What are the hard sealing materials for carbon steel ball valves

Carbon steel ball valve hard seal material types and applications
I. Hard alloy
‌Material properties‌
Hard alloy (such as tungsten carbide) is the core material of carbon steel ball valve hard seal, with a hardness of HRC60 or above, excellent wear resistance and corrosion resistance, especially suitable for high pressure (≥PN40) and particle-containing medium scenes.
Made by high temperature and high pressure process, it can withstand a temperature range of up to 425℃ and is stable in petroleum and chemical pipelines.
II. Stainless steel
‌Applicable scenarios‌
Stainless steel (such as 304/316) is often used for hard seals of small and medium-caliber carbon steel ball valves, taking into account cost-effectiveness and corrosion resistance, and is suitable for water, steam and weakly corrosive media.
Metal-to-metal sealing is achieved through precision machining, with low leakage rate and long maintenance cycle.
III. Alloy steel
‌High temperature and high pressure adaptability‌
Alloy steel (such as WC6, WC9) improves high temperature stability by adding elements such as chromium and molybdenum, and can be used for a long time under working conditions below 570℃, which is suitable for high temperature steam systems in refineries.
Surface plating or heat treatment can further extend the seal life and reduce high-temperature oxidation loss.
4. Nickel-based alloys
Extremely corrosive environments
Nickel-based alloys (such as Hastelloy) are used in strong acid, strong alkali or high chloride ion media, and their corrosion resistance far exceeds that of ordinary stainless steel, but the cost is relatively high.
The risk of seal failure can be significantly reduced in chemical reaction devices or seawater treatment systems.
5. Selection recommendations
Conventional working conditions: cemented carbide or stainless steel is preferred, taking into account both performance and cost; High temperature/particle-containing media: alloy steel or cemented carbide is more durable and needs to be combined with valve body heat treatment process; Strongly corrosive environment: Nickel-based alloy is the optimal solution, but the comprehensive economic efficiency needs to be evaluated.