, William Frost & Associates, Irvine, Calif.
(AWWA)
* Alternate
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L.F. Peters, Weston & Sampson Engineers, Peabody, Mass. (NEWWA) Chris Sundberg, CH2M Hill, Bellevue, Wash.
(AWWA) J.H. Wilber, * Standards Engineer Liaison, AWWA, Denver, Colo.
(AWWA) J.A. Williams, Consulting Engineer, Alpharetta, Ga.
(AWWA) R.S. Wozniak, BowTech Inc., Batavia, Ill.
(AWWA)
Producer Members
D.G. Cull, C T Services Inc., Jeffersonville, Ind. (AWWA) A.M. DeVaul, Pitt–Des Moines Inc., Des Moines, Iowa
(AWS) Francis Grillot Jr., A.O. Smith Harvestore Products, DeKalb, Ill.
(AWWA)
B.E. Kromer, Tank Builders Inc., Euless, Texas (SPFA) S.W. Meier, Chicago Bridge & Iron Co., Plainfield, Ill.
(AWS) L.D. Scott, Trusco Tank Inc., San Luis Obispo, Calif.
(AWWA) Dale Turner, Peabody TecTank Inc., Parsons, Kan.
(AWWA)
* Liaison, nonvoting
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12 Foundation Design
Appendix
12.1 General Requirements ..................... 64
12.2 Soil-Bearing Value ............................ 64
A Bibliography................................. 121
12.3 Safety Factors ................................... 65
Figures
12.4 Foundations for Braced Elevated Tanks............................................... 65
1 Mean Tank Height ........................... 11
12.5 Foundations for Single-Pedestal
2 Diagram for Checking Overturning Tanks............................................... 66
of Pedestal-Type Elevated Tanks
12.6 Foundations for Flat-Bottom (Wind or Seismic Events) .............. 67 Tanks............................................... 66
3 Extreme Frost Penetration—in
12.7 Detail Design of Foundations .......... 68 Inches (Based on State Average) .... 69
12.8 Concrete Design, Materials, and
4 Recommended Depth of Cover (in Construction ................................... 70
Feet Above Top of Pipe) ................. 69
12.9 Backfill .............................................. 70
5 Relative Seismic Resistance of Typical Unanchored Flat-Bottom
13 Seismic Design of Water Storage
Tanks .............................................. 72
Tanks
6 Diagram for Checking Overturning
13.1 General .............................................. 70 of Cross-Braced Elevated Tanks
13.2 Seismic Design Categories ............... 70 (Seismic) ......................................... 75
13.3 Seismic Design Loads....................... 71
7 Seismic Zone Map of the United
13.4 Local Seismic Data ........................... 85 States and Puerto Rico for Seismic
13.5 Piping Connections for Flat-Bottom Design of Water Storage Tanks .... 75 Tanks............................................... 86
8 Curve for Obtaining Factor K p for
13.6 Foundation Design ........................... 86 the Ratio D/H................................. 77
13.7 Specification Sheets for Seismic
9 Curves for Obtaining Factors Data and Examples........................ 87
W 1 / W T and W 2 / W T for the
13.8 Equivalent Metric Equations........... 99 Ratio D/H ....................................... 79
10 Curves for Obtaining Factors X 1 / H
14 Alternative Design Basis for
and X 2 / H for the Ratio D/H ......... 79
Standpipes and Reservoirs
11 Increase in Axial-Compressive
14.1 Alternative Design Basis ............... 100 Buckling-Stress Coefficient of
14.2 Materials ......................................... 103 Cylinders Due to Internal
14.3 General Design ............................... 110 Pressure (for Use With
14.4 Inspection ........................................ 112 Unanchored Tanks Only) .............. 85
14.5 Certification of Compliance ........... 114
12 Bottom Piping Connection of an Unanchored Flat-Bottom Tank ..... 86
15 Structurally Supported
13 Certification to Purchaser of
Aluminum Dome Roofs
Compliance With Inspection
15.1 General ............................................ 115 Requirements Under Sec. 14 ...... 102
15.2 Definition......................................... 115
14 Recommended Nameplate ............. 104
15.3 Design Requirements ..................... 115
15 Isothermal Lines for Lowest One-
15.4 Materials ......................................... 115 Day Mean Temperatures and
15.5 Allowable Stresses .......................... 116 Normal Daily Minimum 30°F
15.6 Design.............................................. 117 (–1.1°C) Temperature Line for
15.7 Roof Attachment Details ................ 118 January, United States and
15.8 Physical Characteristics................. 118 Southern Canada ......................... 108
15.9 Testing and Sealing ........................ 118
16 Radiographic Requirements for
15.10 Fabrication and Erection ............... 118 Tank Shells According to
15.11 Coatings........................................... 119 Sec. 14........................................... 114
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Tables
16 Standard Capacities for Elevated Tanks............................................... 34
1 Thickness Limitations and Special
