Stubborn malleable iron plug

I'm trying to remove a 3/4" malleable iron plug, but it's really stuck. The pipe dope is probably over 30 years old and is like concrete. I put an 18" wrench on it, but it didn't budge. I also sprayed in a little PB Blaster, but that didn't help. I didn't push it too hard though, because I wasn't sure if these things could crack right off.

Do ya'll have any tips for removing fittings when the pipe dope has hardened up? Should I just put a little more leverage on it, or is there a chance that this type of fitting could crack? Is an impact wrench too aggressive? Thanks for your help.

I am gonna assume this brass plug is threaded into another metal body. If so then heat out the thing the plug is threaded in to. This will cause expansion and hopefully loosen up the plug!!

You can take a sawzall and cut the square of the plug off flush with the plug. This will expose a hole behind the square, Now you can take the saw and cut the plug from the hole up, down and to the left and right, but be real careful not to cut into the threads of the fitting. Once you made the cuts then you can use a hammer and chisel to knock out the pieces.

plug

There is a good chance that a 3/4" plug could be solid and cutting off the end would create more problems than it would solve. IF any of the threads are exposed, can you grab them with the wrench? That would eliminate the possibility of snapping the square head off.

Thanks for the replies. I'll try to get a wrench on the exposed threads and break it free. If I end up breaking it, I'll try and drill it out and knock out the remainder. Is there a chance that the threads on the inside of this fitting will be good enough after all these years to screw into and get a good seal?

plug

If you get on the threads you will not break it, and the threads in the fitting will be almost like new. A little heat, or maybe a lot, would help also.