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Radiator Air vent threads
I’ve got a few 1-way cast iron steam radiators that have air vent thread issues.
1. On one of them it looks like the 1/8 male nipple of an old air vent broke off in the radiator. How can I remove that male nipple? I have a Damaged Screw Extractor Kit. Not sure the extractor side is large enough to grab onto ID of the broken male nipple. Pic1
2. Another air vent threads seem full of crud. Pic2
3. Not sure how this last air vent was put on. How can i get it off without damaging it? Pic3
I’ve read I can use a pipe tap 1/8” 27 TPI to fix or refresh the threads on my radiators. Do I need a tapered or straight tap? Can it be carbon steel or do I need hardened steel?
I’d prefer to fix my current threads as opposed to drilling it out and re-tapping to a larger size thread if possible.