Building a Steel Boiler....

[weldsol]

Re coded welder this will depend on the Bar / ltr capacity of the boiler

Paul

[2671jason]

I've never heard this before.I always thought that a steel boiler had to be welded by a coded welder.Does anyone know the capacity where the rules apply/change?

[2671jason]

Having just read the Blue Book all it says is that the welder should be competant and that if the welder is not coded the boiler inspector can ask for samples of welding for examination.Fair enough.I know my welding is up to scratch and i'm willing to have a boiler built by me tested to any pressure anyone likes.This is another point someone out there can maybe answer.Klendo says that a non coded welded boiler has a different test pressure,where is this written? there is no mention of this in the Blue Book.Sorry if this is going over old ground again but i would very much like to build my own boiler for a 7 1/4" gauge loco and see no other way but to do it myself for monetary reasons.

[ewal]

I've built a few boilers & always the tube plates were clamped together to drill & ream. Don't worry about retubing, the copper will last as long as the steel boiler.Thickness of copper 1/16th this is not water pipe. thickness of steel, tube plates 12.5mm, seamless tube 10mm.
I always pumped the boilers up to 600psi

E.W.

Attachments:

[locoman]

Following the theme of steel boilers, I am amazed at the level of opposition to the use of steel boilers within the UK. I am a regular visitor to a Brussels track / club where the use of stainless steel boilers is common. In fact, so far as my translation of their boiler code is, that stainless steel boilers are preferred to copper boilers.

Why is there such an insistance on documentation of all the steel used in a steel boiler, welder approval etc. when, as it appears, anyone can lash up a copper boiler, using any available material from any source and using any available silver solder/soft solder/brazing material without question?

Much emphasis seems to be placed on hydraulic testing. That, in isolation, proves little other than, at the time of testing, that the boiler is 'tight'.

In my own case I have a "Sweet Pea" boiler, fabricated in the early 1980s from solid-drawn steel tube and plate to the old BS 4360/43A plate specification (very similar to the then current BS1501 spec for boiler plate) which is, to all intents and purposes, only fit for scrap. The welder responsible - now I feel no longer with us - handled our pipework at up to 250 psi, and did a superb job, with a TIG root run and capped off with 'stick' manual arc welding. With the thicknesses involved due to the availability of tube, the hoop stresses based on PD/2t (ie pressure times diameter divided by twice the plate thickness) are very low (approximately 1 ton per square inch!)

If steel boilers per se (especially stainless steel boilers) are so unacceptable (as dangerous?) in the UK, why are they seemingly acceptable elsewhere in Europe and in the USA?? I fully accept that only certain grades of stainless are suitable for boiler work, but would also query the open specifications for non-ferrous metals used in copper boilers. For instance there is,it seems, no reason why brass studding could not be used for firebox stays in a copper boiler. No doubt a satisfactory hydraulic test would be passed, but how long in service before said stays start to fracture?

[alanstepney]

The answers to that question are long and involved, but to keep it simple (and skate over some points)

1. We, in the UK, have been building copper boilers for ever (well almost) and the methods and procedures are well established. They dont include brass stays!

2. Stainless steel is a definate NO.

3. Steel is OK, but until recently they could only be made by a qualified welder. Now, they can be made by "us", subject to meeting certain requirments.

That all applies to new builds,
Slightly different rules apply to existing boilers.

The rules are laid down following consultation between the insurance companies, associations representing model engineers, and the government bodies who deal with appropriate legislation, supported by advice from suitably qualified and experienced professionals.

The end result is that we have some of the cheapest insurance rates in the world, have an enviable safety record, and, in most cases, clubs can perform the tests at no charge to their members.

The question of stainless is a different matter.
It can suffer from some serious problems, and even in the US, there is starting to be some opposition to its use.
In addition, it has little benefit and some disadvantages for "our" boilers.

[2671jason]

Alan,Can i ask you to elaborate on your third point about steel boilers? I take it you mean that "we" don't have to be coded welders to build our own steel boiler.What are the certain requirements you mention?

[locoman]

Alan,
Please - why did you decide to 'skate over' some of the points that I raised? My comment re using brass studding as stays was more to illustrate the - apparent - insistance that for steel boilers all material had to be 'traceable' and yet a 'copper' boiler could - apparently - use any non-ferrous materials regardless of source/mechanical/chemical properties without restriction, such as the use of 'brass / bronze' of any/unknown composition/standard for bushes and then face the problems caused by the leaching out of the zinc content? And what filler material to be used during the fabrication? Are some readily available 'self-fluxing' rods not susceptible to cracking/degradation when in contact with sulphur containin products of combustion?

