I have to add a sanitary tee fitting to a PVC 3" vertical waste stack. I haven't cut into the pipe yet, but I'm reasonably certain that I'm not going to have enough slack or play in the either end of the pipe to work in a PVC fitting and cement it. From reading this forum it sounds like a no-hub of flexible coupling is exactly what I need. So my question...

Should I use a so-called "flexible coupling" like these : Fernco Flexible Coupling, fernco, fernco coupling, fernco couplings, fernco fittings, Sewer Flexible Coupling, Plumbing Flexible Coupling, Drain Flexible Coupling, Waste Pipe Flexible Coupling | Fernco (http://www.fernco.com/plumbing/flexible-couplings/stock-couplings) or what they call a "no-hub" coupling like these Fernco No Hub Coupling, fernco, fernco no hub coupling, fernco coupling, fernco couplings, No Hub Connect Coupling, No Hub Flexible Coupling, No Hub Shielded Coupling | Fernco (http://www.fernco.com/plumbing/shielded-couplings/no-hub-couplings) ?

I've looked at both of these in the hardware store, and the flexible couplings are a thick "flexible PVC" but the inside is straight walled. The no-hubs are a thin rubber, but contain a thin metal shield around the outside. The no-hubs also have a 'collar' in the middle on the inside, much like a regular PVC coupler.

I don't really care about the price of the fittings, I just want to use the one that will make the highest quality connection (ie. Do It Right The First Time)

Thanks!

You do not use a flexable coupling on a vertical stack. You need the ridged support that a shielded coupling,(see image) will give you. Good luck, Tom

Professional names for the shielded clamps are MISSION or PROFLEX clamps. Available at most home improvement stores or guaranteed to find at a plumbing supply house... ;)

You will need a 3" plastic to 3" plastic... ;)

Good luck...

MARK

Thanks for the answers guys. Exactly the kind of info I was looking for!