Author Topic: Coal Fired Vertical Boiler  (Read 19791 times)

Offline Chipmaster

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Coal Fired Vertical Boiler
« on: October 24, 2015, 07:49:55 PM »
In 2011 my friend Rob and I decided to build ourselves a coal fired boiler each. We chose the Reeves 6" vertical boiler which they list as drawing RV62 and they also sell the cast iron top for the boiler. We bought and studied the plans very carefully to work out exactly what materials were needed. The shopping list for C106 drawn copper tube was then sent to a few non ferrous stockholders. Surprisingly, only one could supply 6 inch outer diameter 10 gauge copper tube at that time. We ordered all the tube from that supplier and it cost £470.10 as you can see in an extract from the invoice below. The costs continued to mount as we bought silver solder, flux, gun metal, propane gas, burners and some boiler fittings. I think it probably cost about £450 for each boiler by the time we finished. Neither of us had built a boiler before, we set out with our machine tools and standard Bullfinch propane burners - and thoroughly enjoyed the whole process.
I bought four 12mm steel blank discs from a local profile cutter which were machined to make the associated formers required for the tube plates. The ends of the six inch outer shell and five inch firebox copper tubes were trued up on my lathe using  plywood discs and 12mm allthread which resembled bobbins. With care and paraffin to lubricate machining copper the arrangement worked very well.
Andy
« Last Edit: November 01, 2015, 05:28:58 PM by Chipmaster »

Offline Jasonb

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Re: Coal Fired Vertical Boiler
« Reply #1 on: October 24, 2015, 08:10:30 PM »
Thanks for posting this Andy, I'm sure I will enjoy following along.

J

Offline b.lindsey

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Re: Coal Fired Vertical Boiler
« Reply #2 on: October 24, 2015, 08:20:13 PM »
That's quite a nice looking boiler Andy. So is that your finished one in the first picture and if so will you be posting more pictures of the boiler in progress?

Bill

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #3 on: October 24, 2015, 08:21:01 PM »
The formers for the firebox and upper tube plates were marked out and the diameters carefully checked (with pieces cut off the copper sheet to be used for the tube plates) to ensure the flanged tube plates would fit inside the firebox and outer shell. The flanges of the tube plates were then formed by beating the copper discs over the formers. The appropriate fit for the flanged tube plates inside the firebox and outer shell was achieved by a combination of machining on the lathe and careful filing. The necessary gap for the capillary action of silver solder was difficult to achieve - our tube plates were circular but the copper tubes weren't circular throughout. After satisfactory fits had been obtained the marked out formers were drilled and used again as guides to spot the 49 fire tube holes and central flue in each tube plate. Ninety eight 3/8" diameter tubes were cut to length and the ends thoroughly cleaned for soldering.
Andy
« Last Edit: October 24, 2015, 08:38:52 PM by Chipmaster »

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #4 on: October 24, 2015, 08:35:57 PM »
Hi Bill, that is the finished boiler in the picture, well practically finished - some cosmetic work is outstanding in particular cleading and I'd like to fit an injector.
All the 'build pictures' have been re-sized for MEM and I'll continue adding to the account as soon as possible.
Andy

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #5 on: October 24, 2015, 09:03:55 PM »
I forgot to say that the plans for the boiler were shown to the club's boiler inspectors for their approval at the outset. It was also necessary to have the invoice for the copper used and the suppliers certification that all the copper was spec C106.

It was difficult to form the 1.5/8" diameter holes for the fire hole tube through the walls of the firebox and outer shell. There was also a risk of distorting the copper tubes if we weren't careful. Each hole and it's sides had to be perpendicular to the axis of the tubes to ensure a sound silver solder joint. I could get the 5" diameter fire box on a rotary table mounted on my milling machine and mill a perfect hole. Unfortunately that wasn't an option for the much longer shell because the throat of the miller wasn't deep enough so Rob chain drilled and filed the holes in the outer shells to shape and the results were perfect.
The first soldering job was to solder the fire hole tube into the fire box.

Andy
« Last Edit: October 25, 2015, 03:58:35 AM by Chipmaster »

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #6 on: October 25, 2015, 04:33:38 AM »
We kept checking that the fire box would fit inside the outer shell, it was going to be a very close fit with scope to get the innards jammed inside the shell prior to closing up the boiler. The end of the projecting fire hole tube had to be curved to match the outer shell so that it could pass inside the shell but remain long enough to be slightly proud of the outer shell.
Silver solder with the highest melting point was used at the outset, lower melting point solder used for subsequent steps.

We were ready to solder the forty nine 3/8" copper fire tubes and 1.1/8" diameter central flue in to the fire box tube plate. The photograph below shows the set up - upside down with the firebox tube plate held in position by an adapted drill stand and the upper tube plate underneath to keep the tubes upright and parallel.

Everything was kept clean, lengths of silver solder were wound round a 3/8 bar then snipped to form individual rings which were placed around the end of each tube. Our highest melting point solder was again used and we used both of our propane burners simultaneously to do the heating.
Andy
« Last Edit: October 25, 2015, 07:11:25 AM by Chipmaster »

Offline 10KPete

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Re: Coal Fired Vertical Boiler
« Reply #7 on: October 25, 2015, 05:20:05 AM »
Beautiful work!  :praise2:

I just love nice copper work.

