Material Alloy Steel F91 (EN 1.4903) valves are made of high-temperature, creep-resistant chromium-molybdenum forged steel containing approximately 9% chromium, 1% molybdenum, and vanadium. They can withstand extreme pressures and temperatures up to 600°C–650°C, making them ideal for high-temperature steam media, such as high-pressure, high-temperature steam piping systems, power plants, and long-haul fossil fuel boilers.