AWWA C207 is a standard for carbon steel ring flanges for waterworks service, providing guidelines for the design, materials, dimensions, and testing of flanges used in water systems. The C207 standard includes several classes of flanges (B,D,E, and F), each designed to handle different pressure ratings. These flanges are made from carbon steel (such as ASTM A36 or ASTM A105).
Class B is a specific pressure class (86psi) with a matching dimensional system:
| NPS | OD (in) | ID (in) | THK (in) | Bolt circle (in) | # Holes | Hole Ø (in) |
|---|---|---|---|---|---|---|
| 4 | 9.00 | 4.57 | 0.625 | 7.50 | 8 | 0.750 |
| 6 | 11.00 | 6.72 | 0.688 | 9.50 | 8 | 0.875 |
| 8 | 13.50 | 8.72 | 0.688 | 11.75 | 8 | 0.875 |
| 12 | 19.00 | 12.88 | 0.688 | 17.00 | 12 | 1.000 |
| 16 | 23.50 | 16.19 | 0.688 | 21.25 | 16 | 1.125 |
| 24 | 32.00 | 24.19 | 0.750 | 29.50 | 20 | 1.375 |
* The ID values shown in the table refer to slip-on ring flange dimensions.
| NPS | OD (in) | THK (in) | Bolt pattern (BC / holes × hole Ø) |
|---|---|---|---|
| 4 | 9.00 | 0.625 | 7.50 / 8 × 0.750 |
| 6 | 11.00 | 0.688 | 9.50 / 8 × 0.875 |
| 8 | 13.50 | 0.688 | 11.75 / 8 × 0.875 |
| 12 | 19.00 | 0.688 | 17.00 / 12 × 1.000 |
| 16 | 23.50 | 0.688 | 21.25 / 16 × 1.125 |
| 24 | 32.00 | 0.750 | 29.50 / 20 × 1.375 |
See the full size range and specs:
A Slip On Flange is a type of pipe flange that is slipped over the end of a pipe and welded in place.
A Blind Flange is a detachable sealing device used to block off a pipeline or to create a stop.
AWWA C207 covers sizes 4 in through 144 in (100 mm through 3,600 mm) for steel pipe flanges in waterworks service.
No.
AWWA C207 states its pressure ratings are for conditions and temperatures customary in water utility service and should be based on maximum operating pressure plus anticipated surge. They are not ASME-style pressure–temperature tables.
AWWA C207 covers carbon steel flanges, while AWWA C228 covers stainless steel flanges for the same applications. Both define dimensions, pressure classes, and material requirements.
These ratings apply to water service and depend on flange size and material.
API International stocks the pipe sizes, pressure classes, and materials you need for your project. Our machine shop can also modify stock products to accommodate any special project requirements. Contact API International’s experienced sales team, and we will help you select the right flange for your application.
API International is a premier manufacturer and engineering solutions provider that specializes in flanges, expansion joints, valve accessories, and precision-engineered piping components. By offering a wide variety of both AIS/BABA-compliant (Domestic) and imported products, we provide the flexibility and speed the industry demands. Our customers rely on us for more than just parts; they choose us for our superior technical support, rapid national distribution, and commitment to project-critical deadlines. Contact our expert sales team at 503.692.3800 to discuss your next project’s specifications or to request a quote.
• Custom Bolt Holes, Overbore, Counterbore, Tapped, Welds, O-ring Grooves, Threads, Special Serrations, Bevels, Chamfers
• Metric Parallel, Metric Tapered, Parallel (BSPP), Taper Thread (BSPT), UN/UNF/UNC Thread, NPT (National Pipe Thread)
• MWD
• Contact API’s engineering department for exact specifications and tolerances.
