boiler tubes

[hammers-n-nails]

i am wanting to build a horizontal fire-tube boiler (this will be my first) to power my engines instead of the air compressor and after doing my homework i have got a good idea of what i need to build. the only question that remains concerns the fire tubes, it seems that the most common way to hold them in the flue sheet is to buy a tube expander and use copper tubing. my question is this, why not use iron pipe and weld them in, welds break? more difficult to replace? if i is true that copper tube is the right way to go can anyone recomend a brand or type of roller?

 

[te_gui]

I built a vertical fire tube boiler once following the plans in "Live Steam" for the Logging Donkey by Bill Harris. It uses a steel shell and tube sheets with Grade "L" copper tubing expanded in. I'm not 100% sure on the L, I know its the heavier wall version of copper tubing sold for home plumbing. I bought mine at Home Depot. The expansion is done using a driver with a nut that compresses a stack of neoprene washers inside the tube, expanding it into the hole in the sheet. I had my doubts about it until I looked inside the expanded tube and saw where the finish marks left by the reamer in the tube sheet had transferred thru to the ID of the tube. All the plans for Bills models are available , so I'm sure you could modify his ideas to suit yourself.

Brian

 

[Florian]

my question is this, why not use iron pipe and weld them in, welds break? more difficult to replace? if i is true that copper tube is the right way to go can anyone recomend a brand or type of roller?

Because of the heat conductivity which is much better.

I know that in big boilers, they only welded the tubes on one side and expanded them on the other side. This should give the tubes the possibility to equalize the heat expansion. How big is your boiler going to be? If its not too big, you can make it out of copper and then silver solder it.

Florian

 

[Paolo]

Because of the heat conductivity which is much better.
Florian

Yes Florian and not only...You have to consider the corrosion! Copper resist much better than steel!!

 

[Florian]

Hi Paolo

Basically you're right, but there's a problem if the fired coal contains too much sulfur and the boiler has copper tubes. When firing with that coal, sulfur becomes sulfuric acid and then the oxidated copper reacts with that sulfuric acid.
(Not the copper itself luckily) but you can imagine that when the copper is blank again, it oxydates and the copper oxyde will be "removed" by the acid again... somewhen there are there no smoketubes anymore.

Florian

 

[Maryak]

I know that in big boilers, they only welded the tubes on one side and expanded them on the other side. This should give the tubes the possibility to equalize the heat expansion. How big is your boiler going to be? If its not too big, you can make it out of copper and then silver solder it.

In full size practice, with the exception of stay tubes in fire tube boilers and superheater tube to header interface, boiler tubes are commonly expanded at each end. In water tube boilers the ends of the tubes are usually belled on their end inside the drum/header.

In comparison with model boilers, the shell/end plate has a much greater ratio of plate thickness versus tube wall thickness, e.g. a fire tube boiler at 200psi will have a shell some 1-1/4" thick and a normal fire tube wall thickness of some 3/16," making expanding the tube into the shell a viable method of sealing. Not to mention the cost and damage of removing and replacing a tube which was welded to the shell.

Hope this helps

Best Regards
Bob

 

[ChooChooMike]

In full size practice, with the exception of stay tubes in fire tube boilers and superheater tube to header interface, boiler tubes are commonly expanded at each end. In water tube boilers the ends of the tubes are usually belled on their end inside the drum/header.

As a point of reference, I've been working on disassembling a full-sized locomotive We removed all the tubes/flues. The smokebox side of the boiler tubes were expanded & rolled (peaned). The firebox side, the tubes were expanded, rolled and then welded. Probably better to withstand the heat/flues gases, etc. Each railroad had their standard practice when it came to sealing the boiler tubes.

The superheater tube to header interface looks kind of like your hip-socket. A ball in a socket with a washer and large retaining nut. The joint has to be steam tight and able to withstand the higher steam heat/pressure generated in the superheater tubes. Talk about some work to remove those tubes that probably hadn't see the light of day in decades !!! Back-breaking work, but I got them all removed without damaging anything - that was a bit of a miracle

Mike

 

[Jasonb]

I don't know what size boiler you are thinking of making but upto around 5" dia I would go with copper construction with all the tubes silver soldered in.

If you are going bigger than this then steel barrel and welded in tube plate and expanded copper tubes, these will last longer than steel tubes and be easier when it does come to replacement.

Jason

 

[hammers-n-nails]

i have read that copper had better heat conductivity but the boiler i want to build needs to be fairly large because i might not put an artificial draft on it, i have a piece of 8" steel pipe that is about 4' long in the shed that im going to use, the boiler itself will be about 36" long so 3/4" id fire tubes will only be about 50 diameters long. im not really worried about making this boiler super efficient so the extra heat conduction offered by copper isnt a big deal to me. as for replacing a tube if one goes bad and i cant get it cut out i dont have a problem with eliminating it. i dont have a problem with using copper tubes or threading them in like a stay tube, i was just wondering if welding them in was an option and if anyone had any prefered method.

