Exploding boilers?

[havoc]

I think you may be wrong about Gauge 1 boilers not exploding due to amount of water contained. Some time back, there was an article in the ME about "coke-can boilers" tested to destruction. Seems that a fair amount of damage could be caused.

A coke-can is made out of 0.09mm steel (yes, they are below 0.1mm now). I do not consider that suitable material for a boiler. I didn't read the article, so I don't know how they tested it so I'm not able to comment on that.

[the_viffer]

Havoc Hi

If it is the article I think it is then the poster is referring to copper pot boilers of conventional wall thickness but the size of a coke can ie gauge 1 loco boilers.

Some crazy guys steamed some boilers such to destruction in some open land observing the pressure gauge with binoculars from a bunker.

I think this was early 70s but I don't have a reference to it and I'm not inclined to flick through thousands of back copies of ME to find it. It is the only case I know of boilers being tested to destruction under steam.

While the pressure required for destruction was well in excess of the calculated the damage to the boilers and the surroundings was impressive. Certainly on the evidence of that you'd be lucky to walk with a limp if a 7.25" Duchess boiler went off in your crotch.

The pressure inside a coke can btw is of the same order as that in a miniature loco boiler.

[GWRdriver]

Re "testing" -

In recent times there have been at least two articles in ME on "tests" perfomed on closed cannisters tested to destruction, neither of which were scientific and neither of which produced information which could be taken to the workbench and applied, or used by any organization to demonstrate to the "authorities" that we (the live steam hobby) are generally a responsible lot. In fact perhaps the "authorities" could construe the opposite to be true: Only idiots would heat a closed water-filled cannister over a fire and stand around and watch to see what it would do!

For those of you interested in the behavior of small scale (Ga1 or thereabouts) boiler details tested to destruction you might find this study interesting: sgcox.site.net.au/ritg/boiler-tests.pdf This report was recently done Paul Trevaskis (AU) in support of the Sub-Miniature portions of the AMBSC and leaves little to conjecture so far as the aspects of boiler construction it covers. I am not necessarily a proponent nor am I an opponent of the AMBSC and I offer this only as information of interest, however Paul Trevaskis, the author of the study, is a personal friend and I can vouch for his abilities, sincerity, and conscientiousness.

I can only speak of conditions in the USA and these days the live steam hobby is populated by a greater percentage than ever before of folks who have little or no industrial, mechanical, or practical live steam background. Coincidentally there is more history, experience, technology, and instruction on live steam of all sizes in print than at any time in the history of mankind, yet somehow there continue to be blind spots and information vacuums where people are simply unaware that 100 year old pool of technology and documented practice exists. I am regularly astounded at the outlandish ideas that some people come up with for "accepted" live steam practice and the lack of awareness of existing technology. There are also those who don't want to know that this pool of technology exists. To acknowledge it would means they might have to take a difficult path and they would rather avoid that. So as often as not "accepted practice" is newly made up on the spot by folks whos only prior experience is taking things from boxes ready-to-run and are little more than evasive tactics, . . . to avoid the time, expense, and bother of doing it the right way.

A few years ago two noxious weeds of ideas reared their ugly heads, one in large scale and one in small scale. The one in large scale, where the majority of boilers are welded steel, went along these lines: Since we have had no recorded injuries or fatalities from miniature boiler operation, then we must be over-designing or over-building our boilers so we should relax the accepted design requirements. Fortunately this stupid reasoning went away, but for a time no the proponents of relaxed standards could not be convinced that possibly the reason there had been no injuries nor fatalities was for that very reason, that standards had been and continue to be held high.

The second one appeared about the same time in the small scale/garden gauge arena and gave rise to a "campaign" by a few individuals, all relative newcomers to live steam, to declare silver solder for boiler making an unnecessary bother if not a boondoggle perpetrated on the uninformed by old hands who were simply trying to make life difficult. Fortunately cooler, better informed, and more safety conscious heads prevailed and this too went away.

None of this precludes experimentation and improvement. It should and must go forward, however model engineering and live steam is like any other technical discipline, if you first become firmly gounded and proficient in the fundamentals of the technology then you become much better equipped to go looking for ways to make improvements and make good decisions about pushing the technological envelope. We (in the USA) have a large number of folks anxious to get to Part B without successully completing Part A.

[paul]

I can only speak of conditions in the USA and these days the live steam hobby is populated by a greater percentage than ever before of folks who have little or no industrial, mechanical, or practical live steam background.

That's bound to be the case with the general move away from manufacturing to service and 'hi tech' jobs but it's not their fault and at least they perhaps want to understand even if they have been brought up to expect a quick fix. The thing is if nobody new comes into hobbies like this the craft will gradually disappear (when I was at schoold metalwork and woodwork were on the syllabus but they haven't been for years now).

I know lots of people these days who have absolutely no practical skills, not even the ability to wield a screwdriver or a paintbrush! I'm not completely useless in practical matters but I know I'm not a patch on my grandfather and his generation (he could make anything from furniture to fishing rods to musical instruments!).

