# Boiler Safety



## rake60 (Jun 17, 2008)

I've seen several threads about building boilers.
I've never built a boiler myself because I do not have enough knowledge 
on the subject to be positive I could do it safely.
I'm certainly not qualified to discuss boiler design safety.

I do know what runaway steam pressure can do.

*This for instance.*





A few minutes before then, that was a locomotive engine.

Water is a pretty benign compound.
It boils at 212F, 100C at sea level and turns to steam.
When water turns to steam it's volume increases by a factor of *1600*.

If you have a small model boiler that holds 1/4 cup (4 ounces) of water, and
it gets far to hot too quickly, that 1/4 cup becomes *50 gallons* by volume.
If your pressure vessel isn't properly vented something is going to break.
The first thing will obviously be the pressure vessel. 
It's the things that it takes with it that concern me.

A _little_ knowledge can be a *big* hazard.
Let's be careful out there!!!

Rick


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## Mcgyver (Jun 17, 2008)

good advice Rick, you don't want to mess with boilers. Unless you are very comfortable with the engineering, build to published designs.

In fact its not the pressure that you need to be afraid of, its the drop in pressure - that's what causes the explosion.

At say 100 psi, the water is liquid at 328F, which of course it can only be because of the pressure. If you drop this pressure quickly by lets say a rupture in the boiler, you have 328F water at say atmospheric pressure, in other words you have a bomb. It was only the pressure that kept the water liquid, at atmosphere, that liquid needs to instantly flash to steam - explosion results. A lot Newbs don't appreciate this and erroneously assume a boiler letting go is about the same as an air compressor - WRONG! There is many times more energy stored in the boiler.

The boiler safety release valves keep the pressure well under the engineered level where a rupture can occur....but there are still other ways to blow oneself up! Drawing off steam too quickly with too large a pipe can pressure to drop too quickly and an explosion results.....I've been told that valves on large boilers must be opened slowly to avoid this.....or letting the water level get to low, the crown sheet gets exposed and overheats, silver solder melts and there's a big pressure drop.


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## rangerssteamtoys (Jun 17, 2008)

So if one was building a steam buggy, you would NOT want to hit the throttle super fast. Boilers are dangerous, but with saftey precaustions everything can be less dangerous. But with a stupid operator................Well. thats when things go wrong.


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## itowbig (Jun 17, 2008)

WOW!!!


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## rake60 (Jun 17, 2008)

Ranger no one is tryinf to DO anything other then point out the dangers of a 
boiler.

The fireman responsible for the boiler on that exploded loco engine was an
an experienced man.
A sudden change in the rail bed grade caused the water level in the boiler to
shift exposing the metal to an unprotected heat spike.
By the time he would have known something was wrong he was too dead to
talk about it.

It's that REAL!

Rick


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## chuck foster (Jun 17, 2008)

ranger
      i'm not trying to side with anyone or pick a fight with you but i think the last to posts were meant to give you some in site as to what MAY happen. 
we all want you to have fun and be successful with you engine,boiler and buggy. we all want you to live to tell us all about your adventure with steam.
hell i'm envious of such a young guy doing what you are doing, when i was your age i new what a steam engine was but had no idea how it worked and certainly couldn't built one!
you know how an engine works (you proved that) you are well on your way to having a boiler and as far as the buggy part............i'm very certain it is just a matter of you building it.
at you age the sky is the limit, so i for one just want to make sure you are safe and live to be old.

if i'm out of line with this post or too blunt, i apologize and please remove it.

chuck


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## Cedge (Jun 17, 2008)

Chuck
Remove it my great aunt Fannie.... You've just eloquently expressed the thoughts of many of us. Ranger's freedom to explore his imagination is a thing to be envied. In just a few posts, he's managed to assert his bona fides and to scare the crap out of a number of us, but few of us would hesitate very much before trading places with him...LOL He's quickly becoming worthy of the honored title of "House Mouse" on this board.

Steve


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## tmuir (Jun 17, 2008)

Wow that loco photo. 

I remember a few years ago going to the 'Beamish Museum' in England and they had a portable engine that had suffered a boiler expolsion there. The metal was a good half inch thick and had been peeled back like an orange.
Wish I had taken a photo of it. It's scary to think about the power inside a large boiler.


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## ksouers (Jun 17, 2008)

What Chuck said!

