if you think in real terms every thread you cut is a taper
you need the lead in to the die
you need the lead in to the die
bsp threads
- Thread starter notaplumber
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well not really Kev, a female thread which is parallel will almost certainly be finished off with a parallel tap (plug). Similarly a parallel male thread can be formed so that most of the thread is parallel, depending on what form of die is used.
No I was not trying to wind you up, just curious as to the technicalities of applying these threads.
I don't fully understand your answer about more leeway with a taper. Do you mean that if you fit a male taper into a female parallel, say on the previous application of a bayonet outlet, you would have an easier job of getting it facing downward when tight......as opposed to two taper threads coming together and locking up tight before you can face the outlet at the correct position?
If so the advantage of a taper/taper joint would be a better seal, and the advantage of a taper/parallel joint would be slight flexibility with positional assemblies.
As I understand it (the correct grade of) PTFE tape can be used to seal either joint and you do not HAVE to use hemp and paste. Is this correct?
No I was not trying to wind you up, just curious as to the technicalities of applying these threads.
I don't fully understand your answer about more leeway with a taper. Do you mean that if you fit a male taper into a female parallel, say on the previous application of a bayonet outlet, you would have an easier job of getting it facing downward when tight......as opposed to two taper threads coming together and locking up tight before you can face the outlet at the correct position?
If so the advantage of a taper/taper joint would be a better seal, and the advantage of a taper/parallel joint would be slight flexibility with positional assemblies.
As I understand it (the correct grade of) PTFE tape can be used to seal either joint and you do not HAVE to use hemp and paste. Is this correct?
right before this goes any further i obviously owe you an apology
yes you get a bit more leeway with taper into parrallel
i always use hemp cos thats what i was tought
the apprentice uses ptfe and it usually p*sses out
your male thread (allegedly )needs two full threads cut before it constitutes a seal but you still have a taper on the end
unlike stocks and dies these things aint adjustable
well not now
any more questions throw your hat in the ring marra
again i apologise
(one p*ick spoils it for everybody)
yes you get a bit more leeway with taper into parrallel
i always use hemp cos thats what i was tought
the apprentice uses ptfe and it usually p*sses out
your male thread (allegedly )needs two full threads cut before it constitutes a seal but you still have a taper on the end
unlike stocks and dies these things aint adjustable
well not now
any more questions throw your hat in the ring marra
again i apologise
(one p*ick spoils it for everybody)
The tapered thread stems from pipe work where high pressure are used. Generally threads are parallel until it comes to pipe work. The tolerances are such that parallel threads can leave considerable clearances and an easy escape route and is not really suitable. Steam at 150 lbs sq in. is fairly powerful.The tapered thread is applied to the male thread on the pipe end while the coupling is parallel. The clearance is reduced as the pipe is screwed in and a much better seal is achieved. Using a tapered female would improve it further but to mass produce couplings tapered from both ends would mean very high cost.
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cut my teeth on steam
but that was a long long time ago
cheers mandate just jogged my remaining brain cell into action
but that was a long long time ago
cheers mandate just jogged my remaining brain cell into action
Yes Kev! I know, I seem to remember you back in the mid 40s.
no you dont mate
e mail me mandate ?
e mail me mandate ?
Strange but true....
BSP threads and Imperial pipe sizes are used for steel pipe and brass fittings all over Europe, including France, Germany, Italy, Spain, Poland and probably others too.
I guess Metric standard threads are too fine for pipework. Or maybe each country decided individually that changing to Metric was too much hassle so that we were the only ones that actually changed (copper tube sizes).
BSP threads and Imperial pipe sizes are used for steel pipe and brass fittings all over Europe, including France, Germany, Italy, Spain, Poland and probably others too.
I guess Metric standard threads are too fine for pipework. Or maybe each country decided individually that changing to Metric was too much hassle so that we were the only ones that actually changed (copper tube sizes).
about time the rest of the world seen we had a point
thanks john
thanks john
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