Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: Solitary Sailor on August 23, 2010, 01:45:02 am
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(http://s1.postimage.org/Oqn3i.jpg) (http://www.postimage.org/image.php?v=gxOqn3i)
Well here goes. My first attempt at a boiler. If you spot any howlers, please don't hesitate, I need all the help I can get. %)
OK, what I'm trying to make... a 5" dia marine boiler 12" long, with a pressure vessel length of 9". There will be 2 flues/firetubes of 1.5" dia. with 11 cross tubes in each.
The above picture is of the first flue. For this part I have used oxy/acty with a brazing rod with 5% silver. From work experience I know that these joints will easily withstand pressures of around 250 psi. under pressure and are quite safe even up to 500 psi.
(http://s3.postimage.org/zFbf0.jpg) (http://www.postimage.org/image.php?v=PqzFbf0)
(http://s3.postimage.org/zFWDJ.jpg) (http://www.postimage.org/image.php?v=PqzFWDJ)
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The cross tubes are 1/4" ID and are spaced every 3/4" on centres, but offset approx 30* for the second and third tube, before reverting to the original line. This is to create a swirling of the flue gasses (I hope) thereby holding the heat in the fire tube that little bit longer. This pattern repeats down the line.
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(http://s3.postimage.org/zJK5r.jpg) (http://www.postimage.org/image.php?v=PqzJK5r)
OK. Here's a slightly better picture of the cross tubes, at least the first 3. Sorry about the grainy interior of the pipe, well, at least the background is nice and clear :embarrassed:
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Fantastic news, well done!
We need more boiler making in our hobby.
One thing- the brazing rod you have used- although it's rated to those pressures, are you sure they are suitable for steam temperatures- I have been looking at a few different (cheaper!) alternatives to Silver Solder, but not all of them were suitable for the temperatures I wanted it for.
Greg
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"Silver Solder" means different things on opposite sides of the pond, big debate on HMEM regularly between various and Boggy on this one. Are you building to a "Standard" design or is this a home cooked boiler? Trust you Designed it following the proper rules. Not a nark, just thinking of your own safety (AND others)
Regards Ian.
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In reply to Greg and Ian. First off, yes, this is not a "silver solder" as understood by the modeling fraternity, it is a brazing stick with 5 percent silver content. Given the temperature required to melt the solder, after all, an oxy/acty torch burns at a much higher temperature than a propane / butane torch; I feel confident that the heat from the boiler's burners will have no adverse affect.
This type of solder is often as strong as the pipe it welds together. Also, it is used in circumstances where extreme temperature changes can occur very rapidly.
Now, if anybody knows of any possible chemical or structural adverse reactions that may occur, by all means let me know, and I will toss the first attempt out the window...not the first time I've wasted half a day's labour >>:-(
Having had conversations with both Bogstandard who said "no way", and Nick from Monohan Models, who said absolutely OK, and given that Nick makes these things professionally ... I'll differ to the professional. Not that I don't value Boggy's opinion, I just feel that Nick would have more experience in this field. We all, after all, are more comfortable in what we are used to. %)
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As I recall, Boggy's opinion was more to do with the structural changes occuring in the copper piping due to the higher temperatures involved during the brazing process.
Strictly speaking the actual process is known as "Sweating", but by going round talking of sweating, people might end up thinking they're talking to some weirdo from the tropics %%
As to safety Ian. I plan on capping the ends of each pipe and pressure testing with Nitrogen to 350 psi. This will reveal any leaks as well as demonstrate the structural strength
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Nice work so far.
Here's some additional info:
Silver brazing or silver soldering is the preferred method of joining components together during the construction of copper model boilers.
However in the AMBSC Code Part 1, Issue 7 - 2001 Copper boiler code book bronze brazing is acceptable as long as its preformed by persons experienced in the process. Excessive temperatures and prolonged heating shall be avoided during bronze brazing to minimize damage to the parent metal. Filler material must be comply with AS1167.1 - 1993 Welding and Brazing - Filler Metals. Alloy RCuZnA Tobin Bronze.
nick
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I plan on capping the ends of each pipe and pressure testing with Nitrogen to 350 psi. This will reveal any leaks as well as demonstrate the structural strength
So you're planning on a running pressure of 175psi.?
Regards Ian
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As to safety Ian. I plan on capping the ends of each pipe and pressure testing with Nitrogen to 350 psi. This will reveal any leaks as well as demonstrate the structural strength
Can I suggest a hydrostatic test of the boiler components as opposed to a test with pressurized nitrogen. A failure during a hydrostatic test is much less of a hazard than a failure when the vessel contains pressurized gas. There are very ggod reasons why pressure vessels are tested/re-certified using hydrostatic testing!
oCheers,
Adrian
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Nice work so far.
