Hi,

Please help, I used the coupling to connect the 2 10' pipe together - what if I didn't glue them good will I have leaking under slab ? Should I use the black tar around the joining area then would it helps? Thanks

Are we talking about PVC, ABS or CPVC pipe or what? Black tar is not used to seal plumbing pipe in any installation that I know of.

PVC SHEDULE 40

I didn't used black tar to seal the pipe. I used purple primer and pvc glue. My question is what if I did not glued them tight then I can use black tar to help them seal better?

If you used the correct coupling, primer, cement, technique, and have it supported correctly then it should not leak. Have you tested the work? That's the sure way to know it's good before burying. An inspection wouldn't be a bad idea either.

Any plumber who saw someone using black roofing tar to "help" seal a connection would rip it out immediately. An inspector who saw that would fail you and would most likely not be very easy on a follow up inspection. That's not the way it's done.

As I said black tar is not something we use and BigRed concurs. Its like putting duct tape on a compression fitting, you don't need it if your work is good and the tape would fail anyway. The tar would fail about as fast as duct tape. Can you tell us why you think your glue job was not too good, did you skip the primer or something?

No, I did not skip the primer. The reason for doubting is the guy that helped me with this job did performed correctly because one of the pipes connected was not snuggle fit when I check and pipes came off easily. So I wondering what about the rest of the job.
How do I perform the leak test? Thanks - Tonya

If I had the concern about the workmanship of a helper that you seem to have, I would cut out the joint and remake it. This is especially true if it is going to be under the slab. If both pieces of pipe are fixed and cannot be moved to reconnect, cut out the joint and a short section of pipe. Add a short length of pipe and make two joints. Make one joint with a regular coupling and the other with a slip coupling. To insure that you have the pipe well inside the coupling, measure the depth stop ring inside the coupling and then mark the pipe. Then when you glue up you will know how far the pipe goes inside the coupling.

Follow Harolds suggestions about the joints you aren't sure of. You ask,
How do I perform the leak test? Thanks - Tonya When we test for inspection we close off all openings and fill the system from the roof vent and let it set overnight. Good luck, Tom