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Boiler testers and material verification

Identifying materials fit for purpose

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BW06/08/2019 22:40:52
249 forum posts
40 photos

If I present some materials to a boiler inspector prior to building a boiler how does he verify that they are what my suppliers say they are ?

I'd suggest that relying upon a piece of paper from the supplier would not be good practice.

To a beginner lots of stainless steels ( shiny silver colour) and brass or bronze alloys (shiny or dull yellow) will look the same

Do they use hand held x ray diffraction testers to identify material types or use simple physical tests such as specific gravity ie weight in air vs weight in water

Can you put a drop of chemical XYZ onto a piece of yellow metal to determine brass vs bronze or presence of lead / aluminium / other

If I can cut a thread with great difficulty does that mean its likely to be bronze rather than brass

Can simple scratch or penetration or streak tests be used to determine strength or hardness or true colour.

Whilst all of the above could be done in a laboratory what resources does a boiler tester have available ?


Paul Lousick06/08/2019 23:10:38
1374 forum posts
531 photos


A boiler inspector, especially a club inspector would not be able to accurately determine the type of material which you intend to use to build a boiler. As you have said, it would require a testing laboratory. The material surplier should give you a test certificate (not just a sales receipt) which specifies the chemical composition, tensile strength, etc for that batch of material..


mick H07/08/2019 06:46:39
718 forum posts
21 photos

The material surplier should give you a test certificate (not just a sales receipt) which specifies the chemical composition, tensile strength, etc for that batch of material..

I have never ever received or been offered such a document.


J Hancock07/08/2019 07:24:26
391 forum posts

If you have your boiler 'or whatever' supplied by the like of Bechtel I can assure you that level of 'paperwork'

will be supplied with it.

Paul Lousick07/08/2019 07:43:13
1374 forum posts
531 photos


You have to ask for a certificate from the material supplier when you place an order, otherwise there is no guarantee of the material that you receive and it would be a very fool hardy inspector that did not require one.

I have a test certificate for every piece of plate that I used to make my boiler and if any part should fail, it can be tracked back to the supplier and the manufacturer. My insurance would not cover me if I could not prove that it was made from the required materials.


SillyOldDuffer07/08/2019 08:59:56
5624 forum posts
1157 photos
Posted by BW on 06/08/2019 22:40:52:

If I present some materials to a boiler inspector prior to building a boiler how does he verify that they are what my suppliers say they are ?



Would be nice to have a UK boiler inspector confirm this but what I've seen suggests they are practical men, conservative about what's acceptable in an amateur boiler. They much prefer boilers to be made of Copper, which metal is easily identified. And the exact alloy of Copper used to make a small boiler to handle the low steam pressures involved in a home-made locomotive isn't critical. So, provided the boiler is made of copper, the design and construction matter more than the precise material. An experienced chap can evaluate the construction against a code and then back his judgement with a hydraulic test.

Certificates become essential when materials are taken to their limits as when safely reducing the weight of an aircraft. Impressive though they are model steam locomotives aren't aero-space and their construction doesn't require elaborate quality control and assurance with certificates, lab tests and traceability etc.


Former Member07/08/2019 09:12:00

[This posting has been removed]

CuP Alloys 107/08/2019 09:14:12
234 forum posts

And all this assumes that you have made the correct decision in your material selection. You may have decided that a certain alloy is the one for you. It is not unreasonable for you to ask for confirmation of the material analysis. I have been suggesting that the for years with regards to silver solder. However no material or supplier of any product can issue a performance guarantee unless you provide full details as to what you intend to do with it.

In the case of any material, poor performance could result in the loss of life. Now there's a claim.

In the case of silver solder, For just a start I would want to know;

where, how, when, it was being used. Information required would be a method statement detailing the joint design, heating technique, parent material preparation.

I would also like confirmation of your internal arrangements to ensure that you are meeting the design criteria and production techniques.

Add to that, details of the experience, training and competence of any person likely to use the alloy. Don't forget the qualifications of supervisory personnel.

The list goes on! That is why even the biggest suppliers offer the disclaimer of it being your responsibility to establish the suitability of using their product.

The answer to any problem relating to the quality of any joint be it soldered, brazed or welded probably lies in the same place - behind the heat source!

In the past, I supplied a very large film company with alloy. Then the studio decided that all orders had to be on official letterheads. Their conditions of purchase and the responsibility that I faced ran to 17 pages! At the end of page 1, I was smiling. Page 2 and I was angry. The document went into the bin before the end of page 3!

Their supplies dried up and they went back to using their petty cash fund.

In essence, if you are not prepared to accept the responsibility of your actions ; beware of what you ask for.

Now- about this certificate you want.......



Martin Kyte07/08/2019 09:21:06
1794 forum posts
33 photos

f I present some materials to a boiler inspector prior to building a boiler how does he verify that they are what my suppliers say they are ?

I if I was a boiler inspector 'which I'm not' what I would get from your presentation is that the materials appear to be copper or bronze and are the correct thicknesses for the design. In addition, and probably more usefully, it would show me that you appear to be an open and honest person who is interested in getting things right and working with me rather than trying to pull a fast one.

