Stovepipe question

[erikhild59]

My question is about screws in my black stovepipe before it goes thru the ceiling. At a joint, the screws from the outside of the pipe are squeezing the inner pipe in so that the opening looks like an X shape. That said I haven't had problems (yet) but have noticed it's very hot at that spot and wonder if this is allowing exhaust to contact the outer black pipe which to me is dangerous. Should I get some shorter screws or drill the inner liner so that the screws draw the pipe outward. Thanks for any answers..
**This was a professional install , not a do it yourself mess so not sure what's right or wrong here**

 

[Ludlow]

Double wall??

 

[vwmike]

Sounds like they used screws that are too long. On ICC you use different length screws to join pipe in different locations.

 

[begreen]

Some time installers use self-tapping screws but don't let them fully tap the inner layer of the pipe joint. The solution is to remove the screw and drill a pilot hole for the screw so that the threads will grab the inner layer. The pilot hole should be a little smaller than the screw thread size. A size-4 screw should have a pilot-hole drill size of 3/32 inches; size 6, 7/64 inches; size 8, 1/8 inches;

 

[erikhild59]

Some time installers use self-tapping screws but don't let them fully tap the inner layer of the pipe joint. The solution is to remove the screw and drill a pilot hole for the screw so that the threads will grab the inner layer. The pilot hole should be a little smaller than the screw thread size. A size-4 screw should have a pilot-hole drill size of 3/32 inches; size 6, 7/64 inches; size 8, 1/8 inches;

Thank you , I believe that's exactly the case here. I piloted them and it worked like a charm. After disassembling the pieces the areas where it was bent inward were full of creosote. Glad to have this resolved. Thanks to all who responded