Yet, another boil question.

[NYC]

My initial attempt at having a small stationary boiler built for me was disappointing. Now I’m thinking about trying it myself. Right off the bat I have a problem in that W. Harris designed a welded steel boiler for his Steam Donkey. A basic TIG outfit is about $1500. Then there is the learning curve which could be a slippery slope. The pressure vessel itself measures approx. 6”x 12”. I have LS’s that go back to the mid 1972‘s. I know it’s a long shot but does anyone happen to remember a boiler construction series done in copper close to these dimensions? If not it’s time to open some boxes. I know that there are quite a few books on boiler design and construction but the few I’ve seen seem to deal mostly in theory and construction in general terms. Nothing wrong with that, it’s good to know what your dealing with, but does anyone know of a specific ‘How To” book designed for a stationary boiler done in copper close to the size I need?
Thanks in advance,
Tim

[GWRdriver]

Easy for me to say, I know, but it sounds like a simple thing and I don't see that there is any great problem in making the conversion from steel to copper as long as accommodation is made for the differences in material dimension.

I'll be glad to comment further on what might be needed and where the pitfalls might be but before I say anything else I need to have a look at the boiler design so if someone could point me to the issues of LSM, or post a scan of a section of the boiler.

To answer your final question though, the only book I know of which will come close to what you are looking for is "Model Boilers & Boilermaking" by K. N. Harris (ISBN 0852423772). This book includes an array of typical boiler designs and the technical information to design one from scratch.


[This message has been edited by GWRdriver (edited 06-06-2006).]

[NYC]

The boiler spec. are in the July 1989 issue. The series starts with the January issue and ends with the September 1989 issue. If you would like me to make some copies please e-mail me. Thanks

[GWRdriver]

Tim,
I have lots of years of LSM but no that year, if you could scan something, or even a thorough description would do. Let's start with is it horizontal or vertical, and are there water legs or not? If it's vertical and without water legs then it's a piece of cake, if not then it's not such a piece of cake.

PS - I just now found a picture of it which at least answers Question #1. Now I need to see internal details.


[This message has been edited by GWRdriver (edited 06-06-2006).]

[NYC]

GWR, it's vertical and looking at a cross section I'd say it has legs. The firebox is about 1/3 the lenght of the entire boiler and it's surrounded by water and has a mud ring.

[NYC]

GWR, I scanned the boiler chapter ( 7 pages) as jpegs. At one time I used PhotoBucket but I can’t remember exactly how to work it (is age an excuse?). I’ll try an study up on it.
I'm trying to get in touch with a computer guru friend who can probably help with this.

[This message has been edited by NYC (edited 06-06-2006).]

[GWRdriver]

Just post the Photobucket address . . . I'll go have a look.

[NYC]

photobucket.com/ That will only take you to there web page?

[This message has been edited by NYC (edited 06-06-2006).]

[GWRdriver]

The address of the photo file you set up, or if theye aren't too big (say 500Kb each) just transmit them to me. hww at edge dot net

Only the drawings though, I don't need to see the text.


[This message has been edited by GWRdriver (edited 06-06-2006).]

[NYC]

Ordered the K.N.Harris book suggested. Must have been out of print for a while. Only used ones available.

[Unka Jesse]

NYC, that Harris donkey engine boiler can be welded with 3/32" 7018 rods. Just make the "V"s wide and deep enough so the weld goes all the way through. Peen the welds between passes by using an air chisel with a a small slightly rounded punch tip. This will descale the weld and make ready for a second pass.

Don't try to fire that boiler with coal or wood. Build a nice pancake burner and use propane for fuel. Voice of experience here, trust me!! http://bbs.livesteam.net//smile.gif

GWR, yes, the boiler has a water leg.

Unka Jesse

[GWRdriver]

OK here we go, for a copper boiler there are several options, in a nutshell . . .

The most convenient approach will be to use standard seamless hard drawn copper tube for the barrel and firebox. Using a 6" Type L tube for the barrel and a piece of 5" tube for the firebox, your actual barrel OD will be 6.125", you will have a 3/8" water leg space, and the firebox ID will be 4.875". Type L is sufficient for the barrel but Type K (heavy wall) would be optimal for the firebox. The problem with this is that 5" copper tube, especially Type K, is nearly impossible to find these days because although it's a standard mill size it is no longer a stock size. While 6" is no longer just laying around, due to the cost of copper, it is a standard stock size and can be had.

Using a 5" Type L tube for the barrel and a piece of 4" tube for the firebox, your actual barrel OD will be 5.125", you will have a 3/8" water leg space, and the firebox ID will be 3.875". The problem with this is again that 5" copper tube is nearly impossible to find. 4" copper on the other hand is very common and relatively easy to find.

