[modeleng] Re: Vanes Boiler Works

Hi Patrick,

I wouldn't recommend using a propane or any other gas cylinder for a boiler 
because of the following (not in order of importance):

1. unknown what type of steel is used
2. unknown stresses in the steel from forming the tank (especially if you 
cut more holes for fittings)
3. the thin wall offers no corrosion allowance over time
4. safety factor can not be calculated accurately without knowing the 
allowable stress in the steel used, and we don't know what the steel is.
5. good 1/4" (6.4 mm) wall mechanical tubing is relatively inexpensive and a 
known grade can be used. welding is also easier on the thicker material.
6. we don't want you or anyone else hurt if there is an accident with a gas 
cylinder based boiler.

Propane cylinders are designed for a safe working pressure of around 40 psi. 
They will handle more in unusual situations such as outdoor storage in hot 
areas, but they are not designed for 100 psi continuous operation.

Get some thick steel for your boiler and be safe.

Cheers Jeff Dayman


>From: Patrick Coppens-Marian Lynch <develop@xxxxxxxxx>
>Reply-To: modeleng@xxxxxxxxxxxxx
>To: modeleng@xxxxxxxxxxxxx
>Subject: [modeleng] Re: Vanes Boiler Works
>Date: Wed, 19 Sep 2007 20:51:51 +0200
>
>I did some "googling" and found out some wall thickness figures on these
>gas cylinders, and I was surprised how thin these actually are.
>Obviously, they do not have to be heated, but most of these are under 2
>mm ! ( 0.08")
>The fact still remains though, that, if a shell was found of sufficient
>thickness, it would not be and impossible proposition to build one of
>these "Vanes" boilers, or at least something very close to the original.
>I believe the older style LPG tanks for cars to have a wall thickness of
>5,5 mm, so I that is correct, and one could be "liberated" (from a
>future pedestrian for example) there would be something going....all the
>junk that is attached in the middle of the tank could be thrown away,
>and if need be, the location of these "ornaments" could be made into an
>access hole
>The wall thickness, of ALL the elements of these boilers are given as
>1/4 inch,so 5,5 mm is close enough to that, if the pressure would be
>limited to say 100 or 120 psi...
>Patrick
>
>TEL wrote:
> > A lot thinner than you would expect Patrick - way too thin for a boiler
> > shell
> >
> >
> >
> >
> >> Harry,
> >>
> >> I haven't cut up any propane cylinder yet, so I wasn't aware of the 
>wall
> >> thickness of them, do you have any data on that/experience with this?
> >>
> >> Patrick
> >>
> >>
> >> Harry Wade wrote:
> >>
> >>> At 05:38 PM 9/19/07 +0200, you wrote:
> >>>
> >>>
> >>>> Today, I took delivery of a bit of steam ephemera. - Patrick
> >>>>
> >>>>
> >>> Patrick,
> >>>         Of concern should be the wall thickness of your barrel.
> >>>
> > Although
> >
> >>> 1/8" or even less will meet the mathematical strength requirements for 
>a
> >>> small say a small 100psi boiler, if the boiler is to have any life
> >>> expectancy at all the walls (and heads) need to be thicker for heat 
>and
> >>> corrosion allowance.  For welded steel boilers for large scale model
> >>>
> > locos
> >
> >>> in the US, say those with barrel diameters of 8" to 12", 1/4" is an
> >>> absolute minimun with a 5/16" or even 3/8" thickness being common.
> >>>
> >>> Regards,
> >>> Harry
> >>>
> >>> MODEL ENGINEERING DISCUSSION LIST.
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> > MODEL ENGINEERING DISCUSSION LIST.
> >
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>
>MODEL ENGINEERING DISCUSSION LIST.
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>To UNSUBSCRIBE from this list, send a blank email to,
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