Valve Material Reference
ASTM A217 C12A Valve
Grade 91 Cast Steel (C12A)Grade 91 (9Cr-1Mo-V) cast alloy steel - the primary body material for ultra-high-temperature steam service in modern power plants, providing superior creep strength at 500-600°C compared to conventional chrome-moly grades.
Form
Cast
Max Temp
+650°C (+1200°F)
Min Temp
-29°C (-20°F)
Category
Alloy Steel
Chemical Composition - ASTM A217 C12A
Temperature Range
-29°C to +650°C (-20°F to +1200°F)
Maximum Temperature
+650°C (+1200°F)
Minimum Temperature
-29°C (-20°F)
Equivalent Grades - ASTM A217 C12A
| Standard | Equivalent Grade |
|---|---|
| ASTM forged | A182 F91 |
| EN | 1.4903 X10CrMoVNb9-1 |
| UNS | J84090 |
| DIN | P91 / T91 |
Suitable Services
Main steam isolation valves (MSIV) on ultra-supercritical power plants at 600°C / 250 bar
Hot reheat steam isolation valves on supercritical coal-fired boilers
High-pressure turbine bypass valves at 600°C main steam conditions
Feed water valve bodies in high-temperature nuclear power applications
Waste heat recovery steam generators (HRSG) outlet block valves
Not Suitable For
Service below -29°C - LTCS (A352 LCB/LCC) is required
Sour service with H2S - NACE MR0175 limits hardness to 22 HRC, Grade 91 typically exceeds this
When post-weld heat treatment (PWHT) at 730-780°C cannot be performed - critical for creep properties
Valve Body Applications
Gate valve bodies for main steam isolation at 600°C / Class 1500-2500
Globe valve bodies for turbine bypass and throttling in USC power plants
Check valve bodies in hot reheat steam lines at supercritical conditions
Trim Applications
Gate valve wedge with Stellite 6 overlay for high-temperature erosion resistance
Globe valve disc and seat overlaid with Stellite 21 for high-temperature service
Typical Valve Types in ASTM A217 C12A
Gate valves
Globe valves
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We supply ASTM A217 C12A (Grade 91 Cast Steel (C12A)) gate valves, globe valves, ball valves, check valves, and more. Full certification documentation - EN 10204 3.1/3.2 MTCs, hydro test certs - as standard.