Steel boilers have more rigorous requirements regarding certification of materials, but I assume we are talking copper here.

regards Martin

Paul Lousick07/08/2019 09:48:22
1374 forum posts
531 photos

Not all model boilers are the little toy Mamod type that are made from copper and opertate at 5 - 10 psi.

The boilers on a 7 1/4" gauge loco or 4", 6" traction engine have a boiler containing 20 - 50 litres of water and steam at 100 - 130 psi. These are a potential bomb if made from the wrong materials.

If I present some materials to a boiler inspector prior to building a boiler how does he verify that they are what my suppliers say they are ? The inspector can only go by the documents which you present to him and if you end up in court he will present these documents. It is then up to you to show a paper trail of receipts. Yes, a dodgy certificate could be printed or cheaper material substituted, which is a reason to buy from a reputable company and keep good records, otherwise you could go directly to jail, not pass go and not collect £200.

I supply a drawing of all of the boiler parts to the supplier when I order cut plates and the test certificate which they supply with the plates has a reference to each drawing.


Former Member07/08/2019 09:58:42

[This posting has been removed]

Former Member07/08/2019 10:08:06

[This posting has been removed]

Paul Lousick07/08/2019 10:21:45
1374 forum posts
531 photos

I'm not a layer, but if a boiler failed and the inspector could show that he did the checking and testing that was required by the model code and used the documentation supplied by you, that you would be the one that faced a claim.  The inspector would also have to show that he was a competant engineer, capable of doing the job. 

A reason to do everything as required in the model boiler code, keep records and have insurance.


Edited By Paul Lousick on 07/08/2019 10:23:45

Clive India07/08/2019 10:23:04
213 forum posts

Posted by 34046 on 07/08/2019 09:58:42:

What I would like to know. You buy certified materials, build boiler and have it certified by the boiler inspector.

If it failed and injured a member of the public, who would be faced with a claim - would it be you or the boiler inspector or both ? Bill

I think it would be you initially as you are the owner - or your club if you were running at a club public function.

If you had done as you say, and there were no other issues suggesting negligence, then you have operated in good faith. You may have to sue the club whose inspector you used (the inspector is not legally responsible), or a contract inspector, if you were being sued yourself.

That is why we have public liability insurance.

Former Member07/08/2019 10:59:03

[This posting has been removed]

Roderick Jenkins07/08/2019 10:59:12
1855 forum posts
471 photos

Can I put forward this argument, based on no specialist knowledge whatsoever:

The boiler testing code in the UK has been put together between the insurers and model clubs. The code does not guarantee that the boiler is intrinsically safe but that it provides a reasonable risk that the insurer is prepared to underwrite. History has shown that the fairly loose requirements for silver soldered copper boilers have provided a reasonable risk for the insurers. If an exploding boiler is not insured then I suspect that all the risk falls on the operator/owner - regardless of any inspection certificate.



Edited By Roderick Jenkins on 07/08/2019 11:26:00

Martin Kyte07/08/2019 11:11:55
1794 forum posts
33 photos

Surely the only claim can be to the insurance company and would be payed provided there were no acts of negligence which surely must include a valid and current boiler certificate.

Suing for damages needs to prove negligence on your part if down to the operation of the boiler or on the part of the boiler inspector if the boiler certificate was issued fraudulantly and the boiler were not fit for purpose.

I would hope that the inspector is legally responsable for ensuring that the boiler meets all the requirements. If not the certificate is not worth the paper it's written on which is fraud.

My commercial boiler certificate indicated the name third party independent assessors who validated the competence of the boiler tester.

Hopefully none of the above will come to pass if we all do our utmost to stick to the rules and operate as safely as we can.

regards Martin

CuP Alloys 107/08/2019 11:48:17
234 forum posts

And this certificate goes further than a certificate of analysis?

Guarantees joint strength, integrity, freedom from fear of hydrogen embrittlement of the copper by a flame, a ductile joint between aluminium bronze and steel, freedom from liquation, corrosion resistance etc?

Such a certificate would open the door for claims for compensation for any cracked or leaking joint.

I have the t-shirt. 13 years ago I saw such action from an ill-informed individual armed with suspect analysis of the silver solder used. The solder was said to be causing weak and brittle joints. It was alleged to be the tip of the mountain of more claims. The truth of it all was that the silver solder was to speciation and the problem was a mixture of inappropriate parent material and brazing technique and joint design. The problem was behind the torch - not in front of it!

There wasn't, and has not been , any further problem.

So don't think it can't and doesn't happen.

The scars have healed but the memory remains as vivid as it was last week.

I am surprised that any company would give this assurance.


Martin Kyte07/08/2019 11:57:54
1794 forum posts
33 photos

Don't quite understand CuP's point. Boiler certificates attests that the boiler inspector has done everything he is required to do and is happy. If CuP's response was to my post I don't expect it to mean anything else.

Perhaps I've missed something.

regards Martin

Martin Kyte07/08/2019 12:09:52
1794 forum posts
33 photos

Ah you mean the materials certificate.

Go it now.

I suggest the bottom line is the only real test of safety factor is destructive testing (of each boiler), which somehow defeats the object.

The practical solutions is to do what is done now which is more an attempt to detect potentially dangerous boilers than certify absolute safety which cannot be done. If all the elements of the requirements are seen in the light of weeding out the duds it all makes better sense. The boilers that get through are then by implication safe for some given value of safe.


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