# 6" Copper HRT Boiler Build (warning, long build and lots of pictures)



## A310 (Oct 4, 2012)

Hi everyone, I'm new to model steam engines, but have decided to make a boiler to power my P.M. Research 6 CI engine.  I tried to buy a boiler to power my new engine but could not find such a beast, so decided to build one instead.  At first it was going to be a vertical type boiler, but after reading K.N. Harris's book several times over I decided to go for the the horizontal type.  The design is similar to K.N. Harris #1 boiler, but with a few changes, mainly to be heated by a converted Coleman gas burner putting out approximatly 10,000 BTU.  At the moment I'm just in the stages of getting a lathe and milling machine, which will arrive next week, so I'm turning my motorbike shop into a steam shop.  Anyway here's the first of many pictures:


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## PhilMont (Oct 4, 2012)

Good Luck in your new endeavor.


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## GYoung (Oct 4, 2012)

Like your pics , especially you with the golden curls.  

Could you add source of material (vendor) and specs.( nominal size and wall thickness), maybe even approx. cost of the component, please.
How about some background specs. and how you arrived at those parameters.  Us old guys haven't been to school in a long time, and we need a gray matter jogger more often than naught. scratch.gif

Thanks and good luck on your project, I'm sure it will turn out just great.

Gene


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## Dave Sohlstrom (Oct 4, 2012)

Where did you get the copper tube. Did you have to take out a second mortgage to pay for it.

Dave


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## vcutajar (Oct 5, 2012)

Wow.  Mighty big copper tube.  Must have cost an arm and a leg.  Pulling out my chair to follow you on your journey.  And yes we love pictures.

Vince


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## A310 (Oct 5, 2012)

GYoung said:


> Like your pics , especially you with the golden curls.
> 
> Could you add source of material (vendor) and specs.( nominal size and wall thickness), maybe even approx. cost of the component, please.
> How about some background specs. and how you arrived at those parameters.  Us old guys haven't been to school in a long time, and we need a gray matter jogger more often than naught. scratch.gif
> ...


 
I bought this pipe from Ebay in the US and had it shipped to Hong Kong where I live as I could not obtain pipe thick enough for this job.  The Pipe I purchased is Manufactured by Cambridge Lee Industries.  The Tube is SD 6"X16" and is what's called L tube in the US. Outside diameter is is 6.125" and inside is 5.85", giving a wall of .140".  The pipe passes the 8 times safety for this size of pipe by a good margin.  The pipe is sold for 12.49 USD for inch.  This boiler will give me about 950-1000 square inches of evaporative heating surface.  The engine I'm using will require 200 sq. inches of heating surface, so I am over building it by a factor of 5 times capacity.  The boiler is more than I need, but I did not want to limit myself to a small boiler incase I happen to add larger engines in the future.  The exact math hasn't been finished on this design as it started in my head as a vertical boiler, but now has changed to a horizontal one.  The construction will be rivets and silver soldered with Harris Dynaflow rated at 35000 PSI.


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## A310 (Oct 5, 2012)

Dave Sohlstrom said:


> Where did you get the copper tube. Did you have to take out a second mortgage to pay for it.
> 
> Dave


 

Yes it cost an arm and a leg, but safety is my main concern on this build

Harling

P.S. 12.89 USD per inch.  Here's the guys link:http://www.ebay.com/itm/130442268667?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


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## Jasonb (Oct 5, 2012)

Thats a very low silver content solder you are using, generally boilers for steam engines would be using 45% plus and that is certainly the type of solder KN Harris would have been working with in his book not the 6% Dynaflow. The phosphor content is not good either. I would be looking at Safetysilv 45 or higher if you are using the Harris products. Keep the Dynaflow for aircon and refridgeration pipework

Also ensure that any rivited joints maintain a gap for the silver solder to flow into, you don't want to end up just caulking the joint with solder.