Here's some additional info:
Silver brazing or silver soldering is the preferred method of joining components together during the construction of copper model boilers.
However in the AMBSC Code Part 1, Issue 7 - 2001 Copper boiler code book bronze brazing is acceptable as long as its preformed by persons experienced in the process. Excessive temperatures and prolonged heating shall be avoided during bronze brazing to minimize damage to the parent metal. Filler material must be comply with AS1167.1 - 1993 Welding and Brazing - Filler Metals. Alloy RCuZnA Tobin Bronze.
nick
Thanks NIck, my fears are allayed now, perhaps if Solitary Sailor had told us exactly what he was using he wouldn't have been patronised as much %)
With Adrian on this one- ALWAYS hydro test- there should be no gas content in a boiler under test- gas expands- and thus explodes under a breach of integrity- water on the other hand, because it can't be compressed will not explode- it will drip, or spurt out of any leaks.
Would you mind showing the calculations you used to decide upon the gauge of tube you are using?
Keep up the good work, again well done!!!!
Greg
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The Blue Book on THE EXAMINATION & TESTING OF MODEL STEAM BOILERS----( Revised Adition 2008 ) and Authorised by Sun Alliance who insure most clubs for
steam boilers on page 16 clearly says that " WELDED BOILERS ARE ACCEPTABLE, PROVIDING THE PERSON UNDERTAKING THE PROCESS IS COMPETENT TO DO
SO"
If the welding is undertaken by a person who is not a coded welder all sorts of conditions apply.
So in the U.K. welding of boilers is acceptable.
I have over the years made many boilers and always used Silver Solder with a 42% sliver content and found that the solder flows easily and allows many joints to be done at the one time, where as welding I think would take longer as each individual joint would have to be made, as I have never tried welding I can only surmise.
Keep at it Sailor if you find welding easier , go for it, bet you wish you hadn't mentioned it !!!!!
Here are a few pics of some of the boilers made with Silver Solder.
George.
(http://s2.postimage.org/aPBl0.jpg) (http://www.postimage.org/image.php?v=TsaPBl0)
(http://s2.postimage.org/aPDQ9.jpg) (http://www.postimage.org/image.php?v=TsaPDQ9)
(http://s2.postimage.org/aPGki.jpg) (http://www.postimage.org/image.php?v=TsaPGki)
(http://s2.postimage.org/aPIPr.jpg) (http://www.postimage.org/image.php?v=TsaPIPr)
(http://s2.postimage.org/aPLjA.jpg) (http://www.postimage.org/image.php?v=TsaPLjA)
(http://s2.postimage.org/aPXNi.jpg) (http://www.postimage.org/image.php?v=TsaPXNi)
(http://s2.postimage.org/aQ9g0.jpg) (http://www.postimage.org/image.php?v=TsaQ9g0)
(http://s2.postimage.org/aQefi.jpg) (http://www.postimage.org/image.php?v=TsaQefi)
(http://s2.postimage.org/aQgKr.jpg) (http://www.postimage.org/image.php?v=TsaQgKr)
(http://s3.postimage.org/DDQRr.jpg) (http://www.postimage.org/image.php?v=PqDDQRr)
THIS WAS A VERY BIG YARROW TYPE BOILER THAT COULD WORK UP TO 100 psi all Silver Soldered.
(http://s3.postimage.org/DDVQJ.jpg) (http://www.postimage.org/image.php?v=PqDDVQJ)
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Ment to say that I agree with Hydraulic Testing, much safer, better with a jet of water than a jet of gas,
George.
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Thanks for all the tips guys.
George, those boilers definitely look like you've had a bit of practice :-))
Also, I think silver soldering allows for a cleaner finish. I just think, (due to work experience) that brazing / sweating makes for a stronger joint. The only time I have seen one break apart is when the original brazing was done incorrectly ... ie. not get the joint hot enough to get the solder to flow properly, and I've seen plenty of these pipe joints under stresses of 450 psi and more (due to restrictions in the system), and this includes systems operating with some pretty big compressors (20 - 25 tons); these joints seem to hang in there with no problem
Nick, the approach I use is to set up most of the cross tubes in place, then heat up and braze each joint, one after the other. I think my average time per joint would be between 30 - 45 seconds, then on to the next. (The first joint taking a while longer as the surrounding metal has to be warmed up enough to stop bleeding off of the heat at the solder point). So I tend to move to a different section of the tube relatively quickly, although the in aggregate, I guess the whole assembly does get pretty warm, and I do tend to use a hot flame, just to minimize the time where the flame of the torch is in contact with the metal; as can be seen however ( by the dis-colorization of the copper) it does get hot. Needless to say, I have to wait for a few minutes for the metal to cool off before trying to grab a hold of it to set up for the next operation...finishing off on the missing cross tubes.
