Wide Variety of AWWA Pipe Flanges

flanges come in a huge amount of variety. In this article, we look at some of this variety which is on offer, delving into the unique attributes of each.

What is AWWA?

The American Water Works Association, formed in 1881, was developed to identify and unify major requirements for waterworks systems. Today, the international association serves non-profit, educational, and scientific roles to improve and support water quality and supply around the world.

Members of AWWA include water treatment plant management and operations teams, water utility organizations, manufacturers, scientists and environmentalists, regulators, academics, and researchers in the fields of water supply and public health. North America alone is home to 43 distinct AWWA Sections.

AWWA’s standards program began in 1908 with development and research to support regulatory standards for products, processes, and best practices. This invaluable reference is now recognized globally as a key source for scientific and management insight for water supply.

AWWA Standards

With over 150 Standards, AWWA supports a full range of water supply practices, equipment, and components. In addition to Standards, waterworks specialists will find AWWA support covering:

  • Water treatment chemicals
  • Filtration materials
  • Meters and measures
  • Disinfection practices
  • Valves
  • Storage tanks of all sizes
  • Utility management practices
  • Pumps
  • Pipe and Fittings
AWWA Certified Flange Types

Unlike ANSI and standards, AWWA Flange Standards do not address welded auxiliary connections or tapping. They cover a very specific range of flange types, including:

  • Slip-on Ring and Hub Type Flanges, fitted over a pipe
  • Blind Flanges, to seal or close a pipe or vessel
  • Threaded Iron Flanges, fitted to externally threaded pipes
Material Grades and Performance

The AWWA Standards program covers pipes, flanges, and fittings in all manner of materials, including:

  • Plastic
  • Ductile iron
  • Steel and stainless steel
  • Concrete
  • Asbestos-cement

AWWA C207 does not require a specific grade of steel, so long as the flange meets minimum standards for physical and chemical properties. These properties include:

  • .05% Sulfur (maximum)
  • .04% Phosphorus (maximum)
  • .29% Carbon (maximum)
  • 50,000 psi Tensile (minimum)
  • 32,000 psi Yield (minimum)
Industries and Applications

The waterworks-specific AWWA Standard Flanges have been developed to meet light duty applications, typically requiring performance at or below 300 psi. The most common pressure range is AWWA Class D, rated at 175 psi for sizes under 12 inches and 150 psi for larger sizes.

Common applications of AWWA Flanges include:
  • Waterworks
  • Slurry
  • Waste water
  • Plant piping

As a low pressure piping solution, AWWA Standard Flanges can be an effective cost saver over ANSI or ASME forged flanges. These flanges, designed for oil, steam, or chemical applications and their demand for high pressure, are typically more expensive and less necessary for low pressure piping.

At the end, you will have a very good perspective on the different kinds of pipe flanges that are prevalent in the market as well as the exceptional value that comes with every one of them.

