Why this matters
If you are buying valves for any high-integrity piping system, the line-item that decides whether the valve is fit-for-service is the ASME B16.34 rating. B16.34 is the umbrella standard that ties pressure class, material group, design temperature and dimensional / NDE / marking requirements together for cast, forged and fabricated steel and alloy valves with flanged, threaded or weld ends. Misreading the pressure-temperature chart is one of the easiest ways to over- or under-buy a valve.
Scope comparison
| Aspect | B16.34 coverage |
|---|---|
| Pressure classes | 150, 300, 600, 900, 1500, 2500, 4500 |
| Material groups | Group 1 (carbon and low-alloy steel), Group 2 (austenitic and duplex stainless), Group 3 (nickel and nickel alloys) |
| End connections | Flanged, threaded, butt-welded, socket-welded |