Greg, I simply went for the heaviest gauge available. The 1 5/8" pipe is refrigeration type 'L' hard drawn, with a wall thickness of 1/16" Incidentally, refrigeration copper sizes are spec'd outside wall to wall, where plumbing is inside dimension, so my 1 5/8" is actually 1 1/2" inside dia.
The barrel arrived today, now that's a heavy piece of copper
(http://s4.postimage.org/oE7Pi.jpg) (http://www.postimage.org/image.php?v=aVoE7Pi)
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So you're planning on a running pressure of 175psi.?
Ian
Er...not quite. Just testing to verify a high standard of integrity. My aim is for the boiler to operate between 65 - 80 psi, with the lower figure probably sufficient for the twin cylinder engine I'm in the process of making; progress being very slow on that one right now ... actually more like coming to a grinding halt due to frustration...however, will return to the fray when the memories of rage disappears down the memory hole, which given the advancing years wont be too long {:-{
As to every ones concern for pressure testing. I feel pretty confident with this method as I have done it many times to check for structural integrity. However, in consideration of your concern, I will go for an alternative method, I'll draw a vacuum of 29 inches water gauge, and verify it maintains vacuum for 60 Minutes. Don't know what it is about a vacuum, but when you think everything is A OK, pulling a vacuum will invariably find the weak spots. If that doesn't meet with every ones approval, I guess I'll have to go out and buy some more tools ... Oh goody %)
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Hi Sailor,
Pulling a vacuum is O.K. but how do you find the leak, not sure how you would do this.
If you hydraulic it a jet of water can be seen,
Another way for small boilers and firing tubes is to solder plates on the end and solder on a bicycle valve, immerse it in a bucket of water and gently pump up and if leaking you will soon see the stream of bubbles. Be careful as you can pump up to 60 psi very quickly with a hand pump.
Another way and not to be recommended ( unless you know what you are doing ) is that when your boiler is complete and the fire tubes are O.K. is to put a pressure gauge into one of the boiler bushes, fill the boiler FULL of water and gently heat it with a torch and bring up to the test pressure , be aware that when it gets near the test pressure it can whip up very quickly
I don't know if you have made a boiler before but just in case you don't know I would leave 1/4" bridge as a min, between your firing tubes and 1/8" min between the tubes and the boiler internal circumferance.
George.
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Thanks for the tip George. As to finding a leak under a vacuum, that is surprisingly easy...you can see it on the gauge, and you can hear it, provided it is not a tiny fracture, but you will still see it in a loss of vacuum on the gauge. To find the small leaks, simply charge with a small amount of nitrogen, 20 or 30 psi and set to with some dish washing soap, the leak will soon reveal itself, or, as you suggest, immerse in water.
I think everybody here is so used to the standard silver solder process, and is very aware of its possible shortfalls, especially when incorrectly done. Introducing a different concept does bring out concerns, both legitimate and not so. Brazing with oxy/acty is a much tougher proposition from the point of view of its inherent strength when correctly fabricated. Yes I concede that I have much to learn. But unless there is something I am unaware of regarding chemical interactions within the processes of a boiler, I suspect that my approach, especially regarding the fire tubes, will be successful. There again, this is a project in motion, and so subject to revision and outright rejection when errors occur or are revealed by superior experience. So please don't think I am brushing your concerns aside, which my holding to my course would seem to imply. Please keep the comments coming, and hopefully we can all learn something.
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At one time I thought that I had found the ideal brazing rod, It was cheaper and easier to use than silver solder, I asked about it and was shot down in flames every where I asked. Then someone finally posted why you should not use it. Unfortunately when I copied it I forgot to copy where I got it.
"Quote from: steamer on August 15, 2010, 05:06:35 PM
Please check my last post for an important edit....Don't use Silphos on boilers. - Dave
Back in the early 1960's, Sil-Phos (aka, phos-copper brazing alloy) became popular in US live steam circles as a cheaper substitute for silver solder. Another attractive attribute was that it was flux-less for copper-to-copper joining. Inexpensive, flux-less, and readily available, wot's not to like? One of the reasons for phos-copper's popularity in the 1960's was that IIRC the original Little Engines Co (of Lomita CA) suggested it for use on their cast-in-1-piece bronze fireboxes and at that time perhaps 80% of live steam locomotives being built in the US were of one Little Engines design or another.
