|Jun 11, 2013, 06:28 AM|
V.M.Boiler from Scrap bin.
At the start of the year a friend asked me to make him a "V" twin double acting Oscillating engine and I realised that I no longer had a Test Boiler so after a search thro" all my bits and pieces I discovered a 3" copper boiler shell and 2- already flanged end plates so I decided to build a test boiler and I hope that by doing a build log it will take some of the mysteries out of making a boiler.
I use Silver Solder with 42 % silver content not soft solder, I say this as there has been several discussions on the forum as to what is Soft and Silver solder and I have read some remarks from the U.S.A that as long as it's shiny it's Silver solder well it's not Silver solder is a brazing solder that is very hard when cooled and is the only thing advisable to braze a boiler with.
The boiler had to be able to work at 70 psi and have a steam dryer incorporated, to be quick fired by Butane via a ring burner and have all off the necessary bushes to take the fittings but most of all to be a simple build.
The only thing that I had to do was skim the end plates to fit the shell, I always leave 1/4" of a flange in order to drill thro' the shell and fit copper pins to hold the end plates while soldering, to my cost in the early days of boiler building I didn't do this and when the heat hit the job the end plates fell into the shell and stuck while the solder was liquid and the lot was scrapped.
I hope that this has been inspirational and will convince some members to have ago at making a steam boiler and always remember cleanliness and fluxing the job is important.
If any body has any question I shall try to answer them as best as I can.
I shall continue with the build and show it with all fittings and the ring burner.
|Jun 11, 2013, 06:30 PM|
Thanks for the kind words I just hope that at the end of the thread it will encourage members to have a go at building a boiler, there is a great sense of achievement when you steam your own build for the first time.
|Jun 11, 2013, 10:14 PM|
Could you explain what fittings you have put on the side of the boiler and where you got them from? I assume two are probably for a water level sight glass and 1 is for the steam outlet but I'm not sure about the others.
I've been considering building a boiler but was never sure where to get the various fittings for it from since suppliers seem to keep disappearing. PM Research is where I would probably wind up getting supplies from since they seem to have the biggest variety I've seen so far.
|Jun 12, 2013, 05:38 AM|
I make all of my own fittings with the exception of the pressure gauge, perhaps some of the U.S. members can tell where to by fittings.
Here are some suppliers in the U.K..
Hope this helps.
|Jun 12, 2013, 07:21 AM|
V.M.boiler biuld from scrap box.
Continuing with the build the next step was to hydraulic test the boiler,
All the bushes were plugged except one where the test rig was connected to, the boiler was completely filled with cold water and no air space left.
To hydraulic test a boiler or any pressure vessel don't pump it up to the required pressure in one go,as the copper is still very soft from the brazing and you can ruin the boiler, what can happen is that the boiler can take on a barrel shape and no amount of beating the sides will bring it back into shape.
You must pump it up in 10 psi stages holding for 5 mins, releasing the pressure and then pumping up 10 psi+ 10.
As this boiler had to work at 70 psi the hydraulic test pressure is 140 p.s.i.
On examination at 140 psi the boiler shell was perfectly round and had no bulges and held a steady pressure for 2 hrs. so I was very happy with the result.
Next step was to put on all of the fittings and do a steam test which the safety valve must blow at a max of 70 psi + 10% with the burner at full power which gave a satisfactory test.
I then started on the steam dryer which fits onto the bush on the top of the boiler and the steam zig zags thro' the heater and then into the steam valve.
All of the valves and fittings are now screwed into the boiler shall.
2- for the sight glass
1- for the pressure gauge
1- for the non return boiler feed valve ( clack valve )
1- for the 90deg safety valve elbow
1- on top of the boiler end plate for the banjo fitting to take the steam dryer.
I make all off the fittings which are screwed M.E. 32 tpi but anybody contemplating building a boiler should tap the bushes M.E. 40 tpi as I believe that all manufactures of valves and fitting have standardised on 40 tpi.
