I have a 3/4 NPT fitting that broke off flush in a housing on the head of a Curtis Air compressor. It is a steel or case iron fitting.
I have seen a tool with an eccentric on the side of it made just to take out broken pipes. I have not had any luck finding it on line with out a better name/description.
I have easy-outs that size but the hole is not deep enough for them to bite the broke pipe.
I also thought about thinning the broken piece with a carbide cutter in a die grinder but really do not want all of the metal filings around the compressor head.
This compressor fell over while I was hauling it and broke several fittings. I have them all removed other than this one. I would rather not have to take the head off the compressor. This compressor is 40-50 years old and parts are hard/pricey to get.