Our vent pipe leaks a little - is there a sealant for these pipes?

This is pretty basic.revealing how little I know about what I'm doing, here. I installed everything for this King 5502M a number of years ago. There's a very small amount of smoke smell in our den - which is normal, I suppose. I recently did some work on the thing (the igniter went bad

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Our vent pipe leaks a little - is there a sealant for these pipes?

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