Summary of Standards for Ductile Iron Pipe and Ductile Iron Fittings
Most of the standards covering pipe and fittings manufactured by American Cast Iron Pipe Company have been prepared by the American Water Works Association Standards Committee A21. Other applicable standards generally cover specialties or refer to ANSI standards.
In order to take advantage of modern metallurgical science, better testing methods, improved production control, materials with better physical properties, and improvements in manufacturing methods, the A21 Committee has a continuing program for keeping its standards revised to include the latest proven developments.
Development of Standards
The AWWA Standards Committee A21 on Ductile and Gray Iron Pipe and Fittings was organized in 1926 under the procedures of the American Engineering Standards Committee. It was reorganized under American Standards Association Procedures in 1955, and in 1984 it became a member of the AWWA committee structure.
The Committee is responsible for the development of standards and manuals for ductile iron pressure pipe for water and other liquids and for fittings used with such pipe. The Committee’s membership is comprised of representatives from consumer groups, producer groups and general interest groups, including a number of professionals from AMERICAN.
A standard, manual or revision is developed by a subcommittee assigned to that task. The subcommittee prepares and submits the document to the Standards Committee for approval. After approval it is then submitted to the AWWA Standards Council for approval. After all approvals have been received, including a public review by both AWWA and ANSI, the standard, manual or revision is published and made available to the public.
Abbreviations of Organizations
The following is a list of the organizations referred to in this and other sections of this website by abbreviation.
|AASHTO||American Association of State Highway and Transportation Officials|
|ACI||Alloy Casting Institute|
|AISI||American Iron and Steel Institute|
|ANSI||American National Standards Institute|
|API||American Petroleum Institute|
|ASCE||American Society of Civil Engineers|
|ASME||American Society of Mechanical Engineers|
|ASTM||American Society for Testing and Materials|
|AWWA||American Water Works Association|
|BSI||British Standards Institute|
|DIPRA||Ductile Iron Pipe Research Association|
|DIS||Ductile Iron Society|
|ISO||International Organization for Standardization|
|MIL||United States Military|
|NEWWA||New England Water Works Association|
|WEF||Water Environment Federation|
A brief review of the older specifications in chronological order may help define their usefulness, as well as help in the appreciation of the improved modern standards.
The basis for design in almost all specifications to date is the Barlow formula, or “Hoop Stress” formula. It embodies the basic principle for design of a cylinder for internal pressure. The formula may be stated as:
in which t is the thickness of the pipe in inches; P is the internal pressure in pounds per square inch (psi); D is the outside diameter in inches; and S is the allowable working stress of the metal in pounds per square inch.
In the development of the design of cast iron pipe, this formula has been modified in several ways by prominent water works engineers such as Allen Hazen, Thomas H. Wiggin, James T. Fanning, Dexter Brackett, I. J. Fairchild and James P. Kirkwood. Mr. Kirkwood, as chief engineer for the Brooklyn Water Works, developed a design for cast iron pipe which was a variant of the Barlow formula. Kirkwood’s calculations took into consideration casting imperfection, strength of the metal and other factors affecting the life of the pipe. In the late 1880s, a formula by Dexter Brackett, distribution engineer for the City of Boston, was adopted by the New England Water Works Association as their standard.
Although the 1902 NEWWA standards did not provide a formula for pipe thicknesses, the Brackett formula was used in determining the thicknesses recommended.
The AWWA in 1908 adopted a standard covering bell and spigot pipe produced in 12-foot laying lengths by the pit casting method. Prior to 1908, at least two unofficial documents dealing with pipe design were acknowledged by AWWA. The first of these used thicknesses for pipe determined by averaging the thicknesses used in a large number of American cities. The second dealt with actual design of pipe based on Brackett’s method with variations.
The 1908 AWWA standards employed a system of class designations applied to specific wall thicknesses in diameters 4" through 84" inclusive for a range of hydraulic heads. The most common of these classes were A, B, C and D for 100-, 200-, 300- and 400-feet hydraulic head, respectively. The design was based on a variation of the Brackett formula by J. T. Fanning and included a variation in the outside diameter for the different classes of pipe. The basic design of pipe with a different outside diameter for each class was followed in modern specifications until the 1961 revisions. The general acceptance by the water works industry of the standardized mechanical joint necessitated a universal outside diameter for cast iron pipe.
AWWA revised their standards in 1939 to incorporate a new method of designing cast iron pressure pipe. This new method was published as ANSI A21.1. The A21.1 method of determining the required thickness of cast iron pipe took into consideration trench load and internal pressure in combination. Trench load consists of the earth load on the pipe plus any transient load resulting from traffic over the trench; internal pressure consists of the design working pressure plus an additional allowance for surge pressure. Laying conditions and properties of the iron in the pipe are also factors involved in the design. Additions for casting tolerance are included in the design thickness. With the advent of ductile iron pipe and its flexibility, this additive method of design became obsolete. As noted in the following paragraph, ductile iron design employs flexible conduit principles since the internal pressure relieves the external load.
