Hi. I want to extend my black iron gas piping for a new water heater and gas grill. My pipe is 1-1/4 and has a plug at the end of the line that I simply cannot loosen. It's only a few years old, but the sealant the guy used is black, and has hardened. I thought the idea behind pipe sealant was it's supposed to be able to be worked with later. The stuff I'm using says it's non-hardening. Any ideas how I can get this plug out to continue my run would be appreciated.