Simplex 5'' to 71/4 gauge

[Ruben]

Hi everybody there,

Anyone knows how to proceed to convert, simplex 5 inch gauge to 71/4 gauge, which parts must be increased and which not?

Greetings, Ruben

[drjohn]

Simple - Every dimension on every mechanical part will need to be multiplied by 1.45. The boiler outside dimensions will also need to be increased in the same ratio, but the thickness of the copper can probably stay the same.

DJ

[Ruben]

Hi DJ,
Do not think you would have to increase the thickness of the copper boiler or build in steel?

Ruben

[drjohn]

Nope ruben - the pressure will be the same, not incresed by the ratio of the model.

DJ

[Ruben]

Ok, DJ, the pressure is the same, but the surface of the walls of the boiler is 45% higher, proportion should be increased thickness for copper, and that's enough???

Ruben

[kneedeepinswarf]

The boiler shell thickness, for a solid-drawn tube, is given by:

t=(p X d)/2f

where p=pressure
d= diameter
f= working stress of boiler material

So the thickness of the shell must be increased as the diameter is increased. Although the pressure stays the same, the surface area of the barrel increases so the stress is greater.
For a rolled-up barrel, an allowence must also be made for the joint, which will be slightly weaker than a drawn barrel.

[drjohn]

That's a bit more education for mee kneedeep - thanks.

DJ

[Shawki Shlemon]

DJ is right , for a simplex boiler in 7.25" G , 1/8' plate is ample for the boiler , however there are other issues such as stays ,bushes and fittings to consider . As a guide I suggest get yourself a boiler code from UK or Australia ( Australian code is obtainable from smex.net .au ) . they relatively cheap and informative . I hope this may help .

[Ruben]

Thanks Shawki, that was very helpful website

Ruben