Flanges by standard
AWWA C228 stainless steel flanges for water piping
AWWA C228 is the stainless steel counterpart to AWWA C207. It covers flat-faced ring slip-on and blind flanges for stainless water piping, useful where a data center runs stainless facility water mains or heat reuse lines at large diameters.
Choose AWWA C228 when a large stainless water main needs a lightweight flat-face flange rated for water pressures. Specify the class, SD being the usual one at 150 to 175 psi, the grade, and whether you need pickling and passivation.
Classes and ratings
| Class | Rated pressure |
|---|---|
| SA | 50 psi (3.4 bar) |
| SB | 86 psi (5.9 bar) |
| SD | 175 psi (12.1 bar) up to 12 in; 150 psi (10.3 bar) above 12 in |
| SE | 275 psi (19.0 bar) |
| SF | 300 psi (20.7 bar) |
The ratings mirror AWWA C207 for carbon steel, so a stainless C228 main and a carbon steel C207 main of the same class carry the same pressure.
What the standard covers
AWWA C228 covers stainless steel ring-type slip-on flanges and blind flanges from 2 to 72 inches, for waterworks service. The flanges are flat faced. For sizes 6 to 48 inches, the outside diameter and drilling follow the practice of AWWA C500 and the ASME B16.1 cast iron flange standard, so C228 flanges bolt to waterworks valves.
The ring flanges are designed to be welded to stainless pipe. They are not intended as loose backup flanges. If you want a loose flange over a stainless stub end, for example to rotate bolt holes into line on a skid, use a lap joint flange.
Send the class, type (ring slip-on or blind), size, pipe outside diameter and wall, grade and quantity. Add pickling and passivation to ASTM A380/A967 if the line carries treated or clean water.
Where it fits in a data center
- Stainless facility water mains from the central plant to the data halls
- Heat reuse connections that export warm water to district heating networks
- Water-side economiser and plate heat exchanger connections where the project chooses stainless
Frequently asked questions
Does AWWA C228 cover lap joint or backing flanges?
No. AWWA C228 covers stainless ring-type slip-on flanges and blind flanges for integral use on stainless pipe. Its foreword states the ring flanges are not for use as a loose backup flange. For a loose flange on a stainless stub end, specify a lap joint design.
Which classes does AWWA C228 define?
Five classes: SA at 50 psi, SB at 86 psi, SD at 175 psi up to 12 inches and 150 psi above, SE at 275 psi, and SF at 300 psi.
Are AWWA C228 flanges flat faced?
Yes. The standard is limited to flat-faced flanges, used with full-face gaskets such as rubber, compressed fibre or PTFE.