Valves for High-Pressure Steam Service
Steam is the most common industrial utility fluid. High-pressure steam (above 50 bar) requires ASME Class 600+ valves with hardened trim to resist erosion. Drain and condensate traps are critical to prevent water hammer.
Pressure Range
1–300 bar
Temperature
100–650°C
Industries
Power generation, Petrochemical, Refinery
Key Properties — High-Pressure Steam
- Erosive at high velocity — hardened trim required
- Thermal shock from cold water contact causes cracking
- High-temp steam oxidises carbon steel surfaces
- ASME B31.1 (Power Piping) governs boiler steam systems
- Water hammer destroys valve internals rapidly
Material Compatibility — High-Pressure Steam
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 WCB / A105 | Good | Up to ~425°C. Standard for steam to ASME Class 600. |
| Chrome-Moly (1¼Cr-½Mo, 2¼Cr-1Mo) | Excellent | For high-temperature steam above 425°C. ASTM A217 WC6/WC9. |
| SS 316H (high-carbon) | Good | Austenitic SS for steam above 540°C — superior creep resistance. |
| P91 (9Cr-1Mo-V) | Excellent | Ultra-high temperature steam above 560°C — power plant main steam. |
| PTFE seats | Poor | Not recommended above 200°C. Use metal-seated valves for HP steam. |
Recommended Valves
Globe valve (OS&Y, rising stem)
Standard for HP steam throttling and control
Gate valve (rising stem, OS&Y)
Full-bore isolation in steam mains — AS B31.1
Check valve (swing or piston type)
Essential on boiler feed — prevents backflow on trip
Safety relief valve (direct-acting spring)
ASME Section I/VIII SRV — mandatory on every steam drum and vessel
Control valve (cage-guided globe)
Letdown stations — high ΔP throttling with anti-cavitation trim
Valves to Avoid
PTFE-seated ball valves above 200°C
Soft-seated butterfly valves for HP steam
Non-OS&Y gate valves (cannot visually confirm position)
Wafer butterfly valves between pipe flanges in steam mains
Special Considerations
Applicable Standards
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