Author Topic: I have a dumb question about boiler material  (Read 8631 times)

Offline loggerhogger

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I have a dumb question about boiler material
« on: January 21, 2016, 01:56:48 AM »
I notice that a lot of people are building small boilers out of copper tube. I was wondering if brass would also be a suitable material for a boiler shell. If not, why?

Offline cncjunior

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Re: I have a dumb question about boiler material
« Reply #1 on: January 21, 2016, 02:52:36 AM »
Hey,

The thing about brass is that the zinc is leached out when used in a boiler.  It is called dezincification and weakens the metal to the point where it will crack and fail.  Best to use copper.  Steel with copper tubes is a possibility though not as heat conductive as copper.

Daniel

Offline 10KPete

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Re: I have a dumb question about boiler material
« Reply #2 on: January 21, 2016, 03:20:07 AM »
The 'dumb' question is the one you don't ask!!   :slap:

Pete
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Offline Jasonb

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Re: I have a dumb question about boiler material
« Reply #3 on: January 21, 2016, 07:36:56 AM »
Its Ok for very small boilers that won't be running at high pressures say below 30psi and not getting a lot of use. Most of the "toy" steam models like Mamod have used brass boilers for years.

J

Offline K.B.C

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Re: I have a dumb question about boiler material
« Reply #4 on: January 21, 2016, 09:33:11 AM »
Its Ok for very small boilers that won't be running at high pressures say below 30psi and not getting a lot of use. Most of the "toy" steam models like Mamod have used brass boilers for years.

J

Hi Jason,

I am sorry but I must contradict you, it's not O.K. to build a brass boiler.
The reason that Mamod and others who make the "Toy Boilers" is that they know tha quality and grade  of the brass tube used and people seing them think that they can use brass tube that may have come from a scrap yard or any other source and the quality is unknown, this type of brass tube are the ones that can cause trouble Dezincification and leaching.
In the U.K. anybody presenting a brass boiler of unknow quality will have a refusal to test from an appointed Inspector.

However if somebody wishes to make a brass boiler and use it within the confines of their own space that is entirelly up to them.

George.
Your never too old to learn.

Offline Jasonb

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Re: I have a dumb question about boiler material
« Reply #5 on: January 21, 2016, 12:43:41 PM »
George does the same not apply to copper? making one from unknown scrap material could be just as risky and I'm sure most UK inspectors would not want to test something made by re rolling an old hot water cylinder or roofing sheet such like.

Same would apply if you used anyold steel to make a boiler and the welds were not approved
« Last Edit: January 21, 2016, 12:59:21 PM by Jasonb »

Offline Dan Rowe

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Re: I have a dumb question about boiler material
« Reply #6 on: January 21, 2016, 04:31:09 PM »
It really matters where the OP lives to answer the question fully.

Brass boilers are allowed in the AMBSC Code Part 3 Sub-Miniature Boilers. They are limited to 3" or less shell diameter and low pressure only 200kpa (29psi). The inspection certificate is only valid for one year where a similar copper boiler certificate is good for three years.

Personally, I would not build or buy a brass boiler for the reasons already given.

Dan
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Offline NickG

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Re: I have a dumb question about boiler material
« Reply #7 on: January 21, 2016, 04:41:51 PM »
Also, I don't believe a brass boiler of the size Jason is talking about would require testing as long as the fuel source is designed to run out before the water?

Offline K.B.C

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Re: I have a dumb question about boiler material
« Reply #8 on: January 21, 2016, 04:59:18 PM »
George does the same not apply to copper? making one from unknown scrap material could be just as risky and I'm sure most UK inspectors would not want to test something made by re rolling an old hot water cylinder or roofing sheet such like.

Same would apply if you used anyold steel to make a boiler and the welds were not approved


Jason,
Lets make it clear, you can make a boiler from any material that you have, Brass, Copper Steel, I have even read of one being made from a COKE can by a guy in Brazil..
If you made one from these materials without it being Tested and Certified you can fire it up and use it in an open space, i.e your back yard,  with nobody about and if a leak appeared it would only be you at risk.

To fire it up and use it in a public place it would have to be Tested and Certified  if not any accidents would be down to you and you could be sued if you didn't have it Certified for insurance purposes, which is the reason that Boilers and pressure vessals must be insured, most Cubs, Society and Exhibitions will not allow you to Steam a boiler without proof of Certification.

If a Boiler was presented to me and it was made from a re rolled copper domestic heating boiler or roofing copper and the material thickness was known and proven and the joint was made as to the requirements of THE EXAMINATION &TESTING of MINIATURE STEAM BOILERS  I would test it and as long as it stood up to the hydraulic test of 2 x  Working pressure and was made and soldered to my satisfaction I would pass it and Issue a Test Certificate.

