ANSI Class 150 vs Class 300: Pressure-Temperature Selection Guide
Technical guide · Supreme Valves India · 2026
ANSI Class 150 is the most common pressure rating for butterfly, gate, and check valves in water, fire protection, and HVAC. ASME B16.34 defines pressure-temperature limits — at ambient temperature, Class 150 carbon steel allows approximately 285 PSI working pressure before de-rating for elevated temperature.
Class 150 vs Class 300
Upgrade to ANSI Class 300 when the piping specification, flange rating, or hydrocarbon service requires higher pressure capability or metal-seated high-performance designs.
Common Class 150 butterfly end types
- Wafer — sandwiched between flanges
- Lug — dead-end service capability
- Double flanged — large bore waterworks