But after a few years a curoius thing appeared. Boilers assembled with phos-coppers began to spring pinhole leaks in the most inconvenient places, inside front firebox flue sheets for example. (Also, in fairness to phos-copper, the Little Engines 1-pc cast fireboxes were notoriously pourous.) To make a long story short, it was determined by the mfgs that phos-copper, which was originally intended for cold water plumbing, deteriorated in hot sulphurous atmospheres and what could be hotter and more sulphurous than the firebox of a coal-fired model locomotive. Naturally disagreement sprang up over its use (Disgareement amongst live steamers? Surely not?), and a few die-hards remain, but generally speaking phos-copper for live steam is no longer accepted."
Regards,
Gerald.
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To make a long story short, it was determined by the mfgs that phos-copper, which was originally intended for cold water plumbing, deteriorated in hot sulphurous atmospheres and what could be hotter and more sulphurous than the firebox of a coal-fired model locomotive. Gerald
Given that these will operate in a GAS fired environment is the same liable to hold true?
Thanks Gerald I will definitely have to check with a welding supplier, maybe even throw Nick's comment his way, and see his response. Filler material must be comply with AS1167.1 - 1993 Welding and Brazing - Filler Metals. Alloy RCuZnA Tobin Bronze.
So yes, maybe my first attempt is not safe from the scrap heap yet. Far cheaper to throw that out than that 5" barrel <:(
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My biggest concern here is not the method of joining the parts but the seemingly cavalier attitude towards testing the shell afterwards.
There is no comparrisson between pressure testing hydraulically and drawing a partial vacuum. It is quite conceivable that a flaw could be closed up under the unusual forces generated on the parts by a partial vacuum and you could miss a leak. Also 'hearing' the leak will not be accurate enough to be able to identify it and allow you to remedy it.
If you were in the UK your boiler would need to be checked by an inspector at a couple of agreed points during the build process and then, when completed, it would need to be pressure tested hydraulically at twice the working pressure. The working pressure would be determined by the drawing, if built from a plan, or by calculation, if made from a personal design. The only way to test a boiler shell is hydraulically, any other method is not reliable and would not be acceptable. The subsequent certification includes the working pressure and the test pressure. We seem to be drawing numbers out of the air here and then using a 'suck-it-and-see' process to test them.
I think I need to make it quite clear at this point that the views expressed within this thread are not necessarily the views of the Modelboatmayhem team or it's ownership. Pressure testing of boilers is an extreemly serious process and should only be conducted under the guidance and supervision of an experienced and qualified tester as identified by an accredited club.
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Haven't noticed on this forum (having said that, I haven't seriously looked for one) but on other fori which have a "Safety" element involved, I have sent a PM to the site owners to add, for their OWN security, a disclaimer so that anyone injured by blindly following "I saw it on whatever so it must be OK" threads have no recourse for a "Blame Claim".
In general, toy boats don't normally constitute a danger to the owners or general public but steam is an exception and as such, due to the fact that some think they can claim for tripping up over a matchstick, perhaps Martin should cover his a-- posterior and add one for his own safety.
Regards Ian.
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I think Circlip has some merit in his argument. As he says people will sue under any grounds
and sometimes insurance companies will settle rather than have the hassle of a court case.
Finally who knows which side will the court will favour, there have been some very strange
rulings recently. Lets face it when we all get heated up over certain topics we have some
very radical views which some who may be visiting the forum may find offensive but they
can't be held as Martins' personal opinions. A disclaimer somewhere prominent should nicely
cover Martins' back.
Geoff
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Rather than have one too prominent and take up valuable front page real estate we tend to add a statement such as the above to make it very clear that Mayhem does not necessarily condone the views of the membership etc...etc...
We've actually got it written out somewhere but I couldn't find it in time and I wanted to get something up quickly. :embarrassed:
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This is what I was thinking of which is obviously far more sales related. Maybe we need to make it a bit more all encompassing.
http://www.modelboatmayhem.co.uk/Disclaimer.htm
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Bunkerbarge ... obviously the opinions I am expressing are my own and in no way can be construed as being endorsed by Modelboatmayhem, its owners, or its members.