Actually, the first standard covering centrifugally cast pipe was issued by the U.S. government in 1927, and was known as the Federal Specification No. 537. In July 1931, the specification was revised to include pipe cast centrifugally in sand-lined molds, pipe cast centrifugally in metal molds, and pit cast pipe. This specification has been modified several times and is now basically the same as ANSI/AWWA Standards.
Development of ductile iron in the 1950s initiated research into design of ductile iron pipe to take advantage of the superior flexibility, strength, toughness, impact resistance and corrosion resistance of this new metal. The A21 Committee issued the ANSI A21.50 (AWWA H3-65) and ANSI A21.51 (AWWA C151) Standards for ductile iron pipe in 1965. The work of Prof. M. G. Spangler and others at Iowa State University on flexible conduit is the basis for principles that have been applied extensively by the designers of flexible underground pipe. The design principles and procedures for ductile iron pipe that were included in the ANSI Standard A21.50 (AWWA C150) were verified by actual trench tests at AMERICAN and by tests conducted by various researchers. AMERICAN’s technical director, Dr. Ed Sears, was instrumental in these developments.
Continued research on ductile iron pipe reflects through these updated standards the advancements in metallurgical technology and manufacturing skills. Furthermore, the quality of AMERICAN’s products and conformance to appropriate specifications are assured by the British Standards Institute’s certification that AMERICAN’s quality system complies with ISO 9001 Quality Management System Standard.
AMERICAN also subscribes to NSF’s listing program for products under ANSI/NSF Standard 61—Drinking Water System Components—Health Effects. Check with AMERICAN for current listing of our products.
Standards Applicable to AMERICAN Pipe and Fittings
Throughout this website, Standards may be referred to as listed below or by only the ANSI, AWWA, ASTM, NSF, ASME, etc. numbering.
|Ductile Iron Pipe for Water and Other Liquids||Standards|
|4" through 64"||ANSI/AWWA C150/A21.50|
|Ductile Iron Gravity Sewer Pipe||Standards|
|4" through 64"||ASTM A746|
|Ductile Iron Culvert Pipe||Standards|
|14" through 64"||ASTM A716|
|Ductile and Gray Iron Fittings for Water and Other Liquids||Standards|
|4" through 48"||ANSI/AWWA C110/A21.10|
|Ductile Iron Compact Fittings||Standards|
|4" through 64"||ANSI/AWWA C153/A21.53|
|4" through 64"||ANSI/AWWA C115/A21.15|
|Coatings and Linings||Standards|
|Cement Lining||ANSI/AWWA C104/A21.4|
|Fusion-Bonded Epoxy||ANSI/AWWA C116/A21.16|
|Ceramic Epoxy Lining||PROTECTO 401|
|Coal Tar Epoxy Lining||PROTECTO 401|
|Polyethylene Encasement||ANSI/AWWA C105/A21.5|
|Joints — Pipe and Fittings||Standards|
|Grooved and Shouldered||AWWA C606|
Other joints shown in this section are AMERICAN design.
|All Products1||ANSI/NSF Standard 61|
NOTE: Many AMERICAN joints, classes of pipe, fittings and specials are listed by Underwriters Laboratories Inc. and FM Global. The quality of AMERICAN’s products and conformance to appropriate specifications are assured by the British Standards Institute’s certification that AMERICAN’s quality system complies with ISO 9001 Quality Management System Standard.
Standards for the Design, Manufacture, Installation and Certification of Ductile Iron Pipe and Ductile Iron Fittings
|ANSI/AWWA C104/A21.4||Cement-Mortar Lining for Ductile-Iron Pipe and Fittings for Water|
|ANSI/AWWA C105/A21.5||Polyethylene Encasement for Ductile-Iron Pipe Systems|
|ANSI/AWWA C110/A21.10||Ductile-Iron and Gray-Iron Fittings, 3 in. through 48 in., for Water|
|ANSI/AWWA C111/A21.11||Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings|
|ANSI/AWWA C115/A21.15||Flanged Ductile-Iron Pipe with Ductile-Iron or Gray-Iron Threaded Flanges|
|ANSI/AWWA C116/A21.16||Protective Fusion-Bonded Epoxy Coatings for the Interior and Exterior Surfaces of Ductile-Iron and Gray-Iron Fittings for Water Supply Service|
|ANSI/AWWA C150/A21.50||Thickness Design of Ductile-Iron Pipe|
|ANSI/AWWA C151/A21.51||Ductile-Iron Pipe, Centrifugally Cast for Water|
|ANSI/AWWA C153/A21.53||Ductile-Iron Compact Fittings, for Water Service|
|ANSI/AWWA C600||Installation of Ductile-Iron Water Mains and Their Appurtenances|
|ANSI/AWWA C606||Grooved and Shouldered Joints|
|ASTM A674||Polyethylene Encasement for Ductile Iron Pipe for Water or Other Liquids|
|ASTM A716||Ductile Iron Culvert Pipe|
|ASTM A746||Ductile Iron Gravity Sewer Pipe|
|ANSI/NSF 61||Drinking Water System Components—Health Effects|
|ASTM G62||Standard Test Methods for Holiday Detection in Pipeline Coatings|
The following standards are related to ductile iron and gray iron piping and other products, but are generally not directly applicable to the manufacture of AMERICAN pipe and fittings.