17 Standard Capacities for Standpipes Requirements ................................... 7
and Reservoirs................................ 40
2 Wind Drag Coefficient C d ................ 10
18 Minimum Size of Fillet
3 Material Classes ............................... 12 Weld—Shell-to-Bottom Joint......... 46
4 Unit Stresses—Tension .................... 13
19 Minimum Diameter for Plates Not
5 Unit Stresses—Compression ........... 13 Rolled .............................................. 49
6 Unit Stresses—Primary Bending .... 14
20 Maximum Thickness of
7 Unit Stresses—Shearing.................. 14 Reinforcement for Butt Joints ...... 50
8 Unit Stresses—Bearing.................... 15
21 Roundness—Cylindrical Shells ....... 52
9 Values of F L , ( t /R ) c for Class 1
22 Maximum Allowable Offset of and Class 2 Materials.................... 18
Aligned Butt Joints........................ 53
10 Allowable Local Compressive
23 Maximum Height of Weld Stress F L for Class 1 Materials
Reinforcement of Weld for Butt L/r ≤
24 ........................................... 19 Joints Above Plate Surface............ 58
11 Allowable Local Compressive
24 Zone Coefficient Z............................. 74 Stress F L for Class 2 Materials
25 Force Reduction Coefficient R w L/r ≤
24 ........................................... 20 for Type of Tank ............................. 74
12 Allowable Compressive Stress for
26 Use Factor I ...................................... 74 Combined Effects of Local
27 Site Amplification Factor S ............. 74 Buckling and Slenderness for
28 Category 1 Material Requirements Class 1 Materials (psi)................... 21
for Shell Plates in Contact With
13 Allowable Compressive Stress for Water to Be Used for Design Combined Effects of Local
Metal Temperature Tabulated .... 105 Buckling and Slenderness for
29 Category 2 Materials...................... 106 Class 2 Materials (psi)................... 22
30 Category 3 Materials...................... 106
14 Weld Design Values—Tank Plate
31 Maximum Design Tensile Stresses Joints............................................... 27
in Shell Plates in Contact With
15 Minimum Thickness of Cylindrical Water............................................. 111 Shell Plates in Contact With
32 Minimum Thickness of Bottom Water............................................... 30
Annular Rings .............................. 112
33 Bolts and Fasteners ....................... 117
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Foreword
This foreword is for information only and is not a part of AWWA D100.
I. Introduction
I.A. Background. In 1931, American Water Works Association (AWWA) Sub- committee 7H, whose members were L.R. Howson, H.C. Boardman, and James O. Jackson, prepared “Standard Specifications for Riveted Steel Elevated Tanks and Standpipes.” The specifications were published in the November 1935 edition of Journal AWWA . In 1940, the scope of the standard specifications was expanded to include welded construction. The American Welding Society (AWS) cooperated in the revision and became a joint sponsor of the standard. Since its original publication, the standard has gained wide acceptance in the United States and abroad.
I.B. History. In 1965, appendix C was added to provide for the alternative use of higher-strength steels for standpipes and reservoirs. Other changes included the addition of specifications for the use of steel pipe as tubular columns, and a wind- pressure formula for winds in excess of 100 mph. The requirements for loads on balconies and ladders and unit stresses for combinations of wind, seismic, and other loads were clarified. The rules for the minimum thickness of shell plates for stand- pipes and reservoirs were revised to apply only to cylindrical shells and not to knuckles or toroidal or elliptical roof plates containing water. The swivel ladder for standpipes and reservoirs, which was found to be impractical, was eliminated, and a fixed ladder was specified. The rules for welding and for weld qualification were rewritten completely. The qualification procedure of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Sec. IX, was adopted, and the sizes of fillet welds in the shell-to-bottom joints of standpipes and reservoirs were revised, as were the sections on sand cushions and grouting for standpipe and reservoir bottoms. Rules for inspection of welds were rewritten completely. An isothermal map showing the lowest one-day mean temperature in various parts of the continental United States and parts of Canada was included. Concrete foundation design was brought into conformity with American Concrete Institute (ACI) Standard No. 318, Building Code Requirements for Reinforced Concrete.
In 1973, the use of rivets for joints in tank shells was eliminated. Specifications for tank steels were revised to include low-alloy steels. The design of foundations for elevated tanks and standpipes was changed extensively, making foundation design a part of the mandatory specification. Procedures for soil investigation were recommended.
