For valves operating at 260°C, such as soft-seal shut-off valves (taking ball valves as an example), what are the suitable materials for the valve seat and the packing?

I checked online, and it seems that copolymerized phenylene PPL may be more heat-resistant than PEEK; I’m not sure if there are any manufacturers that produce pneumatic shut-off ball valves made from this material

This post was last edited by shiwendong on 2018-8-19 23:17. Pneumatic emergency shut-off valves, with actuators of the Israeli Habonim type or American PERKER type. Medium used: Specifications: Single-acting or double-acting. Requirements for solenoid valve brands: Requirements for air filter brands:

The ultimate temperature of PEEK is 260°C; it’s better to use a metal seal.

It seems that ball valve manufacturers rarely consider using polyphenylene sulfide for valve seats – is it because its hardness is greater than that of PEEK? After checking, it appears that PEEK actually has higher hardness.

Metal sealing is preferred; if a soft seal must be used, PEEK should be employed for the seal, flexible graphite for the packing, and perfluoroelastomer for the O-ring

PPL can be used for polyphenylene alignment, provided that imported brands are chosen; they are expensive. Domestically produced PPLs do not meet quality standards; they cannot withstand large temperature differences, but of course they are much cheaper.

There are significant differences in the performance of PPL and PEEK materials available online. I have communicated with several valve manufacturers, and some of them can use these materials while others cannot. The quality of the raw materials and the manufacturer play an important role here. I have used both hard-sealing and soft-sealing solutions in my work; I am responsible for preparing the specification documents, which generally state the following: 1. For soft-sealing solutions using PPL or PEEK, the manufacturer must provide reports on their performance under pressure and temperature conditions, for review by the client. 2. For hard-sealing solutions using +HF, these options are recommended by the supplier, who also provides the necessary certification documents. If the number of valves is small, it is safer to use hard-sealing solutions throughout

It’s hard to say what the leakage level is for hard-sealed valves; many valves are of VI grade right after leaving the factory, but will they still be at VI grade after 3 months? The leakage level of soft seals is still much better.

I work in the oil and gas field services industry. For high-temperature operating conditions, the only option we have is molecular sieve-based pressure reduction and regeneration systems. Ball valves used for switching between high-temperature low-pressure and high-pressure normal-temperature conditions require strict sealing standards, while those used in other scenarios don’t have such stringent requirements. Theoretically, soft seals provide better sealing performance； But there are no special requirements; hard-sealed valves work just fine as well. For our CL2500 high-pressure welded ball valves used at the wellhead, hard-sealed valves are employed, although owners usually specify imported ones