WC hardness HRC65–75, wear resistance best, suitable for containing >25% particle medium, lifespan improves 3 times but cost high about 20%; Stellite hardness HRC40–50, temperature
In API 6D ball valves: WC coating hardness reaches HRC65–75, suitable for containing 30–40% solid particles medium, wear resistance lifespan improves 3–5 times; but temperature
Under harsh working conditions, tungsten carbide valve seat usually more wear-resistant, hardness can reach HRA 88~92, lifespan often compared to Stellite increased by 2~5 times;
Under strict inspection requirements, forged valve body is better: density ≥ 98%, tensile strength increased by 20%~30%, airtight leakage rate ≤ 1×10⁻⁶. Cast parts easily
When valve body and valve cover need 100% RT inspection, casting pass rate is about 85%-90%, rework cost is high; Forging internal is dense, RT
RT inspection is radiographic flaw detection, used to discover cast steel valve internal porosity, shrinkage and other defects. According to standard (such as ASTM E446),
In export projects, forged valve body strength is high (tensile strength ≥450MPa), suitable for high pressure (>PN100) European and American markets; Cast valve body cost
Cast valve body cost is lower by about 20%-30%, suitable for complex structures, but easy to have blowholes, strength slightly lower; Forged valve body density
Engineering inside often uses two single ball valves replace double ball valve is because maintenance more flexible, single valve failure can alone replace, stopping machine
Double ball valve suitable for needs double isolation’s working conditions, like oil gas conveying pressure ≥4MPa or toxic medium pipeline, often used for maintenance venting
