Good work, you must have sifted through quite a lot. I always get a lot
of references to threads in computer programs clouding the search when
on the thread subject. Thats not to bad for me as I program for a living
but it doesn't help when looking for screw threads.

Many of the modern metric pipe threads are BSP in metric dimensions so
the reference 1 may very well be an obsolete english thread as mentioned
in 2. Searching for "copper pipe thread" turns up an awful lot to sift
through. What the next move?. If its that old and obsolete then you may
not have much luck finding info on the web. Whatever you find you may
have to resort to making another yourself unless the 7/16 x 19 is close
enough. I am not quite sure where I would start to look for a thread
that old and i'm in the UK, possibly send someone an email at the
science museum in London http://www.sciencemuseum.org.uk/ .

I'll mention it to a friend who has a thing about thread systems and see
where he would start.

Paul K. Dickman wrote:

Thanks to all who responded.

After seeing Dave Billington searching on "19 TPI" I did the same and found
a reference to it as an obsolete thread called "Copper pipe thread".

Thanks again

Paul K. Dickman

See below;

1.. Thread "Pas des becs" by Robert GIRARD )
Posted: Nov. 11, 2002 @ 14:22.
Hello I repair lamps in Provence, Luberon, France !!!! Could someone help
me to find the origin of threadings used in lamps, called in France "pas
français" : "Pas des Becs", or "Pas des becs de cuivre" = 10,85 mm diameter
and 1,33mm thread (19 thread/inch) ??? - and the others : "Pas de Paris"
(16,85mm diam.) and "Pas de Rouen" (!!!???!!!) ????? and the threads (may be
Withworth ? Empire ? or other ?) used to screwed ancient statuettes on their
marble base Thanks Best rgds RG

1.. On Nov. 11, 2002 @ 17:47, Alex Marrack ) wrote:
Thread names are often confusing, the first one you mention is the one
often used on French Gas burners and earlier French electric lamps. It is a
whitworth form thread, and is a 'non standard' size of English Pipe thread,
now standardised as British Standard Pipe thread, but dating back to about
1820 and maybe before.
The 19 TPI persists and is still used for 1/4" and 3/8" pies now (these
threads are bigger than the name implies and the 1/4 inch size pipe has an
OD of nearly half an inch (Dont ask!) The odd size thread was used over here
(UK) and called Copper pipe thread, not widely used for over 100 year.