Top-entry, all-metal, hard-sealed ball valves are the preferred choice for high-temperature, high-pressure environments; for ultra-high-temperature and extreme-pressure conditions, three-piece all-metal sealed ball valves are the recommended option.
Key Ball Valve Types
Top-entry high-temperature/high-pressure hard-sealed ball valve: Seals can be replaced in-line by opening the top cover without dismantling the pipeline. Suitable for extreme conditions exceeding Class 1500 pressure and 540°C temperature; a mainstream choice for petroleum hydroprocessing and thermal power main steam lines.
Three-piece forged steel metal hard-sealed ball valve: The center body can be removed entirely for in-line maintenance. Featuring metal self-tightening seats and Inconel stems, it withstands temperatures up to 900°C and pressures up to PN42 MPa (Class 2500), making it suitable for ultra-high-temperature conditions with thermal cycling.
Trunnion-mounted high-temperature/high-pressure ball valve: The preferred choice for large-bore (DN200 and above) high-pressure applications. The ball is fixed while the seat is floating and spring-loaded, offering superior pressure-bearing capacity compared to floating ball designs; suitable for large-bore high-pressure steam and oil/gas transmission lines.
Key Selection Criteria
Temperature ≤ 350°C: High-temperature elastomer-sealed ball valves are an option; they offer the lowest cost and meet requirements for standard medium-temperature, high-pressure conditions.
Temperature 350–550°C: Select metal hard-sealed ball valves; sealing surfaces feature Stellite alloy overlay or HVOF-sprayed tungsten carbide, achieving hardness levels exceeding HRC60.
Temperature > 540°C: An all-metal sealing structure is mandatory, combined with an extended stem and limit nut to prevent the stem from seizing the ball due to thermal expansion.
Pressure > Class 1500:Prioritize top-entry or fully welded structures to eliminate the risk of leakage from body-joint bolts.