I agree with you, but would note that iron NPT threaded joints that leak a bit, will often self seal due to rust, given time. -John ============= > > The relevant US pipe-thread standards are quite clear - straight threads > are for mechanical connections only. For connections that must also > contain fluids under pressure, one uses taper threads such as the > ubiquitous NPT. Over the decades, I have lived in many houses, including > my current house, with circulating hot water heat and cast iron radiators, > and I have never had to redo a radiator connection. I've never had a > leak, and most of these systems were old when I bought the house. > > If you have straight pipe threads going into radiators, there is an > installer who should be made to re-do the job. Maybe he was an > out-of-work electrician, and used rigid electrical conduit for pipe. > > Straight threads and O rings are seen only in hydraulic systems, not > domestic water or heating systems, and the mating parts have correctly > designed pockets to hold the O-rings. And they do not use jam nuts. One > screws them together until they bottom. > > Joe Gwinn > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > >