Classification of main materials for high-pressure gate valves
1. Shell material
Carbon steel
Applicable to non-corrosive media (such as steam and petroleum products) with a temperature of -29℃～425℃. Common grades include WCB (ZG250-485), WCC (ZG275-485) and ASTM A105 forged steel.
Alloy steel (chromium-molybdenum steel)
Resistant to high temperature and high pressure (-29℃～650℃), suitable for thermal power generation and high-pressure scenes in refineries. Typical grades are WC6 (ZG15Cr1Mo1V), WC9 (ZG20CrMo) and ASTM A217 standard steel.
Austenitic stainless steel
Used for both high-pressure and corrosive media (such as acidic oil and gas), austenitic stainless steels such as 304 and 316 are commonly used, with excellent stability under high temperature environment.
2. Valve stem material
Chromium-molybdenum steel
High strength and erosion resistance, such as alloy steels such as 25Cr2MoV, suitable for high-pressure frequent opening and closing scenarios.
Stainless steel
304 and 316 stainless steels have both corrosion resistance and mechanical strength, and surface nitriding can improve abrasion resistance.
3. Sealing surface material
Hard alloy
Surface cladding of Stellite alloy (Stellite 6/12) or tungsten carbide coating improves wear resistance and erosion resistance.
Stainless steel composite layer
Iron-based nickel-chromium alloy cladding is used to balance corrosion resistance and processing economy.
4. Pressure-bearing fasteners
Alloy steel bolts
Commonly used high-strength alloy steels such as 35CrMo and 42CrMo are suitable for high-pressure sealing requirements of mid-flanges.
Low-temperature alloy steel
For extremely low-temperature and high-pressure working conditions (such as -196℃ liquid nitrogen), A193 B7 or A320 L7 materials are selected.