[jackwashere]

How airtight is an abs cleanout adapter with a threaded plug? If I use one of these for inside a bathroom for a vent pipe what are the chances that bad gasses will leak through the thread? Has anybody had any negative experience with using these for a vent pipe?

 

[TheEplumber]

How airtight is an abs cleanout adapter with a threaded plug? If I use one of these for inside a bathroom for a vent pipe what are the chances that bad gasses will leak through the thread? Has anybody had any negative experience with using these for a vent pipe?

Since they are straight threads and not tapered as pipe treads are, you may get gas but probably not.
I use toilet bowl wax to seal the coarse threads- just mush it into the cap threads and screw it in- wipe off the excess and your done. When we have to water test a waste system, this is about the only way to get the plugs water tight. If you don't want to go to that extreme, use liberal amount of teflon pipe dope- should be ok

 

[jagans]

If you are worried about it, just glue in a short piece of pipe and put in an expansion test plug :thumbsup:

 

[jackwashere]

expansion test plug :thumbsup:

that's cool I didn't know about those

so you just turn the screw clockwise to apply pressure to the sides and that creates a tight rubber fit nice

 

[jagans]

You got it. :thumbsup:

 

[Ron S.]

I installed waste and vent system with abs pipe and fittings in single family dwelling. I used teflon on the 3 different size cleanout plugs. The inspector found no leaks in the piping that I tested with 30 lbs. of air pressure. This should answer your question.