boiler design

hi could someone point me in the direction of any documentation around boiler design, i would like to design my own boiler for a model i am building of a traction engine it was off a design but has changed dramaticly so a boiler of a differant design would be needed.... i would like to between me and my grandad ( retired preasure vessel tester ) design a new one and submitt it to a boiler inspector.

basicly the boiler tube was of 4'' dia but the model has been scalled up a fair amount and the boiler now has a diamter off 5 1/2'' it was off a simular design to a mammod boiler as in just a tube with a fire underneath this is how i was going to do the new larger size boiler but was having trouble finding tube i found it at an online supplier at 150 pounds per 12'' length

i was considering rolling it out of flat sheet and joining it wiv a rivited and silver solderd strap down the full length of the barrel going by other boiler designs there would be the approiat stays in place but i was unsure weather a tube for a traction engine of that diameter was safe to use if rolled and joint down the middle like full size boiler tubes i was just worried about it being in copper and the joint failing but i do supose if solderd correctly shouldnt be a prob

i did consider a coal fired boiler but again some info on construction and how to work out the meterial thickness etc would be handy

before anyone jumps down my throat and say dont do this dont do that im still learning and have ideas just need the relavent infomation to act apon these and come up with a safe design

if you would like to chat thru private messege then please do so to keep the thread cluttering up

Edited By michael burton 1 on 02/10/2013 00:35:49

Edited By michael burton 1 on 02/10/2013 00:36:50

I don't think there will be a lot of difference between tube and a rolled boiler. Just had a quick look and found 5.5" x 10swg tube at £108/ft and 3mm sheet at £45/sq ft and you will need almost 2sq ft plus the cost of solder and may also have to go a bit thicker on material due to the joint. Rolled is acceptable at those sizes on a traction engine but would need to do the calcs to see if 3mm or 4mm was needed.

Have a look at Harris' Model Boilers & boiler making also the Australian code.

At those sizes a simple "tube with fire below" will be very inefficient and you will have a job making enough steam.

Edited By JasonB on 02/10/2013 08:46:26

Edited By JasonB on 02/10/2013 08:48:13

The Australian code for miniature boilers is an excellent document which allows amateurs to build boilers. The requirements for material type, size and weld preparation are all explained. The design requirements are higher than would be required by a qualified boiler maker. But this allows a hobby engineer to build a safe boiler.

The code is for boilers up to 50 litre capacity with a working pressure of 100 psi max. There is a separate code for steel boilers and another for copper boilers.

Contact details are at:

http://www.aals.asn.au/AMBSC/AMBSC.htm

Hi Michael,

just seen your post and I would suggest you contact East Midland Alloys . I popped in a couple of weeks ago to enquire for a copper tube for a 2" Minnie ,10g 5"dia and was quoted a far better price than you. Although not in stock they were prepared to order a full length and just cut off what I wanted. can't say fairer than that.

usual disclaimer

East Midlands Alloys & Metals
Unit F
10 Pavillion Way
Loughbrough
LE11 5GW

Tel: 01509 211 255
Fax: 01509 210 066
Email: [email protected]

You can also learn a lot about techniques and thicknesses that are appropriate by reading back issues of ME. When you think about it there has been an engine or two every year for 100 years so lots of examples though they rarely show the calculations.

The best discussion on these aspects that I've seen is on the Home Machinist forum

ive just been re-reading lots of ME's over xmas (as you do!) including john haining's boiler designs for traction engines. if you are a member of a club suggest you have a good look at ME for the 1980's and copy one of john's boilers. he did quite a few 4" dia boilers. i cant imagine why you would not want to consider a proper coal fired boiler! have a look at m-machine metals darlington - ive used them for copper sheet and barrel material and excellent service and very competitive. give them a ring! they have a catalogue online on their website. 13" of 3 3/4" dia 13swg tube cost me £68 a few months ago from them. arrived 2 days after i phoned to make the order.

cheers,

julian