What type of packing is used for valves that can handle temperatures of 400 degrees?

How about this one? ? ------------------------ Flexible graphite packing rings: 1. Flexible graphite packing rings are made by molding flexible graphite strips or woven flexible graphite packing (packing material) into rings of various sizes. This ring possesses good resilience and chemical stability, enabling effective sealing. It is easy to install and can also be used in combination with other end rings; even under harsh conditions, the flexible graphite ring remains highly stable and reliable. It is often used in combination with reinforced flexible graphite rings, yielding more significant results. 2. It is suitable for media such as hot water, high-temperature steam, high-pressure steam, heat exchange fluids, ammonia, hydrogen, organic solvents, hydrocarbons, and cryogenic liquids. 3. Used in compressors, pumps, valves, chemical instruments, meters, etc. It is produced by chemically treating high-carbon phosphorus flake graphite and then subjecting it to high-temperature expansion rolling. It is the basic material for manufacturing various graphite seals. 4. Main uses: It can be used to manufacture various graphite strips, fillers, gaskets, composite sheets, cylinder gaskets, etc. Used for sealing various pipes, valves, pumps, heat exchangers, condensers, pressure vessels, towers, manholes, and handholes at flange connections, as well as for gaskets in water level gauges, level indicators, crystallizers, etc. 5. Characteristics: Operating temperature range of -200°C to 1650°C (in non-oxidizing media) ； -200°C～950°C (in an oxidizing medium).

The information about graphite mentioned upstairs seems to have been copied from a website; actual use and experiments have shown that graphite’s heat resistance and oxidation resistance are much lower than what many manufacturers claim in their promotional materials and product manuals. The heat resistance and oxidation resistance of graphite are directly proportional to its purity. Data from Shell’s laboratories show that graphite with a purity of 98% has an ablation rate of 30% after one month at 450°C, while nuclear-grade graphite with a purity of 99.86% has an ablation rate of around 40% after one month at 550°C. At present, the purity of graphite in China rarely meets industrial standards. The above information is provided for reference only; please do not spread misinformation.

Graphite fillers remain quite durable in high-temperature environments

Using flexible graphite as the structural strands, each of these strands is reinforced with 5 high-temperature alloy wires on the inside, and high-temperature alloy wires are used for weaving around the outside; it is a specialized high-temperature gasket with a square cross-sectional design featuring interlocked weaving!

Polyphenyl powder (PPL) can be used continuously at 400°C, but its strength under stress seems to be poor; the pressure difference on both sides during on/off operations should not be too large. These sealing materials are generally produced domestically

Where is PPL produced that’s so excellent? Even imported versions cannot reach this temperature, not to mention the pressure.

There are two foreign companies that produce PIs: Dupont and Saint-Gobain. The maximum temperature they can handle is 315 degrees; 400 degrees can only be sustained for a short period of time, and it’s not possible to use them at that temperature over an extended period.

Heat-resistant. We are still using graphite for now. I really can’t find any other alternatives. The high-temperature power plant valves we produce also use graphite packing! At room temperature. Generally, perfluorine is used~~~

At a temperature of 400 degrees, PI material is not suitable; special engineering plastics with better performance could be considered. PBI material can meet such requirements, but it is currently very expensive and difficult to obtain.