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[pettyofficernick]

Good Morning all, I have just acquired a boiler kit from Brunell models, originally a Tubal Cain design. A friend of mine owns a refrigeration business, supplying reeffer compartments for MOD and merchant shipping,food factories, hospitals etc, and he has offered to get one of his welders to tig weld said boiler kit for me, claiming it is far superior to silver soldering. All his welders are fully coded and I was wondering if this is an acceptable way of assembling a boiler ( for test certificate purposes) if so, it will save me a few quid, as he will have it done for nowt, which is allways a good thing. Any comments will be well recieved,
regards,
Nick.

[essex2visuvesi]

I don't know about the rules but I would say that would be the best possible way to do it, especially if these guys are doing something similar already

[john s 2]

I see no problems with a skilled welder doing this. Its going to be tested so why not. Depending on what
filler rod is introduced the boiler could be stronger than silver soldering. John.

[Circlip]

Talk to the boiler inspector first.  It's a "New" technology for toy boiler construction and the old guard need to come up to speed with it. Sadly, with the increase in "Welding experts" created by machinery supply shops like Machine Mart/Clarkes, welding is "A piece of cake". Yea, right, at one point had 9 Mig/Tig welders working for me sticking Stainless and Aluminininium fabrications together and although doing it day in and day out, not all of them would be trusted with a boiler.

 Best to check first before having an uninsurable boiler.

  Regards  Ian.

[Martin (Admin)]

Sage words Ian.   

[pettyofficernick]

Hi there, these guys weld up copper parts for refridgeration equipment, so they are geared up for working with copper, I have also emailed MPBA as it is their insurance I am covered by. I will post result of their reply.
Regards,
Nick.

[gondolier88]

Hi Nick,

Perfectly acceptable, there is one model boiler manufacturer that TIG welds as standard, though for the life of me I can't remember which one!!!! A persistent google session may pay dividends on who it is, they may be able to advise on suitable rods etc. Although your skilled freind has a very useable skill, remember his work will typically be smallish bore pipe joints, not large surface area tubeplate/barrel joints etc so make sure his enthusiasm to help, though commendable, is backed up with the experience of doing it before.

If it were my boiler I would be tempted to get the tubeplate/barrel curcumferential joints TIG'd, and then silver solder suitable tubes into the tubeplate, this gives strength were you need it, and the possibilty of reheating the joints that are the most likely to have problems with- whether welded or soldered, ie. the tube ends. If you balls up on one of those with a welder you'll be looking at drilling it out, replacing with a larger tube and starting again- if you silver solder them you can reheat and re-run the solder if needs be.

On the other hand, if your mate is an experienced refrigeratioin engineer he should be able to braze as well as TIG weld, which is a good middleground between silver soldering and welding?

Greg

[pettyofficernick]

Hello Greg, I think Maxitrak TIG weld all their loco and traction engine boilers as standard, and their is another firm called Steam Technology Ltd who, I think, build to order. The boiler I am making is only a simple affair, 3"x6"vertical, with 3 x 5/16" water tubes in the centre flue. I was planning on silver soldering the tubes into the flue  and having the main assembly tig'd. thanks for the advice,
Regards,
Nick.

[HS93 (RIP)]

I saw some Tig welded boilers at Harrogate on the Maxitrack stand they look very nice and the way to go in the future.

Peter

[ooyah/2]

Nick ,
There is no problem with TIG welding boilers as long as  it's a Coded welder who does the welding.
Here is a page from the EXAMINATION  & TESTING of MINIATURE STEAM BOILERS which is the blue book that all engineering societies work to and is acceptable
by insurance companies.


There are all sorts of restrictions if not TIG WELDED   by a Coded welder, some clubs may ask for verification that your boiler was TIG welded by a Coded welder.

Your boiler will come under the 3 bar litre rule which doesn't need a certificate but should have a hydraulic test witnessed by your clubs testers and there after a steam test once a year and  as this is a  known design by an experienced engineer now no longer with us you shouldn't have any problems..

Regarding the assembly of the boiler on no account weld the end plates in before you make the center flue as the projections of the cross tubes will be greater than the holes bored to take the flue.

Make your center flue and hydraulic test it before welding in, as if there are any leaks you will not be able to re-weld or S/Solder to repair the leak once it's all assembled and welded in.

Your on a winner if you are getting it welded F.OC.

George.

[Circlip]

You've gone the right way Nick, check before commitment.

 The use of Silver Solders (Our formulation, not the American translation) allowed the "Common" Muddle Ingineer to construct a safe working pressure vessel designed for a specific operation if the known formulae were observed and the thus calculated and selected materials were used. I wonder if the Tubal Cain design meets the requirements for Tig welding?

  Before everybody and their dog jumps in and states "I" think - - - - , be prepared to put your signature to a document and supply this to the original poster as an insurance get out for him.

 My original statement re Tig welders under my control a few years ago still stands, despite coding, we had to get approval from a higher authority on certain jobs.

 Once "It's OK to Tig weld" comes out of the undergrowth, the "I've just bought a Tig welder and look what I can do" brigade will be burning everyones fingers.

 Just to add a final comment, a friend recently had a Copper boiler made for his 5" gauge loco. Due to his geographical location, this was made by a reccomended manufacturer in Australia to the "AMBSC" coding, one which our anti-podian colleagues will argue to be one of the best in the world. This duly arrived (Late?) with test certs - tested to 150PSI etc. but looked decidedly dog eared to say the least. Me mate eventually decided to put water into it. Ideal for watering the garden with, but not much good for retaining water let alone steam, but certified to have been tested to 150PSI?

 He did get his money back and despite having to pay a total of £1700 for a British manufactured boiler from a supplier who ONLY manufactures toy boilers (Still Silver Soldering at this point in time), can rest easy that the "Tin" does what it says on his paperwork.

