cast iron boiler with bad female threads for vent .

Larry Simon

I have a cast iron radiator with bad female threads for vent valve. I do not think the threads can be fixed with a tapp should I drill and tapp next size.

Larry Simon

bad threads

I have a cast iron radiator with bad female threads for vent valve. I do not think the threads can be fixed with a tapp should I drill and tapp next size.

Charlie from wmass

Depends on your level of skill with such things. It has been done but also I have been on calls were the home owner tried to tap the threads after drilling out to the next size up and they cracked the radiator.

Kool Rod

I think I'd consider a Helicoil before I'd go to a bigger tap size. They make kits for some individual sizes and which comes with a drill, a Helicoil tap, an installation tool and usually half dozen helicoils in that size.

I know they have pipe threads sizes as I had to do a pipe thread in a Caterpillar head a few years ago. Look on the internet under something like: "Helicoil kit 3/4 pipe thread" and see what you can find. You might inquire at a local plumbing supply house.

Since the pipe threads are tapered it would seem to me that you could chase them out a bit with a pipe tap to clean them out.

Charlie from wmass

Youe can try chasing the threads their may be enough meat left to seal a vent. I have used heli coils but never on a tapered thread. If you do tap it out to 1/4" be careful and take it slow.