|ANSI A40.5||Threaded Cast-Iron Pipe for Drainage, Vent, and Waste Services|
|ANSI/ASME B1.1||Unified Inch Screw Threads (UN and UNR Thread Form)|
|ANSI/ASME B16.1||Cast Iron Pipe Flanges and Flanged Fittings, Class 25, 125, 250 and 800|
|ANSI/ASME B16.3||Malleable-Iron Threaded Fittings, 150 and 300 lb.|
|ANSI/ASME B16.4||Cast-Iron Screwed Fittings, 125 and 250 lb.|
|ANSI/ASME B16.5||Pipe Flanges and Flanged Fittings|
|ANSI B16.12||Cast Iron Threaded Drainage Fittings|
|ANSI B16.14||Ferrous Pipe Plugs, Bushings, and Lock-nuts with Pipe Threads|
|ANSI B16.21||Nonmetallic Flat Gaskets for Pipe Flanges|
|ASME/ANSI B16.42||Ductile Iron Pipe Flanges and Flanged Fittings|
|ANSI B18.2.1||Square and Hex Bolts and Screws (Inch Series)|
|ANSI/ASME B18.2.2||Square and Hex Nuts (Inch Series)|
|ANSI B31.1||Power Piping|
|ANSI/ASME B31.8||Gas Transmission and Distribution Piping Systems|
|ANSI/ASME B1.20.1||General Purpose Pipe Threads|
|ANSI/AWWA C207||Steel Pipe Flanges for Waterworks Service, 4” through 144”|
|ANSI/AWWA C500||Gate Valves, 3” through 48” NPS for Water and Sewage Systems|
|ANSI/AWWA C501||Sluice Gates|
|ANSI/AWWA C502||Dry-Barrel Fire Hydrants|
|ANSI/AWWA C503||Wet-Barrel Fire Hydrants|
|ANSI/AWWA C504||Rubber-Seated Butterfly Valves|
|ANSI/AWWA C508||Swing-Check Valves for Ordinary Waterworks Service|
|ANSI/AWWA C509||Resilient-Seated Gate Valves for Water and Sewage Systems|
|ANSI/AWWA C550||Protective Interior Coatings for Valves and Hydrants|
|ASTM A48||Gray Iron Castings|
|ASTM A74||Cast Iron Soil Pipe and Fittings|
|ASTM A126||Gray Iron Castings for Valves, Flanges, and Pipe Fittings|
|ASTM A278||Gray Iron Castings for Pressure-Containing Parts for Temperatures Up to 650°F (345°C)|
|ASTM A319||Gray Iron Castings for Elevated Temperatures for Non-Pressure Containing Parts|
|ASTM A377||Standard Index of Specifications for Ductile Iron Pressure Pipe|
|ASTM A395||Ferritic Ductile Iron Pressure Retaining Castings for Use at Elevated Temperatures|
|ASTM A438||Transverse Testing of Gray Cast Iron|
|ASTM A476||Ductile Iron Castings for Paper Mill Dryer Rolls|
|ASTM A518||Corrosion-Resistant High-Silicon Iron Castings|
|ASTM A536||Ductile Iron Castings|
|ASTM A571||Austenitic Ductile Iron Castings for Pressure Containing Parts Suitable for Low-Temperature Service|
|ASTM C150||Portland Cement|
|ASTM D1248||Polyethylene Plastic Molding and Extrusion Materials|
|ASTM E8||Tension Testing of Metallic Materials|
|AASHTO M64||Cast Iron Culvert Pipe|
|AASHTO M105||Gray Iron Castings|
|AWWA D100||AWWA Standard for Welded Steel Tanks for Water Storage|
1 Check with AMERICAN for current NSF listing of AMERICAN products.