In 1979, appendix A, Non-Mandatory Seismic Design of Water Storage Tanks, and appendix B, Diagrams for Checking Overturning of Elevated Tanks, were added. The sections from the former appendix B, covering information to be fur- nished, were incorporated into Sec. II of the foreword, and the sections dealing with foundations were incorporated into Sec. 12. Section 11 was revised to include inspection and testing requirements that were formerly in Sec. 11 and Sec. 12 and appendixes A and B. Other additions included specifications for additional acceptable steels, re- quirements for design for seismic resistance, a formula for cylindrical shell design, requirements for backfill within ringwall foundations, and requirements for depth of pipe cover. The out-of-date porosity charts in former appendix A were eliminated and reference made to the charts in the ASME Boiler and Pressure Vessel Code, Sec. VIII, or to the identical charts in American Petroleum Institute (API) Standard 650, Welded Steel Tanks for Oil Storage. A section covering permissible inspection by air
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In 1984, revisions included new sections pertaining to single-pedestal tanks incorporating design rules for this type of tank. New design rules were included for columns of elevated tanks having eccentric work point connections. A section covering the design considerations for struts was added. For combined stresses, the unit
stresses for wind and seismic forces were increased from 25 percent to 33 1 ⁄ 3 percent. Shell plates thicker than 2 in. (51 mm) conforming to American Society for Testing
and Materials (ASTM) A36, Specification for Structural Steel, were allowed to be used provided their usage was in compliance with certain stipulated conditions and requirements. Ground-supported tanks not greater than 50 ft (15.2 m) in diameter
were allowed to have a minimum shell thickness of 3 ⁄ 16 in. (7.9 mm). A minimum size and maximum spacing were added for foundation bolts. The previous appendix A on seismic design was incorporated into the standard as Sec. 13. In addition, a new section was added to Sec. 13 to permit scaling down to specific site response spectra when local seismic data are available.
Appendix C, Alternative Rules and Design Stresses for the Use of Steel Plates and Shapes With Suitable Toughness and Ductibility for Use in Welded Standpipes and Reservoirs at Specified Minimum Ambient Temperatures, was made a part of the standard while retaining its title designation as appendix C.
For appendix C tanks with a height to diameter (H/D) ratio of 0.50 or less, the shell design was allowed to be by the Variable Design Point Method in compliance with API 650. Also, for appendix C tanks, inspection of certain members is not required when the material has a tensile strength less than 75,000 psi (517.1 MPa).
The major revisions in this edition are summarized in Sec. IV of this foreword.
I.C. Acceptance. In May 1985, the US Environmental Protection Agency (USEPA) entered into a cooperative agreement with a consortium led by NSF Inter- national (NSF) to develop voluntary third-party consensus standards and a certifica- tion program for all direct and indirect drinking water additives. Other members of the original consortium included the American Water Works Association Research Foundation (AWWARF) and the Conference of State Health and Environmental Managers (COSHEM). The American Water Works Association (AWWA) and the Asso- ciation of State Drinking Water Administrators (ASDWA) joined later.
In the United States, authority to regulate products for use in, or in contact with, drinking water rests with individual states. * Local agencies may choose to impose requirements more stringent than those required by the state. To evaluate the health effects of products and drinking water additives from such products, state and local agencies may use various references, including
1. An advisory program formerly administered by USEPA, Office of Drinking Water, discontinued on Apr. 7, 1990.
2. Specific policies of the state or local agency.
* Persons in Canada, Mexico, and non-North American countries should contact the appropriate authority having jurisdiction.
3. Two standards developed under the direction of NSF, ANSI * /NSF † 60, Drinking Water Treatment Chemicals—Health Effects, and ANSI/NSF 61, Drinking Water System Components—Health Effects.
4. Other references, including AWWA standards, Food Chemicals Codex, Water Chemicals Codex, ‡ and other standards considered appropriate by the state or local agency.
Various certification organizations may be involved in certifying products in accordance with ANSI/NSF 61. Individual states or local agencies have authority to accept or accredit certification organizations within their jurisdiction. Accreditation of certification organizations may vary from jurisdiction to jurisdiction.
Appendix A, “Toxicology Review and Evaluation Procedures,” to ANSI/NSF 61 does not stipulate a maximum allowable level (MAL) of a contaminant for sub- stances not regulated by a USEPA final maximum contaminant level (MCL). The MALs of an unspecified list of “unregulated contaminants” are based on toxicity testing guidelines (noncarcinogens) and risk characterization methodology (carcino- gens). Use of Appendix A procedures may not always be identical, depending on the certifier.
AWWA D100-96 does not address additives requirements. Thus, users of this standard should consult the appropriate state or local agency having jurisdiction in order to
1. Determine additives requirements including applicable standards.
2. Determine the status of certifications by all parties offering to certify products for contact with, or treatment of, drinking water.
3. Determine current information on product certification.
II. Special Issues. This standard has no applicable information for this section.
III. Use of This Standard. AWWA has no responsibility for the suitability or compatibility of the provisions of this standard to any intended application by any user. Accordingly, each user of this standard is responsible for determining that the standard’s provisions are suitable for and compatible with that user’s intended application.
This standard is based on the accumulated knowledge and experience of pur- chasers and manufacturers of welded steel tanks. § Many tanks built in compliance with the first edition of this standard are more than 50 years old and are still in service. Properly operated and maintained welded steel water tanks can have an almost unlimited service life.