Next thing to make was the boiler support ring, this is a piece of the boiler shell material cut to 2" long and a slot cut with the piece cut out so that it fitted into the bottom of the boiler.
Air holes were cut and the ring was held in place by 7 ba c/sunk screws.
Making the burner ring was the next job, a piece of 1/4" dia copper pipe was heated to bright red, quenched and bent into a circle around a 2" wooden mandrel the ends were cut to for a ring , a series of holes were drilled at 3/8" pitch and a TEE piece made to take the ring and the burner jet all joints silver soldered., when completed the burner was bolted into the boiler support.
Must say that I am pleased with the result, the burner can raise steam at 70 psi in 5 mins and with the hand operated boiler feed pump I can now steam test engines.
This has been a very simple and easy build using scrap material and bits and pieces from my scrap box so I would encourage anybody to have a go at building a boiler.
The main things required is a big torch, these can be had at garage sales or car boot sales, 4.5Kg of Butane or Propane and a brazing heart the keep in the heat.
While I was building this Multi tube boiler I also built a Center flue boiler for a friend and I shall start another short thread soon.
I do hope that this build will be of help to potential boiler builder.
|Jun 12, 2013, 10:20 AM|
George, now you are just showing off!!
I hope mine will look half as good...
Question on the guages as on your boiler... are those model spec or were you lucky to find such small guages at some industrial supplier? To date the smallest i can find is 40mm dia (just over 1.5")
What is the differance between a steam "dryer" & a "super-heater"?
& just briefly your dislike (experiance) of the heating-pins protruding into flame/water?
|Jun 12, 2013, 03:05 PM|
Did you use a hand pump to raise the pressure to 140 psi during the test? In the first picture that appears to be what you did.
When you install a boiler feed pump do you also have some sort of heater that the incoming water goes through before reaching the boiler? I sometimes hear people who describe their boiler build process say that they prefer to have some sort of pre-heater for their feed pump water so that it doesn't "shock" the boiler when it goes in.
Do you prefer automatic boiler feed pumps over hand feed pumps?
Do you use easy fitting joints or press fit? In this article: http://sgcox.site.net.au/ritg/boiler-tests.pdf They recommend easy fitting joints rather than press fit in order to increase chances of a good solder joint being made with solder going all the way through rather than only part way.
That is an incredible looking boiler by the way.
|Jun 12, 2013, 04:05 PM|
Pressure gauges are available from the suppliers that I listed, they range from 1/2" dia to 1" dia, the ones that I use are the 3/4" dia x 100 p.s.i. and are about £30 + postage , as you are not in the E.U. you should be able to buy gauges and fittings less V.A.T. @ 20 % , I know that used to be the case but not sure if that still holds but you can ask.
A super heater is directly in the flame of the burner and the super heater tubes should be at least 50% larger in dia than the inlet and the out let, this allows the wet steam from the boiler to be raised in temp which and delivers more power to the engine.
Some boiler manufacturers supply a simple little 5/32 " dia tube down the funnel and call it a super heater which it is not.
My steam dryer will increase the temperature of the steam but it is not super heated steam.
I can't see the benefit of sticking rods into the boiler, if you had to put in copper tubes with the end inside the boiler blanked of and soldered then I could see some benefit, but then it's only my opinion.
|Jun 12, 2013, 04:48 PM|
I use easy fitting joints on boiler end plates with 3/32" copper rivets thro' the shell and the flange to hold everything together for soldering. the solder flows thro' the rivets to make a seal.
You can make a water heater in a couple of ways.
In the Vertical boiler shown a single coil can be made to go into the fire box and the out into the boiler via the clack, but as it's only a test boiler I didn't install one but could in the future.
You can make a heater by putting a coil of copper pipe from the pump and into the oil separator which takes the engine exhaust and heats the water before going into the clack.
