TIG welded copper boilers

[Nigel Graham 2Participant @nigelgraham2]

There should not be a problem with a club boiler inspector faced with a professionally-made copper-boiler, at all; and does not need some sort of extra training for them.

Without ploughing through it, I am pretty sure the matter is covered in the MELG book (the current edition, orange print on white covers). He might be nervous of a home-welded copper boiler, as that does need a particular grade of copper, unlike the "ordinary" metal suitable for silver soldered and indeed rivetted-and-caulked boilers.

Otherwise the test regime and methods are the same and are those laid down in the book, not invented or 'gold-plated' locally! (That tendency has caused problems, such as the bloke who refused a locomotive with a rocking-grate – the code does not even mention grates.)

The boiler inspector though, should have attended at least one reasonably recent, of the Boiler Testing seminars run from time to time around the country, usually once a year.

[JellyParticipant @jelly]

Posted by noel shelley on 30/09/2021 11:20:38:

Like Luker I would be happy to make a steel welded boiler, Though I agree with the need for a strict code for design and construction. That I don't think I have heard of a catastrophic boiler failure would seem to indicate that the current system works.

This exists in the form of the conformity assessment procedures of the Pressure Equipment Directive 2014/68/EU as implemented by the Pressure Equipment (Safety) Regulations 2016 SI 2016/1105.

Which in turn will likely require the design and execution to be conducted with reference to (for a fire-tube boiler) either BS EN 12953 or another relevant standard like the ASME BPVC with some additional sprinkles of validation done in the technical file for UKCA marking.

In some respects, this can seem to be quite onerous at first, however…

• boilers under 2lt are exempted from conformity assessment and must only meet "sound engineering practice", whilst the requirements get increasingly onerous as you increase the desired volume, and pressure…
• boilers where the gauge pressure (in Bar) multiplied by the volume (in litres), referred to as "PS​•V" is less than 50 are subject only to Module A "Internal Production Control", which is a self-certification process.
• where the PS​•V <200, then only modules A2, D1, & E1 apply, in which a final examination of the product by a authorised body. is an acceptable route to compliance.

From a model engineering perspective, many if not most boilers will fall into the first two categories, and those which move through to the lower category are likely part of a very large and complex model with the attendant expectations around cost.

​

Posted by noel shelley on 30/09/2021 11:20:38:

How many boiler inspectors know enough about welding to be able to satisfactorily even test the samples, or even want to test the welded boiler ? In this day and age I'm surprised we are allowed to build any sort of pressure vessel, even a copper one !

The rub to the above statements about how much of the assessment criteria apply for "in-scope" boilers is that the person welding them up would need to take a weld qualification test to either ASME Code Part IX or BS EN ISO 9606 (or hold a valid cert already), to meet the criteria. This means that the person must:

• be genuinely very skilled at the type of welding they intend to use,
• be familiar with following a Weld Procedure Specification in a test environment,
• have the time to take at least a full day to go to a certification body and do a weld-test,
• have the money to do the same (it's not expensive, but it's not nothing, and would add up quickly if your design used several different welded joints with different WPS's)

However, the requirement to go and have quality assurance of your standard of welding done, does take the onus away from boiler inspectors to also be welding inspectors (which is it's own speciality entirely).

Edited By Jelly on 19/10/2022 15:34:06

[Martin KyteParticipant @martinkyte99762]

Posted by Ken Chicken 1 on 19/10/2022 12:39:18:

Hi, your original question: "How do TIG welded copper boilers compare with traditional silver soldered boilers? What are the advantages and disadvantages?"

My opinion:

Welded boilers – properly made and certified – will perform and last as long as silver soldered boilers.

Because of the controlled manufacture and certification required, they both meet the "same" standards – in the result that means you have a boiler powering your loco. I should not expect you to experience any difference when using your loco, even in 50 year's time. Abuse will destroy anything quickly, but treated with appropriate care (no difference between a welded or silver soldered copper boiler) they should both outlast many of us.

However, a steel welded boiler is a different animal. It NEEDS water treatment and more cars due to the normal corrosion of the steel.

Boiler testing and certification is basically the same, whatever you have on your loco. But the inspector may be trained to certify silver soldered copper boilers, but not other types, so won't do those. Check your local club, to be sure.