III.A. Purchaser Options and Alternatives. If tanks are purchased in accordance with this standard, the purchaser is required to specify certain basic requirements. The purchaser may desire to modify, delete, or amplify sections of this standard to suit special conditions. It is strongly recommended that such modifications, deletions, or amplifications be made by supplementing this standard. This standard is not intended to cover storage tanks that are to be erected in areas subject to regulations
* American National Standards Institute, 11 W. 42nd St., New York, NY 10036. † NSF International, 3475 Plymouth Rd., Ann Arbor, MI 48106. ‡ Both publications available from National Academy of Sciences, 2102 Constitution Ave.
N.W., Washington, DC 20418. § The word “tanks” is used hereinafter broadly in place of the lengthy phrase “elevated
tanks, standpipes, and reservoirs for water storage.”
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stipulates a building roof snow load of 40 lb/ft 2 (195 kg/m 2 ) and it is intended that the tank roof be designed for this load, the purchaser is to include this as a clarification. The details of design and construction covered by this standard are minimum requirements. At a minimum, it is important that all of the design conditions in this standard be met. *
A tank cannot be represented as an AWWA D100 tank if it does not meet the minimum requirements of this standard. The foundations of tanks are one of the more important aspects of tank design; detailed requirements are covered in Sec. 12. This standard requires the constructor to be responsible for the design and construction of the tank foundations. The purchaser must obtain an adequate soil investigation at the site, including recommendation of the type of foundation to be used, the depth of foundation required, and the design soil-bearing pressure. This information, as well as specifications for an adequate soil investigation, should be established by a qualified geotechnical engineer.
A drainage inlet structure or suitable erosion protection should be provided to receive discharge from the tank overflow. The overflow should not be connected directly to a sewer or a storm drain without an air break.
Annual inspection and maintenance of the exposed side of the tank shell-to-bottom connection for a standpipe or reservoir is important if maximum tank life is to be attained. In particular, accumulations of dirt and weeds, which may trap moisture and accelerate corrosion, should be removed. Inspection of the interior and exterior of the entire tank with corrective maintenance at three- to five-year intervals is recommended.
This standard assumes that the purchaser (owner) provides sufficient water replacement and circulation to prevent freezing in the tank and riser pipe. Where low usage may result in the possibility of freezing, the owner should waste water or provide heat to prevent freezing. The purchaser is referred to National Fire Protection Association (NFPA) document NFPA 22, Water Tanks for Private Fire Protection, for heater sizing. Purchasers are cautioned against allowing ice buildup for insulation, which may break loose and damage the tank. Where reference to ice damage is discussed in the standard, it is in anticipation of improper operation rather than approval of an icing condition.
This standard does not cover tank disinfection procedures or cleaning and painting. ANSI/AWWA C652, Standard for Disinfection of Water Storage Facilities, should be consulted for recommended procedures for disinfection of water storage facilities. Often it is desirable for the purchaser to perform the disinfection to eliminate the necessity for the painting constructor to return afterward or to stand by until the inside paint has dried completely. If the disinfecting is to be done by either the
* Dawe, J.L., C.K. Seah, and A.K. Abdel-Zaher, Investigation of the Regent Street Water Tower Collapse; Jour. AWWA, 93(5):34–47.
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The following recommendations are believed to represent good practice, but they are not requirements of ANSI/AWWA D100. When a welded steel tank is to be purchased under this standard, the purchaser should provide the following:
1. The site on which the tank is to be built, including sufficient space to permit the structure to be erected by customary methods.
2. Water at the proper pressure for testing, as required, and facilities for disposal of wastewater after testing.
3. A suitable right-of-way from the nearest public road to the erection site.
4. Materials furnished by the purchaser to be used by the constructor for construction of the tank. The constructor should furnish the following items:
1. Foundation and tank design, drawings, and specifications.
2. All labor and materials, except materials furnished by the purchaser, nec- essary to complete the structure including the foundations and accessories required by this standard.
3. Any additional work, separately specified by the purchaser, such as soil investigations, painting, disinfection, or accessories. Variations in the responsibilities of both the purchaser and the constructor, as previously outlined, may be made by contractual agreement. The purchaser and the bidder should each furnish the information identified in the following listings.
III.A.1 Information to Be Furnished by Purchaser for an Elevated Tank. The following information should be furnished by the purchaser when taking bids for an elevated tank:
1. Capacity.
2. Bottom capacity level (BCL) and top capacity level (TCL) above top of column foundations.
3. Type of roof, roof pitch, and projection at eaves (unless the purchaser desires to leave to the constructor the selection of appropriate dimensions).
4. Head range, if specific range is required.
5. Diameter and type of riser.
6. Location of site.
7. Desired time for completion.
8. Name of, and distance to, nearest town.
9. Name of, and distance to, nearest railroad siding.
10. Type of road available for access to the site and whether it is public or private.
11. Availability of electric power; who furnishes it; at what fee, if any; what voltage; whether direct or alternating current; and, if alternating current, what cycle and phase.
12. Availability of compressed air; pressure, volume, and fee, if any.
13. Whether details of all welded joints referenced on the constructor’s drawings are to be submitted for approval (Sec. 1.4).
