Valves for Carbon Dioxide (CO₂) Service
CO₂ is used in supercritical extraction, fire suppression, EOR (Enhanced Oil Recovery), CCS (Carbon Capture Storage), and beverage carbonation. Dry CO₂ is relatively benign; wet CO₂ forms carbonic acid — highly corrosive to carbon steel.
Pressure Range
1–300 bar (beverage to CCS pipeline)
Temperature
-40°C (liquid CO₂) to 200°C (process)
Industries
Beverage / food, EOR (oil recovery), CCS / CCUS
Key Properties — Carbon Dioxide (CO₂)
- Dry CO₂: benign to carbon steel
- Wet CO₂ (CO₂ + H₂O): forms H₂CO₃ — corrosive
- Supercritical point: 31.1°C, 73.8 bar
- Dense phase CO₂ (CCS): high-pressure pipeline service
- CO₂ asphyxiant above 5% — risk in enclosed spaces
Material Compatibility — Carbon Dioxide (CO₂)
Ratings are indicative. Actual compatibility depends on concentration, temperature, velocity, and presence of contaminants. Always consult corrosion tables or a materials engineer.
| Material | Rating | Notes |
|---|---|---|
| Carbon Steel | Good | Dry CO₂ only. Wet CO₂ corrodes rapidly — specify corrosion inhibitor or upgrade material. |
| SS 316L | Excellent | Standard for wet CO₂ or food-grade CO₂ service. |
| Duplex 2205 | Excellent | CO₂ + H₂S service (EOR wells). Superior to 316L. |
| PTFE | Excellent | Seals and seats — chemically inert to CO₂. |
| Nitrile (NBR) | Fair | CO₂ causes explosive decompression in NBR at pressure cycling. Use HNBR or PTFE. |
| EPDM | Good | More resistant to explosive decompression than NBR. |
Recommended Valves
SS 316L ball valve
Food-grade or wet CO₂ — cleanable, zero crevices
ASME 2500 Class gate valve
Dense-phase CO₂ pipeline (CCS) at 150+ bar
Duplex check valve
EOR CO₂ injection — H₂S + CO₂ sour service
PTFE-seated ball valve
Supercritical CO₂ extraction systems
Valves to Avoid
NBR-sealed valves in pressure-cycling CO₂ (explosive decompression)
Carbon steel in wet CO₂ without corrosion inhibitor
Copper alloys (marginal but not preferred)
Special Considerations
Applicable Standards
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