Boiler build: help requested

[davidsuffolkParticipant @davidsuffolk]

I would like to make a boiler to run my stationary engine. It has a 2 1/2" bore and 4 1/2" stroke so would take quite a lot of steam.

It runs happily on air at about 90-120rpm with my compressor turned fairly well down so how much steam is likely to be required?

I have a copper tube 20" long by 8" diameter. Might this be large enough as a basis and what would be the best design and most appropriate heat source etc etc. Presume I would need to keep adding water as so much would be used?

If there was any helpful soul in Suffolk who would be able to offer practical advice or assistance that would be very much appreciated!

Failing that any suggestions for a book or other source material that I can use to try and work out what is needed?

[davidsuffolkParticipant @davidsuffolk]

[JohnFParticipant @johnf59703]

Hi sorry can't help but this will bump your post up again

[JasonBModerator @jasonb]

Well the ideal solution would be to make the centre engine to mount the Tidman on

You could go for either a loco type boiler that is with your copper tube as the barrel and then a wrapper to form the firebox or you could have a vertical boiler using your tube as the water/steam space and a separate round firebox for it to stand on.

You don't say what wall thickness your tube is but based on the available traction engine and loco boilers of a similar design you would be looking for about 4 to 5mm wall thickness.

The usual book to have a read through is K.N. Harris's "Model Boilers and Boiler Making" This gives the forulas to work out how much steam is needed, what heating area to achieve that and also has some examples of different types of boilers though I think 6" dia is about as big as he goes.

Yes you will need to get water into the boiler, the organ engine did not have its own feed pump as that was taken off the crankshaft of the main centre engine. You could add one but it would probably be easier to make a hand pump to add water as and when needed.

J

Edited By JasonB on 21/02/2015 20:18:15

[davidsuffolkParticipant @davidsuffolk]

On looking into this further and as I want a fairly big boiler is there any practical reason why it cannot be made of steel and welded? I am not much of a silver solderer but I can weld pretty well.

I realise that steel will rust but apart from that are there any issues as I do have a source of nice large steel tubes?

At present I am thinking of having the internal tubes also steel & threaded (with a spanner flat at the top) screwed into the base plate then soft soldered at the top.

Good/bad idea?

[michael coleParticipant @michaelcole91146]

Again to push the Steamboat Association, (**LINK**) they have a boiler design library of the size you are looking at. There are VFT and loco types and water tube designs.

Mike

[davidsuffolkParticipant @davidsuffolk]

Looks good, I will give them a try. £5 is reasonable if they have one suitable already.

[davidsuffolkParticipant @davidsuffolk]

On reading through other forum posts I can see this is a bit of a minefield! I wasn't planing on public display once finished but on the assumption that maybe one day I might I will have to go down the full route. My friend who is helping me is a fully qualified and certificated welder so that part and having it Tig welded would be met. I don't believe I need to CE mark if I make it myself? That would leave having the stages certified and then tested if my understanding is correct?

[michael coleParticipant @michaelcole91146]

Basicly yes, but allways talk to the boiler inspector first before any work is started.

[JasonBModerator @jasonb]

Provided you did not pay your mate to do the welding then no CE required.

As the tubes act as stays to stop the endplates from bulging out soft solder would be a no no and the screw and nut method is not the best. I'd probably go with copper pipes expanded in or you could get steel ones welded but due to wastage (rusting) allowance they can take up valuable water space.

You won't be able to use an off cut or ERW tube from the local structural steel fabricators it will need to be boiler spec as will the other flat plates need to be boiler plate with certificates. For an 8" dia barrel you would be looking at around an 8mm wall thickness.

J

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