Double!


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## Mcgyver (Jun 17, 2008)

> Mcgyver, I know what your doing.



??? then that makes one of us - enlighten me


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## 1Kenny (Jun 17, 2008)

A quick Google search of _steam boiler operation _ gave me quite an in site.
http://www.doli.state.mn.us/pdf/guide2saferboiler.pdf

http://www.licensedelectrician.com/Store/AT/Boiler_Oper_Wbk.htm

It seems like it takes around 2000 hours of training to be able to take the test get a license and run a boiler system in a trust worthy manner.

When I taught aviation maintenance it was a 1950 hour course to qualify to test for the license. We would tell our students after testing they were now qualified to learn.

Kenny


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## PTsideshow (Jun 18, 2008)

Here is the investigation results for the Medina Ohio traction engine boiler failure from a couple of years ago,with pictures. 
http://www.doli.state.mn.us/boilerohio.html
and here is the state of Michigan's boiler licensing info for all types of boilers model small or full size.
http://www.legislature.mi.gov/(S(tpo0ip55foguqs55iqchdt55))/mileg.aspx?page=getobject&objectname=mcl-act-290-of-1965&queryid=39491&highlight=
Called the boiler act of 1965. the sections are broken down into type etc.
glen


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## Alphawolf45 (Jun 18, 2008)

Mcgyver  said:
			
		

> .
> 
> Lets not pass quickly by this point..What about the pressure relief valves- if they let go as they supposed to do, does letting off the extra pressure exacerbate the situation?
> .


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## PTsideshow (Jun 18, 2008)

Alphawolf45 said:
			
		

> Lets not pass quickly by this point..What about the pressure relief valves- if they let go as they supposed to do, does letting off the extra pressure exacerbate the situation?



When the safety valves operate as they should whether there is one or more they reduce the pressure at a controlled rate. Makes no difference if a model or full size. Most of the older toy and plans for model boiler safety valves are spiring loaded and also acted as as the fill valve for the boiler. So they would be assured of opening upward. Since they would have to be pulled up against the spring inside the boiler to fill. Unless they were of the knurled threaded type that could be removed for filling and could be visually checked.
The pull up style would leak a little, if they received heavy use for filling. As the springs were compressed.


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## Mcgyver (Jun 18, 2008)

Alpha, the relief valves set an upper limit on pressure and that protects the structure of the boiler from undergoing more force than it was engineered to handle. The water, heated continuously will continue to rise in temp which correspondingly increases pressure. Safety relief valves create a pressure ceiling, but i sense you know all that.

To your question, the safety relief valve would only exacerbate the situation if it was so large in diameter that it dropped the pressure too rapidly. So don't build a 1" dia relief value . As to what rates and sizes for given boiler lead to instability, not something Id know offhand, but every safety relief valve Ive seen is quite small compared to the steam lines so i hardly think it an issue.

For the poor victim of an explosion, that its not the rupture of the vessel itself that causes the explosion but the resulting sudden drop in pressure likely would seem painfully academic. However in trying to understand where the danger lies and in preventing a boiler explosion it is important to properly understand this

Here's another way of coming to understanding it. Situation 1, hydrostatically testing a boiler to 150 lbs and the end lets go. What happens? nothing other than a bit of mopping up and sheepish looks from the builder. Situation 2, same boiler, same pressure, same failure but this time the pressure is create by the water being heated instead of a hand pump. the end lets go there's a major explosion - all the water (which is at 365F) is brought to atmospheric almost at once and as water doesn't want to be a liquid at 365, flashes into steam.

Point is, that as shown in situation one, the hydrostatic test, the boiler being under too much pressure and lets go is in itself fairly benign - the boiler 'exploded' under pressure but there's not a lot of energy in what was in the boiler. In situation 2, when that energy is stored as water heated over 212, there can be a lot of stored energy that wants to express its self by suddenly occupying a very large volume, kind of the definition of a bomb.

Ranger, still wondering what were talking about with the crack-off about knowing what Im doing, are you peaking in my windows or something? seriously, wtf were you talking about?


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## SandyC (Jun 18, 2008)

Hi Guys,

Lets get this a bit more in context....... Water reaches boiling point at 212deg F...however, it does not turn to steam...... this requires the input of additional heat energy to change it from one state to the other, however...there would be no increase in temperature during this process.
This is known as 'the specific enthalpy of evaporation' and for water at 0psi.. this is 970Btu/lb.