As I have stated above, I realize that these methods are not those which are normally accepted within the modeling fraternity, I am bringing a different experience to this project. One from a lifetime spent working with pressure containing systems, not water boilers true, but pressure containing closed systems. Believe it or not Bunkerbarge, my desire is to have a boiler as safe as you or anyone else could wish it to be.
I am simply trying to ascertain the structural integrity of these fire tubes before proceeding with any further construction.
Your disapproval is duly noted.
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Further to the above, it has always been my intention to have the finished boiler tested and certified, by an independent 'Certified' authority, as I also wish to know whether it is safe to operate.
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We seem to be drawing numbers out of the air here and then using a 'suck-it-and-see' process to test them.
The reason for the quoted testing pressures, is that I wish to go above and beyond the normally accepted requirements, to be absolutely sure that what I am building is indeed safe to operate. Just testing to twice the operating pressure, would only require a test pressure of 160 psi. Double that figure, and I think we can all agree allows for a greater safety margin.
It has been my experience over many years of work that pressure failures in closed systems are due to small pinhole leaks occurring due to poor brazing of joints, long term vibration of the affected pipe, or small ruptures of heavily corroded pipe (after many years exposure to saltwater air conditions prevalent in the areas where I ply my trade). These leaks DO NOT suddenly expand into some great explosion as the high pressurized gas seeks to escape.
I recognize that boilers do operate under high pressure conditions coupled with high heat. Hence the reason for using the brazing technique, since getting the solder to melt and flow around the joint requires a much hotter flame than a normal propane torch, therefore the heat stresses would not affect the soldered joint ... ie. the heat from a propane torch (or boiler's gas burner), is insufficient to melt the solder on the joints. Yes, there may be conditions where this rule fails, but by that time, any joint soldered under the normal process of 'silver solder', done with a propane torch, will have long since melted away.
It has also been my experience, when faults occur in the operation of equipment which I deal with on a daily basis, that conditions can occur where pressures within a closed refrigerant circuit can exceed 450 psi, with no structural breakdown of the copper tubing / brazed joints involved, they simply continue to hold pressure, until such time as someone comes to correct the fault. Yes, this is in a different environment than a boiler, but as Nick says, providing I follow AS1167.1, I should have no problem. In short, experience has taught me that refrigeration copper can and will withstand high tolerances for structural integrity when put under these sort of pressures.
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Solitary Sailor,
Our experiences tend to shape our world view and I think that is happening here.
I would imagine that refrigeration systems tend to operate at low temperatures (no pun intended) when compared to boilers. This would mean that the integrity of the joint is the primary operational concern and that the material properties of the copper tubing used would be relatively static. Failure modes would not be due to the tubing exceeding yield strength but to other causes. This would lead to a focus on the joint material and the joining process. A pressure test of the "cold" system would provide a comfort level that everything is great.
The difference in the boiler world is that when we add heat, the material properties of the copper change considerably. Now the joint is not the only failure mode. The tube material itself has becomes a potential failure point. All industrial codes and the boiler formula that are used for model boilers "de-rate" the mechanical properties of copper to account for the change in strength due to heating.
What you are hearing from the members here is that the design of a model boiler needs to take into account many factors, not just the joint method. A safe boiler starts with a structured design approach including setting the design goals for the boiler, running calculations to determine acceptable shell thickness, looking at stay requirements for end shells, etc. Then build and test to confirm the design.
Cheers,
Adrian
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Solitary Sailor,
I think it's great that you have decided to build your own boiler. I'm all about finding new and improved ways of doing things especially if these new ways increase safety. The way to find these new and improved ways of doing things is to first have a firm understanding of why certain materials and welding practices for building boilers and certain testing methods for them have been done they way they have in the past.
It sounds like you are drawing on the years of experience that you have gained working in a certain field of expertise to help you construct this boiler. I can respect that. Although refrigeration equipment and model boilers both share similar materials in their basic construction the two are not the same and need to be engineered and constructed to withstand the operating conditions specific to their nature.
As I mentioned before, Silver Solder is the standard joining material most copper boiler builders use. This is not your standard garden variety Silver Solder either. This is typically a high temp high silver content welding material. Welding with this type of Silver Solder can not be done with a propane torch. It requires an oxy/acetylene torch to successfully weld a joint. Typical melting temperature can range from 1150F to 1300F+ . Standard accepted joint designs in standard boiler building practice were designed for and depend on the capillary nature of silver solder to make a strong joint capable of withstanding the shearing force that they will be exposed too. Also these joints are designed to work with the limitations of strength copper tubing has when heated during use. Silver solder can be expensive when compared to other welding materials but, considering the fact that you are only building one boiler, you may not want to rule out its use completely.
