New Steel Boiler for under £200

[Oompa LumpaParticipant @oompalumpa34302]

I learned a good deal from this post, thank you for taking the trouble.

My next question of course is why is there a two year wait? You would have thought someone would have jumped in to fill the void? But the fact is I know absolutely nothing about this but I would like to learn more.

[nigel jones 5Participant @nigeljones5]

Hi – I cant remember what grade of steel I used, but I am sure that it wasnt anything special. I did do my research and basic mild steel (I forget the spec – there are alot) is fine for this application, plenty strong enough!

I costed the whole thing at about £310. This was including £60 for a professional NTD cert. I didnh have to pay for the Tube as I have a friend who sells the stuff, and sorry but I can not pass his details on to you unless you want to buy £1000 of it!

It was a basic 150amp machinemart mig, but to be honest it was at its limit, only just going into spray. Im planning a 71/4 for Invicta so might try to source a better mig. Point to note is that you need to be very experienced to produce a good weld. The reassuring thing is that if you are anything less than up to the job it will simply leak like a sieve!

I will be happy to make the plans availible, if I can find them!

No doubt the armchair pundits will moan, complain and tell me that they are not correct……..

Nije

[wendy jacksonParticipant @wendyjackson]

I think you have done a great job.and yes there are far to many armchair pundits on the forum.i would be interested in knowing more re this project.first when do you plan to get a club test.and second.i have a 7 11/4 invicta and the old copper boiler is shot.over the past few weeks I have been asking re prices for a replacement boiler.copper comes in at just over 2500 pounds, a steel one at just over 1500 pounds.a invicta will never recover the price in a million years.so as an ex welder I can see a few weeks getting back in the grove and a new tig welder in the workshop.pleaee keep us all informed on updates, I am very interested and I sure many others are as well.michael

[Carl Wilson 4Participant @carlwilson4]

Hello,

Thanks for replying re the spec of the material. The armchair pundits will likely tell you that you have done it wrong. I suspect that there are a hard core of individuals who come on the forum purely for that reason.

[wendy jacksonParticipant @wendyjackson]

Is this post dead, one of the most interesting on this forum for some time

[JasonBModerator @jasonb]

It was already dead until someone posted here a few days ago.

J

[Ian S CParticipant @iansc]

I'm sure Fizzy will tell us of a successful hydraulic test etc. Ian S C

[wendy jacksonParticipant @wendyjackson]

I hope so.if the welds have been all tested I see know reason why it should not pass.using steel to make the boiler is cheaper then copper, and tig welding in my view a lot safer for home use then blow torches and the very high levels of heat needed.michael

[nigel jones 5Participant @nigeljones5]

Ian, posted some time ago, all tests passed with no issue – now happily puffinf round a track in staffs. Now working on a 6" dia for Invicta – going for a better tube layout this time.

[wendy jacksonParticipant @wendyjackson]

Having read this I to will be having ago at making a boiler in steel for my old 7 1/4 gauge invicta.i have been in contact with a local company that can test the welds and are able to provide the correct paperwork etc.just to check my welding before hand I will dye test them first myself.i plan to start this project around feb next year after I have checked the plans in solidworks.michael

[nigel jones 5Participant @nigeljones5]

Michael – just be aware that if you are in the UK you are not technically allowed by the rules to pay someone to weld it up. Makes absolutely no sense to me but if you do then it is classed as being commercially constructed. Thats if you are using the fact that they are coded as proof of good welds. Whilst the green book doesnt precisely say that a complete NDT cert is acceptible it does state that welds must have been tested if no code is present. At the end of the day, if your welding skills are not up to it it will certainly leak like a sieve long before it tears itself apart and explodes! I know, I proved it!

[wendy jacksonParticipant @wendyjackson]

Fizzy, I am a time served welder.ok not coded as I never needed to be.my plan is to obtain the correct spec steel with the correct paperwork etc.this I have found possible to do vie the internet. There is a local weld test company that are happy to test my welding and issue the correct paperwork if all ok. I can't see an issue.after looking at a steel boiler for a 7 1/4 gauge loco paid for by my local club.if I can't weld better then that then I am a dutchman.from what I have read there is a lot of misinformation around about steel boilers.for me tig welding is far more safe to undertake then the masses of gas and heat needed to silver solder a larger boiler.how are you getting on with the invicta boiler.may I ask what gauge steel you are using for the outer casing and the tubes.michael

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Just a couple of things that I don’t remember seeing mentioned in these discussions :

(1) A boiler weld has to be designed in detail and so does the form of all surrounding metal .

(2) Focus of attention to begin with should be weld stress .

High stress means most careful design and weld / test process .

