I. Valve types suitable for high-pressure fluid conditions
For high-pressure fluid applications (usually referring to medium and ultra-high pressure conditions, such as pressure ratings of PN ≥ 1.6MPa or higher), the three types of valves are most commonly used and highly adaptable: wedge gate valves, forged steel globe valves, and high-pressure ball valves. The specific choice depends on the detailed operating conditions, as follows:
Wedge gate valve - the preferred choice for high-pressure large-diameter pipelines
Core strengths
They achieve self sealing through the "wedging effect" of wedge-shaped gate discs. The higher the medium pressure, the tighter the fit between the gate and valve body sealing surfaces, ensuring excellent sealing reliability. Low flow resistance, suitable for high pressure pipelines with large flow rates and diameters (such as long-distance oil and gas pipelines, power plant main steam pipelines).
Appropriate operating conditions
High pressure, high temperature, large diameter; Suitable for clean or mildly polluted gaseous/liquid media. They are mainly used for full switch control and are not suitable for flow throttling.
remark
Double disc wedge gate valve is preferred. Their spring compensation structure can adapt to thermal deformation under high pressure and prevent blockage.
Forged steel globe valve - the preferred choice for high pressure, small diameter, and precision throttling applications
Core strengths
The valve body is made of forged steel (such as A105, F11), which has much higher pressure resistance than cast steel and can withstand ultra-high pressure (up to PN100 and above). The sealing surface between the valve disc and the valve seat adopts line sealing to ensure stable sealing performance under high pressure. By controlling the lift height of the valve disc, the flow rate can be precisely adjusted, enabling the valve to perform on/off and throttling functions.
Appropriate operating conditions
High pressure, small diameter; Suitable for media such as steam, high-temperature oil products, high-pressure water, etc. They are commonly used for high-pressure auxiliary pipelines in chemical plants and power plant boilers.
remark
Their flow resistance is slightly higher than that of gate valves, making them unsuitable for high flow pipelines.
High pressure ball valve - the preferred choice for high pressure, high flow rate, and corrosive media applications
Core strengths
The ball and valve seat adopt surface contact sealing, which has excellent sealing performance under high pressure, low torque required for opening and closing, and easy operation. The valve stem adopts an anti spray structure with high safety. Some high-pressure ball valves use hard alloy sealing surfaces, which can resist corrosive high-pressure media (such as strong acids, strong alkalis) or media containing particles.
Appropriate operating conditions
Ultra high pressure (such as oil field injection wells, hydraulic systems, with pressures up to tens of MPa or higher), high flow rate; Suitable for corrosive fluids or fine particulate fluids. They have fast opening and closing speeds, suitable for high-voltage circuits that require frequent operation.
remark
Large diameter high-pressure ball valves have high costs and are generally used for small-diameter high-pressure pipelines.
2、 Key considerations for valve selection
Material Matching
For high-pressure conditions, the valve body is best made of forged steel (for medium and high pressure) or alloy steel (for ultra-high pressure). The sealing surface should be made of hard alloy (such as tungsten chromium cobalt alloy) to avoid sealing failure caused by high-pressure erosion.
structural design
Choose flange connection or welding connection; Prohibit threaded connections (prone to leakage under high pressure). The valve stem should be equipped with a lift indicator or anti rotation structure to prevent deformation under high pressure.
Detailed information on operating conditions
If the medium contains particles, wear-resistant high-pressure ball valves are preferred. If high temperature and high pressure resistance are required, wedge gate valves or forged steel globe valves are more suitable.