As I stated on here before, Bronze brazing is an accepted method of creating welds on copper pressure vessels but it must be carried out by someone who knows what their doing and the Filler material must comply with AS1167.1 - 1993 Welding and Brazing - Filler Metals. Alloy RCuZnA Tobin Bronze.
In my opinion there can be no substitute for hydro testing a boiler.
Using high pressure air or inert gases to test welded joints is a very bad idea. The amount of energy that will be release if a failure does occur during the use of this testing method can potentially cause severe damage and injury. Copper becomes annealed when exposed to high heat during the welding process. It will deform much easier and will tear or burst much more effectively.
Although I personally use an industrial certified hydro testing pump for testing my boilers this is not necessarily needed by the home model boiler builder. I own one of these testing rigs because I regularly use it to test our full sized boilers. I'm sure you have seen the small hand force model water pumps advertised on the net produced by companies like Stuart, Cheddar, PM Research, Main Steam Models and so on. You can use one of these small hand pumps in conjunction with a certified pressure gauge to build your own hydro testing rig for a very reasonable cost. When Cheddar Models was still producing their range they offered a hydro testing rig build from these components for model steam clubs to purchase for testing their club members boilers. It's worth investing in this equipment especially if you plan to build more than one boiler for yourself.
I hope you will continue building your boiler and enjoy the experience that you will gain by doing so. I also hope that you will soak up the knowledge being expressed by other forum members here and employ their thoughtful suggestions and advice during your construction of your boiler. We are just all looking out for one another safety.
nick
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Thanks Adrian
You are correct, I am indeed drawing upon years of experience within my own field of work. Your assumption regarding the low temperatures and pressures found in the field of refrigeration is only partially correct; for while the evaporative process removes heat from the medium being cooled (air), that heat needs to be dissipated into the ambient air of the great outdoors. This means that while we do indeed have a cold environment at the working end, the evaporator, we also have a warm, often hot environment at the disposal end, the condenser; that heat that you are extracting has to go somewhere. This is where temperatures can get hot and pressures get quite high ... under normal operating conditions (speaking of air conditioning in the typical South Florida environment), the high side pressure would be in the range of 190 - 250 psi dependent upon system design and outdoor ambient temperature, maybe even a little higher in some circumstances. However, when things go wrong, as they sometimes do, those conditions can change, quite dramatically, hence the references above to experiencing conditions where the pressures could be found in the 450 psi range. The potential exists for the pressure to go higher, however, the safety features built into the systems will cause a shut down, and so relieve all pressure build up, restoring the system to a static pressure, subject only to the expansion forces caused by surrounding ambient air temperatures. With R-22 having a boiling point of - 41*F at atmospheric pressure, and with the action of the compressor turning the vaporous gas into a liquid state, laden with recovered heat, the temperatures in the condenser can become very hot.
Sorry to be so long winded about it, but it is an aspect which is overlooked by the layman, and in the context of this debate, it does have some, but by no means all characteristics pertinent to this subject.
As I said before, I am on a learning curve.
Again, thanks for your comment, especially the reference to the material changes in the base metal itself when placed under heat
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Hi Nick
Many thanks for your input. Further to your previous comment and in association with one from Gerald ... I had indeed used a 'silphos' type solder with a silver content of 5 %. Given Gerald's comment about a deterioration found in the brazed joints using this type of solder when used in boilers, I may have to discard the first attempt at a fire tube <:(
After a cursory look on the net, I was unable to find much about AS1167.1 Welding and brazing. That of course may be me, looking in all the wrong places. Yes, I did find my way to the 'Australian Miniature Boiler Safety Committee', part 1, but only an offer to buy the complete 56 page book. So I am still none the wiser regarding AS1167.1
After a visit to a local welding supply house, where much discussion ensued by all parties ... with little knowledge of the practices involved. It was determined that the higher silver content, the more likely a strong joint would be obtained, although all The less likely for deterioration of the brazed joint over time would likely transpire. Such brazing processes required the use of oxy/acty with temperatures ranging in the 1200 to 1300 *F area, so at least there I am on the same page as you. With this in mind, I purchased an ounce of 'Harris' Safety-silv 35, having a silver content of 35%. We shall have to try it and see what results I get.
I am also stuck with the fact that there appears to be no model engineering group in the Florida area, who could assist me in the certification process.
As to your suggestion, I will look into the possibility of obtaining some equipment for me to be able to hydro-statically test my own work. An expense I had hoped to avoid {:-{, but with all comments pushing towards that direction, I will, out of common sense, proceed on that course.
