A hard-seal butterfly valve is a butterfly valve where both sides of the sealing surface are made of metal or other relatively hard materials. Its working principle is that rotating the valve stem drives the butterfly plate to rotate, thereby opening and closing the valve. During rotation, the butterfly plate drives the valve seat to rotate as well, creating a seal between the butterfly plate and the valve seat. When the butterfly plate rotates to 90°, the valve is fully open, at which point the only resistance to fluid flow is the thickness of the butterfly plate, resulting in very low flow resistance.
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Hard sealed butterfly valve specification
Nominal Diameter: DN50～DN1000
Seat Seal: Alloy, Stellite, Stainless Steel
Nominal Pressure: 1.0Mpa～4.0Mpa
Connection Type: Wafer, Flange
Applicable Temperature: -20ºC～+150ºC～425ºC
Actuation Method: Manual, Worm Gear, Pneumatic, Electric
Valve Body Material: Cast Steel, Stainless Steel
Manufacturing Standard: GB (Chinese National Standard), DIN (German Standard), API (American Standard), ANSI (American Standard)
Applicable Media: Water, Oil, Steam, Gas, Powder, Liquid
Wide Applications: Petroleum, Chemical, Power, Environmental Protection, Water Conservancy, Heating, Water Supply and Drainage, Industrial, Machinery
Hard sealed butterfly valve Structural Features
The structural features of the hard-seal butterfly valve include:
Rational design, compact structure, small size, light weight, and easy installation and operation.
The sealing surface is made of metal material, precision machined and ground to ensure an extremely low leakage rate even under high pressure differentials.
The ingenious wedge design gives the valve an automatic sealing function that tightens as it closes, with compensatory sealing surfaces achieving zero leakage.
The unique three-way eccentric design eliminates friction between the sealing surfaces, extending the valve's service life.
Analysis of the Core Features and Advantages/Disadvantages of Hard-Seal Butterfly Valves
1. Core Advantages
(1) Excellent Wear Resistance
The sealing pair is made of hard material, which can resist the erosion of media containing solid particles, fibers, or suspended matter. It is suitable for highly abrasive working conditions such as slurry, ash, and mud. For example, in the desulfurization system of a power plant, when conveying slurry containing gypsum particles, the service life of a hard-seal butterfly valve can be 3 to 5 times that of a soft-seal butterfly valve.
(2) High Temperature and High Pressure Resistance
Temperature Range: Generally can withstand -20℃ to 450℃ (depending on the material, such as ceramic seals which can withstand higher temperatures), far exceeding the upper temperature limit of soft-seal butterfly valves (generally ≤200℃);
Pressure Rating: Can meet the high pressure requirements of PN16~PN100 (or even higher), suitable for scenarios such as oil pipelines and steam networks.
(3) Reliable sealing and long service life
The metal sealing surface is not easily aged or deformed due to changes in medium temperature or long-term use. Especially under high pressure, it can achieve "self-sealing" through medium pressure, resulting in low leakage (usually meeting the API 598 standard VI sealing requirements).
(4) Wide range of applicable media
It can be used for water, steam, oil, acidic and alkaline media, and fluids containing particles. Especially in corrosive environments, the durability can be significantly improved by selecting corrosion-resistant alloys (such as 316L and Hastelloy).
2. Limitations
(1) High processing cost
The cutting and grinding of hard materials is difficult, requiring the use of special tools and precision equipment (such as a five-axis machining center), resulting in higher manufacturing costs than soft-seal butterfly valves.
(2) Large opening and closing torque
The friction coefficient between the metal sealing surfaces is high, especially under high-pressure conditions, requiring a more powerful actuator, increasing installation space and cost.
(3) Limited Low-Temperature Sealing Performance
Some metal materials may become brittle at low temperatures (e.g., ordinary stainless steel below -100℃), requiring the selection of low-temperature steels (e.g., LCB, LC3) or special sealing structures.
(4) Limited Adjustment Accuracy
The linear relationship between the butterfly valve's rotation angle and flow rate is not as strong as that of ball valves or regulating valves; therefore, careful selection is necessary in precise flow control scenarios.
Hard sealed butterfly valve Performance Characteristics
High Temperature Resistance: Due to the metal sealing surface, the hard-seal butterfly valve has high high-temperature resistance, maintaining a stable sealing effect in high-temperature environments.
Wear Resistance: The excellent wear resistance of the metal sealing material extends the service life of the hard-seal butterfly valve, reducing the frequency of replacement and maintenance.
Good Mechanical Properties: The hard-seal butterfly valve has high mechanical strength and rigidity, capable of withstanding large pressures and torques.
Hard sealed butterfly valve factory
GNEE Group owns hundreds of valve production and testing equipment, and provides customized valve services-send us your drawings, and we'll tailor-make them for you.