Steel Boilers are a different thing as you know that all welded joints must be inspected and welded by a coded welder, as I have never had one presented to me I can make no comment.

Making one from scrap brass tube , I would not entertain it for the reason given previously as the quality of the brass tube is unknown.

Hope this helps.

George. 
Your never too old to learn.

Offline Jasonb

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Re: I have a dumb question about boiler material
« Reply #9 on: January 21, 2016, 05:19:23 PM »
But would you test one if the brass was from a known source with paperwork to prove it and to the right spec?

And would you know if that seconhand copper was C106 or something else that could have suffered embrittlement during construction?

Also don't have to be a coded welder for steel, you can just submit  the welds for NDT at a cost of £50-60, show the welds have been designed correctly and if they pass you are OK.

Should also say that as the OP is in the US he should go buy his state boiler code and not what applies to clubs in the UK. Basically use materials that are allowed by the code and to the required specification, do the calculations to get correct thickness, joints, stays etc and consult with whoever will be testing the boiler if going to be used in public.

Seems SMEE are happy with brass Poly boilers ;)
http://www.modelenginemaker.com/index.php/topic,5690.msg110959.html#msg110959
« Last Edit: January 21, 2016, 06:02:04 PM by Jasonb »

Offline S.D.L.

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Re: I have a dumb question about boiler material
« Reply #10 on: January 21, 2016, 06:41:32 PM »

Also don't have to be a coded welder for steel, you can just submit  the welds for NDT at a cost of £50-60, show the welds have been designed correctly and if they pass you are OK.



Weld samples of each type would be required (Fillet butt etc), and more importantly the club Inspector would have to feel competent to look at the welds on the boiler at the various stages. The inspector can say happy to test copper but not steel it is the inspectors choice.

Steve
If you always do what you always did,
You always get what you always got.

Offline K.B.C

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Re: I have a dumb question about boiler material
« Reply #11 on: January 21, 2016, 08:43:35 PM »
But would you test one if the brass was from a known source with paperwork to prove it and to the right spec?

And would you know if that seconhand copper was C106 or something else that could have suffered embrittlement during construction?

Also don't have to be a coded welder for steel, you can just submit  the welds for NDT at a cost of £50-60, show the welds have been designed correctly and if they pass you are OK.

Should also say that as the OP is in the US he should go buy his state boiler code and not what applies to clubs in the UK. Basically use materials that are allowed by the code and to the required specification, do the calculations to get correct thickness, joints, stays etc and consult with whoever will be testing the boiler if going to be used in public.

Seems SMEE are happy with brass Poly boilers ;)
http://www.modelenginemaker.com/index.php/topic,5690.msg110959.html#msg110959

Jason,

Your questions on your last post are purly Hypothetical, on the brass tube and the copper sheet, do you think for a minute that somebody could come out of a scrap yard with a brass tube and a piece of copper sheet with all the appropriate paper work to prove the metal.
I thought that we were discussing the merits of some scrap materials and nothing has been said to convince me to ever test a boiler made from a piece of scrap brass tube.

I have already said that I have no exprience of being asked to test a steel boiler so I cannot comment on one.

You pointed me in the direction of the S.M.E.E. which I have looked up and then went to the actual web page of the said society and here is a copy what they say in building the Polly boiler 
  [ The boiler

We discuss boiler construction, choice of materials and choice of solder/braze metals. The “Polly” boiler is silver soldered using copper with bronze fittings and flanged end plates. Skills covered include turning, thread tapping, flanging using a former and silver brazing.
The firebox

Constructed from sheet steel you can make this from scratch or we can supply a laser cut piece. Skills covered include sheet metal cutting, drilling and forming plus soft soldering. ]

So I don't know where you get the info that they made them in brass?

I really don't have anything else to contribute to this thread other than  "[t's not O.K. to make a boiler from brass tube.] "

George.
Your never too old to learn.

Offline NickG

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Re: I have a dumb question about boiler material
« Reply #12 on: January 21, 2016, 09:06:38 PM »
This is playing devils advocate to a certain extent here but it is raising some valid points. I agree that any boiler that is to be run in public should be subject to proper hydraulic and steam test. However, I am still confused around the subject of "small" boilers. What would make a mamod for example exempt from this? What about 20 or 50 years down the line? Do the regs not require a boiler test for boilers under 3bar litres or has that changed? It seems to mention something about whether it has a pressure gauge and safety valve? So what about these so called 'toy' boilers - I bet not many people have hydraulically tested them? Are they OK to use in public?

fcheslop

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Re: I have a dumb question about boiler material
« Reply #13 on: January 21, 2016, 09:18:58 PM »
Not wishing to muddy the waters any further
From another perspective the cost involved buying good quality COPPER tubing for a simple pot boiler is a small sum to pay when you consider the amount of work involved in building the boiler.
I hold my hands up to the fact I have made brass boiler in the past but the material was supplied by Mamod
As already mentioned the regs differer around the world but one thing that does not is the fact that come an accident Im sure the no win no fee legal crowd will be knocking on youre door.
Personally for a first boiler built it to a proven design that meets the regulations of part of the world you live in. They are there for a reason and should not be thought of as a thing to be got round.
Just simply my perspective on things .
Oh and please use bronze not brass for the bushes
Check out the blue book the 3bar litre rule has been changed
Mamod has to meet the TOY regulations as well as CE and has its own insurance to cover any mishap as per the American incident in the 1970s
cheers

Offline loggerhogger

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Re: I have a dumb question about boiler material
« Reply #14 on: January 24, 2016, 08:23:52 AM »
Thank you all for the replies. I was curious as to the difference.

Offline steam guy willy

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Re: I have a dumb question about boiler material
« Reply #15 on: January 24, 2016, 12:25:39 PM »
Not wishing to muddy the waters any further
From another perspective the cost involved buying good quality COPPER tubing for a simple pot boiler is a small sum to pay when you consider the amount of work involved in building the boiler.
I hold my hands up to the fact I have made brass boiler in the past but the material was supplied by Mamod
As already mentioned the regs differer around the world but one thing that does not is the fact that come an accident Im sure the no win no fee legal crowd will be knocking on youre door.
Personally for a first boiler built it to a proven design that meets the regulations of part of the world you live in. They are there for a reason and should not be thought of as a thing to be got round.
Just simply my perspective on things .
Oh and please use bronze not brass for the bushes
Check out the blue book the 3bar litre rule has been changed
Mamod has to meet the TOY regulations as well as CE and has its own insurance to cover any mishap as per the American incident in the 1970s
cheers
Can you tell us more about the "American Incident" of the 1970's please ...Thanks...

Offline Firebird

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Re: I have a dumb question about boiler material
« Reply #16 on: February 04, 2016, 06:01:33 PM »
Hi

I have just had to change the oxygen bottle on my small gas welding kit, they are disposable. Being a curios type I took the brass valve out and saved that then stuck it in the bandsaw and chopped the end off.







The steel must be of a known quality, the welds are obviously perfect and with a test pressure of 165 bar = 2425 psi is it suitable boiler material?

Cheers

Rich

Offline Jasonb

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Re: I have a dumb question about boiler material
« Reply #17 on: February 04, 2016, 06:24:01 PM »
At that thickness there is not much allowance for wasting of the metal

Offline Firebird

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Re: I have a dumb question about boiler material
« Reply #18 on: February 04, 2016, 06:29:41 PM »
So a steel boiler must be made of thicker material compared to copper?

Cheers

Rich

Offline Jasonb

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Re: I have a dumb question about boiler material
« Reply #19 on: February 04, 2016, 06:43:45 PM »
Generally yes. For example my 2" Fowler A7 has a 4.75" dia copper boiler WP of 100psi and that is 10swg or 0.128" but the Superba is designed for a 6" steel boiler, similar WP but the wall is 5swg or 0.212" so quite an increase in thickness for similar size & pressure.

Online Jo

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Re: I have a dumb question about boiler material
« Reply #20 on: February 04, 2016, 06:48:34 PM »
Don't waste your time Rich, get a bit of tube with the right certificates of the right type of steel for welding into a boiler. There is no point in saving a few pounds and creating something that you are not sure if it could cause an explosion  :-[.

There must be plenty of other things it could be made into  :)

Jo
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Offline Jasonb

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Re: I have a dumb question about boiler material
« Reply #21 on: February 04, 2016, 07:05:29 PM »
It would have made a better boiler if someone had not cut the end off :LittleDevil:

Is that a welded seam at about the 5 o'clock position?

Offline Firebird

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Re: I have a dumb question about boiler material
« Reply #22 on: February 04, 2016, 08:00:19 PM »
Hi

Yes its a seam at the 5 o/c position.

I have no plans for a steel boiler, I'm busy with my portable engine copper boiler at the moment and I have a reasonable stock of copper in various diameters for some future boilers. I was just curious  :thinking:

Cheers

Rich

Offline Firebird

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Re: I have a dumb question about boiler material
« Reply #23 on: February 04, 2016, 08:38:58 PM »
Hi

While we are on the subject and purely out of curiosity, this stuff is high pressure steam pipe, around 110mm dia



Cheers

Rich

Offline steam1993

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Re: I have a dumb question about boiler material
« Reply #24 on: August 15, 2016, 06:45:38 PM »
You can weld up a steel boiler as long as you are a certified welder. I live in Minnesota and will be welding up my own boiler, for my 6in engine. As I am exempt from ASME code ,I can do it, but it will still be inspected.


peter

 

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