14. Whether copper-bearing steel is required (Sec. 2.2.6).
15. Type of pipe and fittings for fluid conductors (Sec. 2.2.12). Also, type of pipe joint if different from that permitted in Sec. 2.2.12.
16. Whether design snow loading is to be reduced if tank is located where the lowest one-day mean low temperature is 5°F (–15°C) or warmer (Sec. 3.1.3).
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17. Whether special wind conditions are required and, if so, the specific wind load requirements (Sec. 3.1.4).
18. Whether seismic design is required, and which seismic zone (1, 2A, 2B, 3, or 4) is to be used (Sec. 3.1.5).
19. Corrosion allowance, if any, to be added to parts that will be in contact with water and to parts that will not be in contact with water (Sec. 3.9).
20. Whether a balcony is required for inspection and painting when a horizontal girder is not required by the tank design (Sec. 4.7).
21. Whether increased wind loads are to be considered for high, slender tanks (Sec. 4.11).
22. Location of manholes, ladders, and any additional accessories required (Sec. 5).
23. Number and location of pipe connections, and type and size of pipe to be accommodated. N OTE: Connections to the piping furnished by the tank constructor are to be made by the purchaser (Sec. 5.2).
24. Whether a removable silt stop is required (Sec. 5.2.1).
25. Overflow type, whether stub or to ground or (if applicable) to extend below balcony; size of pipe; pumping and discharge rates (Sec. 5.3).
26. Whether the roof ladder for providing access to roof hatches and vents is to
be omitted (Sec. 5.4.3).
27. Whether safety cages, rest platforms, roof-ladder handrails, or other safety devices are required and on which ladders (Sec. 5.5). N OTE: Purchaser is to specify beginning location of outside tank ladder if other than at a level of 8 ft (2.4 m) above the level of the tank bottom.
28. Whether a special pressure-vacuum screened vent, or a pressure-vacuum relief mechanism is required for the tank vent (Sec. 5.7.2).
29. Specifications for any additional accessories required (Sec. 5.8).
30. For butt-joint welds subject to secondary stress, whether complete joint penetration is to be provided at joints in base metals of thicknesses greater than
3 ⁄ 8 in. (9.5 mm) (Sec. 8.5.2).
31. Whether mill or shop inspection is required and whether mill test reports are required (Sec. 11.1).
32. Whether a written report is required certifying that the work was inspected as set forth in Sec. 11.2.1.
33. Whether radiographic film or test segments, or both, are to become the property of the purchaser (Sec. 11.2.1.1).
34. Type of inspection to be performed on complete joint penetration welded- shell butt joints (Sec. 11.4.1.1).
35. Whether steel is to be blast cleaned, pickled, or otherwise cleaned of mill scale. Kinds of paint or protective coatings and number of coats for inside and out- side surfaces, and whether materials are to be furnished and applied by the tank constructor (Sec. 11.13.1). Also, whether the tank is to be painted before or after water testing of the tank.
36. Whether seal welding is required and, if so, where it is required (Sec. 8.12.2).
37. Soil investigation including foundation design criteria, type of foundation (Sec. 12.1), depth of foundation below existing grade, S factor for seismic areas, and design soil-bearing pressure, including factor of safety (Sec. 12.3). N OTE: Unless other- wise specified by the purchaser, the top of foundation(s) shall be a minimum of 6 in. (150 mm) above finish grade (Sec. 12.7.1).
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38. Pile type and depth below existing grade when a pile-supported foundation is required (Sec. 12.7.3). The purchaser shall make appropriate provisions for establishing criteria for compensation adjustment due to piling length changes resulting from varying subsurface conditions.
39. Whether the effect of buoyancy is to be considered in the foundation design (Sec. 12.7.4).
40. Whether all requirements of ACI 301, Specifications for Structural Concrete for Buildings, are applicable to the concrete work (Sec. 12.8).
41. Vertical distance from finished ground level to the crown of inlet and out- let pipe (earth cover) at riser pier (Sec. 12.9.2).
42. Completion of the Specification Sheet for Seismic Data when seismic design is required (Sec. 13.1.2).
43. Whether vertical acceleration is to be considered for cross-braced or pedestal- type elevated tanks (Sec. 13.3.1.3(4) and Sec. 13.3.2.3).
44. Whether local seismic data are available and whether they are to be used in place of acceleration and spectral velocity values (Sec. 13.4). Also, the reduction factor to be used if scaled-down response spectra are used for ductile-mode stresses (Sec. 13.4.1).
45. Whether third-party inspection will be used by the purchaser and for which items.
III.A.2 Information to Be Furnished by Purchaser for a Standpipe or Reservoir (Ground-Supported Tanks). The following information should be furnished by the purchaser when taking bids for a ground-supported tank:
1. If a standpipe, capacity and top capacity level.
2. If a reservoir, capacity and diameter.
3. Type of roof, roof pitch, and projection at eaves (unless the purchaser allows the constructor to select the appropriate dimensions).
