AWWA Standard flange

Since the first edition of the AWWA Standard C207 was printed in 1952, AWWA flanges have commonly been used in waterworks, wastewater, slurry, plant piping, and other light duty applications. Pressure ratings for AWWA flanges range from the Class B flange rated at 86 psi to the Class F flange rated at 300 psi. The AWWA C207-01 standard describes two types of slip-on flanges, ring type and hub type that may be used interchangeably if the dimensions given in the standard are used. The standard also describes blind flanges. Flanges described in the AWWA C207-01 tables are intended for use with steel pipe, fittings or appurtenances meeting the requirements of ANSI/AWWA C200, ANSI/AWWA C208, ASTM A134, ASTM 139, or other equivalent standards. It is further intended that these flanges be attached by welding in accordance with AWWA C207-01 Sec.4.3.

Dimensional tolerances

Pressure Ratings

As per AWWA C207-01 Sec. 1.3, the pressure ratings listed for AWWA Class B, D, E and F flanges are for conditions and temperatures customary in water utility services. The pressure ratings for the flange should be based on the design of the maximum operating pressure plus the anticipated sure pressure. Test pressures should not exceed 125 percent of the ratings. Flange design is based on pressure considerations, not for stresses induced by external moments when pipe acts as a beam. The tables of the AWWA C207-01 standard have been developed using a design stress of 16,000 psi for the working pressure design.

Flange Material

As per AWWA C207-01, Sec 4.1, flanges shall be made from seamless forgings, cut from plate as a single piece, welded bar rings or segmented and welded plates as per C207-01 Sec 4.2.4.

Forgings shall meet the minimum requirements or ASTM A105 or A181.

Steel plate or bar used in the manufacture of flanges shall meet the following requirements:

1. Tensile strength = 50,000 psi (345 mpa) (min.)
2. Yield strength = 32,000 psi (221 mpa) (min.)
3. Carbon = 0.29 percent (max.)
4. Phosphorous = 0.04 percent (max.)
5. Sulfur = 0.05 percent (max.)

Plate steel designations that will meet the previously listed requirements include but are not limited to the following designation:

1. A36
2. A516, grade 60, 65, and 70

Pacific Coast Flange Inc will provide mill test reports showing conformance to the physical and chemical requirements for all flanges ordered.

Flange Facing

As per AWWA C207-01 Sec 4.2.2, all AWWA flanges shall be flat-faced without projection or raised area of face. Either a serrated concentric or serrated spiral finish having from 24 grooves per inch to 470 grooves per inch shall be used. The cutting tool employed shall have an approximate 0.06 inch or larger radius. The resultant surface finish shall have a 250 to 500-uin. roughness.

Drilling Templates

As per AWWA C207-01 Sec. 4.2.3 drilling templates are in multiples of four so that fittings can be make to face any quarter. Bolt holes shall straddle the center line, except where special mating conditions exist and shall be drilled 1/8 in. (3.2mm) larger in diameter than the nominal diameter of the bolt, except on flanges larger that 84 inches (2,100mm) diameter, bolt holes shall be drilled 3/16 inches (4.8mm) larger than the nominal bolt diameter. Bolt holes may be over drilled by an additional 1/8 in (3.2mm) to accommodate insulators or to facilitate alignment with the mating flange.

Flange Marking

Flanges shall be steel stamped with the trademark, nominal size, class, material designation and material heat number.

Standards, Dimensions & Weight  AWWA Class B-Ring and Blind Flanges AWWA Class B-Hub and Blind Flanges AWWA Class D-Ring and Blind Flanges AWWA Class D-Hub and Blind Flanges AWWA Class E-Ring and Blind Flanges AWWA Class E-Hub and Blind Flanges AWWA Class F-Ring and Blind Flanges

+ General Information + AWWA Flange Dimensional tolerances

AWWA Class B-Ring and Blind Flanges

As per AWWA C207-01 Sec. 1.3, the pressure ratings listed for AWWA Class B, D, E and F flanges are for conditions and temperatures customary in water utility services. The pressure ratings for the flange should be based on the design of the maximum operating pressure plus the anticipated sure pressure. 
Test pressures should not exceed 125 percent of the ratings. Flange design is based on pressure considerations, not for stresses induced by external moments when pipe acts as a beam. The tables of the AWWA C207-01 standard have been developed using a design stress of 16,000 psi for the working pressure design.

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.

AWWA Class D-Hub and Blind Flanges

Since the first edition of the AWWA Standard C207 was printed in 1952, AWWA flanges have commonly been used in waterworks, wastewater, slurry, plant piping, and other light duty applications. Pressure ratings for AWWA flanges range from the Class B flange rated at 86 psi to the Class F flange rated at 300 psi. The AWWA C207-01 standard describes two types of slip-on flanges, ring type and hub type that may be used interchangeably if the dimensions given in the standard are used. The standard also describes blind flanges. Flanges described in the AWWA C207-01 tables are intended for use with steel pipe, fittings or appurtenances meeting the requirements of ANSI/AWWA C200, ANSI/AWWA C208, ASTM A134, ASTM 139, or other equivalent standards. It is further intended that these flanges be attached by welding in accordance with AWWA C207-01 Sec.4.3.

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.

AWWA Class D-Ring and Blind Flanges

The blind flange is used to close ends of piping systems. It is a kind of round plate with no center hold but with all the proper bolt holes. This blind flange is available in various sizes and materials and is used to provide positive closer on the ends of pipes, valves or equipment nozzles.

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.

Dimensional tolerances for AWWA pipe flanges

Listed below are the Dimensional Tolerances to which flanges are manufactured.  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.

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 +.03"(0.8mm),-0"	I.D.	10" and Samller	+.03"(0.8mm)
	Slip-on and Lap Joint	12" and Larger +.06"(1.6mm),-0"		12"-18"	+/-.06"(1.6mm)
				20"-42"	+.12"(3.2mm) +.06"(1.6mm)
O.D. of Hub	<=12"	+.09"(2.4mm), -.06"(1.6mm)	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), -0"	Diameter of Hub at point of Welding	<=5"	+.09"(2.4mm), -.03"(0.8mm)
	12"-42"	+.06"(1.6mm), -0"		>=6"	+.16"(4.0mm), -.03"(0.8mm)
Drilling	Bolt Circle	1/2"-24" /26"-42"	Drilling	Bolt Circle	1/2"-24" /26"-42"
		+/-.06"(1.6mm) +/-.06"			+/-.06"(1.6mm) +/-.06"
	Bolt hole spacing	+/-.03"(0.8mm)		Bolt hole spacing	+/-.03"(0.8mm)
	Eccentricity of Bolt circle with respect to bore	.03" Max. (0.8mm)		Eccentricity of Bolt circle with respect to bore	.03" Max. (0.8mm)
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)