Tips for removing rusted 2" galvanized nipple / fittings

I am trying to remove several 2" galvanized fittings / nipples from our kitchen sink drain assembly. They are quite rusty, possibly as old as 60 years. I can just barely get a pipe wrench on it, but working inside the kitchen base cabinet cannot get too much leverage.

Any tips for how to remove these fittings? Any hope for penetrating oil? There is about 1/4" inch of nipple visible between the fittings. If I saws-all off the nipple, any chance I will have success removing the remainder of the nipple from the female fitting in the wall? I'd like to get back to the female fitting in the wall, and start fresh with a PVC male adaptor.

Thanks very much for any suggestions.

I've had a little luck breaking old rusty fittings loose by applying some pentrating oil and/or heating the fittings. If you sawzall the nipple then you may have to take a hacksaw blade to cut the remainder into pieces by inserting the hacksaw blade inside the rest of the nipple... this is the way I've had to remove pieces of pipe that broke off in fittings.

pipe

You will probably have to cut and chisel the threaded portion out of the fitting. Then, hopefully, there will still be some threads left for you to screw into, but that is not always the case.

Thanks very much for the help. I did eventually get the nipple cut out, and the threads were actually OK still.

Thanks again.

I have a supply house that carries a product called Pipe Break. This stuff is amazing. I had a fitting I needed to save, and I had a 36" pipe wrench on it and it would not budge. So we sprayed some Pipe Break on it, and went and worked on a different part of the project. After about twenty minutes we put the pipe wrench on the fitting and it spun like if it was just hand tightened.