What are the specifications for the gaskets of external thread M27x2 bimetallic thermometers and thermocouples?

Bimetallic M27*2 gasket 24*14*2 (lower sealing) – placed at the bottom of the thread; Thermocouple M27*2 gasket 44*27.5*2 (upper sealing) – fitted over the thread

For bimetallics, the outer diameter of the sleeve is 18, and the gasket is 24*14*2; the inner diameter of this gasket seems too small

The sleeve is either a base or a flange; flanged sleeves require asbestos gaskets or PTFE gaskets!

The gasket you’re referring to is likely the one used at the process interface, that is, the gasket between the thermocouple nozzle, the thermocouple, and the bimetallic thermometer. The common specifications for such a gasket are 44*27.5*2, as mentioned on the second floor: 44 represents the outer diameter, 27.5 the inner diameter, and 2 the thickness. However, these specifications aren’t strictly mandatory; the outer diameter can be slightly smaller and the inner diameter slightly larger. This variation depends on the specifications of the thermocouple nozzle being used, with the aim of ensuring that the gasket fits within the outer edge of the nozzle without affecting the M27 thread. Depending on the temperature and medium, Bakelite (asbestos rubber sheets) or copper gaskets can be used. Our factory has also recently employed metal wave-shaped gaskets of the aforementioned size; this way, in case of leaks due to installation issues, it is possible to tighten the connections with greater force without having to worry about the gaskets breaking.

42*27*2 copper gasket, which requires quenching treatment before use