I have tile shower with fiberglass pan. Once the drain screen is removed there is a 2" black pipe sticking up through the pan with a black rubber seal. There is not a nut. The shower pan has a molded recess. I removed the old seal and replaced it with a new seal however my shower still leaks. How do you correctly install the seal. I have been told to use silicon and told not to use silicone because it will rot the seal. I did not use any silicon this time.

Thanks,
John

That seal should be greased with silicone jel or plumbers grease and then you force it down into the sump hole of the shower pan floor. The black seal is between the shower pan sump and that black 2" pipe. The 2" pipe gets trimmed flush with the top edge of the rubber seal. Whoever told you silicone would rot the seal was not experienced with plumbing so try not to take anymore advice from him.

So in regard to sealing a drain in a tub or shower... You say that simply putting plumbers grease instead of silicone will withstand time and temperatures?

So in regard to sealing a drain in a tub or shower... You say that simply putting plumbers grease instead of silicone will withstand time and temperatures?
One of the major causes of shower leaks is the putty or Silicon Jel seal on the lip of the drain. It's easy to form this seal. Make a small rope of plumbers putty or Silicon Jel and place it under the lip before tightening the drain down. Wipe off the excess that squeezed out and you have your lip seal. Good luck, Tom