The other alternatives are (a) to have the barrel and firebox tubes rolled from a flat sheet which can get you right on a 5-1/2" OD, or (b) split a 6" tube and re-roll it to 5-1/2" OD, and do likewise for the firebox tube. You could also use a combination of any of the above.

Any rolled or split tube would require either a dovetailed flush joint, or a rivetted lap or strap joint to join the tube seam. The best joint is the dovetail but these require quite a bit cutting and fitting handwork and can be tedious.

The other components, mud ring, firehole ring, heads, and flues will be the same for whichever tube option you choose. The mud ring can be rolled up from 3/8" square copper rod which is available through most all the on-line metals services. My own preference would be to buy 1/2" square and anneal and hand roll it to rough diameter, silver solder the ring closed, and then lathe turn the ring to exact size. The firehole ring can also be made of a piece of Type K or L pipe.

The formula for optimal firetube diameter produces a possible flue ID range of .316" to .370" so you may use either 1/4" or 3/8" (nominal) Type K or L copper and be fine. I agree with Jesse, propane firing is preferred. If you coal fire, then bump this flue size range up one step. In any case I would also recommend more flues, and the reduced flue size will allow this without encroaching on steam space.

The two heads can be formed from 1/8" copper sheet beaten over wood or metal formers, as I described the process in a previous thread.

Everything else, bushings, etc, can be as described in the construction articles, only fabricated in bronze or copper rather than steel. Remember, there should be no brass used in the non-renewable structure of a boiler.


[This message has been edited by GWRdriver (edited 06-07-2006).]

[Jan-Eric Nystrom]

Very good advice, all of it.

Browsing the AMBSC codebook, I note one thing:

Dovetail joints (they call them "castellated") are not recommended practise, at least down there in Oz.

Why this is so, I don't know. Maybe because it requires the silver-soldered joints to be extremely good, if not perfect, for the joint to be strong?

The code is very conservative, so I don't say that dovetail joints are unsafe, but it is always better to be safe than sorry...

Greetings,
J-E

[Alan Stepney]

Quote:
Dovetail joints (they call them "castellated") are not recommended practise, at least down there in Oz.
===================

Surprised to see that.
As you probably know, they are widely used in the UK.
As you say, they do need to be well made.

[NYC]

Gentlemen, gentlemen, thanks for the response’s. After reading them I’ve developed an old fashioned “Excedrin headache #9”. It appears that steel would probably be the easiest way to go as far as the availability of material goes. But the treasure say’s “you want to spend $1500 on a what?” followed by “you don’t even know how to use it”. It being a TIG outfit. Again followed by “you just spent $200 on a gas cylinder and a torch kit, can’t you use that ?” Actually I’d really would like to try and do it in copper. I’ve done only a very limited amount of silver soldering but perhaps the chance of successfully completing the boiler would be better than trying to TIG weld one. I could be wrong on this but I might end up scrapping a lot more material by burning holes in it, or making welds so ugly that you’d end up grinding away so much parent material you’d end up junking it. According to Kozo H. a bad silver solder joint can be re-done without a problem. But I sure that has it’s limitation too. GRW, you have given me several options in copper. But as far as getting the material need it almost seem like “you can’t get there from here” if you follow my meaning. Rolling or forming tools I don’t have. Love to buy some but I’m sure I’d get stonewalled on that issue. I ‘d bookmarked a copper supplier from a previous poster, I’ll see if them have anything the GWR suggests. Jesse, I’d really would like to burn coal. I love the smell and I’ve got a bunch of it. Any suggestions greatly appreciated.
Thanks, Tim

[NYC]

<font face="Verdana, Arial" size="2">Originally posted by NYC:
Gentlemen, gentlemen, thanks for the response’s. After reading them I’ve developed an old fashioned “Excedrin headache #9”. It appears that steel would probably be the easiest way to go as far as the availability of material goes. But the treasure say’s “you want to spend $1500 on a what?” followed by “you don’t even know how to use it”. It being a TIG outfit. Again followed by “you just spent $200 on a gas cylinder and a torch kit, can’t you use that ?” Actually I’d really would like to try and do it in copper. I’ve done only a very limited amount of silver soldering but perhaps the chance of successfully completing the boiler would be better than trying to TIG weld one. I could be wrong on this but I might end up scrapping a lot more material by burning holes in it, or making welds so ugly that you’d end up grinding away so much parent material you’d end up junking it. According to Kozo H. a bad silver solder joint can be re-done without a problem. But I sure that has it’s limitation too. GRW, you have given me several options in copper. But as far as getting the material need it almost seem like “you can’t get there from here” if you follow my meaning. Rolling or forming tools I don’t have. Love to buy some but I’m sure I’d get stonewalled on that issue. I ‘d bookmarked a copper supplier from a previous poster, I’ll see if them have anything the GWR suggests. Jesse, I’d really would like to burn coal. I love the smell and I’ve got a bunch of it. Any suggestions greatly appreciated.
Thanks, Tim</font>

[GWRdriver]

NYC,
You don't need to own the rolling equipment, especially since it is something you might not use again for a long time. Any decent sheet metal shop will be able to roll the shells for you for a nominal cost, or nothing, depending upon your begging skills.