1lb of water at 4deg F would occupy 27.7cu ins of space... the same 1lb of water, when turned to steam @ 0psi would occupy 26.8 cu ft (46,324 cu in) and it's temperature would be 212deg F.

It is only when restricted from free expansion, that steam can increase in pressure. 

It is not a pressure drop that creates an explosion.... it is the sudden, 'UNCONTROLLED', release of the contained energy, via E.G a failed stay, or a corrosion hole in the shell.

Any release of this energy will result in a pressure drop, if the rate of release is greater than the rate of evaporation.

In the first case posted by ptslideshow... 'The michigan traction engine boiler'...... the problem was caused by poor maintenance/inspection procedure...... when the first stay gave way, at the very much weakened plate juncture, the load was immediately transfered to the remaining stays, thus increasing their load.... which then gave way one after the other, resulting in a massive, and almost sudden release of the boilers stored energy..... the pressure drop to zero was a direct result of this action..... it was not the pressure drop which caused the explosion.

Safety valves are designed to give a controlled release of unwanted pressure and their throughput/capacity is carefully calculated to do this....... when they do open, it is usually a sudden action (pop action) and they open into what is probably the biggest dia pipe you can get...I.E the atmosphere.... so pipe dia has very little to do with it..... if this were not the case, and things happened as has been suggested... then the sudden opening of a safety valve would instigate an explosion...... NOT SO.

The same applies to boiler steam valves.....they are controlled release devices and if correctly matched to the service they are connected to will operate safely.

The reason boiler valves are generally opened slowly is to eliminate/minimise thermal shock, not only on the valve, but also on the pipework leading from the valve to the receiving service device.
There were many maritime cases of CAST IRON steam deck valves (such as would be used for deck winches), especially in cold climates, being opened to quickly with the result that the valve, or the pipework leading from it, cracked, due to thermal shock, and subsequently broke off, which then allowed a huge amount of steam to escape uncontrollably...resulting in a nasty accident....... certainly the pressure in the ships boilers dropped pretty quickly, however, the boilers did not explode.

A few years back it was necessary to change all UK boiler and deck service valves from cast iron types to cast steel types, since these have a higher shock load strength and are deemed less prone to failure.

So...yes steam can be dangerous, if not used with proper caution.... But so can driving your car.

Treat it with respect, learn about it's peculiarities and you should have little to worry about.
Above all, if you are not comfortable designing a boiler yourself, then build from a published design. 

Best regards.

SandyC &#160;  ;D ;D


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## te_gui (Jun 18, 2008)

Can someone let me know how to post pictures. I wanted to tag a couple on here and can't figure out how to upload them. I'm certainly no boiler expert but have been involved in rebuilding a couple full sized ones. I also ran the calcs and presented my findings to my state boiler board on a non ASME code boiler in order to receive a certificate to operate it.

While we are on the subject of devices to drop pressure quickly, let's not overlook whistles. They can be real steam hogs and some overzealous folks like to blow the hell out of them. It makes me cringe at some of our local steam shows when I see a big mill whistle up on the dome of a traction engine, usually with several reduceres to get it down to the engine plumbing. Between the volume of steam and the large unsupported mass hanging off the small pipe, Yikes.

Brian


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## PTsideshow (Jun 18, 2008)

te_gui  said:
			
		

> Can someone let me know how to post pictures. I wanted to tag a couple on here and can't figure out how to upload them.
> Brian


For some reason on this thread The attachment window below this message window doesn't show. With the additional options a plus or minus.
I'm having the same problem when I went to add pictures of the two safety valves in my other post. For me at least it seems to work in other threads!


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## Mcgyver (Jun 18, 2008)

SandyC  said:
			
		

> It is not a pressure drop that creates an explosion.... it is the sudden, 'UNCONTROLLED', release of the contained energy, via E.G a failed stay, or a corrosion hole in the shell.



and



			
				SandyC  said:
			
		

> .... which then gave way one after the other, reulting in a massive, and almost sudden release of the boilers stored energy..... the pressure drop to zero was a direct result of this action..... it was not the pressure drop which caused the explosion.



Sandy, i think we're basically saying the same thing, but it sounds like disagreeing on the chicken and egg. With the greatest respect to you, _It is_ the sudden pressure drop that causes the instability and hence the uncontrolled release of energy - I perhaps should have been more specific in saying the SUDDEN pressure drop. At least everything Ive ever read or been able to find on the engineering of what's going on says so. The two are of course dependent, but it doesn't matter how the sudden pressure drop occurs.  Put some ridiculously oversized valve on the boiler and you can create the same explosion by cracking it open. I agree with you open valves slowly is to prevent thermal shock, as well as gently clearing out any condensate in the line but it is also to prevent sudden pressure drops.....granted in a balanced design the later might not be paramount but its not just in my imagination ;D




> when they do open, it is usually a sudden action (pop action) and they open into what is probably the biggest dia pipe you can get...I.E the atmosphere



do they? I think they open up a small dia passage that creates a restriction to how suddenly the pressure is dropped


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## doubleboost (Jun 18, 2008)

Hi 
I am in total agreement with the safety issues brought up hear.
I am busy with a large vertical steel boiler for my marine engine at the minute
The exploded boiler at Beamish Museum is just that ,the army put a charge in to a worn out boiler to simulate a boiler explosion ,next time i go i will photograph it for you and post it hear




boiler shell 8 inch diameter 20 inches high 




Tube plates 10 mm thick 19 1 inch tubes 
The boiler will be tig welded together hydraulic ed to 250 psi the working pressure will be 100 psi it will be fitted with 2 safety valves of good size
Regards
John


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## rake60 (Jun 18, 2008)

The *MAIN* point is a boiler is a pressure producing unit.

Pressure wants to be find a release point and it *WILL!*
If that weakest point happens to be someting other than the outlet or
the safety relief valve, you have a grenade in front of you.

That is also a very useful tool in it's place, but *NOT* one you want in
a hobby environment.

Rick


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## Hilmar (Jun 18, 2008)

> 1lb of water at 4deg F would occupy 27.7cu ins of space... the same 1lb of water, when turned to steam @ 0psi would occupy 26.8 cu ft (46,324 cu in) and it's temperature would be 212deg F.



Hi Sandy are you sure about the 4° F ? or is it 4° C


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## PTsideshow (Jun 18, 2008)

here is one style of the Jensen external spring/fill plug safety valve





here is the safety valve with the spring compressed so it was in the open or relief position 




here is the PM research internal safety valve taken apart. there are three holes in the top of the cap for the steam to come out when the valve is open. this valve has a spring pressure of 60 to 80 pounds.




No o-rings,or other type packing that can melt or impede the operation of the relief valve.


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## Cedge (Jun 19, 2008)

You guys seem to be getting trapped in a terminology vortex. To a point, both of you are right. The controlled release of the steam at any pressure or temp is not likely to create any problems at all. . ie ... whistles, throttles, blow downs or even a safety plug drop. Where the argued problem rears its fatal head is when there is an instantaneous event where the super heated liquid is suddenly exposed to normal atmospheric conditions such as through a catastrophic vessel failure. Once this type of event occurs, the damage to the pressure vessel is rapidly progressive as additional components can't withstand the added stress. The fluid state which has been maintained due to the high atmospheric pressure within the vessel is suddenly unleashed, "accompanied" by an extreme drop in pressure which results in a super expansion of the now highly unstable fluid. The flash to steam results in the stored energy seeking equilibrium in a normal atmospheric pressure environment. Results.... Big boom with a huge speedily expanding cloud of very angry searing hot water vapor that happens to be hiding rather large chucks of high velocity metal. 

You'd see a similar effect if a decompression chamber failed, as the very air inside sought equilibrium through rapid expansion. The results would be exhibited as intense heat. One of the most unsightly deaths I've seen was from a truck tire failure, while it was being mounted back on the truck. The man was never struck by the tire at all, but the super heated air generated during the sudden loss of "containment" burned his flesh and seared his lungs beyond function. He was a dead man before the rest of us even heard the explosion. 

Boiler size is not much protection either, as even a mistreated toy boiler can become a grenade, in a worst case scenario. 

Steve


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## SandyC (Jun 19, 2008)

Hi Guys,

You are quite correct here Steve it is a terminology thing&#8230;&#8230; and Yes Mcgyver we are indeed talking about the same thing in our own, NOT SO CORRECT WAY.