K

In addition and I refer to professional Tig welded boilers which is the route I took, whilst the copper cost remin the sme the cost saving in silver solder is appreciable. Also the technique usually goes for a fusion welded shell with silver soldered bushes fo if at some stage there is a problem with a bush it can be heated to melt the solder and replaced. Not something you could do with a fully silver soldered boiler without fear of causing issues in other joints.

regards Martin

[Ken Chicken 1Participant @kenchicken1]

Posted by duncan webster on 29/09/2021 15:42:28:

The SFED rules on testing say

An Inspector acting as a competent person who carries out an examination under the Written Scheme of Examination shall have such sound practical and theoretical knowledge and actual experience of the type of system which is to be examined as will enable defects or weaknesses to be detected which is the purpose of the examination to discover and their importance in relation to the integrity and safety of the system to be assessed

which implies that the inspector should know about copper welding and possible defects. Not all will. Don't get me wrong, welded boilers are fine as long as stuck together by someone who knows what he is doing.

Noted: But the Midland Federation book (2018), and others, instruct: "The individual should know his own limitations and should not act outside his level of qualification or knowledge." – I.E. if you don't know "welding", don't inspect a welded boiler. – I can weld, but only after a bit of practice do my welds look OK. – 10 rods a decade does NOT make me a welder! – Nor an inspector of welded boilers! – Though my job has involved me with certifying welders after taking tests and destroying and examining their samples, communicating with the Welding Institute on various welding matters, Aluminium, steel and copper welding (Including MIG copper to aluminium), Hydraulic testing of air receivers, design of pressure vessels, Dye penetrant testing, micrographic examination, etc. – BUT I still do not consider that I have the "Sound practical and theoretical knowledge and actual experience of the type of system which is to be examined as will enable defects or weaknesses to be detected which is the purpose of the examination to discover". – The challenge I face is how to obtain such "knowledge and expertise," etc. and be certified "OK"…

Don't knock people who say "No, I am not adequately experienced" – or whatever, as they are being responsible within the Federation codes and national regulations.

Stay safe.

Ken

[A SmithParticipant @asmith78105]

I wonder if anyone else is interested to know if the "well known UK based professional boiler manufacturer" mentioned by Luker is still in business?

I only know of two firms that advertise this type of construction, maybe there are others.

Andy

[Nick Clarke 3Participant @nickclarke3]

Posted by Luker on 30/09/2021 12:11:27:

I would encourage anyone to give boiler manufacture a bash (this includes TIG welding copper). If the club has members that guide and help the builder, and a boiler inspector that keeps up with modern manufacturing techniques I can see no reason for a ‘poor boiler’ outcome. If on the other hand the boiler inspectors are not knowledgeable enough and are unwilling to up skill; that is an entirely different matter…

Unfortunately the UK FMES code is quite specific in saying:-

6.2 If welding is undertaken by a person who is not a coded welder the Inspector shall require that weld samples be made available for inspection and testing prior to the commencement of the welding of the boiler, or that the welder shall have proof of test pieces being satisfactorily tested within the 12 months prior to the jointing being undertaken. Weld samples shall be tested by appropriate testing laboratories.

The material being welded is not specified so both steel and TIG Copper are equally covered by this requirement if they are to be tested and certified.

While an amateur could I suppose meet these requirements, I suspect the expense of professional materials testing might be prohibitive.

[JellyParticipant @jelly]

Posted by Nick Clarke 3 on 20/10/2022 14:27:29:

Unfortunately the UK FMES code is quite specific in saying:-

6.2 If welding is undertaken by a person who is not a coded welder the Inspector shall require that weld samples be made available for inspection and testing prior to the commencement of the welding of the boiler, or that the welder shall have proof of test pieces being satisfactorily tested within the 12 months prior to the jointing being undertaken. Weld samples shall be tested by appropriate testing laboratories.

The material being welded is not specified so both steel and TIG Copper are equally covered by this requirement if they are to be tested and certified.

While an amateur could I suppose meet these requirements, I suspect the expense of professional materials testing might be prohibitive.

£150-175 per mode (welding process and material type) for a ASME IX or BS EN ISO 9606 weld test which would meet the requirement of:

"the welder shall have proof of test pieces being satisfactorily tested within the 12 months prior to the jointing being undertaken"

Via national providers like The Engineering College, The Welding Academy and TWIcert (the certification body of The Welding Institute), most local colleges doing welding could probably arrange something similar via their external certification body.

That includes the coupons being tested internally (twice, examiner and verifier) and then externally including both NDT and destructive (sectioned and etched) testing.

 

That would almost certainly work out cheaper than commissioning bespoke materials testing on weld coupons by a lab.