However if you do take the copper path I would advise you when dealing with commercial shops and suppliers to be making a "lamp base" or "bird feeder", not a boiler. Many shops won't want to have anything to do with an amatuer boiler project, or any boiler project for that matter.


[This message has been edited by GWRdriver (edited 06-07-2006).]

[NYC]

GWR, I read you on that. Sort of like when I went to auto parts store and asked clerk A. for a wheel bearing No. xyz. What’s it for? A wheel bearing for a Cessna. No, we don’t have anything like that. Asked clerk B. for wheel bearing No. xyz. What’s it for? My old Ford. Sure we have those.
So far my search for large dia. copper tube has turned up zilch. Waiting for some e-mail returns also.

[GWRdriver]

Depending upon your location a small piece of large diameter copper tube may be hard to come by.

First call all local pipe suppliers/distributors, although they will only sell in full lengths (10ft & 20ft) ask them who has used 4", 5" and 6" locally lately. Call the poeple they mention and ask if they have any short lengths/scraps.

Then begin calling plumbers of both kinds, commercial and residential. Although most large doiameter copper tube will be used by "mechanical contractors" on commercial projects, you never know what a small guy might have in the back shed.

To complicate the problem copper prices (and therefore SCRAP copper prices) are near an all-time high, above $3/lb, so there is now a much greater incentive to not allow scrap bits of copper to lay around the warehouse for very long.

[Jan-Eric Nystrom]

What a coincidence, guys! Here you can see what I did today:

http://www.saunalahti.fi/~animato/steam/460/PICT2916.JPG

You don't have to own a roller in order to use it, you only need to know someone who has one... http://bbs.livesteam.net//biggrin.gif

The CuNi tube was a bit too large for my 4-6-0 boiler, so I had to cut away a 5" wide strip, and then I needed to "shrink" the tube to the proper diameter - and here, the workshop at the workplace of a friend was the right place, with a suitable roller. It can handle maybe 12 or 16 gauge steel, so the approx. 8 gauge CuNi was no problem.

Oh, another thing: A TIG welder is NOT the best to weld a steel boiler with. Professionally, only the first bead is TIGged, in order to get a nicely formed root, the subsequent beads are stick welded, which gives better penetration.

Also, TIG welding thick(ish) copper is something I wouldn't even try - you need to pre-heat the copper (i.e. the entire boiler!) to maybe 600°F or so, depending on the amperage the TIG welder can output. My little 160 A hobby welder can manage perhaps 16 gauge copper, no more, but could probably weld 1/2" CuNi. Since CuNi has only 1/10th the thermal conductivity of copper, a lower amperage will suffice. Welding on a hot copper boiler is something I'd loathe to do...

Greetings,
J-E

[This message has been edited by Jan-Eric Nystrom (edited 06-07-2006).]

[Jan-Eric Nystrom]

Oops, deleted... was going to edit the above! J-E

[This message has been edited by Jan-Eric Nystrom (edited 06-07-2006).]

[NYC]

Have about a dozen e-mails out to copper suppliers concerning tube stock. Who knows maybe I’ll get lucky. If the barrel were rolled from sheet stock don’t you think that a lap joint would be the easiest to make. With lagging who would notice. Plus easier to silver solder.

[watt-steam]

Lap joint would be a LOT stronger than a simple butt joint (obviously) but also probably a lot stronger than a castellated joint. Think about it - a lap joint has a large area of solder,well adhered to both sides. The joint under presuure is trying to open the seam from side to side, aka in shear. A castellated joint resists the shear force along the edges of the sheet in the joints only radially, only the material thickness wide. A lap joint might have many times this area, so the stress is distributed over a larger area. The lap joint is much easier to make. If you want to see a REALLY strong lap joint for full size practice have a look in Machinery's handbook under riveting and you will see the famous double butt strap joint used on the strongest highest quality boiler barrels of the old days.