4. Location of site.
5. Desired time for completion.
6. Name of, and distance to, nearest town.
7. Name of, and distance to, nearest railroad siding.
8. Type of road available for access to the site and whether it is public or private.
9. Availability of electric power; who furnishes it; at what fee, if any; what voltage; whether it is a direct or an alternating current; and, if it is an alternating current, what cycle and phase.
10. Availability of compressed air; pressure, volume, and fee, if any.
11. The bottom capacity level of the tank, when empty, if it differs from the level when the tank would be emptied through the specified discharge fittings (Sec. 1.2.1.1).
12. Whether details of all welded joints referenced on the constructor’s drawings are to be submitted for approval (Sec. 1.4).
13. Whether copper-bearing steel is required (Sec. 2.2.6).
14. Type of pipe and fittings for fluid conductors (Sec. 2.2.12). Also, type of pipe joint if different from that permitted in Sec. 2.2.12.
15. Whether snow loading is to be reduced if tank is located where the lowest one-day mean low temperature is 5°F (–15°C) or warmer (Sec. 3.1.3).
16. Whether special wind conditions are required and, if so, the specific wind requirements (Sec. 3.1.4).
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17. Whether seismic design is required, and which seismic zone (1, 2A, 2B, 3, or 4) is to be used (Sec. 3.1.5).
18. Type, thickness, and kind of roof support, if required (Sec. 3.6).
19. Corrosion allowance, if any, to be added to parts that will be in contact with water and to parts that will not be in contact with water (Sec. 3.9). This also applies when a tank is to be furnished to comply with Sec. 14.
20. Design, details, and installation of flush-type cleanouts, if required (Sec. 3.13.2.5).
21. Location of manholes, ladders, and additional accessories required (Sec. 7).
22. Number and location of pipe connections, and type and size of pipe to be accommodated. N OTE: Connections to the piping furnished by the tank constructor are to be made by the purchaser (Sec. 7.2).
23. Whether a removable silt stop is required (Sec. 7.2.1).
24. Overflow type, whether stub or to ground; size of pipe; pumping and discharge rates (Sec. 7.3).
25. Whether the roof ladder for providing access to roof hatches and vents is to
be omitted (Sec. 7.4.3).
26. Whether safety cages, rest platforms, roof-ladder handrails, or other safety devices are required and on which ladders (Sec. 7.5). N OTE: Purchaser is to specify beginning location of outside tank ladder if other than at a level of 8 ft (2.5 m) above the level of the tank bottom.
27. Whether a special pressure-vacuum screened vent or a pressure-vacuum relief mechanism is required for the tank vent (Sec. 7.7).
28. Specifications for any additional accessories required (Sec. 7.8).
29. Whether a certified welding inspector is required for Sec. 14 tanks (Sec. 8.2).
30. For butt-joint welds subject to secondary stress, whether complete joint penetration is to be provided at joints in materials of thicknesses greater than 3 ⁄ 8 in. (9.5 mm) (Sec. 8.5.2).
31. Whether mill or shop inspection is required and whether mill test reports are required (Sec. 11.1).
32. Whether a written report is required certifying that the work was inspected as set forth in Sec. 11.2.1.
33. Whether radiographic film or test segments, or both, are to become the property of the purchaser (Sec. 11.2.1.1).
34. Type of inspection to be performed on complete joint penetration welded- shell butt joints (Sec. 11.4.1.1).
35. Whether steel is to be blast cleaned, pickled, or otherwise cleaned of mill scale. Kinds of paint or protective coatings and number of coats required for inside and outside surfaces except underside of bottom, and whether materials are to be furnished and applied by tank constructor (Sec. 11.13.1).
36. Whether seal welding is required and, if so, where it is required.
37. Soil investigation including foundation design criteria, type of foundation (Sec. 12.6), depth of foundation below existing grade, S factor for seismic areas, and design soil-bearing pressure, including factor of safety. N OTE: The top of the foundation is to be a minimum of 6 in. (150 mm) above the finish grade, unless otherwise specified by the purchaser (Sec. 12.7.1).
38. Pile type and depth below existing grade when a pile-supported foundation is required (Sec. 12.7.3).
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39. Whether all requirements of ACI 301 are applicable to the concrete work (Sec. 12.8).
40. Vertical distance from finished ground level to the crown of inlet and out- let pipes (earth cover) at tank foundation (Sec. 12.9.2).
41. Completion of the Specification Sheet for Seismic Data when seismic design is required (Sec. 13.1.2).
42. Whether vertical acceleration is to be considered (Sec. 13.3.3.7.1).
43. Amount of freeboard for sloshing wave (Sec. 13.3.3.7.2).
44. Whether seismic design of roof framing and columns is required (Sec. 13.3.3.7.3) and amount of live loads and vertical acceleration to be used.
45. Whether local seismic data are available and whether they are to be used in place of acceleration and spectral velocity values (Sec. 13.4). Also, the reduction factor to be used if scaled-down response spectra are used (Sec. 13.4.1).
46. For tanks designed under Sec. 14, design metal temperature (Sec. 14.2.4).
47. Whether third-party inspection will be used by the purchaser and for which items.
III.B. Information to Be Furnished by Bidder.
