Boiler testers and material verification

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Thanks for all of the discussion above - initial question was prompted by me wondering how I (a total novice) might ensure materials are fit for purpose. All I can do is trust the suppliers to give me what I ask for and that trust has apply all the way back through the supply chain.

I will never sell a boiler, will only ever use them for my own amusement, and they will always be tiny compared to what some of you chaps are building.

Some of the discussion above mentions certificates, how are they relevant ? How does one prove that certificate XYZ is related to the piece of metal used to make the boiler that Fred Jones bought last week ? Unless all bits of metal are identified by a unique number or ID code that is stamped on them and that number is mentioned in the certificate then I don't understand how those certificates could be related to any specific boiler. Please forgive the question if its silly, I just don't "get it".

We don't see regular stories about boilers blowing up all the time so the current systems and checking must be working reasonably well. I am aware of occasional posts about old toy boilers failing due to dezincification of brass.

Certificates are only as good as the process and people behind them. I've been directly involved in an aircraft case that shows this I'm changing details due to confidentiality. We ordered some one way valves with male and female ports from an approved suppler who sourced them directly from the manufacturer. Normal flow direction is male to female but optionally it can be reversed, this adds a R to the part number. Valves arrived with all correct paper work and were installed on aircraft. They would not fit with the marked flow arrow in the correct direction. Turned out that the reverse flow valves had been supplied. They had the correct part number on valve (no R) but the marked flow arrow and actual operation was for the reverse flow type. Turned out to be marking error but neither the makers or distributors inspection picked it up. This type of thing could cause all sorts of issues as it is often hard to check non return valves when installed in applications like vent lines.
Liability in this case would have gone back to the manufacturer.

A material certificate is also of little value unless there is the quality process in place to support it along with proper stores controls etc. You might have bought the right material and then picked up the wrong bit by mistake.

Conservative design and hydrostatic testing are the best defence. The most useful high tech instrument for a boiler inspector is an ultrasonic thickness meter.

Robert G8RPI.

The Mill Certificate is for a particular 'lot' of material, the material should be marked with the 'lot' identifier in some way (printed or stamped typically). When material is cut, the identifier should be transferred to both sides of the cut, before cutting. Where that isn't practical, material isolation as part of a quality system and record trail can be an acceptable alternative.

It isn't uncommon in industry to see material scrapped if either certificate or the marking on the material can't be found - as it is no longer possible to guarantee that the material is what it should be.

Once you as the customer accept delivery of a certified material with its relevant material certificate, then you cut the material and make the relevant parts for your boiler construction, the chain of traceability can be frustrated if you are making parts from more than one piece of copper and different material certificates apply to each piece of copper used. At best, unless you record which batch of material each part is made from and I doubt that as model engineers we are going to those lengths, then the traceability has been lost and the only surety is that you can quote that all material used was of the relevant material specification but in the event of any failure it is not possible to trace a fault to a specific certified batch of material. In industry, and I have worked on components that are used in nuclear engineering situations, traceability of all materials, via an accredited quality system, is required such that faulty material has to be traceable back to the casting process, to expect this with a model engineering boiler is in practical terms not possible as the end users I.e. the model engineers, do not have a recognised quality system and appropriate regulation, therefore any legal processes would unfortunately rest with the boiler constructors.

Dave W

So you buy your copper etc from your reputable supplier and get a copy of the mill cert, fine, but now can you as joe bloggs, model engineer prove that this new material is kept segregated from your stock of odds and ends and not just chucked on the bench with all the other bits of silver solder, copper tube and sheet etc. To prove this you would need a quality system and manual and need robust procedures in place for incoming material, a quarantine area and a bonded store. You would also have to have your system audited, by who I do not know, the bottom line is that most steel boilers are professionally made and come with paperwork, copper boilers professionally made will have paperwork but home made, you can prove you purchased the material but you cannot prove that you used it.

Isn't this getting a little silly. The system in place works. Boilers are not blowing up all over the place and it's affordable. Traceability is not required. If one boiler goes pop the rest of the fleet will not have to be grounded so each boiler is treated seperately and you don't need to know what batch of material each bit came from. I would suspect that all boilers finally end their days either leaking beyond reasonable use or by failing their periodic pressure test. The fact that you are going to sit with the boiler pretty much between your legs is sufficient cause to generate a reasonable degree of caution. )

Martin

Martin, I think the discussion progressed the way it did because the original poster questioned material certification linking this to legal liabilities and was unsure how the process worked in respect of home built boilers, the system, such as it is, works and we are all relatively safe from hordes of exploding boilers.

