Threaded pipe sealant for NPT threads up to 1200 °F 1

[Stefan2211]

Hello,
we have flexible hoses in SS for high temperature exhaust gases (mainly nitrogen) up to 1200°F. Does anyone has experiences with one of the following sealants
X-Pando and attached products such as Deacon 8875-Thin, Flexitallic Graoil GTS and Loctite NS 5550?

Is any of these sealants long lasting and can hot/cold cycles?

Thanks

 

[TugboatEng]

Oxidizing or not? That is a very important consideration at these temperatures. For example, graphite may tolerate 1200°F in non-oxidizing conditions but is only good to 800°F if oxygen is present. Remember, even though you have nitrogen inside you still have oxygen outside.


I can vouche for Copaltite at these temperatures but it's quite hazardous until it cures and has an odor that will haunt you. It needs to be heated to 300°F to cure, I suggest it only if you can bake or commission the assembly shortly after application.

 

[XL83NL]

We’ve used Rocol foliac manganese and Grafoil tape. Foliac manganese is for steam service but not for 1200F. Grafoil would follow the advice by TugBoat.
Also, both require some experienced technician that knows good manufacturing practice, as these products have a very narrow band between success and fail.

Huub
- You never get what you expect, you only get what you inspect.

 

[Krausen]

NPT threads on flex hose ends at 1200F? May want to consider changing those to flanged end connections & use a high temp gasket.

 

[Stefan2211]

Krausen, theoretical possible for long tern use but right now it is commissioning and they want to run the system