Whilst that sort of money is not nothing, it's not really prohibitive either when considering the cost of building a boiler in the first place and the potential savings of using a welded construction.

Edited By Jelly on 20/10/2022 15:20:19

[Nick Clarke 3Participant @nickclarke3]

A look online confirms that a test is £175 from several places but that is for the test to become BS EN ISO 9606 coded and half of that is deducted from the £500 cost of the day – so it will still cost you £600 just for the test with no training beforehand – and if you don't pass it will be another £600 or no boiler.

[JellyParticipant @jelly]

This suggests that there is an opportunity to engage with a company like TWI who charges for the Assessor's time by the day (or a local college who are open minded) rather than per candidate.

That could allow a group of interested model engineers go take their weld-test together (like colleagues would in a manufacturing environment) to keep costs manageable.

[Mark RandParticipant @markrand96270]

Certainly Northampton College, where I did my C&G II arc and TIG courses, did 'coding days' with multiple paople as well as individual coding tests.

[JasonBModerator @jasonb]

Fizzy has posted before that getting your welds non destructive tested is a cheaper route if they are not done by a coded welder. Whole boiler for less than £200 (steel)

Edited By JasonB on 20/10/2022 16:54:32

[Ken Chicken 1Participant @kenchicken1]

I think my Club's attempt to get the Welding Institute to visit and advise on TIG Welding of copper boilers, although welcomed and planned, fell through due to costs of certification and equipment. – Beyond the Club's financial resources. Then Covid, cancer, ageing personnel and a few other troubles hit the club, so that will not happen in the foreseeable future now.

C'est la Vie!

[Nigel Graham 2Participant @nigelgraham2]

A gentle reminder not to forget two aspects:

Under the UK codes –

– A boiler built commercially, whether silver-soldered or welded, copper or welded steel, since (2012? I forget the actual year) will have complied with the Regulations and come with the appropriate paperwork.

– If home-built by welding, the materials, welder and welding have to meet certain regulatory minima.

'

– For the first case, the club boiler-inspector does not need know welding, weld-analysis, etc. The donkey-work has been done for him by the manufacturer, and he needs only follow only what the MELG book tells him – and only what it tells him.

– For the second, both the builder and the boiler inspector will need knowledge and equipment few model-engineering clubs are likely to have; and the inspector can decline to admire it on the basis of that lack.

'

In both cases – no gold-plating. No refusing feed clacks moved from the design's back-head bushes to a prototypical and preferable top-feed, a slightly longer shell or 4mm firebox plates instead of the drawing's 10swg! (Worry if bigger diameter or thinner plate.)

'

Please note that remark about test equipment.

Commercial boiler-testers and weld-inspectors have access to sophisticated NDT methods and tools – and the skill to use them – the majority of us lack. Consequently the MELG system does not call for them.

At the seminar I attended hosted by the Wimborne society, someone asked about ultrasound. We were advised not even to think about it.

They are not part of the test regime designed for amateur model-engineers, so using only simple, practical external examinations, hydraulic and steam-accumulation tests.

[D.A.GodleyParticipant @d-a-godley]

Please explain, because I am failing to understand the aversion to tig welded boilers .

At the point of hydraulic testing , does a tig welded boiler fail with a bigger bang than that of a silver soldered boiler ?

If not , where is the greater risk , it either satisfies the test requirements, as does a silver soldered boiler , or it does not , and there can not be any greater risk involved since they both fail or pass that particular test before moving on to the next examination under steam .

[JellyParticipant @jelly]

It's quite easy to make a weld which visually looks good but conceals a defect which makes it susceptible to rapid fatigue once in service.

Without NDT, the only person who can detect that is the welder who makes the weld (if they're knowledgeable/skilled enough to understand).

Consequently either detailed testing of the workpiece or validation of the skill of the welder is required.

As compared to the level of scrutiny that welded pressure vessels in industry come under, the model engineering approach to welding seems entirely proportionate.

[LukerParticipant @luker]

Posted by Jelly on 20/10/2022 23:04:54:

It's quite easy to make a weld which visually looks good but conceals a defect which makes it susceptible to rapid fatigue once in service.

Without NDT, the only person who can detect that is the welder who makes the weld (if they're knowledgeable/skilled enough to understand).

Consequently either detailed testing of the workpiece or validation of the skill of the welder is required.

As compared to the level of scrutiny that welded pressure vessels in industry come under, the model engineering approach to welding seems entirely proportionate.