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Hi Sailor,
I think that you are looking at a solder that is way above the requirements for building a boiler.
You are working on very high temperatures and so is Nick.
In the U.K. most model engineering society members use Johnson, Matthey silver solder 'Easy-Flow which has a melting point of 620-630 deg for boiler making.
I have tried to find them on the net but can't get any info on their Silver Solder.
I use a Company called C.U.P.Alloys and their solder that I use is 42% silver. you can get them at ( www.cupalloy.co.uk ) with some data on their Silver Solder Rods.
I don't find them exceptionally expensive, Last time I bought 50 rods it was about £2 per 600 mm long rod.
I have made many boilers using a 1" dia burner head with a .018 "jet ( all home made ) using straight Butane from a 4.5kg bottle and all my boilers are Hydraulic tested as I progress with the build.
When I asked about the Vacuum test I realized that you would use a vacuum gauge but I couldn't see how you could detect the leak, B.B. has explained it adequately.
I fail to see that you are Cavalier with your experiments as with your work experience you know what you are doing, however Hydraulic testing every time.
B.B. might have been a bit more diplomatic and left out his first line and then pointed out that Vacuum testing is not on as far as the U.K. is concerned.
Please don't be put of.
Regards
George.
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Thanks for the words of encouragement George.
Anyone have an address where I can purchase some equipment for hydrostatic testing purposes?
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Mainsteam models pump is very good quality- just type 'mainsteam models' into google, theirs is the first site that comes up.
Then you just need some cheap hosing from a tub to the pump, then copper pipe from the pump to the boiler, the pump has an integral check valve- but just to make sure I would purchase one to go on the boiler- preferably from steamfittings.co.uk (http://steamfittings.co.uk), they are VERY good check valves and give no blowback at all.
Then you will need a callibrated pressure gauge (I would think in your line of work you can get one quite easily), make a threaded adaptor to go from the pressure gauge straight onto the boiler- safety valve connection is the usual place.
Fill the boiler right up with water, then pump until you have the required test pressure, leave for 30 mins for thermal balancing, then re-pump to test pressure again if it has dropped, this is the true test- a new boiler should NEVER have a drop on it (as soon as you steam it it's not classed as new however...!).
Leave at test pressure for a further 30 mins.
If it's succesful then slowly get it ready to steam.
Greg
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You are working on very high temperatures and so is Nick.
In the U.K. most model engineering society members use Johnson, Matthey silver solder 'Easy-Flow which has a melting point of 620-630 deg for boiler making.
Are you referring to 620-630 Degrees Centigrade or Fahrenheit ?
Yes, I do openly admit to using a higher temp Silver solder on my boilers than what most other people commonly use but remember I was building boilers with the Village idiot in mind. I personally use Cadmium free Harris brand Safety Silver 45. It's expensive stuff to use especially considering the large number of boilers that I was producing but I found that it's stronger and takes more punishment than what other Silver Solders would take. Another reason I chose to use this Silver Solder opposed to the lower temp stuff was that I was considering boilers that are run dry by accident by beginners. I didn't mind spending the extra money. I looked at it as cheap insurance for the end user.
nick
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Hi Greg
Yes I went to the Mainsteam site, it was one of the first places I looked, but other than the little boiler feed pumps, or the weir pump, I can't find what; maybe I just need to ferret around so more. As you say, the gauge will be no problem, and piping is in the bag. Just the actual pump. :((
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Hi Nick
Well it looks like I found the right solder, even if a little less of a silver content, 35% as opposed to the 45% you use. I shall just have to learn to be a little economical with my brazing technique %)
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Hi Nick,
Temps quoted are in Deg "C"
Don't blame you for using high melting point solder, as a commercial venture you must protect your self, however I have only made boilers for myself and friends
and 42% silver solder is more than acceptable and doesn't require the heat that amateure boiler makers require.
George.
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Hi George
What would be the lowest silver content you would recommend. The type which I just purchased is from the same manufacturer and same cadmium free 'Safety Silv' as that used by Nick, but with a lower silver content. So if 35% is too low, I'd better find out now, before I do another fire tube.
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I am also stuck with the fact that there appears to be no model engineering group in the Florida area, who could assist me in the certification process.
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There should be lots of groups in Florida! Check for the ride on size Model Trains.
I did find a reference to a state Boiler Code at;
http://www.homemodelenginemachinist.com/index.php?topic=8846.0
The code is at;
http://www.myfloridacfo.com/SFM/pdf/FAC_69A-51_03_1118.pdf
Regards,
Gerald.