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline fumopuc

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Re: Coal Fired Vertical Boiler
« Reply #8 on: October 25, 2015, 05:55:30 AM »
Hi Andy, I am following along. I have never made a boiler so far, so I will take the opportunity to learn. Your boiler work looks very professional and these boilers seems to be masterpieces.
Kind Regards
Achim

Offline Jo

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Re: Coal Fired Vertical Boiler
« Reply #9 on: October 25, 2015, 07:27:42 AM »
Pleased to hear you had a friend to help Andy. I was making a boiler for my 5" simplex and it is too much on one's own to be able to maintain a stable heat :ShakeHead:

A question: why did you choose coal fired? I am planning on propane firing my Locomotion as it avoids all the shovelling, getting filthy and is less likely to cause stray fires when used. (The locomotion boiler is also lined up as my boiler for running stationary engines  ;))

Jo
Enjoyment is more important than achievement.

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #10 on: October 25, 2015, 07:46:34 AM »
Thanks for the compliments.
The risk of ruining all that expensive copper made us very cautious. It was a relief to see the parts all clean when they came out of the citric acid pickling bath (large plastic bucket) so the joints could be inspected.

The next stage was to solder the firebox and its tube plate together. We realised that as the mass of copper to be heated with our large propane burners was increasing there was a risk that joints made with higher melting point silver solder could suffer as we blasted the assembly with our Bullfinch 1260, 19.6kw burners. We took great care to ensure everything was supported. The tube plate was loosely riveted to the firebox with three 1/16" copper rivets through the flange. A fire brick was fashioned to fit inside the firebox to support and prevent any of the 49 fire tubes dropping if their solder re-melted. A further precaution was to apply flux to all the previously soldered joints prior to reheating.

This stage went fairly well for both boilers despite having to reheat them when a couple of the fire tubes moved and our confidence was increasing.

This is hot work, definitely best done out of doors - we were perspiring profusely.
Andy
« Last Edit: October 25, 2015, 11:33:38 AM by Chipmaster »

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #11 on: October 25, 2015, 08:05:35 AM »
Good morning Jo.
Spot on Jo there's no way you could do this on your own with our 'blunderbuss style' propane burners and there are occasions when the operation certainly needs two pairs of hands.

You ask why we chose coal fired.... well we like the smell of a coal fired boiler, that's the full experience and for a stationary steam plant it gives you something to do. I like setting the fire and the excitement / fun of steam raising and using the blower. I don't get too filthy - gas is clinical and civilised. Will that suffice, have I blown my green credentials?

I have the option of gas firing, I could make up a suitable burner. A member of our club uses gas to fire his traction engines and it's clearly convenient, very effective and hygienic.


Andy
« Last Edit: October 25, 2015, 11:13:29 AM by Chipmaster »

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #12 on: October 25, 2015, 09:05:54 AM »
The next step was to solder the forty nine fire tubes, central flue and wet header in to the upper tube plate. Three lengths of allthread were used to hold the tube plate in position and our shaped firebrick was inside the firebox to support all the tubes and prevent them from dropping. Rings of silver solder were placed round the end of each tube, flux applied fairly generously and we soldered them up without any problems.

When the fire box and top plate were clean we checked that they could be fitted inside and removed from the outer shell. This required great care and patience as all the copper was soft and we could see it would be even more difficult when the bushes and bosses had been soldered into the outer shell.
Andy
« Last Edit: October 25, 2015, 11:14:33 AM by Chipmaster »

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #13 on: October 25, 2015, 09:48:33 AM »
I machined the bronze bushes for the boilers. The blind bushes were for mounting the fire box door. Meanwhile Rob made the flanges that would attach the doorframe to the boiler and used them to determine the position of the blind bushes that would be drilled and tapped after they were soldered in. We used the highest melting point silver solder again for the fixing the bushes.

Andy
« Last Edit: October 26, 2015, 07:45:33 AM by Chipmaster »

Offline Chipmaster

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Re: Coal Fired Vertical Boiler
« Reply #14 on: October 25, 2015, 11:12:34 AM »
As all the bushes were now soldered in to the outer shell it had become very difficult to get the innards in and out of the boiler shell, we had to file little bits off the inner ends of some bushes, it was similar to making a key fit a lock. There were several occasions when we couldn't get the innards to move at all and had to squeeze the outer shell to achieve the necessary clearance.

With the innards in position the foundation rings were next. Rob formed these from 10mm square copper bar. It was quite a painstaking task getting the foundation rings to fit because neither the five inch diameter firebox tube or the six inch were  truly circular. We fitted brass rods/handles to the foundation ring to make it easier to lift it in rotate it and remove it. Getting a satisfactory capillary gap for the silver solder on both sides of the foundation ring took a lot of careful filing and the occasional tap.

Before closing up the boiler I took mine along to a club meeting so that the boiler inspectors could examine our work. Everything was in order so I was given the go-ahead for the final soldering session.

Andy
« Last Edit: October 25, 2015, 01:39:22 PM by Chipmaster »

 

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