  • AWWA C207 Class D-Rings and Blinds
    C207 Class D-Rings and Blinds AWWA flanges between 4 and 12 inches are meant for pressure ratings of up to 175 psi while those 14 inches and above are meant for pressure ratings of up to 150 psi. These rings and blinds range from 2 to 144 inches in nominal size with an outside diameter anywhere between 6 and 167.25 inches. The number of bolt holes on them can range from 4 to 84.
  • AWWA C207 Class E-Rings and Blinds
    AWWA C207 Class E-Rings and Blinds are meant for pressure ratings of up to 275 psi. These rings and blinds range from 4 to 144 inches in nominal size with an outside diameter anywhere between 9 and 167.25 inches. The number of bolt holes on them can range from 8 to 84.
  • AWWA C207 Class F-Rings and Blinds
    AWWA C207 Class F-Rings and Blinds are meant for pressure ratings of up to 300 psi. These rings and blinds range from 4 to 48 inches in nominal size with an outside diameter anywhere between 10 and 65 inches. The number of bolt holes on them can range from 8 to 40.
  • AWWA C207 Class B-Rings and Blinds
    C207 Class B-Rings and Blinds AWWA flanges are meant for pressure ratings of up to 86 psi. These rings and blinds range from 4 to 144 inches in nominal size with an outside diameter anywhere between 9 and 167.25 inches. The number of bolt holes on them can range from 8 to 84.
  • AWWA C207 Steel Hub Flanges
    AWWA C207 Steel Hub Flanges can include Table 3 Class D flanges meant for pressure ratings between 150 – 175 psi, as well as Table 4 Class E flanges, meant for pressure ratings of up to 275 psi. These steel hub flanges range from 4 to 96 inches in nominal size with an outside diameter anywhere between 9 and 113.25 inches. The number of bolt holes on them can range from 8 to 68.
  • AWWA C228 SF Stainless Steel Ring Flanges
    C228 SF Stainless Steel Ring AWWA flanges are meant for pressure ratings of up to 300 psi. These stainless steel ring flanges can range from 4 to 48 inches in nominal size with an outside diameter anywhere between 10 and 65 inches. The number of bolt holes on them can range from 8 to 40.
  • AWWA C228 SA/SB/SD/SE Stainless Steel Ring Flanges
    When we talk about C228 SA/SB/SD/SE Stainless Steel Ring AWWA flanges, each class or sub-class has its set of pressure ratings that, in this case, are 50, 86, 150 and 275 psi respectively for SA/SB/SD/SE stainless steel ring flanges. These stainless steel ring flanges can range from 2 to 72 inches in nominal size with an outside diameter anywhere between 6 and 86.5 inches. The number of bolt holes on them can range from 4 to 60.
  • AWWA C228 Stainless Steel Blind Flanges
    Like the previous set of C228 SA/SB/SD/SE Stainless Steel Ring AWWA flanges that we discussed above, AWWA C228 Stainless Steel Blind Flanges also come in the same set of sub-classes that have their own set of pressure ratings which in this case are also 50, 86, 150 and 275 psi respectively for SA/SB/SD/SE stainless steel blind flanges. These stainless steel blind flanges range from 2 to 66 inches in nominal size.
American Waterworks (AWWA) C207 and C228 Pipe Flanges

The AWWA C207 specification does not require a specific grade of steel. Instead it establishes minimum physical and chemical properties as follows:

  • Minimum Tensile  50,000 psi
  • Minimum Yield 32,000 psi
  • Elongation 2″ – 18%; 8″ – 14″
  • Maximum Carbon .29%
  • Maximum Phosphorus .04 %
  • Maximum Sulfur .05 %

Frequently used materials might include: A-36 or A-283 plate steels or A181 or forged steel meeting the requirements of AWWA C207.

Flange Facing

Flange Face Surface Finish

Flanges shall have a serrated finish of approximately 24 to 55 grooves per inch resulting in a 125-500 RMS surface finish. Serrations may be spiral or concentric. Other types of facings are also available upon request. AWWA flanges are normally supplied as flat faced, unless raised face is specified by customer.

Drilling Templates

Drilling templates are in multiples of four so that fittings may be made to face any quarter. Bolt holes straddle the center line. For flanges up to 84″ holes are drilled 1/8 inch larger in diameter than the diameter of the bolt. For flanges larger than 84″ holes are drilling 3/16″ larger than the bolt diameter. Bolt holes may also be oversized by an additional 1/8″ to accommodate insulators or to facilitate alignment.

Flange Marking

CAB flanges are customarily stamped with the trademark, nominal size, class, material designation and heat.

Flange Tolerances

  • Inside Diameter + 1/16″ – 0
  • Outside Diameter +- 1/8″
  • Thickness (18″ and smaller) + 1/8″ -0
  • Thickness (20″ and larger) +3/16″ -0
  • Bolt Circle Diameter +- 1/16″
  • Bolt Hole Spacing +- 1/32″
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