J


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## gus (Oct 5, 2012)

May I recommend buying and reading  " AMBSC Code Part 1 Issue 7--2001  Copper Boilers"
complied by the Australian Miniature Boiler Safety Committee to check on boiler design/fabrication/inspection/testing,pipe thickness,head thickness,stay rod diameter,brazing material,sockets etc etc.Safety valves must be sized for steam capacity.
Same book can be bought on line from "Ameng.com.au.

Silver Brazing is not an easy skill and takes time to master. Canned camping gas torch cannot deliver the heat required. With 50mm O.D. Boliers I brazed,I had to use two MappGas Torches to bring up to red heat before flux will run and silver rods melt and run.You may require a DIY brazing hearth to avoid burning up the kitchen table.I have not silver brazed 150mm O.D. Boilers. I would imagine six MappGas Torches required.
Tubal Cain's book on Soldering and Brazing is worth reading.

Gus used to manage a plant designing/fabricating/welding/testing/certifying air receivers.I certified welders/brazers too. Good Luck


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## A310 (Oct 5, 2012)

Jasonb said:


> Thats a very low silver content solder you are using, generally boilers for steam engines would be using 45% plus and that is certainly the type of solder KN Harris would have been working with in his book not the 6% Dynaflow. The phosphor content is not good either. I would be looking at Safetysilv 45 or higher if you are using the Harris products. Keep the Dynaflow for aircon and refridgeration pipework
> 
> Also ensure that any rivited joints maintain a gap for the silver solder to flow into, you don't want to end up just caulking the joint with solder.
> 
> J


 
Thanks, I'll have a look again at the different Harris products and see if I can get those in Hong Kong.


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## A310 (Oct 5, 2012)

gus said:


> May I recommend buying and reading " AMBSC Code Part 1 Issue 7--2001 Copper Boilers"
> complied by the Australian Miniature Boiler Safety Committee to check on boiler design/fabrication/inspection/testing,pipe thickness,head thickness,stay rod diameter,brazing material,sockets etc etc.Safety valves must be sized for steam capacity.
> Same book can be bought on line from "Ameng.com.au.
> 
> ...


 
Thanks Gus, I'll have a look at that issue and see if it's any different than the values I'm using from the K.N. Harris book on boilers.  I'm new to silver solder but not brazing or welding, so I hope it's not a huge leap to braze copper?  I'm buying a nozzle for my propane bottle which should be ok for this job as the butane torch is not.  Short of that I'll stike up my oxy-acetylene and try that.  I'll have a good go at some scraps before I try it on my boiler

Harling


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## Jasonb (Oct 5, 2012)

A big nozzle on a propane torch should do the job and some fire bricks around the boiler to help reflect the heat back onto the work. The risk with Oxy-acet is that the heat is very local and there is the risk of the solder not flowing into the joint.

The Aussy Code is more upto date with current practice, the calcs in Harris's book will be much the same but his suggestion of rivits and soft solder calking are not really used now, the fully silver soldered method is usual.

J


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## A310 (Oct 7, 2012)

Jasonb said:


> A big nozzle on a propane torch should do the job and some fire bricks around the boiler to help reflect the heat back onto the work. The risk with Oxy-acet is that the heat is very local and there is the risk of the solder not flowing into the joint.
> 
> The Aussy Code is more upto date with current practice, the calcs in Harris's book will be much the same but his suggestion of rivits and soft solder calking are not really used now, the fully silver soldered method is usual.
> 
> J


 
Thanks Jason, I've ordered both AMBSC Code Part 1 and 2, so I'll have some more reading to do. From what I gather there is a lot more details for boiler fittings etc than the K.N. Harris book. 

Harling


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## basement_guy (Oct 7, 2012)

I don't know anything about boilers, but I do know the belgian beers.*beer*


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## A310 (Oct 7, 2012)

basement_guy said:


> I don't know anything about boilers, but I do know the belgian beers.*beer*


Yes I do admit they are tasty.


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## Chris AW (Oct 11, 2012)

I also have the PMR #6 steam engine and needed a boiler.  I built one from 6" copper pipe, but made mine vertical because it was easier.  I have the K. N. Harris book and planned to use soft solder and rivets, but was convinced by the experts on this site that it was worth using 'silver solder'.  I used Safety Silv 45 by Harris.  

I have lots of electronics soldering experience and some plumbing soldering experience.  I practiced silver soldering, and never could get it right.  I ended up shipping my boiler, ready to solder, to a guy in Tennessee who's built over 100 copper boilers so it would be done right.  

If you search YouTube for Chipwahl, you'll see some videos of my boiler and engine.  Good luck with yours.

Chris


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## A310 (Oct 12, 2012)

Chris AW said:


> I also have the PMR #6 steam engine and needed a boiler. I built one from 6" copper pipe, but made mine vertical because it was easier. I have the K. N. Harris book and planned to use soft solder and rivets, but was convinced by the experts on this site that it was worth using 'silver solder'. I used Safety Silv 45 by Harris.
> 
> I have lots of electronics soldering experience and some plumbing soldering experience. I practiced silver soldering, and never could get it right. I ended up shipping my boiler, ready to solder, to a guy in Tennessee who's built over 100 copper boilers so it would be done right.
> 
> ...


 
Thanks Chris, I've looked at your boiler and engine before in a search for different engine and boiler combo's, nice job. At the moment I'm just waiting for the Aussie code books (copper boilers is on back order so won't be ready for a month), so in the mean time I'm just setting up my shop. 

Cheers

Harling


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## ned100 (Mar 27, 2013)

I watched your thread start and have followed it with interest.  As I am about to embark on a boiler build to run a 1.5" bore mill engine, just wondered if you have made any more progress with your boiler.

Cheers,

Ned


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## bazmak (Apr 2, 2013)

With a copper boiler that size i would recommend the large brazing torch for the main heat source
COMBINED with oxy acetyline for local heating and the actual silver soldering.With copper the heat
disapates quicker than you apply it.And you need local red heat for the solder to flow.Plenty of rivits for location
and they must be soldered also.Biggest boiler i have made was 4" with 1/8 wall. Like running a marathon
in the Desert.(O AND YOU WILL NEED A CASE OF THE BEER) Bazmak


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## bazmak (Apr 2, 2013)

Need a large Pickle bath as well. Bazmak


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## gus (Apr 3, 2013)

bazmak said:


> With a copper boiler that size i would recommend the large brazing torch for the main heat source
> COMBINED with oxy acetyline for local heating and the actual silver soldering.With copper the heat
> disapates quicker than you apply it.And you need local red heat for the solder to flow.Plenty of rivits for location
> and they must be soldered also.Biggest boiler i have made was 4" with 1/8 wall. Like running a marathon
> in the Desert.(O AND YOU WILL NEED A CASE OF THE BEER) Bazmak



Hi Bazmak,

Good advice.I have a 4" Vertical Boiler yet to be silver brazed.Sure hate to see same done half baked. Your advice confirmed my fear of not having enough fire-power on hand. 

Now in hobby machinist paradize----HongKong. Found sources for cutting tools and dividing heads.Machineshops here preferred Japanese or Taiwanese tools for reliability over Chinese tools. European made is high on the preferred list.


Gus Teng


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## Charles Lamont (Apr 6, 2013)

bazmak said:


> With a copper boiler that size I would recommend the large brazing torch for the main heat source
> COMBINED with oxy-acetylene for local heating and the actual silver soldering. With copper the heat dissipates quicker than you apply it. And you need local red heat for the solder to flow. Plenty of rivets for location and they must be soldered also. Biggest boiler I have made was 4" with 1/8 wall. Like running a marathon in the Desert. (OH, AND YOU WILL NEED A CASE OF THE BEER) Bazmak


I would suggest  you only need enough rivets or other fasteners to hold the pieces in place for making a joint. The strength is in the joint, not the rivets, and the fewer places to ensure penetration the better.
A very useful half-way between propane and oxy-acetylene is oxy-propane. This is the most common heat source I use doing 12" scale model engineering on my days here: (http://www.svr-engineering.co.uk/news/news.html)


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