gas thread, calculation by external diameter

[Nioh17]

hello to all, for gas threads which is the formula to calculate the outer diameter? for example a 1" gas has a nominal diameter (inside for tubes) of 25,4 mm and an external diameter of 33,249 mm. is there a formula, relationship or expression to have the value 33,249? I know there are tables but I need the formula for a job.
Thank you all.

 

[Marco F inox]

attention, do not confuse the English thumb which is 25.4 mm. with the gas thumb.
1" gas is 33.25 mm. (external diameter), but the half inch is not the middle of 33,25, but it is 20,96 mm. so the three/quarters of thumb is 26,44 mm.
This has been done, with approximation, because speaking of conduct, you have to make comparisons with the sections, that is, the courses, instead of the diameters.

 

[batleo]

Hi.
the gas thread as it says "stainless bow" was born for the pipes in fact the correlation with the tubes in English inches is the diameter of the inner tube , that is 1" gas (33.25) is the external thread for a tube that has inside the passage from 1" ( 25.4mm)

 

[MassiVonWeizen]

take the thread table for single-iso pipes 228(you find it on the baldssini and on the net) where all sizes and formulas are specified and, as you have seen to do to @meccanicamg, make you a excel sheet.

 

[Marco F inox]

I must point out that 25.4 (English) has nothing to do with gas thread and, does not correspond to the inner diameter of a 1" tube, which can be even much less.
the measure in English inches, like the Italian millimeter, follow an arithmetic progression, where the difference between successive numbers is a constant. (see the caliber).
the sequence of gas measurements, does not respect this rule, just think that 1/2" is equal to 20,96 mm. of external diameter, 1"= 59,61 mm 3"= 87,88 mm 4"=113,03 mm 5"=138,43 mm
6"= 163,83 mm and so on.
It is not even a geometric progression, where instead of sum, multiplies, but even the internet can give an answer.
Does anyone know?
is it possible to obtain a formula?
It should always refer to the tables, as has already been suggested.

 

[Fabietto]

in reference to what asked by @marco f inox, on the net I found this:

COME MISURARE I POLLICI IN IDRAULICA

COME MISURARE I POLLICI IN IDRAULICA

www.evvvai.com

 

[Marco F inox]

@face, I downloaded this table too, but not only is not exhaustive, but also contains two imperfections.
where there is written tube diameter, I corrected with inch-mm conversion.
to the right, to the written thread diameters I added gas in mm.