Dave W

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No that isn't a silly question at all which is concerned with getting a boiler past the boiler inspectors.

When the thread heads for the realms of military and aerospace traceability I would say it is getting a little silly. Generally threads stay mostly around things that are practically helpful and I for one tend to pick up many usefull things from them. I was merely saying that the thread seemed to be getting a little fancifull.

It would be helpfull to know the answer to this but if you re making a boiler yourself maybe the better route would be to involve your club boiler inspector when you start and at strategic points along the way. That way you can ask if they are happy with the material/process/design mods etc as you go and will be in a position to act accordingly if something different is required. If I was a boiler inspector I'm sure I would be happier to work that way rather than be presented with a done deal.

As far as commercial boilers are concerned mine has a CE mark which shows it conforms.

regards Martin

Edited By Martin Kyte on 07/08/2019 16:25:03

Martin, 34046, yes this is getting totally silly, the trouble is that a lot of boiler inspectors make up their own rules on top of what the Southern, Northern fed state in their book. In my previous post I tried, perhaps not very well to illustrate that any traceability ends when raw material goes into your workshop, I would love someone to tell me where in the rule book traceability for copper boilers is mentioned. As for all this involving boiler inspectors, if you are building a boiler to a previously published design, say for instance a Simplex, the design has been around long enough to prove its safety and apart from perhaps showing your chosen inspector your flanged plates and firebox assembly, that in my humble opinion is all they would need to see, they are not gods, they don’t have x Ray eyes to examine penetration, the proof of the pudding is in the 2x hydraulic test, if it passes, jobs a good un, if it leaks like a sieve, weigh it in for scrap, learn from it and try again. If you are designing your own boiler, how many club boiler inspectors are competent enough, or would want to get involved?

I've designed a couple of boilers in the past and I had all the calculations ready to present to the inspectors at the initial pressure test. No problem with getting the complete set of tests done with the subsequent issue of a boiler certificate..

Brian

It is simple enough to follow the principles of traceability if you choose to. Nobody said you have to have ISO 9000.

Commercial vessel builders can manage without ISO 9000 quality systems for even very high level pressure systems - just have inspection in place of an approved quality system. That doesn't sound so far from working with your club inspector and knowing what he/she expects to see.

Can only find the following in Vol 1, 7.4, but maybe enough? Dunno! I'm not clever enough.

The Inspector shall satisfy himself:

a.That the materials used are of adequate thickness and the correct specification.

b.That, where required by the build procedure, the relevant material certificates are provided.

Clive, a and b seem to nail it if you are abiding by said volume.

Dave W

1. You try your best to buy the right copper and the right bronze - usually from a model suppliers.

2. Bronze definitely looks different to brass. I don't wish to bring sexism into this or be dismissive but my wife has zero technical training and she can tell the difference.

3. Quality assurance ISO 9000? - what bo****s!! Don't bother going there because the questions never stop e.g., how do you know the model supplier received the right stuff, have they sold the right stuff from the right pile and did you pick up the right bar when you did the machining? If you have the certificates - well done frame them but I have no idea how they will help.

Phil H

Assuming we are talking about anything bigger than a Mamod boiler...

Forget all that analytical stuff. The MELG Guide Book (latest has a white cover with orange titles) tells you what you actually need to know.

It mentions certificates only for steel boilers, but places so many obstacles in their way that making a steel boiler is for the professional only, for all practical purposes.

(Curiously the original EU Pressure Equipment Regulations that our hobby sort of uses, mentions only two materials for pressure-vessels: aluminium-alloy and stainless-steel; but not which of a plethora of their alloys and grades!)

Copper and cuprous alloys, and silver-solders and fluxes - purchase by what it says on the drawings, and if you buy them from reputable suppliers they are what they say they are on the invoice. You don't need certificates of conformity for them, for amateur construction not by way of trade, and nor should your club's boiler-testers demand them, though they might want to inspect progress.

Just don't use brass in any structural component including the bushes for clacks etc. Rather according to alloy, it can become brittle in some circumstances and conditions.

The question mentions stainless-steel. I am afraid that is irrelevant. I think it's still ruled out, but anyway it comes in so many flavours with their own welding characteristics, that whilst there is no logical reason against stainless-steel boiler shells in principle, it is definitely a material for the professional boiler-makers able to choose the right alloy and weld it correctly.