I have an old pipe under my tub that I patched (reaching up from the basement after removing the ceiling) a couple years ago with epoxy. I am renovating my bathroom and have removed my tub and wanted to remove the old drain pipe that was patched and replace it with pvc. I can't budge the old pipe, although it looks like it is threaded, but when it comes to plumbing I am clueless. This will be the only time I can get to the pipe easily and I wanted to get this done before I installed the new tub. I am including a link to a picture below. Any help would be greatly appreciated.

http://i277.photobucket.com/albums/kk79/telluriccheese/P1050002-1.jpg

I have an old pipe under my tub that I patched (reaching up from the basement after removing the ceiling) a couple years ago with epoxy. I am renovating my bathroom and have removed my tub and wanted to remove the old drain pipe that was patched and replace it with pvc. I can't budge the old pipe, although it looks like it is threaded, but when it comes to plumbing I am clueless. This will be the only time I can get to the pipe easily and I wanted to get this done before I installed the new tub. I am including a link to a picture below. any help would be greatly appreciated.

http://i277.photobucket.com/albums/kk79/telluriccheese/P1050002-1.jpg
Was the leak on the threaded nipple or trap?

I have an old pipe under my tub that I patched (reaching up from the basement after removing the ceiling) a couple years ago with epoxy. I am renovating my bathroom and have removed my tub and wanted to remove the old drain pipe that was patched and replace it with pvc. I can't budge the old pipe, although it looks like it is threaded, but when it comes to plumbing I am clueless. This will be the only time I can get to the pipe easily and I wanted to get this done before I installed the new tub. I am including a link to a picture below. any help would be greatly appreciated.

http://i277.photobucket.com/albums/kk79/telluriccheese/P1050002-1.jpg
The leak was on the trap, you can almost see the epoxy to the left of the threaded nipple, towards the bottom of the pipe. It was rusted and had a few small holes.

The easy way is to cut the threaded nipple right next to the trap and use a mission band to tie a piece of pvc pipe and then the pvc trap. But I would have a licenced plumbing contractor look at the rest of the drainlines before you do any more work to assure that the drainlines are in good condition, you don't want to finish your project and find out a few months later that there's another leak on the same drainline in the same area, its better to get rid of as much of the old system if you are remodeling your bathroom.
Good luck

Beat the heck out of it with a regular pipe wrench or a 1 handed 4lb sledge hammer.

I'm assuming you already have a chain pipe wrench like this one; http://www.daviddarling.info/images/chain_pipe_wrench.jpg

The longer the handle the easier it's going to be.

Then you just wrap it up tight and start hanging on it until it gives. If that doesn't work, put a carbide or cobalt blade on a circular saw and cut it out. The people at home depot can show you the right blades. They'll kind of look like an old record.

Thanks for the advice. I used a sledge hammer to loosen it some, then used a plumbers wrench with a longer pipe over it for leverage and with a little elbow grease it came off! Now I just have to figure out how to put the pvc piping on. I know how to attach it to the cast iron pipe, but I am having trouble finding the right trap and drain parts that will fit the small area I have to work with.