I have never seen a castellated joint on any full size boiler. I doubt if they would be allowed. I think the castellated joint was invented or at least popularized by Alec Farmer of Reeves Models in England. It's the kind of fussy perfection style method common to English designs and machinery - not real necessary and there are much simpler ways of getting a strong joint on copper, like the lap joint. However, for small boilers the castellated ones obviously work - I've seen lots on complete locos in the english magazines, and are strong enough. If you check the boiler books like KN Harris etc. and their stress calculations most published loco designs are overdesigned for safety and to allow for hobby workmanship.

If you think about it, soldered copper water pipe joints are a lap joint, the lap being wrapped around the diameter of the pipe. I've seen soft soldered 1/2" copper water pipe joints take up to 2000 psi in tests and not pop. The pipe will burst before the joint does, the copper pipe itself is only rated to 400 psi burst. This is a good argument for a lap joint being strong and being good practice. the band of soldered lap area in these joints is about 1/2" wide and 5/8" diameter, so the total area is about .15 square inches.

Personaly I would make a lap joint or double lap joint (one lap outside, one lap inside, silver soldered separately) for a rolled barrel if I were making a copper boiler.

I wouldn;t make a copper boiler though, cause steel's so much cheaper and stronger than copper and also is EASY to stick weld. No TIG here. Silver solder also costs a fortune. I can buy 10 pounds of 7018 rod for about $15 at the most expensive store. 10 lb will weld a BIG model boiler. Try that with silver solder.

[NYC]

I’m happy to hear that the lap joint would be a good choice. But now I’m starting to get confused regarding steel boilers. Some say TIG some say STICK. What about MIG, I never hear it mentioned.

[pkastagehand]

For the small boilers I understand copper is still the way to go. On the bigger ones probably steel but could go either way up to a point.

MIG has an inherent problem which they call "cold starts" which is why it is not much used or mentioned for pressure vessels I suspect.

[GWRdriver]

IMHO, if someone wishes promote their preference or even prejudice for a material, say steel, propagandizing and blowing smoke is not the way. Describe the pros an cons of your preference and let whatever advantages there are stand or fall on their own merit without running down, denegrating, or applying misleading and inapplicable references to the other choices. Especially when the other choices have a much longer and safer history than yours.

It's a poor salesman (or poor goods) who must resort to running down the other man's wares. Full size practice, Machinery's details, and cold water pipe joints have nothing whatsoever to do with current sound miniature live steam boiler design.

[Jan-Eric Nystrom]

<font face="Verdana, Arial" size="2">But now I’m starting to get confused regarding steel boilers. Some say TIG some say STICK. What about MIG, I never hear it mentioned. </font>

It's all about penetration, here is the information as I've understood it:

TIG can get good penetration, but then it is very, VERY slow. That's why usually only the root pass is done with TIG. The advantage with TIG is the fine control you can have, making a good looking bead. The disadvantage is the low deposition of filler (per bead).

STICK is the preferred method by boiler builders - you have a large choice of filler rods, and the penetration is probably the best of all methods.

MIG use is discouraged for boiler welding - you can get a good looking weld, but it hasn't penetrated much, so you may have a welded "skin" on the steel that might "peel off" under stress.

SILVER solder is the best method for copper boilers, but NOT for CuNi, as I, and you, already know...

The Aussie code does allow TIG welding of copper, but only by a professional certified welder, since it is a difficult procedure.

I'ver reckoned that I can build a safe CuNi boiler using TIG, from the experience I've gained welding "coupons", i.e. small welded samples, and cutting & breaking them up and studying the results.

I'm also going to TIG weld the copper tubes to the CuNi tubeplates. Before I do, I will do many, many samples, to find out the right technique and amperage - my first test was not very good looking, even though it was watertight...

I'll keep you posted on the progress!

Greetings,
J-E

[NYC]

This is indeed becoming very educational

[Bill Shields]

MIG on boilers is NOT something that I would normally recommend..

There IS a wire that is the equivalent of 7018, but it is not something that is normally used by the home welder..

[This message has been edited by Bill Shields (edited 06-07-2006).]

[GWRdriver]

Here is where a US Model Boiler Code would come in real handy. I know that to some the mere mention of a model code has the same affect as shouting "gun control" at an NRA meeting, but there has GOT to be a narrow "best" path with respect to welding equipment, materials, and procedures. It seems that in every discussion of steel boilers and welding nowadays the same old things get thrashed about endlessly, typically with no resolution. I may need to build a steel boiler in the future and as it now stands, even being privvy to all the conversations that take place, I would have no idea which direction to head in.

Certainly there will, and can, be differences between experienced individuals about what constitutes "best", but what is needed in a code is not to dictate "best" but rather to define an acceptable range of materials and practices where a wide range of materials and practices is available to the builder.

