[time-nuts] OT Euro/US plumbing was 14 tpi UNS die

J. Forster jfor at quik.com
Wed Jul 8 00:48:06 UTC 2009


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
>
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