PPL sealing and hard sealing for ball valves
Thread Content
For one project, the manufacturer suggested that when selecting valves, if a hard seal is used for the ball valve, zero leakage cannot be achieved; however, by using PPL (polyphenylene sulfide) for the valve seat, the operating temperature can reach 200°C and zero leakage can be attained. What are the advantages and disadvantages of PPL compared to hard seals?
If the temperature is below 260°C, ball valves made with PEEK sealing material can be used; this type of sealing material can withstand temperatures of around 300°C for a short period of time. However, for use in media at temperatures above 260°C over a long period of time, metal hard-sealed ball valves are the only option.
It depends on temperature and pressure; if the pressure is not high and the temperature is high, PPL material, which is a polyphenylene material, can indeed achieve zero leakage. Hard-sealed versions in China cannot achieve zero leakage.
With these temperature conditions these days, achieving a level 6 seal performance for both soft-sealed and hard-sealed systems is not difficult at all; even some small workshops can do it. However, although some hard-sealed systems meet the required standards at the time of production, things may not go as well once they are installed in pipelines. So, PPL remains the reliable choice
With a hard-sealed design, six-stage leakage is not an issue even after 50,000 cycles of opening and closing. The key is to be able to charge a proper price; imported sand is used during grinding, but this also depends on the design pressure of the valve