Brit Progress: TIG Boiler Update

[drjohn]

Hi JB

Looks like and excellent boiler.

I'm no expert, but I did build an almost finished 5" Brit. Looks to me like you will need to make an extension rear smokebox ring to move the boiler back a fraction so it sits on the frames above the pony truck. Others may know better.

Or even enlarge the smokebox - this is what my 5" looked like with the arrangement for the cladding.

dr-john.org/images-web/gallery/smaller/macness - 9.jpg[/img]

Seasonal gruntings to you and Jan by the way! ;D

DJ

[drjohn]

Renewing an old topic -

I emailed Marco for a price for a boiler for a 5" black 5 and he quoted 2/3 of the price of a silver soldered one, with a lead time of 10-11 weeks as opposed to about 35 weeks for the other type.

What did occur to me is that with a TIG welded boiler, because there's no silver solder (except perhaps on bushes) that it's not nearly so critical to keep the water level above the crown of the firebox as there's no solder to melt.

Am I deluding myself?

DJ

[albert]

Hello DJ.
It is not only melting the solder but also the bending and bulging of the boiler plates.
Loss of water is still an important issue.
Albert.

[drjohn]

I was thinking more about the radiant heat on the crown stays, Albert, but I take your point.

DJ

[Shawki Shlemon]

Welcome back DJ .My personal opinion is that the crown is the hottest part of the fie box and therefore it is necessary to have it covered with water at all times .

[GeorgeRay]

Dont forget if the crown doesn't collapse from the heat then it might well when water comes back over it when the rate of steam generation will rapidly increase, and unless you're very lucky the safety valve(s) might not cope. Hasn't happened yet in our size but I suspect that is because most people try to keep water over the crown sheet.

[mutley]

Doesnt copper have significant loss of strength at high heat levels making it very weak in such circumstances? You only have to look at the quilted effected on the copper fireboxes of full size locos to see this.

Andy

[drjohn]

George and Mutley, I personally have the idea that copper is a fantastic conductor of heat - anyone who has held a 1 foot length of half inch copper tube in their bare hands while silver soldering to the other end, I'm sure will vouch for that! ;D

So assuming the firebox wrapper is an integral part of the crown, and the sides are still in contact with water, I don't see the temperature rising to the point where the books say that copper will weaken.

Shades of high grade steel in the twin towers being melted by a wee bit of kerosene and falling into their own footprint sort of like a controlled demolition!!

DJ

[Deleted]

DJ, you promised that you wouldn't hijack any more of my threads!
As an aside, assuming that heat wasn't localised, I seem to remember Science teachers muttering something about 'Latent Heat of Vapourisation' or something like that.....
JB

[drjohn]

I wasn't hijacking JB, merely extolling the merits of your tig welded boiler - sorry if I upset you!

DJ

[nonort]

Earlier in this thread the subject of inspection was mentioned. I understand that we club inspectors are basically the same as 'full size' inspectors we use a set of rules and are answerable to thee insurance company that underwrites the various federations, should anythinf go wrong. Have a care for your inspector and actually clean the firebox and smokebox before bothering the inspector.Also carry out a home test to at least the working pressure.