We certainly don't have this problem with copper! (Harrumph, harrumph!)


PS - By model "Code" I do NOT mean a law, . . . I mean a voluntary guidleine developed by live steamers, published by live steamers, for live steamers.


[This message has been edited by GWRdriver (edited 06-07-2006).]

[NYC]

Speaking only for myself I’d love to see LS do a series on the different kinds of welding. Kozo Hiraoka sure has done a great job explaining silver soldering applications and techniques. But I don’t ever recall seeing a series on any of the other branch’s of welding. I know there are guys out there that have mastered all the different types. Just some basic explanations of the different types, what it’s good for and what it’s not. Some do’s and don’ts. Some trick’s of the trade. Sort of welding 101.

[Unka Jesse]

NYC, you say you have a new oxy/acet torch outfit? You can weld up that boiler with a fairly large torch tip, but it is like TIG, a bit slow. I would use 7018 stick welding myself though I have used TIG on some of my boilers by doing as J-E suggested and just make the root pass.

Unka Jesse

[NYC]

Jesse, just a small tank of acetylene and a presto-lite handle and some tips. A few years ago I bought a small Miller arc welder. Thought I’d teach myself to stick weld. Any tremor of the hand is sure magnified at the end of the rod. That can make a bad weld even worse.

[watt-steam]

Quote- IMHO, if someone wishes promote their preference or even prejudice for a material, say steel, propagandizing and blowing smoke is not the way. Describe the pros an cons of your preference and let whatever advantages there are stand or fall on their own merit without running down, denegrating, or applying misleading and inapplicable references to the other choices. Especially when the other choices have a much longer and safer history than yours.
It's a poor salesman (or poor goods) who must resort to running down the other man's wares. Full size practice, Machinery's details, and cold water pipe joints have nothing whatsoever to do with current sound miniature live steam boiler design.

Well thanks for your opinion GWR. You can attack all you like, I really could care less. Stress in materials at a given pressure and temperature is EXACTLY the same in miniature or in full size.

If you want to continue the mystical UK model design approach, ie castellated joints, be my guest. If you want to think about what youre doing on every job for a loco and use the least expensive material, and simple to construct joints, that will still do the job safely, I'm there.

What worries me most is people coming off as some sort of experts, when most of us, me especially, are NOT experts and are only hobbyists offering OPINIONS for dicussion.

[Bill Shields]

Harry:

Agreed on the code idea...but look what happened to IBLS?

Too diverse a country...nobody agrees on anything..

FIRST thing we need to agree on is an officlal language of communication (don't get me started).....

[GWRdriver]

Bill,
I think the key would be don't ask permission. If it was well done some folks might say well this is as good as any other information we have and start to pass it around. But you know how folks are, if they weren't consulted, or it wasn't done "their" way, they would try to discredit and kill it.

Copper would be the same way, the information is already out there and has a proven history, it just needs to be packaged for the US market. Don't ask, . . . I haven't got time to write a "code."

[Alan Stepney]

Before the castellated joint, some people used to advocate a dovetailed joint. Compared to that, the castellated one was gar easier to make and proved to be equally as strong.

Yes, UK boiler designs are over-engineered, but that means that even if built to less-than-perfect standards, provided a novice follows the instructions, the result will be a safe woking boiler.
That has given us a safety record that much of industry would envy.

With steel, one needs plety of practice and a degree of skill.

(The other advantage over here, is that for many years, we were not allowed to build steel boilers, they had to be professionally made, whereas we have always been allowed to build in copper, a reflection on the relative skills required.)

Another advantage of copper is the ease of forming obscure shapes and tight curves, such as on some Belpair fireboxes.

Yes, both silver solder and copper are expensive, but the total is still a small proportion of the total value of a completed engine.

My personal rule-of-thumb, is to use copper below 6" diameter, steel over 8" diam. and between those sizes, whichever is appropiate for the particular design.

[Bill Shields]

Alan:

can you actually GET 5" copper pipe where you are?

Other than the 8' section I have in storage, it has virtually dissapeared off our continent.

[Alan Stepney]

Last time I checked it was still a standard item here.

My local non-ferrous metal stockist only lists 4.75", but often carries sizes other than those on their list.


That sole remaining 8' you have might eventually be worth a fortune!

[railfancwb]

FWIW, the series on a small boiler published in Modeltec beginning October 1986 is available on CD.

http://cgi.ebay.com/Build-the-NIFTY-NINE-TUBER-boiler_W0QQitemZ6011016670QQcategoryZ2594QQssPageN ameZWD1VQQrdZ1QQcmdZViewItem

Charles