  Without wishing to criticise the competency of any coded operative, until full approval is given by ALL insuring bodies, tread warily.

  Regards  Ian.

[ooyah/2]

Hi Ian,

Nick originally asked the question if it was acceptable to TIG weld a boiler, according to the Blue book guide this is acceptable if done by a Coded welder.

I heartily agree with you on your post and in all the years that I have been building boilers and in all the Engineering Societies that I have been involved with to this day I have never seen a TIG welded boiler nor been asked to test one, all of the boilers that I have made and tested have been Silver Soldered.

Mike at Maccsteam still Silver Solders his boilers and Matrix I think are the only people TIG welding, but these are Loco Boilers so I don't know what the Loco clubs do in testing them and accepting them for insurance purposes.

It's true to say that most of us interested in steam have our own workshops and don't posses TIG welding gear hence we all use Silver Solder in the construction of boilers.

The easy access to The Internet and the Machine Mart places open up a whole new can of worms for the people who say , JUST BOUGHT A TIG WELDER AND I WILL MAKE MY OWN BOILER. fortunately they have to present their boilers to a club tester for certification and and insurance , that should sort out all the dummy's.

My preference every time would be S/S and as Tubal Cane designs are all for fairly small boilers I don't know how it would take to being TIG welded.

So although Nick may get his boiler welded for now't it might cost him in the long run as who ever is to test it may not pass it.

George.

[sjoormen]

Hi all I just noticed this topic and I couldn't resist. TIG welding can be used for welding copper but get guy that knows what is doing. Let me explain I work in maintenance for pharmaceutical industry and I' ve been welding with TIG almost 20 years now and I also had certificates few times (they last only year long),.. and I wouldn't try weld thin copper pipes if my life depended on this- why - because I don't know enough about copper. And I am enough honest to talk about it. Certificates mean nothing without experience. Troubles I know from welding thin tubes ( I weld mostly AISI 304 and 316) is that weld falls into the tube but that can be avoided with gas mix or argon gas in the tube that way weld in inner side can't oxidise and can't fall trough. Troubles that may cause trouble lays in weld itself.
When you look at it you can see that weld itself is thicker than tube but line between weld and tube might be thinner than tube and there tube may crack. Because my English is not good enough I will try to find photo if anyone is interested. So be very careful. You never know what can go wrong with things that you don't know enough.

[ooyah/2]

sjoormen.
Thank's for your explanation on TIG welding thin copper boilers, it may be O.K. to TIG weld Loco boilers which are just that little bit heavier than model Boat boilers and welded by a Company with the know how and experience, but I will now be very wary if ever asked to test a model boat boiler.

George.

[Circlip]

Sjoormen, your "Not very good English" far exceeds my best Slovenian and as someone who earns a wage welding "Exotic" materials, you have perfectly explained some thing that many hobbyists will have never considered.

  The basic difference between Welding and Brazing joints together. In welding, the parent metals are melted and fused together, the addition of a "Filler" metal, usually of the same or a compatible material strengthens the joint. What should be realised is that the joint has been designed to allow the weakening of the parent metal by the process of undercutting to be brought back to a safe working condition with the filler.  

  Back in post No 10  , I asked the question 

I wonder if the Tubal Cain design meets the requirements for Tig welding?

     This has not been answered, basically because the answer is NO. That design was generated using the old formulae for brazing the joint together , a method of not reducing the parent metal thicknesses, a bit like "Gluing" the bits together but the glue length has been calculated to allow the joint not to fail providing it has been glued together properly.

 Re the examples given of TIG welded toy boilers, I know of one boiler that was made three times, at least once that was due to the "Maker" (Known and insured in the industry and certified to Tig Copper) being unable to follow the original designers dimensions, of which many examples have been previously made by "Amateurs"

  Make sure that the guy that is doing the welding knows what he's doing, but also, make sure the guy that's told him to weld it understands what he's asking.


   Regards   Ian.

[SteamboatPhil]

I have to say (withput wishing to put a damp blanket on things) that Sjoormen has a very very valid point. Without being too critical of your chum pettyofficernick I would get him to do you some "test" type joints first using the same material that will be used during boiler construction, then cut the joint in half and inspect it. Don't then throw away the test piece as you will need it later (stick with me here) If you feel the work is up to scratch (as it were) you might wish to proceed, but remember welding (as has been explained) produces a different heating area and some distortion may cause the boiler to "twist" rare but it may happen (that would be a boiler fail MPBA steam rule 3.3). And as Sjoormen has pointed out what has happened inside the tube. Tig welding refrigeration units is one thing, but there are a lot more joints in a small area on a boiler. The MPBA will accept this method of construction but you will have to show the test piece (see thats why you didn't throw it away) the reason being is that you are coming away from the accepted method of construction as originally seen by the designer (MPBA Steam rule 3.5). If all goes well it should then be tested to twice working pressure (any leak or weep ) would however be a fail.
George he will need a test as the MPBA do not (yet) follow the bar litre chart.
Ok thats my bit, good luck whichever way you go.
Phil  (MPBA   NEC Steam)   

[pettyofficernick]

Hi Folks, many thanks for all your advice, as a result, I have decided to stick with silver solder. Maxitrak's website has an informative article on tig welding boilers, and after reading it, I noted that a particular grade of copper must be used ( C 106 ) other grades contain arsenic, causing cracking when reheated, even at relatively low temperatures, and I cannot verify what grade of copper I have. the boiler kit came from a long established, reputable supplier, (Brunell Model Engineering) so I have no reason to doubt that the materials I have are not suitable for silver solder all being of 16g copper.
Regards,
Nick.