I’m sorry Jelly but I don’t agree. ‘Rapid fatigue’ (low-cycle fatigue) failure is uncommon in welded copper (or copper in general for that matter) due to the ductility of the material and the heating/annealing during the welding process. When welds fail due to ‘cracking’ in copper it’s normally due to hot tears because of low melting point (elements) contaminants that never went into solution; or just poorly designed welds.

TIG welding isn’t very forgiving when it comes to visual inspection. Unlike some of the other welding processes it is very easy to pick up poor quality welds. In industry, 100% NDT is normally limited to dye pen and MPI, both of which won’t pick up root defects, and won’t pick up much more than a good set of eyes and some good light. UT and X-ray picks up root defects and sidewall fusion defects but this is practically limited to a percentage of the welds. Personally I have very little faith in these reports, they only good for the bureaucrats and lawyers. I’ve stopped a few components from going to site where all the NTD passed inspection scrutiny but visual inspection made me look a little deeper and low and behold there were welding defects that were very dangerous.

To Godley’s point (and I agree with him): In industry, as with hobby boilers, my go-to has always been the pressure test and the visual inspection of the welds. It’s not easy to gippo these two tests.

The sad fact is; with all the legislation/ bureaucracy and club boiler inspectors that are unwilling to up-skill you effectively limiting innovation and restricting the hobby to people with deep pockets. Where, in the past, the rest of the world was looking to the UK for innovative designs and manufacturing techniques with our models, now it seems like other countries are leading, especially with boilers. Maybe its time to take your hobby back from these bureaucrats!

[SillyOldDufferModerator @sillyoldduffer]

Posted by Luker on 21/10/2022 07:10:10:

Posted by Jelly on 20/10/2022 23:04:54:

…

…

The sad fact is; with all the legislation/ bureaucracy and club boiler inspectors that are unwilling to up-skill you effectively limiting innovation and restricting the hobby to people with deep pockets. Where, in the past, the rest of the world was looking to the UK for innovative designs and manufacturing techniques with our models, now it seems like other countries are leading, especially with boilers. Maybe its time to take your hobby back from these bureaucrats!

I agree there's a problem, but a typical engineer mistake is to blame bureaucrats! The real issue is the need for someone to take responsibility in the event of an accident: in the event a boiler accident causes a life changing injury such as blinding a child, who is going to pay.

Clubs are covered by an Insurance Policy which is bureaucratic because insurance companies don't take on unbounded risks especially when injury costs can run into millions. Thus engineers aren't free to do as they please: they have to follow the rules, at least in public.

Much more freedom when boilers are steamed in private. The financial risk is taken by the owner, who could end up being forced to sell his house to pay the an injury bill, or finding his House and Contents Policies don't cover fires started in a home workshop! In the UK the NHS will pay personal medical bills, but not all taxpayers are keen to cover self-inflicted injuries due to irresponsible behaviour.

Many are blissfully ignorant about the amount of trouble that ensues after an accident. The accident itself is the tip of an iceberg, potentially followed by a blizzard of claims, investigations, blame shifting, bad publicity and legal action. Engineering is much easier if you don't have to deal with the consequences!

It's true Model Boiler development in the UK is stuck because the system favours Brazed Copper Boilers built to an established design. They work well, can be built by determined amateurs, don't require super-educated Inspectors to confirm they're safe, and a proven low accident rate. But, the system doesn't cope well with innovation, leaving Model Engineers with a boiler technology the professionals have pretty much abandoned. They're highly unlikely to make a pressure vessel from brazed copper, partly because of the cost, and partly because well-made welded steel boilers are considerably stronger.

I don't think the problem is making welded boilers, it's getting them insured. If a club can't cover it, it's always possible for individuals to run in private or to take out their own insurance, or to have the boiler checked commercially. The main obstacle is cost! There doesn't seem to be a cheap way for an individual to prove a welded boiler is safe.

How is it done in other countries? If they've got the answer we should copy it.

Dave

[HopperParticipant @hopper]

I'm too nervous to use my Italian coffee maker machine after reading this lot.

But an hour's entertainment can be had by simply Googling "boiler explosion" and selecting "Images". The days when men were men and train drivers were superhuman, soon to become extra-terrestrial, were something to behold. I hate to think of something like that happening next time I go to make an espresso.