I would still like to understand why, in the UK in many clubs, stainless steel boilers are not acceptable? So far as I am aware, model engineers in Holland/Belgium/Germany have no problems with stainless steel boilers built with specific grades of steel and approved welding techniques? Are they wrong and we are right?

[Deleted]

Locoman

The answer to your question may be found in this thread from a couple of years ago: the subject was 'done to death' so to speak!
JB
modeleng.proboards.com/index.cgi?board=boiler&action=display&thread=3719

[alanstepney]

I decided to "skate over" some points as it would take almost this entire board, and lots of time, to cover the entire subject.
Looking at old posts here, particularly that thread that John mentioned, will give the basics.

To go further, read the Blue Book, the article by Mike Leahy in Model Engineer, the PED and other legislation, and, if you dont get bored to death, you will have some idea of the complexity of the subject.

Steel can be of numerous grades and types, so knowing which one is essential to ensure it is capable of carrying the stresses that it is subjected to.
Copper, being an element, is far more consistant (although some can be oxygen free), so all should have the same basic properties.
You can not use any old non-ferrous material for bushes etc.
They should be GM or PB, and both are zinc free.

Stainless has some worrying properties that can result in failures, often far sooner than people imagine.
I have seen photos of a boiler that had worn almost through in less than a year.
Our insurance companies have decided that they are not prepared to insure SS boilers, so, as far as we are concerned, that is the end of the matter.
(I gather that the foregoing doesnt apply to duplex steels.)

As I said before, there is no advantage in stainless so little point in using it anyway.

[locoman]

Although I accept the most helpful comments of 'simply locoman' as being factual (I will still wave these past our works metallurgists - I am a mechanical designer in one of the few remaining UK steel plants) - but other issues that I have raised seem to be unanswered. Just what rules / regulations will / do apply to the home manufacture of steel boilers? Material specifications? Branding of plates? Traceability?

It seems more and more likely that the pair of 5" gauge Crampton locos currently in build will have to have two boilers - one to satisfy the UK opposition to stainless boilers and the other to suit the Belgian/Dutch/German idea that stainless is acceptable and that copper is 'non-preferred'?

[locoman]

Alan, I am afraid to tell you that copper itself has many other near specifications, such as an arsenical containing grade much in use in earier years for locomotive fireboxes (and now supposedly banned due to its arsenical content). Also cadmium-containing grades were used as electrodes in spot-welding machines built by AI Welders in Inverness where I served part of my apprenticeship. Some of the copper-bearing alloys approach - in ultimate tensile strength - that of mild steel. As for the inference that the cost of insurance should be a matter of concern amazes me. What of the old precept that safety has no cost?

[alanstepney]

My understanding (and I dont have time right now to go through the books) is that, for a steel boiler, on eneeds traceability of materials, an approved design that is acceptable to the insurers (and that includes types of joint, weld, etc), and it must be built by a "competant" welder.

Obviously, what we used to call a "coded welder", would be considered competant, but otherwise, I assume test welds, etc would be required.
(They were when I built a steel boiler, and my welds passed all the tests.)


As for Stainless, whilst clubs may not test them, a professional independent boiler inspector may do so, and one of the insurance companies may be willing to insure them. (I dont know for certain, so cannot be definate on that).
That applies to full-size steam, but that is obviously outside of the scope for the model boiler / club regime.

[2671jason]

Alan,What tests did your welds have to pass and who carried out these tests?

[alanstepney]

It was back in the late 60's, so this, from memory, may not be 100% accurate, and the situation may well have changed since then.

The insurance company appointed an engineer, who checked my weld proparation, and watched all my welds, horizontal, vertical, and deep and shallow welds. Some with a root weld and two passes over it.

Fortunately, it didnt need me to do overhead welding.
He also asked me loads of questions about welding prep, techniques, joint design and general engineering.
(More a chat session, in which he threw some questions to see what I knew.)

He then took away some welded pieces that went for testing, both NDT and DT.
He said at the time that he thought the test pieces would pass, and they did.

He also checked the prepared plates for a boiler I was building, & gave them the OK.

Eventually, I got a piece of paper to say that I could stick bits of metal together.
(Now long out of date, and apart from that, I cannot do welding for medical reasons.)

As I said, this may have changed.

