AWWA Standard flange

Download AWWA C200 steel water pipe

AWWA Flange Standards differ from ANSI (American National Standards Institute) and ASME (American Society of Mechanical Engineers) certifications in a variety of ways, the most important being their specificity: AWWA standards evaluate properties that particularly affect potable water use, as opposed to broader industrial flange applications.

AWWA Flange Charts and Drawings

These tolerances are a part of ANSI B16.5 and AWWA C207-01 Sec. 4.2 except where noted otherwise.
AWWA Ring Flanges

Our company provides an array of AWWA flanges to meet your application's specifications.

General Information

American Water Works Association (AWWA) is an international non-profit, scientific and educational association founded to improve water quality and supply. Established in 1881, it has a membership (as of 2012) of around 50,000 members worldwide.

Dimensional tolerances

Ring type Slip-on and Blind flanges HUB type slip-on
O.D. <=24" +/- 0.6"(1.6mm) O.D. <=24" +/- 0.6"(1.6mm)
>24" +/- .12"(3.2mm) >24" +/- .12"(3.2mm)
I.D. Socket-Welding 10" and Samller
I.D. 10" and Samller +.03"(0.8mm)
Slip-on and
Lap Joint
12" and Larger
12"-18" +/-.06"(1.6mm)
20"-42" +.12"(3.2mm)
O.D. of Hub <=12" +.09"(2.4mm),
Diameter of
Contact Face
0.06" Raised Face +/-.03"(0.8mm)
14"-42" +/-.12"(3.2mm)
Diameter of Contact face 0.06" Raised Face +/- .03"(0.8mm) Diameter of Hub at base X<=24" +/-.06"(1.6mm)
X>24" +/-.12"(3.2mm)
Deameter of Contact face <=10" +.03"(0.8mm),
Diameter of Hub at point of Welding <=5" +.09"(2.4mm),
12"-42" +.06"(1.6mm),
>=6" +.16"(4.0mm),
Drilling Bolt Circle 1/2"-24"
Drilling Bolt Circle 1/2"-24"
Bolt hole
Bolt hole
Eccentricity of Bolt circle with respect to bore .03" Max.
Eccentricity of Bolt circle with respect to bore .03" Max.
Thickness 18"& Small +.12"(3.2mm),-0" Thickness 18"& Small +.12"(3.2mm),-0"
20"-42" +.19"(1.6mm) 20"-42" +.19"(1.6mm)
Length Thru Hub <=10" +/-.06"(1.6mm) Length Thru Hub <=10" +/-.06"(1.6mm)
12"-42" +/1.12"(3.2mm) 12"-42" +/1.12"(3.2mm)

These tolerances are a part of ANSI B16.5 and AWWA C207-01 Sec. 4.2 except where noted otherwise.  The limits given are maximum.  Rigid inspection procedure assures the maintenance of high standards of accuracy in regular day to day production.

AWWA Vs. ANSI Flange Standards

Both the AWWA and ANSI have thorough standards for flanges, and the two standards are different in several ways. AWWA standards provide flange properties intended for potable water use only. In contrast, ANSI standards are aimed at industrial flange applications.

  1. Ring flanges available overbored or counterbored per customer specification.
  2. Bolt holes shall be drilled 1/8th inch larger in diameter than the nominal diameter of the bolt, except for flanges larger than 84 inch in diameter which shall be drilled 3/16th inch larger than the nominal diameter of the bolt.
  3. Drilling same as ANSI/ASME B16.1 125 lb and B16.5 150 lb pattern.
  4. Flanges available overdrilled to accommodate insulators.
  5. AWWA recommends the use of dished head assemblies as alternate to blind flanges, sizes over 72" nominal.
  6. AWWA C207-01 Class B and D Hub Flanges are identical to Industry Standard Class 125 Light Weight Flanges.


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