Notwithstanding this, I feel it is important, for the newbies who may be reading this, to get the actual cause correct.

As Steve has pointed out&#8230;&#160; &#8220;Where the argued problem rears its fatal head is when there is an instantaneous event where the super heated liquid is suddenly exposed to normal atmospheric conditions such as through a catastrophic vessel failure&#8221;

Not so much an argument, but rather a poor explanation by both Myself, and Mcgyver of what actually occurs.
so lets take another quick look at the thing: -

Since PRESSURE is a MEASURE of energy density expressed as: -

P = force/area which, when related to fluids (and yes, steam is actually classified as a fluid, not a gas),&#160; can also be expressed as P = energy/volume (Bernoulli equation).

It follows then that you cannot have a sudden change in PRESSURE, since this is determined by the other two parameters.

By definition, it cannot, therefore, be a SUDDEN DROP IN PRESSURE that instigates the problem&#8230;. a change I one of the other two parameters MUST occur first.

In the case of a boiler rupture the sequence will be as follows: -

Boiler shell fractures (cause irrelevant) which initially connects two separate VOLUMES together (in other words we have a change in the VOLUME parameter.

If the added volume is at a different PRESSURE (in this case a lower one (atmospheric))

We now have a situation where there is a PRESSURE DIFFERENTIAL, and also, by definition, an ENERGY DIFFERENTIAL, between the two connected (via the fracture) volumes&#8230;. 
What follows is the rapid shift of the ENERGY content, in order to eliminate/equalise the ENERGY DIFFERENTIAL&#8230;&#8230; the high energy content within the boiler volume will move towards the lower energy content of the connected, increased,&#160;volume.

As a result of this exchange/movement of ENERGY the resulting FINAL PRESSURE as a whole will drop and is in fact the LAST thing to stabilise.

(if the added volume pressure was higher (meaning there was higher energy within it), then the ENERGY exchange would occur in the opposite direction, and the resulting final pressure within the boiler would rise)

That is not to say that this happens slowly, in fact it happens extremely quickly, however, the sequence of events does not change&#8230;&#8230; just don&#8217;t be anywhere near the thing when it happens.

So you see guys, we all are wrong, yet right at the same time&#8230;. It is a complex subject, and one where terminology can often become miss-used; I for one hold my hand up to that one.

Ok chaps, lets put this to bed now, Else we will get told off for arguing by the MOD&#8217;s    ; 8) ??? ???
'Spoilsports.....Can't have any fun these days' ;D ;D ;D ;D ;D

 Best regards.

SandyC.


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## raym 11 (Jun 19, 2008)

One bit of fun before bedtime;

Popped corn is a result of a steam explosion.
I wonder what the average pressure is at rupture?

Ray M


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## SandyC (Jun 19, 2008)

Hilmar  said:
			
		

> Hi Sandy are you sure about the 4° F ? or is it 4° C



Hi Hilmar,

OOPS.....You are quite correct..... that should have read 4deg C (39.2deg F)..... my mistake when typing.

SandyC


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## Mcgyver (Jun 19, 2008)

Oh jeez, this may be long ;D



> Ok chaps, lets put this to bed now, Else we will get told off for arguing by the MODs


If you dont want to debate further, peace, to me its a debate not arguing, but dont hold off for the wrong reasonsimo, so long as no one is using foul language or being mean spirited/malicious, these discussions should carry on. If for some reader it becomes too esoteric, they can walk on by. 

They should go on because they bring about learning. Its not about having to be right, I can and do admit when Im wrong  but in having to debate a point forces a more complete understanding and often enlightenment when you learned something new or even the flaws in your existing thinking. Imo its a cop-out to the second there are differing views on something quickly proclaim theres more than one way to do something and stop the discussion.provided everyone is being polite that just creates mush not learning and is not as interesting/engaging. 

So in the friendly spirit of lively discussion..



> As Steve has pointed out Where the argued problem rears its fatal head is when there is an instantaneous event where the super heated liquid is suddenly exposed to normal atmospheric conditions such as through a catastrophic vessel failure



Steve phrased this very well but missed a crucial point  its not that the superheated water is exposed to atmosphere, its that its exposed to a lower pressure.there would just as readily be an explosion if the pressure suddenly dropped from say 100 psi to 1 psi or 10psi etc over atmosphere  while the water is still at an elevated, superheated temp. Where he did nail it is that it is the fact that the water is now super heated the causes the trouble. 



