Which to choose, hard seal or soft seal? ?
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Select an O-type ball valve； Medium: Dry HCL gas Pressure: 1.0 MPa Temperature: 30 degrees Diameter: DN150 ； Previously, we used grade 6 hard-sealed ball valves (imported); now we want to acquire one. Most domestic ones can only reach grade 4 in terms of hard sealing, and in special cases grade 5 is possible, but they are very expensive! I’m a bit hesitant about using a soft seal; mainly, I don’t understand why a hard seal was chosen in the initial design – was it for safety reasons? Is it possible to use a soft seal instead? ? Solve.....
With dry HCL at 30 degrees Celsius and a pressure of 1 Mpa, in a DN150 setup, there aren’t any major issues; the corrosivity isn’t very high either. A PTFE soft seal should work fine. Let’s discuss this further with the design team Is it because the manufacturer charges high fees for the selection and design of instruments?
The main differences between hard-sealed and soft-sealed valves lie in their corrosion resistance and the service life of their sealing surfaces; depending on your application, what should be given priority to is the valve’s pressure rating.
Based on the operating conditions of the valve, a soft seal can definitely be used. At the same time, hard seals require high standards for assembly – they are usually ground one by one, making it difficult to match them properly. If there is welding slag or other impurities inside the pipe, these can easily scratch the sealing surface during the operation of the hard-sealed ball valve, and such damage is often difficult to repair. As a result, the required level of leakage control cannot be achieved. In such cases, soft seals can be used; for the operating conditions described, polytetrafluoroethylene soft seals are more than sufficient to meet the requirements, and they also help to extend the valve’s service life and facilitate maintenance.
Considering diameter, pressure rating, temperature, and medium, it is appropriate to choose a floating ball valve with a soft seat. It is recommended that you verify again whether the temperature and pressure curve of the valve seat (which is presumed to be fine) meets the requirements.
From a process conditions perspective, soft seals should have been used from the start!
Our company specializes in imported seals from Germany, focusing on seals designed for extremely low temperatures of -270°C, as well as for ultra-high temperatures of +1100°C. They are also suitable for high pressures up to 680 MPa, and for applications requiring exceptional corrosion resistance. We offer both dynamic and static seals; the dynamic seals can handle speeds of up to 40 m/s (or even higher). For more information, please contact 18678860293 via VX
Wuxi KOSO offers both hard-sealed and soft-sealed versions that can meet your requirements. As it is a Japanese-owned company operating in China, its products are cheaper than imported ones, but slightly more expensive than domestic alternatives.
There’s nothing special about temperature and pressure
It falls under normal operating conditions, and soft seals can be used as a substitute; the sealing performance of soft seals is better than that of hard seals, and they are also much cheaper than hard-sealed valves that are in use