What sealants conform to "flexible fire resistant compound"?

[Fredxxx]

This would be for a sealant between a sleeve and a pipe carrying gas.

I notice that the IGEM procedures use the term "mastic seal" as an example but the description "mastic" is very vague.

Can anyone provide what sealant the trade use?

[A.Lee]

Something from the Pyrocoustic range:

[Fredxxx]

Many thanks for the idea. I can't see any reference to sealing sleeves carrying gas pipe.

I have come across intumescent sealant:

though perhaps this is more appropriate:

It says fire retardant in the headline, but it does claim to have fire resistance.

What do plumbers really use?

[johnejeg]

Plumba Flue Is widely for this job.

Note that a seal is only used on the the interior sleeve in a building.

The exterior of the sleeve is left open

[Fredxxx]

Many thanks. I see it can only stand 300 degs C but if that is what is used............

I was aware of that, but this is for an internal wall. I had presumed best practice would be to seal the end with the smallest volume of space.