III.B.1 Information to Be Furnished by Bidder for an Elevated Tank. The follow- ing information should be furnished by the bidder for an elevated tank:
1. A drawing showing the dimensions of the tank and tower including the tank diameter, the height to bottom and top capacity levels (BCL and TCL), sizes of principal members, and thickness of plates in all parts of the tank and tower. Also, the maximum wind or seismic gross moment and shear on the foundation system should be identified.
2. The number, names, and sizes of all accessories.
3. Painting information, if included.
III.B.2 Information to Be Furnished by Bidder for a Standpipe or Reservoir (Ground-Supported Tanks). The following information shall be furnished by the bid- der for a ground-supported tank:
1. A drawing showing the dimensions of the standpipe or reservoir including the diameter, top capacity level (TCL), shell height including plate thickness, type and thickness of the roof, thickness of the bottom plates, and thickness of the bot- tom annular ring. Also, the maximum wind or seismic gross moment and shear on the foundation system shall be identified.
2. The number, names, and sizes of all accessories.
3. Painting information, if included.
III.C. Modification to Standard. Any modification of the provisions, definitions, or terminology in this standard must be provided in the purchaser’s specifications.
IV. Major Revisions. This edition of the standard includes numerous correc- tions, updates, and new material to clarify some of the existing requirements. Section 2 includes new data on the types and thicknesses of materials and their uses in tank construction. Section 3 has been extensively revised in the area of design load definitions, and the reference tables, figures, and equations used in the design of welded steel tanks. Minimum plate thicknesses, roofs, anchor bolts, and flush-type cleanouts have been defined. The buckling requirements of conical and double-curved shells have been clarified.
Section 4 clarifies the design of tension members carrying wind and seismic loads and steel risers. Updates of criteria for accessories including safety grills, over- flows, and screening have been added to Sec. 5. Section 7 includes updates similar to those found in Sec. 5.
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Section 8, concerning the quality control of welders, welding operators, and welding inspectors, has been expanded to improve quality control during construction. Critical joint details, materials, and sizes of welds are also clarified.
Section 10 has been revised to better define temperature limits for welding and limits of weld “reinforcement.” Section 11 includes extensive changes concerning the inspection of welded joints. Tank shell, tubular support columns, tension member bracing, and large-diameter riser joints are discussed, and radiograph requirements have been revised. The pene- trometer techniques and details have also been revised to conform to ASME criteria.
Section 12 has minor changes, and Sec. 12.6 concerning foundations for flat-bottom tanks has been revised. Section 13 covering seismic design has extensive revisions updating the methods to calculate forces and stresses. A new seismic map of the United States is included along with new and revised equations for calculating such things as hydrodynamic seismic hoop tensile stresses, and sloshing wave height to determine minimum freeboard.
Appendix C of the previous edition has been incorporated into the standard as Sec. 14. Reference standards have been moved to Sec. 1. Electrode criteria and requirements for permanent and temporary attachment criteria have been revised. The type of inspection and number of weld joint inspections have also been updated for better quality control.
A new Sec. 15, entitled Structurally Supported Aluminum Dome Roofs, has been added. It provides the purchaser with the flexibility to choose an alternative roof system.
The entire standard was reviewed carefully, and minor changes were made in many of the sections to improve understanding and readability. Tabulated values and equations throughout this standard have been revised to include English and SI units of measurement. In the event of a discrepancy between the values, the English unit values shall govern.
IV.A. Comment Regarding Sec. 14. Advancements in production techniques for higher-strength steels, coupled with increasing production volumes, have resulted in
a reduction in the cost differential between high-strength and structural-grade steels. Consequently, the trend in the steel tank industry has been increasing application of the alternative Sec. 14 design procedure for welded standpipes and reservoirs, espe- cially in the case of larger structures. Although appendix C was made a part of the ANSI/AWWA D100 (AWS D5.2) standard for the 1984 revision while retaining its position as an appendix, it has now been placed in the standard as Sec. 14 to comply with AWWA’s standard procedures.
V. Comments. If you have any comments or questions about this standard, please call the AWWA Standards and Materials Development Department, (303) 794-7711, ext. 6283, FAX (303) 794-7310, or write to the department at 6666 W. Quincy Ave., Denver, CO 80235.
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American Water Works Association
ANSI/AWWA D100-96
(Revision of AWWA D100-84)
AWWA STANDARD FOR WELDED STEEL TANKS FOR WATER STORAGE
WELDED STEEL TANKS FOR WATER STORAGE
SECTION 1: GENERAL
Sec. 1.1 Scope
The purpose of this standard is to provide guidance to facilitate the design, manufacture, and procurement of welded steel tanks for the storage of water.
1.1.1 Tank roofs. All tanks storing potable water shall have roofs. Tanks storing nonpotable water may be constructed without roofs.