 

[Maryak]

The superheater tube to header interface looks kind of like your hip-socket. A ball in a socket with a washer and large retaining nut. The joint has to be steam tight and able to withstand the higher steam heat/pressure generated in the superheater tubes. Talk about some work to remove those tubes that probably hadn't see the light of day in decades !!! Back-breaking work, but I got them all removed without damaging anything - that was a bit of a miracle

Mike

I don't envy you that job. :bow: :bow:

Best Regards
Bob

 

[CrewCab]

I've been working on disassembling a full-sized locomotive

And where is your camera ;D ;D

As you know, pictures are mandatory 8) ................ have fun Mike

CC

 

[Paolo]

I'm curious to see how much bigger it is!!!!
th_wwp th_wwp th_wwp
Best regards
Paolo

 

[vlmarshall]

As a point of reference, I've been working on disassembling a full-sized locomotive We removed all the tubes/flues. .... Talk about some work to remove those tubes that probably hadn't see the light of day in decades !!! Back-breaking work, but I got them all removed without damaging anything - that was a bit of a miracle.

What do you use to remove them? Just curious, because at work, we often make some expanding, internal tube-gripping things that, as far as I know, remove some sort of heat-exchanger tubes.

 

[ChooChooMike]

And where is your camera ;D ;D

As you know, pictures are mandatory 8) ................ have fun Mike

Oooopppss, I deleted all my pictures from that ..... NOT !! ;D This was such a unique experience, I made sure I captured it in bits & bytes !

Thanks for the interests folks, giving me some incentive to organize the pictures. I've got a TON of pictures I can post from the disassembly process. I'll post a few of removing the boiler flues/tubes/& superheater tubes.

What do you use to remove them? Just curious, because at work, we often make some expanding, internal tube-gripping things that, as far as I know, remove some sort of heat-exchanger tubes.

The 8" boiler flues were cut at both ends (firebox/smokebox) with a cutoff wheel and pulled out from the smokebox ends. The 2" boiler tubes ends were cut using a pneumatic rotating tube cutter. The actual cutting tool looks very much like a standard lathe tool.

On the superheater tubes, a lot of ingenuity, rose-bud torch to heat the nuts (on the t-bolt hold the retaining collar) and retaining collar, squirted water into nut/bolt connection to see if the resulting generated steam would help loosen nut, kroil (penetrating oil), 1" - heavy duty impact wrench/socket (absolutely the most helpful tool !!), hammer, breaker bars, lots and lots of ball-busting effort.

They probably don't look like what you are thinking, here's what the superheater setup looks like on a typical steam locomotive boiler :

Images from Wikipedia

http://en.wikipedia.org/wiki/Superheater

Here's some actual pictures from another site :

http://www.watercressline.co.uk/tw/pages/howworks.htm

Smokebox end of the boiler with a few superheater tubes installed. You can see how the tubes fit into the actual boiler flue :

Superheater tubes laying on ground :

Superheater header (upside down)

Full set of superheater tubes installed in boiler flues :

All picture credits to the above web site.

----------------------------------------------------

I'll organize some of my pix and post them too.

This was all volunteer work I did ..... didn't get a dime, busted by butt, came home very tired and very sore and very satisfied and LOVED IT ALL !! Nothing like some hard work to sooth your psyche ! Would do it again in a heartbeat. The whole process has been incredibly interesting to me. Talk about learning how a locomotive is put together, nothing like getting up close and personal with one ;D :big:

Stay tuned !!

Mike

 

[CrewCab]

Thanks Mike, sounds like you really enjoyed it, good experience methinks, albeit a bit wearing .......... anyway, looking forward to the pictures (all of us that is, not just me ) ............ pressure, what pressure ........... ;D

OK .......... when do you start putting it all back together 8)

CC

 

[deverett]

i have read that copper had better heat conductivity but the boiler i want to build needs to be fairly large because i might not put an artificial draft on it, i have a piece of 8" steel pipe that is about 4' long in the shed that im going to use, the boiler itself will be about 36" long so 3/4" id fire tubes will only be about 50 diameters long. im not really worried about making this boiler super efficient so the extra heat conduction offered by copper isnt a big deal to me. as for replacing a tube if one goes bad and i cant get it cut out i dont have a problem with eliminating it. i dont have a problem with using copper tubes or threading them in like a stay tube, i was just wondering if welding them in was an option and if anyone had any prefered method.

It sounds like quite a big boiler. To get it insured you will need to follow some recognised code, will have to be pressure tested and inspected by a competent authority. Your boiler inspector would be the best person to advise you on materials and methods to complete your project.

Dave
The Emerald Isle