Plastic: Delrin, POM, Lexan, Nylon 66, Nylon 6, PEEK, PP, PE, Acetal
Rubber: EPDM, Neoprene, Buna-N, Viton
Aluminum: A2011, A2024, A2017, A5052, A5056, A6061, A6063, A6463, A6082, A7075
Copper: 3600, 3604, 3771
Titanium: 1-28
Steel Series:
• Ductile Iron: ASTM A536
• Carbon/Mild Steel: A105, A36, A516-70, A572-50, etc.
• Stainless Steel:
- 300 Series – 303, 304, 304L, 316, 316L
- 400 Series – 420J2, 430, 434, 442
Special Metals: Hastelloy, Inconel, Incoloy, Duplex 2205, Super Duplex 2507, Chrome Steel, alloys, or their equivalents
Stock Finish, Spiral Serrated (Phonographic), Concentric Serrated, Smooth Finish, Cold Water Finish, MWD, Phonographic
Dipped, Nickel Plating, Zinc Plating (clear, yellow, black, red, blue), Super Agitine, Powder, Painted, Galvanized, Epoxy, Lacquer
Water/Wastewater, Irrigation, Agriculture, HVAC, Marine, Exhaust, Mining, Energy/Power Generation/Oil
• Forged:
- Ring Rolling:
• Materials: Carbon Steel, Stainless Steel, Duplex
• Size: 2–202”
• Cast:
- Centrifugal Casting (Industrial):
• Material: Stainless Steel
- Continuous Casting:
• Stainless Steel
- Sand Casting:
• Material: A536, Stainless Steel, Ductile Iron
- Investment/Lost-Wax/Precision Casting
• Stainless Steel
Machining: Milling, Turning, Facing, Boring, Drilling, Tapping, Counter Sinking, Laser Cutting, Water Jet, Plasma Cutting
Products | Type | Materials | Size Range |
|---|---|---|---|
Flanges | Flat-Face, Raised-Face, & Plate: Slip-On/Ring Weld, Neck, Blind, Socket Weld, Orifice, Reducing, Threaded | See Materials List | 5–202″ |
Gaskets | Molded, Extruded, sheet | EPDM, Buna-N, NBR, Non-Asbestos (GNA), Red Rubber (GRR), Viton | 5–60″ |
Screens For Filters | Basket Screens and Cone Screens (Perforated, Mesh) | Galv. Carbon Steel, Carbon Steel, Stainless Steel | 6”D x 8’-H |
Rings | Exhaust Rings (Marmon Flanges for DPF Filters) | Carbon Steel, Stainless Steel, Aluminum | 1–16” |
Seamless Rolled Rings | Forged | Carbon Steel, Stainless Steel, Aluminum | 1–165” |
Square Hole Rings | Repair Couplers | Stainless Steel, Carbon Steel, Galvanized, Epoxy Coated | 3–32” |
Fabricated Assemblies | Weldments, Pipe Spools, Valve Bodies, Silencer Housings | Carbon Steel, Stainless Steel | 2–24” |
Long/Short Radius Elbows | EN 10253-2–S235, P235GH–P265GH–P265NL and ASTM A234, WPB, WPC/ A420 WPL6, WPL3/ A860 WPHY52/ ASTM A234 WP11, WP22, WP5, WP9–16Mo3 | 304L & 316L Stainless Steel | (45° & 90°): OD: 21.3mm (1/2”)–3048mm (120”) WT: Up to SCH. XXS/160 |
Miscellaneous | Tubesheets / Diffuser Plates / Baffles / Ferrules / Sleeves / Pins | Carbon Steel, Stainless Steel, Duplex | 5–104” |
Who we are
API International is a manufacturer and engineering solutions provider that specializes in flanges, expansion joints, valve accessories, other pipe fittings, and custom-fabricated parts. We offer a wide variety of AIS & imported flanges along with other industrial pipe fittings and accessories. Customers turn to us when they need quick delivery of parts and are looking for a higher level of customer service. Standard parts are stocked in one of our conveniently located warehouses for quick distribution throughout the United States.