III、 Precautions for equipping electric actuators
When selecting electric actuators for valves under high pressure conditions, the core focus should be on four key dimensions: torque matching, structural safety, protection level, and control accuracy. This is to avoid valve opening/closing failures, seal damage, and even safety accidents caused by improper actuator selection. The specific considerations are as follows:

1. Accurate Torque/Thrust Calculation and Redundancy Design 1. Accurate Torque/Thrust Calculation and Redundancy Design
This is the core of actuator selection under high pressure conditions, as valve opening/closing resistance will significantly increase under high pressure. The key points are as follows:
Calculate actual opening/closing torque: Do not only refer to the rated torque on the valve nameplate. On the contrary, increase the additional pressure of high-pressure medium on the valve disc/gate disc, the frictional resistance of the sealing surface, and the frictional resistance of the valve stem packing. The opening/closing torque of high-pressure gate/globe valves is usually 2-5 times that of normal pressure. For ultra-high pressure conditions, separate torque verification is required.
Reserve sufficient safety redundancy: The rated torque of the actuator should be ≥ 1.5-2.0 times the calculated torque. Valves may become clogged under high pressure (e.g. due to deposition of impurities or thermal deformation), and redundant torque can prevent actuators from burning out due to overload.
Distinguish between "on/off torque" and "holding torque": After the high-pressure valve is closed, the medium pressure will continue to act on the sealing surface. The actuator must have sufficient pressure holding capacity to prevent the valve disc from being pushed away by reverse pressure and causing leakage.
2. Structural and material adaptability of actuators under high pressure conditions
Shell material and protection
The preferred actuator is one with a cast steel or stainless steel casing to prevent cracking of the casing caused by high-pressure pipeline vibration. The protection level should be at least IP67; For corrosive environments such as chemical plants and oil fields, it should be upgraded to IP68.
Valve stem connection structure
Use rigid key connection or flange connection; Prohibit pin connections (prone to breakage under high voltage). The output shaft of the actuator must have sufficient torsional strength to match the torque carrying capacity of the valve stem.
Explosion proof design
If the medium is flammable and explosive (such as high-pressure natural gas, oil), the actuator must comply with explosion-proof standards such as Ex d Ⅱ C T4 to prevent explosions caused by motor sparks.
3. Control functions and security protection mechanisms
Under high pressure conditions, the safety protection of actuators is more important than control accuracy. The following functions must be configured:
Overload protection: The built-in torque sensor or current overload protection device should automatically close the actuator when the valve is blocked, to prevent the actuator from burning out or the valve stem from breaking.
Dual protection of limit switches and torque limiters: Travel limit (controlling valve open/close position) and torque limit (preventing excessive torque) should be set to provide dual protection and avoid damage to the sealing surface due to excessive compression under high pressure.
Power outage protection: equipped with a power-off reset device or manual emergency operation mechanism. High pressure pipelines cannot remain uncontrolled for a long time; During power outages, it should be possible to manually open/close valves to ensure system safety.
Signal feedback: Output 4-20mA analog signal or switch signal to provide real-time feedback on valve opening and actuator operation status, facilitating remote monitoring of high-pressure systems.
4. Match special requirements for different valve types
Different high-pressure valves have different requirements for the actuator, requiring targeted selection:
High pressure wedge gate valve: The actuator should have high torque and slow opening/closing characteristics to avoid water hammer caused by rapid operation. Preferred multi turn electric actuators (such as Z-type).
High pressure shut-off valve: The actuator requires precise stroke adjustment capability; It is recommended to use intelligent electric actuators that support proportional control to adapt to throttling conditions.
High pressure ball valve: The actuator can have a relatively fast opening/closing speed, but must be equipped with a buffer device to prevent the ball from hitting the valve seat at high speed and damaging the high-pressure sealing surface. Preferred partial rotary electric actuators (such as Q-type).
5. Installation and maintenance precautions
During installation, ensure the coaxiality between the actuator and valve to avoid additional torque caused by eccentricity. High pressure pipelines will experience significant vibrations, therefore anti vibration brackets must be installed.
Regularly inspect the lubrication and sealing aging of the gearbox of the actuator. The failure rate of actuators under high pressure conditions increases with wear, therefore the maintenance cycle should be shortened.