[AT] Russian Metric uses BSPP was Thought to ponder

[John Hall]

I've got 30 years in a machine shop and have yet to see a metric pipe 
thread--because it doesn't exist to my knowledge. We do a lot of German 
and Japanese work, it is always British pipe thread, either tapered or 
straight. The whole planet seems to scream at the US to go metric, but 
they haven't developed a metric pipe thread. Yet all "normal" threads 
are 60 degree V thread form, but the British pipe are 55 degree. 
Furthermore, it depends on what country is building the piece of 
equipment as to the actual designation of the thread on the print--Trust 
me, no blue print ever made it so simple as to say "British pipe 
thread". There are 3 or 4 accepted/common designations for British pipe 
threads.  It is a mess of a system to say the least.

John Hall


On 5/12/2019 7:11 AM, James Peck wrote:
> I added  an oil pressure gauge to my long gone 80 VW. I used a 1/8  BSPP to tube fitting from the Festo product line into an already tapped port on the block. That is when I learned that German metric uses BSPP straight thread fittings. I had not known that Russian metric did the same. We have discussed that Belarus is not Russian but I bet the practice came from the Soviet era.
>
> Later, I worked for a company that used BSPP fittings on the hydraulic lines to shift Reaction Injection Molding mix head plungers.
>
> Sometimes people use Teflon tape on the straight threads not knowing that all the sealing is done by the o ring.
>
> [Cecil Bearden] Metric fasteners are the easiest to cross thread for me.  I really have to be careful on my ATV's with the aluminum cases.  My Belarus tractors are not a real problem.  However, the British Straight pipe thread on the hydraulic fittings is a real pain to keep from cross threading..
>
> Cross threading is easier if you start the fastener with the impact wrench. If you start the fastener with your fingers you feel the cross threading.
> _______________________________________________
> AT mailing list
> AT at lists.antique-tractor.com
> http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com