1. Metal sealing materials
Stainless steel
F321 stainless steel: Contains titanium (0.8%), enhances resistance to intergranular corrosion, and is suitable for high-temperature steam, acid and alkali media (withstands 600°C continuous high temperature).
CF8C stainless steel: Contains niobium stabilization treatment, used in corrosive high-temperature environments such as molten salt systems (such as nuclear power and chemical plants), and has excellent resistance to chloride ion corrosion.
Hard alloy
Stellite: A high-hardness (HRC40-50) sealing surface is formed by surfacing or spraying, and the erosion resistance is improved by more than 3 times, which is suitable for high-pressure valves containing particulate media.
2. Non-metallic sealing materials
Polytetrafluoroethylene (PTFE)
Strong chemical stability, resistance to strong acids, strong alkalis and organic solvents, low friction coefficient, often used in scenarios requiring two-way sealing (such as pharmaceutical and food industries). Carbon graphite
Excellent self-lubricating performance, high temperature resistance (≤400℃), suitable for high-speed flow media (such as gas, high-temperature flue gas system), reducing opening and closing torque.
3. Composite sealing solution
PTFE+metal spiral wound gasket: a double sealing structure combining soft and hard, PTFE provides low friction seal, metal spiral wound gasket enhances high pressure stability (maximum pressure bearing 10MPa), suitable for oil and gas, chemical high-pressure pipelines.
Fluororubber coating + metal matrix: Fluororubber has outstanding oil resistance and temperature resistance (-20℃~200℃), and covering the metal sealing surface can extend the service life under corrosive media.
4. Material selection for special working conditions
High-temperature molten salt system: CF8C stainless steel or nickel-based alloy (such as Inconel 625) is required, which is resistant to molten salt corrosion and resistant to short-term high temperature impact of 800℃.
Nuclear-grade valves: Sealing surfaces are often made of titanium-stabilized stainless steel (such as 321, 347) or high-purity ceramic coatings, meeting the ASME B16.34 nuclear-grade standard.
Summary: The sealing surface material of the Y-type stop valve needs to be comprehensively selected based on the medium characteristics (corrosiveness, temperature, particle content) and pressure level. Metal materials focus on high pressure and high temperature resistance, while non-metallic and composite materials are suitable for precision sealing or complex chemical environments.