Imagine this in your kitchen:

Edited By Hopper on 21/10/2022 10:52:46

[LukerParticipant @luker]

Posted by SillyOldDuffer on 21/10/2022 10:26:44:

Posted by Luker on 21/10/2022 07:10:10:

Posted by Jelly on 20/10/2022 23:04:54:

…

…

The sad fact is; with all the legislation/ bureaucracy and club boiler inspectors that are unwilling to up-skill you effectively limiting innovation and restricting the hobby to people with deep pockets. Where, in the past, the rest of the world was looking to the UK for innovative designs and manufacturing techniques with our models, now it seems like other countries are leading, especially with boilers. Maybe its time to take your hobby back from these bureaucrats!

I agree there's a problem, but a typical engineer mistake is to blame bureaucrats! The real issue is the need for someone to take responsibility in the event of an accident: in the event a boiler accident causes a life changing injury such as blinding a child, who is going to pay….

There's lots of; could happen, might, what if (fear and more fear)… a little like what insurance companies and bureaucrats preach when they try to get you to do what they want you to do. Engineers do take responsibility by driving directly behind the boiler(s) they made; this position and the front of the boiler is arguably the most dangerous. ME shell design safety factors are orders of magnitude larger than large scale.

Don’t get me wrong, rules and guidelines are welcomed especially for the beginner. But honestly, professional weld sample tests for a small welded boiler. A couple of destructive weld samples tested for the boiler inspector at the club workshop should be ample.

At our club we emphasis good driving and boiler management practices; nearly all failures I’ve come across can be attributed to abuse while on steam. If the boiler passes the shell test and the safety valves are adequately designed and maintained then any problems are driver related.

[noel shelleyParticipant @noelshelley55608]

Whilst I agree with LukeR that a CLOSE visual inspection by someone who knows what their looking at and a hydraulic test should show up a faulty boiler, I also feel that the constructor should show a degree of competency to the inspector prior to welding the boiler and even some basic test of weld samples. Having been involved in a serious accident due to the failure of a commercially carried out weld I am painfully aware of the issues in this area of our hobby that encompasses experts down to those who know very little about the subject.

Why are rivetted steel boilers seldom seen ?

Knowing the weld process used and having passed a CLOSE visual inspection, with a drawn tube shell and staying of all flat surfaces, a boiler that had passed a hydraulic test + steam test I would consider highly unlikely to suffer a catastrophic failure.

Having started to build acopper boiler to a well known design only to have my club boiler inspector refuse to test the boiler as he did not consider the design to be safe, not withstanding that it's designer was well respected AND that it complied with the oft mentioned Australian rules left me feeling very strongly on this matter ! Noel..

[Mark RandParticipant @markrand96270]

It is curious that a repair to a load bearing part of a motor car must be welded. Gas brazing and soldering are an MOT failure unless the panel was originally manufactured that way.

To quote the bard:- The first thing we do, let's kill all the lawyers.

[JellyParticipant @jelly]

Posted by Luker on 21/10/2022 07:10:10:

Posted by Jelly on 20/10/2022 23:04:54:

…

I’m sorry Jelly but I don’t agree. ‘Rapid fatigue’ (low-cycle fatigue) failure is uncommon in welded copper (or copper in general for that matter) due to the ductility of the material and the heating/annealing during the welding process. When welds fail due to ‘cracking’ in copper it’s normally due to hot tears because of low melting point (elements) contaminants that never went into solution; or just poorly designed welds.

In fairness, I wasn't explicitly thinking of copper when I wrote that but of low-carbon steel and stainless steel, which are the de-facto materials for any welded pressure vessel design in my professional life.

I'm more than willing to accept that copper has it's own specific faults and modes of failure.

(Although I can't actually see why you would choose to use it in a welded boiler given the high cost, high weight, reduced tensile strength, reduced operating temperature envelope, worse long-term fatigue properties, and more challenging welding procedures compared to steel).

 

It's also notable that incorrect parent metal selection, or inappropriate consumables (for welding of phosphorous bearing copper) can cause oxidation, and/or HAZ related defects which do result in rapid-fatigue faults…

Just like joint design, those factors shouldn't be an issue if the constructor is competent, which is why validating that by having them explain/document decisions for review by another competent person is important.

 

Posted by Luker on 21/10/2022 07:10:10:

TIG welding isn’t very forgiving when it comes to visual inspection. Unlike some of the other welding processes it is very easy to pick up poor quality welds. In industry, 100% NDT is normally limited to dye pen and MPI, both of which won’t pick up root defects, and won’t pick up much more than a good set of eyes and some good light. UT and X-ray picks up root defects and sidewall fusion defects but this is practically limited to a percentage of the welds. Personally I have very little faith in these reports, they only good for the bureaucrats and lawyers. I’ve stopped a few components from going to site where all the NTD passed inspection scrutiny but visual inspection made me look a little deeper and low and behold there were welding defects that were very dangerous.

