Tubes annealed ?

[lennard1200]

Hi,
was wondering about the firebox heat produced in a 7 1/4g briggs type boiler. Enough to anneal the ends of copper firetubes with each firing ?
Simply a difference of opinion & I havent got the ability to measure the temp. which would need to be about 600c to get the tubes to a cherry red.
Leonard

[jma1009]

hi Leonard,
i dont think you will get much sympathy or info here re briggs type boilers. we all build proper loco boilers so far as im aware. certainly in the UK. i cant for the life of me understand why any one would want to build a briggs type boiler these days. in a traditional loco boiler most of the heat transfer to the water takes place via radiant heat in the firebox. in a briggs boiler this heat transfer is completely wasted and the boiler as a result very inefficient. seems to be a peculiar 'aussie' habit to build these briggs things. cant understand why anyone with an once of sense would want to do so!
the fire gets as hot as in fullsize so yes the copper tubes in the briggs firebox will get red hot, reduced only by the temperature of the water at what ever boiler pressure you use.
cheers,
julian

[GeorgeRay]

Leonard
Are you meaning the fire tubes through the boiler, because if so they are are no different to the fire tubes in a conventional boiler. if you are talking about the water tubes around a Briggs firebox as Julian says they will get to the temperature corresponding to the steam pressure. One thing is certain though, unless you are using extremely high pressures the tube temperature will not approach annealing temperature unless the water level comes below the firebox crown, in which case I think you will have other problems to deal with.
George Ray

[lennard1200]

Thanks GeorgeRay, your concise answer verified my opinion. Yes I meant the fire tubes through the boiler - the others are water tubes I think.

Julian, Thanks for your info too although I didnt ask for opinions on a Briggs boiler, merely mentioned the name to maybe aid with an answer, & yes the loco in question is a very poor steamer. The loco isnt in fact mine,was built some 40 years ago when designs were a little different, & my interest came about when it underwent a boiler test; some firebox end firetubes were found to be weeping, & the owner opined that the ends could be rerolled in situ as the tubes were annealed with each firing. He was, in my opinion, starting to undergo a very iffy repair procedure.
By the way Julian, maybe you could give us an update on Britains progress with Duplex boilers. Still back in the dark ages? or have you managed to get reasonable legislation & building guidlines yet?
cheers,
Leonard

[bhk]

Nov 29, 2013 0:22:29 GMT lennard1200 said:

Britains progress with Duplex boilers. Still back in the dark ages? or have you managed to get reasonable legislation & building guidlines yet?
cheers,
Leonard

NZ failed in the adoption of the code, bloody frustrating to as from what I'm told they guy who was part of the team who presented it too the underwriters has a personnel grudge against it and made every effort to discredit the code based on no more than his personal opinion.

[lennard1200]

Hi bhk,
my understanding is that the underwriters wanted a NZ code, not just Oz's.
Probably a matter of patience. Certainly the way to go in the future, providing that the legislators remember we are model engineers & dont make it TOO complicated legally.
cheers,
Leonard

[isc]

Only thing is the insurance companies in NZ are mainly Austrailian anyway, don't think you'll find a Kiwi one. isc

[ettingtonliam]

Nov 29, 2013 0:22:29 GMT lennard1200 said:

Thanks GeorgeRay, your concise answer verified my opinion. Yes I meant the fire tubes through the boiler - the others are water tubes I think.

. The loco isnt in fact mine,was built some 40 years ago when designs were a little different, & my interest came about when it underwent a boiler test; some firebox end firetubes were found to be weeping, & the owner opined that the ends could be rerolled in situ as the tubes were annealed with each firing. He was, in my opinion, starting to undergo a very iffy repair procedure.
By the way Julian, maybe you could give us an update on Britains progress with Duplex boilers. Still back in the dark ages? or have you managed to get reasonable legislation & building guidlines yet?
cheers,
Leonard

Umm, how do you reroll tubes if they are not insitu? Ceratinly reexpanding leaking tubes was normal practice full size, with no hint of annealing them. When I put copper tubes in my 4" traction engine boiler, I expanded them in the 'as bought' condition, no annealing.

To cure a little bit of my ignorance, whats a Duplex boiler?

Richard

[bhk]

Hi Richard,

Duplex boiler are that made from Duplex SAF 2205, Oz have a accepted code for these boilers which NZ tried to ratify but it fell through sadly.

From what I'm told due to the fact there is no way for a club inspector to tell if the steel had been overheated, I personally think serial coded with an inspector stamp fuseable plug is the way around this.

Further reading here

sonadaworks.com/duplex_stainless_boilers/