A WATERTUBE BOILER FOR MY TRIPLE EXPANSION ENGINE

[Zephyrin]

very impressive boiler, nice work, should be very efficient too.
the feedwater heater (the tightly rolled tube ?) IMO, seems to be exposed to intense heat, the pump wouldn't cope with boiling water.

[MJM460]

Nice work on that soldering and tubing John.  Pity about running out of tube for the feedwater heater, but at least it will not be as hot as the superheater.

MJM460

[simplyloco]

very impressive boiler, nice work, should be very efficient too.
the feedwater heater (the tightly rolled tube ?) IMO, seems to be exposed to intense heat, the pump wouldn't cope with boiling water.

Forgive me, but I don't understand your comment. The coil is the superheater: it's meant to get hot.

[bobh]

Excuse my ignorance on boilers but why doesn't the superheater coil draw steam from the very top of the boiler? Bob

[simplyloco]

Excuse my ignorance on boilers but why doesn't the superheater coil draw steam from the very top of the boiler? Bob

It does. Have a look at the design drawing on page 4. There is a pickup tube running the length of the steam drum.
John

[Laurentic]

Nice work John, looking good. 

The feed water inlet pipe, does it just go down and terminate below the water level or does it have a distribution tube running along the length of the steam drum - the plans didn't seem to make that clear, and the longitudinal stay inside the steam drum, how was the attachment to the end caps made, flanged and soldered at each end?

The pipe to the pressure gauge, could that be made to have a soldered flange with a joint ring and a loose nut, save you having to buy another gauge? (I sometimes squeek when I walk!!)

Chris

[simplyloco]

Nice work John, looking good. 

The feed water inlet pipe, does it just go down and terminate below the water level or does it have a distribution tube running along the length of the steam drum - the plans didn't seem to make that clear, and the longitudinal stay inside the steam drum, how was the attachment to the end caps made, flanged and soldered at each end?

The pipe to the pressure gauge, could that be made to have a soldered flange with a joint ring and a loose nut, save you having to buy another gauge? (I sometimes squeek when I walk!!)

Chris

Hi Chris. I'm just going to put a peg on the water feeder  to drip onto the hot contents below. It's well out of the way of the water pickup tube. Nothing clever, as befits my knowledge of boiler construction!
The longitudinal stay is silver soldered in bronze flanges: a proper job!
I just sold my Britannia locomotive for serious money so I can afford a new gauge...
John

[simplyloco]

Project aborted.

Tested OK at 150psi, slight leak from one of the downcomers at 200 psi. Three tubes melted and collapsed when I tried resoldering it. Pure copper isn't supposed to melt until 1085 C...

It's irrepairable, so I'm off to Spain for two months when hopefully, I'll recover enough to think about another...

[Laurentic]

 Ouch!  Nightmare!  Oh my word, what a disaster.  Just when things were going so well too.  I do feel for you, enjoy Spain!

Looking at the picture, wondering why, how, that could happen, wondered if you used too large a burner head, that just gave too much heat to the area?      I don't have enough soldering experience to know for sure, but you always need to know the reason why, to learn and to avoid making that same mistake again.

It seems a shame to waste all that time, effort and money and then just bin it, are you 100% for sure certain a repair could not be effected, perhaps remake that bank?  Replacing the three tubes would be extremely tricky, being so small and awkward to access, but maybe doable, but replacing the whole bank may be easier and more doable.  Just thinking.

Chris 

[simplyloco]

SNIP

Looking at the picture, wondering why, how, that could happen, wondered if you used too large a burner head, that just gave too much heat to the area?      I don't have enough soldering experience to know for sure, but you always need to know the reason why, to learn and to avoid making that same mistake again.

SNIP

Chris 

Hi Chris. You hit the nail on the head with your burner comment. However, it's not supposed to melt. I'll bin it for sure. It only stands me in for £20 in materials and a similar amount for the silver solder. I'll do it differently next time: commercial end caps and solder rings.  I still have the gauges and the housing...
John

[Laurentic]

OK John, at least you have sorted that out. 

Was just thinking before that perhaps for repairs it might be a two burner job, one burner to get it all up to a 'reasonable' temperature, not to hot but a bit below soldering temp,  then a small pencil jet for tackling the wee leak, so as the heat required for that repair soldering is only concentrated in one very small spot where its needed.  I don't know - just thinking out loud really - I'm no expert!!

You surprised me with the material costs - thought they would be way higher than that - who is your supplier?

Chris

[tghs]

a good method is to silver solder in a darkened space,, that way you can see the glow of the sections, where you need more heat and where you need less..

[Laurentic]

John - having looked at the drawing again I can see that the boiler dimensions are much smaller than I had envisaged looking at the photos, so yes, much less material needed at much less cost!  But would stiil like to know the supplier you favour!!!

Chris

[simplyloco]

John - having looked at the drawing again I can see that the boiler dimensions are much smaller than I had envisaged looking at the photos, so yes, much less material needed at much less cost!  But would stiil like to know the supplier you favour!!!

Chris

The 6mm tubing came from an auto supplier, very cheap. This guy is not a metal supplier, but he has stuff at sensible money! This piece makes two boilers: I still have the other half...

https://www.ebay.co.uk/itm/235228385642

John

[Kim]

Ugh... I feel your pain! 

Very sorry to see that damage. Could you just cap those three tubes off? Or solder a repair patch over the top?  Probalby not possible, but it's just so sad... :'(

Placing a heat shield around the areas you're not trying to solder might help.  Just keep the heat off the areas you're not focusing on.

Enjoy your trip! 
Kim