Contemplating a boiler build

[Brass_Machine]

So I have this small boiler that I use to run my engines occasionally. However, it is very small and needs some work. I have been debating building a small boiler myself along the lines of Firebirds build. I have been looking over the plans Sandy has uploaded and think I will give one of them a shot. Not sure if I am going to do the vertical or the horizontal yet.

Here is my question. I have seen posts before about not using plumbing grade copper for the tube. Where in the states can I find a 3" copper tube to use?

anyone?

Bueller? Bueller?

Thanks
Eric

 

[Divided He ad]

No Idea about your Question Eric..... But got to love that reference ;D :big: ;D

Good luck on the build, I hope that you are paying attention to Firebirds very informative build and all of those safety things we've all been discussing...? I know I am!




Ralph.

Oh, I dropped something in your 'water cooler'

 

[rangerssteamtoys]

Are you thinking about a firetube boiler? Or a "pot" boiler?

 

[Bernd]

Eric,

There are two kinds of copper pipe one can get at the "Home Horror" centers. I believe one is marked "K" and the other I don't remember. One problem will be finding 3" pipe at those stores.

What you'll need to do is go to a store that handles large plumbing supplies. Ask for the copper pipe they use for commercial airconditioning. This stuff is thick walled. I'm sure you'll have sticker shock as to price. There is a letter system used for the different wall thickness. Go for the one that's the thickest.

A nice boiler to build is Jan Gunnarsson's. He wrote an article in Live Steam in April 1979 on how to build a "Miniature Boiler Works for marine or stationary use."

Bernd

 

[Brass_Machine]

Eric,

There are two kinds of copper pipe one can get at the "Home Horror" centers. I believe one is marked "K" and the other I don't remember. One problem will be finding 3" pipe at those stores.

What you'll need to do is go to a store that handles large plumbing supplies. Ask for the copper pipe they use for commercial airconditioning. This stuff is thick walled. I'm sure you'll have sticker shock as to price. There is a letter system used for the different wall thickness. Go for the one that's the thickest.

A nice boiler to build is Jan Gunnarsson's. He wrote an article in Live Steam in April 1979 on how to build a "Miniature Boiler Works for marine or stationary use."

Bernd

Yeah sticker shock is right. I looked online at McMaster Carr (I have one fairly local)... $92 for 2 feet of 3" copper pipe. If I can find some cheaper, I may see if some people want to split the cost... I don't see me needed a full 2 feet.

Eric

 

[Powder keg]

Does it have to be copper? Why not make a steel one? Case made them out of steel for years)

Wes

 

[Loose nut]

Other options
-steel boiler all the way
-steel shell with copper tubes
-Steel shell with copper firebox and tubes
all of these have been done at one time or another, can't say how successful, different rates of expansion come to mind although full size boilers have used these methods.

 

[BobWarfield]

I'm with Wes.

Copper is so expensive, and so soft. Why not stainless steel?

As I disclosed on my ill-fated TB Boiler thread, I lean towards a Yarrow water tube boiler design. I like the idea that the parts likely to go "boom" live completely inside a metal shroud. I also like the idea of working with stainless steel rather than copper. My experience with it throughout my welding career is that its really nice to work with. I like the Yarrow design also because I like the aesthetics of the curvy boiler tubes. I have a lot more research to do, but maybe you will find some value in some of the links i have so far come across.

Consider this stainless tubing supplier recommended on PM:

http://www.eagletube.com/pipe.asp

Here is there page on pressures: http://www.eagletube.com/theoretical.asp

Check out page 30 of their catalog: http://www.eagletube.com/05 Eagle Cat.pdf

You will have to scroll to page 30, but it gives a nice table of theoretical bulging and bursting pressures that's worth a gander and some thought. I read this and my reaction is "keep the tubing sizes small". It is the area of the inside wall that the pressure has to act on that determines the key issue of how much pressure before you have a bomb and not a boiler. In this sense, copper is soft and stainless is tougher. I like that aspect of it. You are giving up some conductivity of heat, but I think a little less efficiency is acceptible if there is greater strength and safety margin.

But heck, I'm no boiler expert, this is just what I see so far in researching it.

Cheers,

BW

 

[Mcgyver]

I have seen posts before about not using plumbing grade copper for the tube

curious about that.....if the concern is well founded it has to do with the alloy of copper but i can't recall ever hearing or reading that a particular alloy of copper is or isn't acceptable. Of course there are different schedules for plumbing copper L, M etc, but that has nothing to do with its appropriateness only what the safe operating pressure would be. In fact I bought some 4" copper years ago from a model engineer supply place and it was for plumbing....I remember chatting with him that he bought 12' lengths of it from one of the big industrial plumbing supply places like Westburne....come to think of it, what other kind of 3 4 or 5" copper tube is there that isn't for plumbing ??? ???

 

[Mcgyver]

I also like the idea of working with stainless steel rather than copper. My experience with it throughout my welding career is that its really nice to work with.

If your career has made you an experience stainless steel welder I suppose that's half the battle, but so far as working it, you'd take stainless over copper ??? Man you are tough.

Lots of considerations, thermal conductivity of about 1/25 that of copper and its tricky stuff. miserable to work, bend, machine whatever and suffers fatigue cracks etc. imo there's lots of reasons you don't see many stainless boilers...steel on the other hand seems to be getting used for smaller and smaller boilers given the price of copper.

Are you an ASME certified welder? I can't remember all the details but it seems like there's a lot of regulatory bodies that perk up when you're talking about welded pressure vessels. Mill certs and ASME qualified welder etc required.....as annoying as that crap is you don't want to sweep it under the carpet...if something happens it'll be on your shoulders and bank account as all insurance co's will scream gross negligence and run for the hills.

imo, for a small simple boiler, one would be better to bite the bullet and buy a foot of tube.

 

[BobWarfield]

I've used it for fuel lines and brake lines on cars. No problems bending it in those applications. I'll be using more of it in conjunction with my one shot oiler on my mill. It can be silver soldered or welded. The former is the more likely route as Tigging little bitty tubing is pretty finicky.

It certainly does stink on thermal conductivity though there is no shortage of data on commercial stainless boilers out there.

Cheers,

BW