high temp silicone for double wall pipe installation?

[crackshot]

sup yall,..... so after reading the instalation manual for my duratech pipe system ..... no where in it says to put silicone around the twistlock part of the pipe. only put some just around where the storm collar sits on the flashing.. I thought I read on here that you put a bead around the joint of the pipe..... also what kind should I use and where to get it,... i was at lowes last night and could not find the right stuff...thanks all.

 

[RustyShackleford]

There's some stuff called Mill-Pac that was recommended here recently. I don't think hi-temp silicon is gonna handle the temps, at least if it is in contact with the inner wall.

 

[summit]

no to the hi temp silicone: it can catch fire at @ 800 deg f

 

[webbie]

Our store used regular clear silicone for years on the outside seams of some exterior double wall insulated pipe (which sometimes had a tendency to leak).....

Obviously, the storm collar and the pipe get just as hot as the outside of a seam joint - or close to it.

However, if you don't have leakage problems......and if the maker does not call for it, I see no reason to use it! As I mentioned, we occasionally would have a troublesome install or pipe batches, etc. where we felt it prudent to seal.

I can't imagine that the outside of any insulated chimney exceeds 4-500 degrees in any normal use, especially when it is exposed to the cold! In fact, I would say that in most cases the outer pipe stays under 200......that is, I always could easily touch them (those outside).....

I should clarify - "bead around the pipe" does not mean IN the joint......or contacting the inside pipe. In our case, we were sealing the outside joint and band that pulls down over it AFTER the pipe was put together. I even occasionally sealed the vertical joint in some double wall that had a folded joint...just to make sure!

 

[begreen]

I had to do a bead of silicone on the seam and joint our old metalbestos pipe to make it tight. But with have two Simpson DuraVent installations that have gone through some hellaciously strong rains and are totally dry. They only have a bead of silicone around the storm collar.

 

[The Dude]

The outside of an insulated pipe better stay 200º or below, because I am going to be framing in the second floor portion of mine that's in my daughter's closet, and the chimney installer told me that it needs only 2" clearance from combustibles.

 

[BurnIt13]

The outside of an insulated pipe better stay 200º or below, because I am going to be framing in the second floor portion of mine that's in my daughter's closet, and the chimney installer told me that it needs only 2" clearance from combustibles.

This is my concern as well, mine will be framed in the corner of my child-on-the-way's room. I'm pretty sure it would absolutely have to stay below 212. Temps above this would cause any moisture in the wood to evaporate and make the wood "more easily combustible".

Someone mentioned that they can put thier hand on the outside of the pipe...like a cup of coffee. Well 160 degrees you can usually touch for 1 second without a burn. 140 degrees is 3 seconds, and 120 degrees is the normal max comfort level.

 

[The Dude]

This is is probably stupid of me to mention because it's just a technicality, but the number 212º might not have any significance here. It's the temperate that water boils at sea level, but moisture does not need boiling temperatures to evaporate. I think I read on here that the temperature for wood to slowly char over time is somewhere around 260º. Or maybe that is the combustion temperature, making the dangerous temperature even lower. There is a certain temperature that can change the properties of wood over a long period of exposure, lowering the wood's combustion temperature. Some of the more experienced people on here probably know these figures.

I think the hot-to-the-touch method is good to go by for eliminating any concern or prompting it.