I am doing a job for a friend on her water heater; the fitting for the emergency relief valve is busted (theives) off 'flush' with the threads. The ID opening is " 5/8 inch" & the extractor set I bought only has 1/8, 1/4, 3/8, 1/2, & 3/4... there is NO 5/8 extractor. How do I get the broken off fitting out... it is cast iron (or cast something). Thank you for your prompt answer.

I am doing a job for a friend on her water heater; the fitting for the emergency relief valve is busted (theives) off 'flush' with the threads. The ID opening is " 5/8 inch" & the extractor set I bought only has 1/8, 1/4, 3/8, 1/2, & 3/4...there is NO 5/8 extractor. How do I get the broken off fitting out...it is cast iron (or cast something). Thank you for your prompt answer.

Your T&P Valve's is made from cast brass.As a rule it has 3/4"threads. However, if your extractor won't fit then take a small sharp chisel and work it under the threads . Pry up and from there simply peel the threads out. Don't forget to Teflon Tape the new threads before tightening. Good luck and thank you for rating my answer. Tom

Of course there is no 5/8" extractor: One of those extractors you purchsed should fit. If 1/2" is too skinny, than take hack saw and cut of first 1" from the tip. Insert it in, tap it with hammer and remove the broken threads.