Kitchen sink drain piping loosening up

This isn't a huge problem, but I would like some comments. I installed a SS double sink in my kitchen about 5 years ago with a garbage disposal on the right sink. The left sink is the one that leads to the main drain, & is seldom used. Plastic pvc trap & connections are used (the hand tightened type) after the metal tail piece that comes out of the sink drains. So, after washing both sinks, I notice alot of water in the cabinet under the sink. The problem was that all the plastic pipe nuts were loose, & the plastic tailpiece extension coming out of the left sink was almost disengaged.

For a permanent corrective action, should I use all metal piping in this application? In the original piping before I changed the sink & added the disposal, I noticed the original plumber liked to use pipe dope on the threads of the plastic piping. Was his intent that the pipe dope would act as a thread locker? I should add the disposal really "roars" when a full sink of water is draining, but calms down when just facet water is just running. I assume over time (5 years) the disposal vibration is loosening the fittings.

What do you guys think?

Thanks, FJK

I think there was poor assembly techniques used.

• The slip joints should have the tube overlapping in the joint as much as possible without bottoming out in the socket.
• The Joints should be put together dry without and pipe dope, Teflon paste or, Teflon tape.
• The pipes should fit together in a relaxed manner where even if you loosened a slip joint nut the joint would remain together.

Those nuts are NOT just hand tightened. Use a pair of pliers to finish tightening them after you have snugged them hand tight. My "hand tight" might be tighter than yours anyway.

Redwood hit the nail on the head, & the nail is me! I usually pride myself on good assembly technique, but I definitely blew it on this one. I can remember being a little frantic plumbing in the disopsal & made some poor choices. In looking what I have, I used the tailpiece pipe that came with the sink drain. It was too short. What was really needed is a long tailpiece to avoid the plastic extension I used. The best piece of advice Redwood offered, that I won't forget in the future, is that all the piping should fit together in the relaxed manner. Then, you know you have it plumbed correctly.

Also thanks to HJ for stating the ovbious of final tightening with a wrench or channel locks. The plastic piping I used has thumb tabs on the nuts, making me think just tightening by hand. Well, I thought wrong there too.


Thanks for the good advice.
FJK