1.1.2 Items not covered. This standard does not cover all details of design and construction because of the large variety of sizes and shapes of tanks. Where details for any specific design are not given, it is intended that the constructor, subject to the approval of the purchaser, shall provide details that are designed and constructed to
be adequate and as safe as those that would otherwise be provided under this standard. This standard does not cover concrete-steel composite tank construction. *
Sec. 1.2 Definitions
The following definitions shall apply in this standard:
1.2.1 Capacity: The net volume, in gallons (litres), that may be removed from
a tank filled to top capacity level (TCL) and emptied to the bottom capacity level (BCL).
A separate AWWA standards committee has been appointed to develop an AWWA standard covering concrete-steel composite tank construction.
2 AWWA D100-96
1. In a ground-supported tank (reservoir or standpipe), the BCL shall be the water level in the tank shell when the tank is emptied through the specified discharge fittings, unless otherwise specified by the purchaser.
2. In an elevated tank, the elevation of the BCL or TCL shall be specified by the purchaser.
3. The TCL is the elevation to the lip of the overflow.
4. The BCL is the elevation above which the required capacity is provided.
5. The head range is the vertical distance between the BCL and the TCL.
1.2.2 Constructor: The party that furnishes the work and materials for place- ment and installation.
1.2.3 Elevated tank: A container or storage tank supported on a tower.
1.2.4 Manufacturer: The party that manufactures, fabricates, or produces materials or products.
1.2.5 Purchaser: The person, company, or organization that purchases any materials or work to be performed.
1.2.6 Reservoir: A ground-supported, flat-bottom cylindrical tank having a shell height equal to or smaller than its diameter.
1.2.7 Standpipe: A ground-supported, flat-bottom cylindrical tank having a shell height greater than its diameter.
1.2.8 Supplier: The party that supplies materials or services. A supplier may or may not be the manufacturer.
1.2.9 Tank: An elevated tank, a standpipe, or a reservoir.
Sec. 1.3 Guarantee
The constructor shall guarantee the structure against any defective materials or workmanship, including paint and painting if furnished by the constructor, for a period of one year from the date of completion. If any materials or workmanship prove to be defective within one year, they shall be replaced or repaired by the constructor.
Sec. 1.4 Drawings to Be Furnished
After award of the contract, the constructor shall submit foundation and tank construction drawings which shall bear the certification of a professional engi- neer licensed in the jurisdiction where the tank is to be erected. Where foundation and tank design are performed by separate parties, each party shall provide draw- ings bearing the certification of a licensed professional engineer. Construct-only con- tracts shall bear the professional engineering certification of the original designer or the purchaser’s engineer.
Drawings shall be submitted to the purchaser for approval before proceeding with fabrication. If waived by the purchaser, fabrication may proceed prior to approval of the drawings. If required by the purchaser, details of all welded joints shall be submitted for approval. Standard weld symbols as listed in ANSI/AWS 2.4 shall be used, unless joint details are shown.
Sec. 1.5 References
This standard references the following documents. In their latest editions, these documents form a part of this standard to the extent specified within the standard. In any case of conflict, the requirements of this standard shall prevail.
3 AA SAS * —Specifications for Aluminum Structures.
WELDED STEEL TANKS FOR WATER STORAGE
AAMA † 605.1—Voluntary Specification for High-Performance Organic Coatings on Architectural Extrusions. ACI ‡ 301—Specifications for Structural Concrete for Buildings. ACI 318—Building Code Requirements for Reinforced Concrete. ACI 349—Code Requirements for Nuclear Safety Related Concrete Structures.
Appendix B. AISC § (ASD)—Manual of Steel Construction (Allowable Stress Design) and Specification for Structural Steel Buildings—Allowable Stress Design and Plastic Design.
ANSI ** B16.5—Steel Pipe Flanges and Flanged Fittings. ANSI Z49.1—Safety in Welding and Cutting and Allied Processes. ANSI/AWS †† A1.1—Metric Practice Guide for the Welding Industry. ANSI/AWS A2.4—Standard Symbols for Welding, Brazing and Nondestructive
Examination. ANSI/AWS A3.0—Standard Welding Terms and Definitions Including Terms for Brazing, Soldering Thermal Spraying, and Thermal Cutting. ANSI/AWS A5.1—Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding. ANSI/AWS A5.5—Specification for Low Alloy Steel Electrodes for Shielded Metal Arc Welding. ANSI/AWS B2.1—Standard Welding Procedure Specification (WPS). ANSI/AWS D1.1—Structural Welding Code Steel. ANSI/AWS D1.2—Structural Welding Code Aluminum. ANSI/AWWA C652—Standard for Disinfection of Water-Storage Facilities. ANSI/AWWA D103—Standard for Factory-Coated Bolted Steel Tanks for Water
Storage. API ‡‡ SPEC 5L—Specification for Line Pipe. API STD 650—Welded Steel Tanks for Oil Storage. ASME SEC V—Boiler and Pressure Vessel Code, Nondestructive Examination. ASME §§ SEC VIII D1—Boiler and Pressure Vessel Code, Pressure Vessels,