In a horizontal Scotch marine boiler you can take a copper pipe into the smoke box and then into the boiler via the clack ,
When I have a boiler installed in a model I always have a water heater, wouldn't be without one.
My preference for boiler feed pumps are mechanical driven from the engine,
these electronic gizmos are Black magic to me, you must remember that I am only an old Clydeside Hammer and Chisel engineer !!!!!!
Just a few pics of boilers and engines built in the past.
|Jun 13, 2013, 12:20 AM|
Once you had the bushings inside the holes of the boiler, how did you cap them for the test? Did you solder them in?
The hand pump you used looks considerably larger than the hand pumps I have seen for model steam but still a lot smaller than any hydraulic pumps I have seen in machine shops. Could you direct me to a good one to purchase?
This is one that I have seen but it is limited to 400psi. http://www.ebay.com/itm/Live-Steam-E...-/130436266823
I don't think I would ever build a boiler (or at least not anytime soon) that would run at above 75psi since I plan to use a small engine like this:
http://www.grahamind.com/tvr1a.html or http://loyalhannadockyard.com (most likely the first one which only requires 35psi)
This is the electric pump I had seen.
Another member on this forum BernardBB uses it, I think.
I had considered using it over a steam driven one because it supposedly turns on and off by itself based on the water level of the boiler. This is probably a dumb question but I never understood how the boiler does not get overfilled if a steam engine powered pump is constantly on. Could you explain how it doesn't wind up overfilling? I know they have shut off valves but assuming you are just driving your boat around, you wouldn't be able to see the boiler water level gauge to check if you needed to turn the pump valve on or off.
Could you explain the riveting a bit more? Do you make a sort of double cap on the top and bottom of the boilers? So only the outer caps are riveted through the body of the boiler? Are the inner caps flanged like the outer caps?
It would be great if you could post a complete parts list of all the fittings you used. I think that would help a lot in clarifying at least for me personally.
How did you cap the pipes going up the middle of the Scott return flue boiler? Did you cap them individually them put the end cap on? Are there 2 end caps on one side and only 1 on the other?
Apologies for all the questions. They're ones I've always had ever since getting into live steam with the Midwest Fantail Launch. If one is not clear, I can draw a picture to clarify.
Thanks for all the pictures, they help a lot.
|Jun 13, 2013, 12:58 AM|
Joined Mar 2012
nice build and presentation.
What kind of torch (I suppose propane) do you use and how many BTU from the burner for brazing this boiler ?
|Jun 13, 2013, 07:36 AM|
Don't be put off by my statement on the pump being capable of 600 psi, remember this is a test rig and it was made for all occasions of testing .
The pump on my test boiler is only used for filling and topping up the test boiler.
I really can't recommend a pump as I have never purchased one ,I make all my own pumps but the pump that you have posted the link to will be fine.
The Graham TVR engine is a fine little working engine and many members on the forum use it.
If you look at B.B.'s video you will see water pumping into a small pail, this is because there is a by-pass valve between the delivery end of the pump and the boiler ,so with experience of running you can adjust the pump out put to the boilers needs and what this does is returns some excess water overboard or back to an on-board water supply.
I think that you have miss understood my explanation of the copper rivets, they there only to hold the end plates in position when brazing and are not riveted over, these rivets are 3/32 " dia but any thin copper rod will do as the outside ends are cut off when the boiler is brazed, have another look at the first pics and you can see the rivets sticking out.
What do you mean by a parts list, I don't have a complete list of the materials used but if you mean all the valves and external fittings I can give you that.
I don't know what you mean by your last question.
In a Scotch marine return flu boiler the burner blows down the large dia pipe and the heat then returns thro' all the small 5/16" dia pipes and then up the chimney ,
So like the vertical boiler described the end plates are held in place by the copper rods and the the ends of the 5/16" pipes are swagged slightly to prevent them falling during the brazing process. The hot end is the fire box which is made from steel and slipped over the end of the boiler and it's similar to the smoke box end but it has a funnel on it.
Hope this helps
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