The core difference between soft-seal ball valves and hard-seal ball valves

1. Sealing performance
Soft-seal ball valve: Excellent zero leakage level. The flexible material exhibits strong conformability, achieving complete zero leakage under conventional operating conditions. With a sealing level up to Class VI, it is the preferred choice for clean media and low leakage requirements.
Hard-seal ball valve: micro-leakage, slightly weak sealing performance. Metal hard contact cannot eliminate microscopic gaps, resulting in slight leakage under conventional operating conditions. The sealing level is mostly IV-V, which cannot meet the stringent zero-leakage requirement.
2. Temperature and pressure resistance
Soft-seal ball valve: The upper limit of operating conditions is low. Due to the heat resistance limitations of rubber and PTFE materials, the applicable temperature range is generally -40℃ to 180℃, and it is not resistant to high temperatures. The pressure rating is medium, suitable for medium and low-pressure conventional pipelines. Under high pressure, the sealing material is prone to extrusion deformation, failure, and leakage.
Hard-seal ball valve: Highly adaptable to working conditions. Made of metal, it is resistant to high temperatures, high pressures, and deformation, with an applicable temperature range of -196℃ to 600℃. It can adapt to high and ultra-high pressure conditions above 16MPa, and exhibits outstanding resistance to pressure shock and thermal deformation.
3. Medium adaptability
Soft-seal ball valve: It is only suitable for clean, particle-free, and non-abrasive media, such as clear water, pure water, clean gas, and conventional oils. Sediment, impurities, and hard particles in the medium can directly scratch the soft sealing surface, resulting in permanent sealing failure. At the same time, it is not resistant to strong corrosion and high-temperature media, and is prone to aging and swelling.
Hard seal ball valve: suitable for complex and harsh media, capable of withstanding particles, dust, slurry, high-temperature steam, strong corrosion, and high-viscosity media, resistant to wear, erosion, and anti-aging, with almost no limitations in media adaptation.
4. Service life, operation, and maintenance
Soft-seal ball valve: The sealing components are prone to aging, wear, and fatigue. Under long-term start-stop operations and temperature fluctuations, they experience rapid wear and tear, resulting in a medium service life. Regular replacement of sealing gaskets and valve seats is required, leading to a high frequency of operation and maintenance. However, the maintenance cost is low, and replacement is convenient.
Hard seal ball valve: The metal sealing surface is wear-resistant and resistant to damage, with no aging issues. It has high mechanical strength, impact resistance, and erosion resistance, with a service life far exceeding that of soft seal products. It has strong long-term operational stability and basically requires no frequent maintenance; however, once the sealing surface is worn, it is difficult and costly to repair.
5. Operating torque and cost
Soft-seal ball valve: It features an elastic fit with low resistance, light torque for opening and closing, and can be adapted to small electric and pneumatic actuators. The overall equipment cost is low, and the cost-performance ratio is high.
Hard seal ball valve: Due to the large friction force caused by the rigid metal fit, the opening and closing torque is high, requiring a high-power actuator. Additionally, the processing and grinding processes are complex, leading to higher overall manufacturing costs and equipment prices.