Going through brick, block and stone wall

[Wkpride]

My wall thimble accommodates wall thickness of 6-11". My block & brick wall are 12" combined. I'm also putting a stone veneer on interior block, which increases total thickness to 16".
I'm using 6" stainless triple wall pipe... I believe I'll need to run the stainless pipe through the entire wall - but I don't find any 16" stainless sections. 12" or 24" only.
It looks like my only option is to attach the interior thimble to the interior block wall and the stone veneer will be laid around it, rather than under it. Unless I'm missing something... Appreciate comments/suggestions. Kp

 

[begreen]

So for the entire wall there are no combustibles at all within 12" of the pipe coming through the wall? If so, it sounds like the thimble will be more of an indoor trim kit and outdoor flashing.

 

[Wkpride]

So for the entire wall there are no combustibles at all within 12" of the pipe coming through the wall? If so, it sounds like the thimble will be more of an indoor trim kit and outdoor flashing.

Yes. 16" stone/block/brick entire wall. No combustibles within 12".
It was my understanding that triple wall had to go thru exterior wall. I'm not sure if the reason is to keep proper heating of gases? Is running triple required?

 

[begreen]

It should be class A pipe, but whether it is triple or double wall class A just depends on the manufacturer. Personally I would go with double-wall class A.

 

[bholler]

Yes you need to run class a the whole way through the wall i have seen 18" sections but i would get a 24" you will want it to extend out both sides a little anyway