[locoman]

It seems as though I may have stirred up a bit of a 'wasp's nest' over my queries concerning steel boilers in general and stainless boilers in particular. I do NOT wish this discussion to deteriorate into any form of slanging match/personal attack/general nastiness, but would like to think that some common ground may be reached.

In a previous post I mentioned that I have two 5" gauge Cramptons in current build. On retirement it is my hope to possibly relocate to Brussels. On the outskirts of Brussels there is one of the most fantastic ground level 5" and 7 1/4" tracks that I have ever seen and I would like to think that my locos would be acceptable there. Hence the possible need for a boiler change between countries.

At the risk of boring those who do not speak French I would like to quote part of their boiler spec --

Les chaudieres en acier, cuivre ou inox sont acceptees, meme si le PTVF marque se nette preference pour les chaudieres en acier inoxidable (type 316L plus particulierement.

To the best of my French, that indicates that although steel, copper, and stainless steel are acceptable, the preference is for stainless steel to 316L.

The standard continues, mentioning the work that Luc Tennstedt had done, and the fact that they have had more than 25 years of experience with stainless steel boilers.

There are also some concerns over boilers which have been heavily used over ten years.

I await, with interest, your further commentsd

Ian

[Deleted]

Ian
I have no wish to stifle discussion, and you certainly make your case, but you might just be flogging a dead horse on this one. It's obvious to me from the various threads and posts that SS boilers here in the UK are just not on!
Regards
JB

[alanstepney]

Ian,
There is nothing to stop you building a boiler out of whatever material you choose. (They have even been made of wood!)

The problem arises if you want to use it at a club, and want it to pass their tests and to get a club-issues certificate.
They CANNOT test it. The rules, laid down by the insurance companies for clubs, preclude the testing or use of stainless steel boilers.

You could approach one of the insurance companies direct, and if they agree to insure it, have it tested by one of the commercial testers.
That is what you would have to do if it was a full size engine (loco, traction engine, etc.).

If they will insure it, then the majority of clubs would allow you to run on their track. (Some may not, it is their option.)

That is my understanding of the situation at present.
That may well change, due to the introduction of duplex steel boilers, (which many confuse with stainless steel).
(In fact, it might have changed already, I am sure someone will tell me if that is the case.)

[Shawki Shlemon]

I have been reading this but trying to avoid the problems , my best advice is to have a look at www.aals.asn.au/ , standards , boilers ,boiler code mark 4 for duplex ( most people may call it SS but it is special material like SS ) . You may purchase a copy of the code and find all the details . I hope this helps

[Paul Rowell]

I been involved with running a 1922 Aveling porter E-type roller for 30 years, so understand steam vessels and know a bit about the dynamics/metallurgy and why material are accepted, if the material has no prof of grade you can only class it as scrap! REMEMBER five PSI will give a man third degree burns, and a boiler is a control potential explosive situation.

Boiler plate "BS1501 replaced by European norm EN10028" is heat treated uni-formally to the British standard for pressure vessels it is the same strength as mild steel but is proven it entire length and width, stay material is the same a grade being EN3b/EN32 sometime referred as bright..
The filler rod and Welding process is as important as the basis material for example.. Full size steam ARC welding with Low Hydrogen rods "E7018" is only accepted for route pass in boiler plate, the tensile stength is 70,000 PSI, it starts and finishes hot unlike mig this process is not acceptable, this is why Tig is acceptable process for welding model boilers the filler rod still has to be the same grade and tensile strength as ARC process, it is widely use at the industrial level for pipelines welding and their for proved accepted practice.

Welders are coded on the basis material, its thickness and type of rod used so just because your coded on one material doesn't mean your coded for another, this is why NDT and x-ray process is a commonly used to proving a weld integrity.

Stainless 316L was mention, this is a marine grade material its number meaning it resistant to chlorine the L mean it is low carbon it can be welded and there for is more magnetic properties and doesn't mean it proven for pressure vessels, another example commonly used 303 this contains sulphur and will crack if welded the sulphur content is added for ease of turning, you can't tell unless you have the bit of paper.
stainless will rust where it is heated, oxygen has to be purged out the back of the weld during welding with argon to stop oxide building up and make the weld porous, brittle so why use it.

The next new one is welded copper boiler how can they be proved I have heard there are clubs out there that will not accept them because its an unknown quantity and there for can not insure there safety.
UK is responsible for the historical development of knowledge of all types of pressure vessel the set of rules have been drawn to be followed as safe acceptable practice.

This is why anybody can rivet a boiler together if there is an approved design to follow, using the correct materials.