This is why welder certification (be it formally, or informally) is so important, validating the skills and knowledge of the welder creates a chain of trust that they're both

• able to recognise when they're including a defect in a weld, and
• that they will rectify it or raise the issue pro-actively rather than let it slide.

100% and Intermittent NDT are additional "Layers of Protection", not a replacement for keystones like technical competence, or the application of experience and judgement in a visual inspection.

 

Posted by Luker on 21/10/2022 07:10:10:

To Godley’s point (and I agree with him): In industry, as with hobby boilers, my go-to has always been the pressure test and the visual inspection of the welds. It’s not easy to gippo these two tests.

But they only address one sub-set of the potential issues.

A boiler which holds pressure when it's first tested, but after 30 firings, will suddenly fail catastrophically due to fatigue, is every bit as unsafe as one which goes "pop" during it's hydraulic test.

 

Posted by Luker on 21/10/2022 07:10:10:

The sad fact is; with all the legislation/ bureaucracy and club boiler inspectors that are unwilling to up-skill you effectively limiting innovation and restricting the hobby to people with deep pockets. Where, in the past, the rest of the world was looking to the UK for innovative designs and manufacturing techniques with our models, now it seems like other countries are leading, especially with boilers. Maybe its time to take your hobby back from these bureaucrats!

IMO blaming bureaucracy is a cop out, engineering is at its core applying science to solve problems within a set of constraints.

Legislation, Regulation, Insurance and Liability are all important constraints, which modern engineers have to work with, and frequently act as drivers for (not limits to) innovation.

 

Club Inspectors (as a general class of people, not as a criticism of any one person who is volunteering out of the goodness of their heart) being either unwilling or unable to up-skill to meet the challenges of welded boiler construction and assessing novel designs sounds like a much more significant limitation.

Respecting that they are all volunteers, the question then becomes how do clubs and the community as a whole find, attract and retain people who have the right transferable skills to help meet those new challenges?

Edited By Jelly on 21/10/2022 12:32:44

Edited By Jelly on 21/10/2022 12:35:02

[JAParticipant @ja]

I am intrigued that this thread has reappeared.

After considering advise from the early part of this thread and others I ordered a silver soldered boiler from a reputable manufacturer a year ago.

JA

[LukerParticipant @luker]

Posted by Jelly on 21/10/2022 12:30:01:

Posted by Luker on 21/10/2022 07:10:10:

Posted by Jelly on 20/10/2022 23:04:54:

…

In fairness, I wasn't explicitly thinking of copper when I wrote that but of low-carbon steel and stainless steel, which are the de-facto materials for any welded pressure vessel design in my professional life.

I'm more than willing to accept that copper has it's own specific faults and modes of failure.

The OP was for a TIG welded copper boiler, and this is to save the cost of silver soldering the joints. I’ve only built (TIG welded copper) one such boiler and it still steams just fine (10 years later). I agree with you questioning the use of copper instead of stainless. To digress a little, stainless steel TIG welded boilers work incredibly well. I’ve designed and built 4. Life cycle fatigue (and surface potential calculations for corrosion cracking) is normally catered for in the design phase and cannot be determined by NDT, but that is outside the scope of this thread. Boiler plate is technically more difficult to TIG weld than stainless (and normally not recommended), so we need to be specific with materials and welding procedures.

Of course if you weld with clothe hangers, and rusty wire you’ll get rubbish… I’m not sure why anybody would TIG weld copper with Phosphor bearing rods, this doesn’t make sense.

Engineers solve real world problems from first principles. Bureaucracy hamstrings that process by adding unnecessary constraints restricting solutions. I.e. How does a professionally checked sample add any more value than having a technically competent club boiler inspector check the sample, and then help and guide the model ‘boiler maker’?

[JasonBModerator @jasonb]

Posted by noel shelley on 21/10/2022 11:26:58:

.

Why are rivetted steel boilers seldom seen ?

 

Because you can't fit inside the manhole of a scale model to get at the back of the rivits ditto getting into the firebox. There is also the problem that small rivits will loose their heat very quickly so won't shrink as they cool to pull the joint up that bit tighter after forming 

Still commonly seen in full size rebuilds and restorations

Edited By JasonB on 21/10/2022 14:20:33

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