Use some heat on it if you can, tap it alot with a hammer, and use a nipple extractor. I have been lucky with a sharp chisel and slowly chisel the nipple out but be careful not to damage the threads if all fails buy new parts.
PVC compression couplings are OK to use, if properly installed. I've used them for almost 20 yrs. on high pressure (125+ psi) schedule 80 golf course lines with no problems whatsoever.Originally posted by koster_irrigation
stay away from those pvc compression couplings. they tend to not hold up, and develop leaks. you need to rethread the galvanized pipe, and use a female pvc adapter with teflon tape, most rental stores rent ridgid pony threaders which will do the job in 10 seconds