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Gerald. Fantastic, thanks. I did get in touch with the treasurer of the Australian Miniature Boiler Safety Committee, asking for a copy of the code. We will see what he comes up with.
I am not saying a model engineering society does not exist in South Florida, just that I have been unable to locate one, and I have made some extensive inquires. There is not much support here in general for the model making fraternity.
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You might find it interesting to have a read through the following:
http://www.ntet.co.uk/pdf/miniatures_exam_and_test_code_nov_08.pdf
This booklet is the agreed document that the four model engineering societies quoted follow but is not supported by the Model Power Boat Association in the UK.
Obviously this is not relevent to where you are in Florida however it does provide interesting reading and guidance no matter where you are.
This is the test rig we use at my club to calibrate pressure gauges and hydraulicaly test boilers. The pump cost about £60.00, $90.00 US and the gauge is a calibrated and certificated gauge and cost about £30.00, $45.0 US. I'm sure that you could find a similar piece of kit in Florida, probably considerably cheaper as well!!
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Hi George
What would be the lowest silver content you would recommend. The type which I just purchased is from the same manufacturer and same cadmium free 'Safety Silv' as that used by Nick, but with a lower silver content. So if 35% is too low, I'd better find out now, before I do another fire tube.
Hi Sailor.
I have always used C.U.P. Alloys at 42% silver as it flows very easily, I don't think that there would be much difference.
I would mail them and speak to Kieth, he will let you know the difference.
Tell him that George From Glasgow recommended him, nice guy.
If you P.M. me I will give you a tip on hydraulic testing at a very low cost.
George.
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Hi Bunkerbarge
Thanks for the link, have copied it to my files for future reading and to ensure I don't lose the information in my travels.
In the photo of the test station ... what is the second small gauge for.
I also have found a lead to obtaining a small, hand operated water pump.
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Gerald. Fantastic, thanks. I did get in touch with the treasurer of the Australian Miniature Boiler Safety Committee, asking for a copy of the code. We will see what he comes up with.
I am not saying a model engineering society does not exist in South Florida, just that I have been unable to locate one, and I have made some extensive inquires. There is not much support here in general for the model making fraternity.
Here is there web site where you can order the codes
http://www.ameng.com.au/ame_retail_dvds_boiler_codes_and_miscellaneous.htm
I ordered A.M.B.S.C. Sub-Miniature Boiler Code part 3, paid for it on line and received it in one week ( I have had letters take longer just coming from the other side of the city).
Regards,
Gerald.
PS IN the photo it looks like they are testing the model gauge and calibrating it to the master certified gauge.
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Hi Bunkerbarge
Thanks for the link, have copied it to my files for future reading and to ensure I don't lose the information in my travels.
In the photo of the test station ... what is the second small gauge for.
I also have found a lead to obtaining a small, hand operated water pump.
As Gerald rightly points out the small gauge is a boiler pressure gauge which is being calibrated against a certified gauge. If you are doing this for your own home purposes however you could simply leave the original pressure rig gauge on and either don't bother with the expense of a calibrated and certificated gause or 'borrow' one from work!
A little rig like this is very easy to use, very portable and can be used for all sorts of pressure tests. You'll wonder how you managed without one.
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BB, I'm looking for one of these test rigs myself at the moment- I can't afford the huge prices of the Rothenberger ones, but £60 is quite reasonable- where did you get yours from?
Greg
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Hi Gerald,
I'm afraid it's gone up a bit since I bought ours but it is still a lot more reasonable than a Rothenburger and it is a very useful investment for home and club use.
http://www.online-pumpshop.com/xcart/product.php?productid=318&cat=0&page=1
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Well, took the plunge and purchased the test rig Bunkerbarge recommends... you don't have shares in the company do you BB ;)
The price was great, the shipping though was something else ...OOWwwwww.
Anyway, thanks for the link Bunkerbarge. At least I will know everything is ok each step of the way.
Might have been cheaper to just buy the boiler from Mike at Maccsteam {:-{ , still, not quite the challenge.
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The thing is though you should get good service from it for many years to come and it will give you a peace of mind when you put your boilers into operation.
Glad I could help, sadly no shares in the company but maybe I should approach them to go on commission!!!
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OK, here is a second attempt, although this one has not gone under the torch yet
(http://s4.postimage.org/zpee0.jpg) (http://www.postimage.org/image.php?v=aVzpee0)
(http://s4.postimage.org/zpgJ9.jpg) (http://www.postimage.org/image.php?v=aVzpgJ9)
Cleaner, and this time with 12 cross tubes