Tuff Stuff around steam pipes?

I have a gap around a steam pipe in my bathroom that I would like to close up because dust and tiny debris falls down through the gap. I put a ring around the pipe, but things just accumulate in the ring. Can I use Tuff Stuff around a steam pipe? The directions on the can say not to use it on a object that gets hotter than 240F. How hot does a steam pipe usually get? I usually heat my house around 68 or 70 degrees, if that matters.

I just want to add that obviously if I end up using Tuff Stuff, I would only do it when the pipe is completely cold, and can stay cold until it cures.

Any and all advice will be much appreciated -

Thanks,
Janet