What is the main difference between AWWA C207 and AWWA C228?

The primary difference is material and coating strategy. AWWA C207 uses zinc-coated (galvanized) carbon steel for general water systems, providing cost-effective corrosion protection. AWWA C228 uses stainless steel (typically 304/316L) for environments with high chloride or acidic conditions where galvanizing alone is insufficient. Choose C207 for inland freshwater systems; choose C228 for coastal, brackish, or corrosive environments.

Can I use AWWA C207 flanges instead of ASME B16.5 in water systems?

Not in all cases. AWWA C207 is specifically designed for waterworks applications and uses different pressure class designations, coating requirements, and gasket standards (AWWA C209). ASME B16.5 is for general industrial piping. While dimensions may be similar for some sizes, the specifications differ in pressure ratings, materials, and design intent. Always use the standard specified in your system design. Many water utilities mandate AWWA standards for compliance.

What is the benefit of epoxy coating over galvanizing?

Epoxy coating (AWWA C213) provides superior protection in aggressive water conditions and protects both interior and exterior surfaces comprehensively. However, epoxy costs more than galvanizing. Galvanizing is adequate for most freshwater systems and is more economical. For coastal areas, high-temperature water, or aggressive chemistry, epoxy is the preferred option. Service life for both coatings depends on environmental conditions.

Do AWWA flanges work with standard industrial bolts?

AWWA C207 and C228 typically specify stainless steel bolts and fasteners to avoid galvanic corrosion where dissimilar metals contact. Using regular carbon steel bolts on galvanized AWWA C207 flanges can create corrosion problems over time. Always use fasteners meeting AWWA requirements. If substituting bolts, verify material compatibility with your engineer.

What temperature range are AWWA C207/C228 flanges rated for?

AWWA flanges are optimized for water temperatures typically ranging from -20°F to 250°F. Higher temperatures can affect gasket and coating performance. AWWA standards do not address high-temperature steam or process heat applications. For hot water, hot oil, or steam service, consult ASME B16.5, which extends to 850°F.

Are AWWA gaskets different from standard gasket materials?

Yes. AWWA C209 specifies gasket materials formulated for potable water compatibility and non-corrosive service. Common AWWA gasket materials include nitrile and EPDM rubber, chosen for water compatibility. Industrial ASME B16.5 applications may use different gasket materials (graphite-filled, spiral wound, etc.). Always match gaskets to the flange standard and confirm potable water approval when required.

AWWA C207 & C228 Flange Standards

Complete technical guide to American Water Works Association flange standards for water and waterworks applications

AWWA Flange Standards Overview

The American Water Works Association (AWWA) develops standards specifically for water transmission, distribution, and treatment systems. AWWA C207 and C228 are the primary flange standards covering flanged steel pipe for waterworks. These standards differ significantly from general industrial standards like ASME B16.5 because they address the unique demands of water systems.

AWWA standards mandate corrosion protection (galvanizing or stainless steel), establish potable water-safe materials, and specify pressure classes optimized for water system economics. If you're specifying flanges for a waterworks project, AWWA standards are typically required for regulatory compliance and system reliability.

Two Standards for Different Needs

AWWA C207

Steel pipe flanges with galvanized or epoxy coating for general water systems. Sizes 4" to 144", Classes B/D/E/F.

AWWA C228

Stainless steel pipe flanges for corrosive or brackish water environments. Sizes 2" to 72", Classes 125/150/200 PSI.

Why Water Utilities Use AWWA Standards

• Regulatory requirement in many jurisdictions
• Ensures long-term corrosion resistance in water environments
• Guarantees potable water safety of all materials and coatings
• Optimizes cost for typical water operating pressures (100-350 PSI)
• Specifies stainless steel fasteners to prevent galvanic corrosion

AWWA C207: Steel Pipe Flanges for Waterworks

AWWA C207 specifies flanged steel pipe fittings for waterworks systems. Available in carbon steel with galvanized or epoxy coating, these flanges are designed for water transmission, distribution, and treatment applications. The standard covers pipe sizes from 4 inches to 144 inches with four pressure classes.

Pressure Classes (AWWA C207)

Class	Design Pressure	Size Range	Face Type	Primary Uses
Class B	86 PSI	up to 144"	Flat Face	Low-pressure water transmission
Class D	175 PSI	up to 144"	Flat Face	Standard water distribution (most common)
Class E	275 PSI	up to 144"	Flat Face	High-pressure water transmission lines
Class F	300 PSI	up to 48"	Flat Face	Maximum pressure waterworks service

Class D (Most Common)

Class D at 175 PSI is the industry standard for most water distribution systems. It represents the optimal balance between pressure capability and cost for typical municipal water operations.

✓Most sizes available in stock
✓Economical for large-diameter systems
✓Adequate for most transmission lines
✓Interchangeable with most utility networks

Class B vs. Class E/F

Class B (86 PSI)

For low-pressure applications; less common due to economic constraints.

Class E (275 PSI)

For high-elevation systems and long-distance transmission with pressure boost.

Class F (300 PSI)

Premium high-pressure service; used in critical transmission bottlenecks.

Frequently Asked Questions

Common questions about AWWA C207 and C228 flange standards

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