Low stress allows slightly more relaxed approach .

(2) A welded boiler is designed in a different way to a silver soldered one . Converting a silver soldered design direct to a welded one is an unsafe procedure .

Regards ,

Michael Williams .

[nigel jones 5Participant @nigeljones5]

I use general purpose low carbon mild steel – 6mm thick for boiler up to 6" diameter. All with mill certs. Tube tends to be a higher carbon content and is harder/stronger. There is no problem with TIG but unless you have a good water cooled torch it will take forever to weld up. I used MIG with a hot root then a single pass and cap. I always use copper tubes so they dont rust – you need oxy for these. And yes, I too was suprised by the amount of undercut on proffesionaly welded boilers – pretty poor!

[wendy jacksonParticipant @wendyjackson]

Hi fizzy.i have been looking at a few boilers which have been made and written on in dome details on american forums.i don't intend to use copper for the tubes.i run at times a polly 4 at my local club, this has a copper boiler.also at the club is a polly with s full steel boiler.cant really see any difference between the two boilers when firing up or running.is bad luck re watercooled tig, most as you know are 3 phase which I dont have at home, and my misses would go mad if I blow fuses all day long.time is not much of an issue and I intend to do a bit each day.the time of welding 10 hour shifts have long passed thank good.michael

[Jono 9304Participant @jono9304]

Hi fizzy

your post is very interesting and you have done a great job on your boiler.

i uave always been interested in tig or mig welding a boiler either in steel or copper as i have been wekding for several years although not coded.

The tricky part for me is the design calculations, do you use a guide book for the calcs or have any advice on designing.

I am currently making a 5 inch speedy

thanks jono

[nigel jones 5Participant @nigeljones5]

Hi jono. I do use design calculations but an easy way is to copy the general layout of an in print copper boiler. There are lots of web sites with the basic formulae in them. I used a xl spreadsheet for the safety calcs, kindly provided by John Baguley (sorry if ive spelt your name wrong John!). I checked and the formula in it is sound – boiler examiner was also happy with it. I design mine in visio as I dont have autocad, then print out every part to scale – this has been invaluable.

[Robert Johnson 3Participant @robertjohnson3]

A little late to the game but amazing work on the Boiler Fizzy, Im new to this forum and fairly new to the concept of steam. Currently undergoing a 2" build as i have had so many people defer me from building my own larger scale model. I am a time served fabricator welder of 8 years and experienced in heavy industrial equipment with my own small workshop. seeing this thread has filled me with confidence to build my own larger scale model. Thanks for taking the time to document this build.

Rob.

[JasonBModerator @jasonb]

Robert, also read Fizzy's last post in this thread particularly comments on welding ability before you get carried away

[Robert Johnson 3Participant @robertjohnson3]

Posted by JasonB on 11/05/2020 18:26:38:

Robert, also read Fizzy's last post in this thread particularly comments on welding ability before you get carried away

Thanks for this read yes I am aware of the welding experience as I have 8 years of welding experience at professional standard, my full-time job I fweld hydraulic rams along with custom agricultural machinery so this shouldn't be a problem. I am coded in mig andqand hold basic qualification in TIG stainless food grade as I worked as a maintenance engineer within the food industry for a short while before returning to the agricultural engineering.

[nigel jones 5Participant @nigeljones5]

Nice to know someone actually reads my posts! They might not be what people want to hear (read) but there is no armchair in my workshop…couple of three leg stools somewhere……Robert you should have little problem with the welding, place most likely to fail is the start stop on the foundation ring. I dont know why but this is the only weld which ever gave me grief, and not just once.

[Ady1Participant @ady1]

Inspirational stuff fizzy

[Alan Waddington 2Participant @alanwaddington2]

Things have probably changed in the 30 years since i was a boiler maker / coded welder but MIG was not accepted for pressure work.

Most of the 4ft diameter and upwards shells and dished ends were done automatically with submerged arc, and all the bosses etc stick welded with low hydrogen rods.

Smaller vessels especially stainless would be TIG root and capped with stick.

Mig was only ever used for non pressure stuff.

Way before my time there, a very small upright vessel approx 18” diameter failed under pressure test. The fella doing the testing failed to get all the air out. The door which would have been probably 4” thick blew off and bent one of the angle iron rafters in the roof, that would have been around 30ft above. Luckily no one was around when it took off for space.

[Paul LousickParticipant @paullousick59116]

Not sure of your boiler code in UK but here ia Australia MIG is not allowed. MMA (stick) or TIG only for model steel boilers.

Paul.

[Neil WyattModerator @neilwyatt]

Wow, I'd forgotten about this thread!

Neil

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