I have an RV which has a 1-1/2" PVC piping to ventilate the waste tank. I need to extend the roof end of the pipe by about 3 inches or so to install a different vent cap. I have no idea what I'm doing, but my research thus far leads me to believe I should buy a 1-1/2" "slip" coupling and then prime and glue that. Is this a valid approach?
Plumbing – How to extend PVC vent pipe
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Related Solutions
I see no reason why you should cut threads on a PVC pipe. It seems to me that this would be unnecessarily difficult and would weaken the pipe.
You should, instead, get a slip to thread adapter and glue it onto the pipe to thread it wherever you like. Any big-box hardware store or irrigation department should be able to provide this adapter.
Edit: Here is a link to such an adapter for $1.56at big orange hardware store. :
We use liquid sealant all the time with great success at 1-1/2" diameter and less.
Make sure you are coating the threads completely and evenly.
Some dopes require coating both male and female ends over certain sizes.
Maybe try a different brand.
Might just use teflon tape instead.
Plumber we know for a large local company uses teflon (to seal) and pipe dope (to lubricate) at the same time although we do not practice the same.
If these don't work, look at your threads and make sure they do not have a scratch or nick in them.
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Best Answer
Yes, that will work; coupling, additional length of pipe, adhesive kit, preferably sandpaper to clean the surface before gluing, saw or appropriate-sized tubing cutter if you need to cut the pipe section to length.
I presume you aren't going to have to redo the flashing around the wall or roof pentration; if that has to be disturbed add supplies to deal with that.