I suppose this is progress

[houstonceng]

Andy

The Martin Evans "solution" (probably not his design but in his book - think it was originally in ME) was a three transister circuit with three LEDs. There were two electrodes, insulated from the boiler shell connected to the circuit and screwed into bushes in the boiler so that they were in the water & steam space. One electrode drove one Orange LED via one transistor and was placed at High water mark. The other electrode - placed at Low Water mark drove two LEDs - Green & Red - via a "flip-flop" (two transistors) so that only one light could be on at any one time. The lights were arranged to indicate RED = Low Water, Green = Ok, Orange+Green = Too much.

I'm sure that with modern circuitry you could arrange for an alarm "bell" and, if you were really cute, automatic control of the injector - but that's maybe going too far.

My build on his idea would be to have a little delay built into the circuit so that the LEDs didn't flash on and off with water surge.

Andy

[alanstepney]

As an alternative, some years ago in ME was described an automatic boiler feed pump that pumped when the water level was low, and only then. Purely mechanical, and quite ingenious.

[ron]

Paul, I think the problem of lack of practical skills nowadays is caused by lack of apprenticeships, when I was an engineering apprentice in ICI many moons ago you did 6 months solid on bench tools and six months solid on machine tools before you were allowed near anything, if you didn't know basic practical skills at the end of that you were in the wrong job! It was a great training that set me up for life as a classic car restorer, general DIYer and now a newby model engineer. [as well as keeping me in well paid employment for 35 years]
I see so called tradesmen nowadays who I wouldn't use even if they did the job for free, I dread the time when I'm too old to do my own DIY and have to employ these comedians.
Ron

[modeng2000]

Hi all,
I have been following this line with interest and have to agree with Ron about the standard of 'tradesmen' these days. My apprenticeship was a mix of mechanical and electronics and has not let me down.
My biggest fear is having to get someone to do jobs for me. Perhaps I am too particular but I do like things to be done properly.
John

[steammadman]

Sorry GWRdriver iam afraid i can't remember the exact details of the incident in theUS i referred to,it was a few years ago,i remember reading about it in the model press,
if i remember correctly a chid was scalded, but ican't be sure of the details, so it would
be unfair to elabourate any further.

[frank]

Interested to read about the "Springbok" boiler it is not so much the water flashing off to steam with the rapid rise of pressure but the fact that the boiler had been subjected to a period of heating with out any water to take a way the heat, copper starts to becomes plastic at temperatures above 400C, sliver solder has a melting point at 650c or there about, it is quit conceivable that crown of the fire box was in a plastic state and any pressure would have caused it to claps. If it had been noted that the boiler had no water and was allowed to cool it should be subjected to a hydraulic test before a second steaming was attempted

[Phil Sutton]

Hi.I read a book from our local library about British loco boiler explosions,from the beginningof steam power,up to the end of steam on BR.I seem to remember that "water flashing into steam caused excess pressure,and thus the boiler to fail" was incorrect,and that Frank's comment about the heat causing the copper in the firebox to change state and become elastic is correct.Mind you,that is apart from wastage causing the boiler plates to become so thin as to be incapable of holding the pressure.The other biggest factor was, in early days,boiler plates could not be manufactured in large sizes.Boilers were therfore made of a number of plates riveted together,and could not be made perfectly circular.The stresses in the heating and cooling of the boilers work hardened the plates around the rivets,causing cracking, and hence failure.Of course metalurgy was in its infancy,and as it became better understood,as well as the problems with scale and not removing same ,boiler explosions became a rarity.

Phil

[chris vine]

Hi Phil,

If that is the book I have then there are some spectacular pictures in it. The best is of a locomotive with no shell on the boiler and the tubes all splayed out and in some cases wrapped round the front of the smokebox. No one was hurt in that explosion.

Chris.

[martyn]

I have found the report from Australia most interesting in spite of it being directed at gauge 1 and such like. It would be interesting to see a copy of the Australian copper boiler regs, as
I understand they have a section apertaining to boiler design and construction, which as far as I am aware we don't. Yes I know there are calculations out there we use, but who's do you use, Martin Evans, Keith Wilson, Jim Ewins etc etc, they all give slightly different results. To my mind although the Southern Fed and the Northern Fed have tightened up on testing etc we have no standard guidlines for design and construction. Before any one replys, no I am not one of the, "this is the end of the world as far making boiler goes brigade" as I am having a go myself at a medium sized 7 1/4" boiler. I agree over the last 100 years or so Model Engineers have a pretty good track record as far as boiler safety goes.

[Phil Sutton]

Hi Chris,If its the one with the NER 060 on the front,thats it.

Phil

[chris vine]

That's it! No 510 from the NER. Anyone who doubts the energy in a boiler full of steam and water will doubt no more if they see this picture.

You might get in trouble if you were to scan it and put it on the site but the book is called Locomotive Boiler Explosions by C H Hewison. Well worth a read.

I see there is a copy on www.nene-valleyrailwaybooks.co.uk

Chris.

[gwrfan]

Chris,

Your link is not working, sorry. Try here:

www.nenevalley-railwaybooks.co.uk/

And type in C H Hewison in the search box.

Geoff