> (and yes, steam is actually classified as a fluid, not a gas),



All liquids and gasses are fluids. 



> Since PRESSURE is a MEASURE of energy density expressed as: - P = force/area which, when related to fluids can also be expressed as P = energy/volume (Bernoulli equation).



I understand P=F/A but can you walk me through how you go from Bernoullis equation to P=E/V?? Bernoullis equations deal with flow, right? I can see that for compressed air where the added potential energy all shows up as pressure, but this equation P=E/V? for a boiler? Rearranged thats E=P*V. Thats saying then that a 100psi 1 gallon boiler with .7 gallons of water at room temp has the same energy as a 100psi 1 gallon boiler with .7 gallons of water at 328F which is obviously false.

The potential energy of water/steam is function of its temp and mass not volume iirc its same energy whether its held within a boiler or as steam occupying 1600xs the area (the explosion comes from the rapid transition from one to the other).



> It follows then that you cannot have a sudden change in PRESSURE, since this is determined by the other two parameters.



But you can  the explosion is the violent attempt of the super heated water to again reach equilibrium with the sudden drop in pressure  the equation balances because of the increase in volume.



> By definition, it cannot, therefore, be a SUDDEN DROP IN PRESSURE that instigates the problem. a change I one of the other two parameters MUST occur first.



I guess were just contradicting ourselves on this point  It is the sudden drop in pressure that instigates the problem, however the pressure drop is achieved. I dont want you to actually try this, but if you build a model engine sized boiler and put a large dia quick throw valve on it, opening up that valve would bring about an explosion just as a rupture would. Nothing magical about the rupture or going to atmosphere, the cause is the sudden drop in pressure that forces the water flash to steam to maintain equilibrium. To much water flashing to steam to quickly is what a boiler explosion is 

Anyway, Im just repeating myself on that point, heres some additional info, an excerpt from Johnson Controls intro to boilers (it was a google book, this was the only way I knew to capture it)

http://i20.photobucket.com/albums/b201/michael0100/causeofboilerexposion.jpg

heres another detail piece from the National Board of Boiler and Pressure Vessel Inspectors. It goes through the sequence of events and clearly says it is the sudden drop in pressure that instigates events.

http://www.hsengco.com/nbexplosion/nbx.htm



> Boiler shell fractures (cause irrelevant) which initially connects two separate VOLUMES together (in other words we have a change in the VOLUME parameter.
> 
> If the added volume is at a different PRESSURE (in this case a lower one (atmospheric))
> 
> ...



What you have described well is what happens when an air compressor lets go. There is potential energy and the theres a rush to equalize the pressure differential. In a boiler, the resulting explosion is many magnitudes larger than say an air compressor because of the of enthalpy  the massive amount of energy in the super heated water. 

The rush of the tiny bit of steam and big bit of water in a boiler to equalize pressure isnt a big deal, think about what happens when a model boiler lets go under hydrostatic testing  almost nothing, yet that scenario would perfectly fit your description of the rush to equalize pressure. Its not equalizing pressures that is a boiler explosion its the super heated water and all of a sudden, because of the lower pressure, needing to occupy 1600x the volume.



> (if the added volume pressure was higher (meaning there was higher energy within it), then the ENERGY exchange would occur in the opposite direction, and the resulting final pressure within the boiler would rise) .



I think again what you are saying is accurate for pressure vessel like a compressor where only have the idea gas law to deal with. Energy in a boiler is temp * mass, sum of the enthalpies, or basically how much stuff is there at what temperature. 

thanks for challenging my thinking on this  I enjoy the lively debate


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## rake60 (Jun 19, 2008)

Mcgyver  said:
			
		

> thanks for challenging my thinking on this  I enjoy the lively debate



And a very valuable debate it is!

There has been more information brought to light in this thread than I had even 
hoped for. I'm very pleased to see it!

Rick


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## tmuir (Jun 22, 2008)

A little video that was brought to my attention a little while ago showing what can happen even with small 'toy' or 'model' boilers that is fired with the incorrect heat source and has either a non functioning SV or one set too high.

Watch it to the end.
[youtube=425,350]<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/0R348vGkjyw&hl=en"></param><embed src="http://www.youtube.com/v/0R348vGkjyw&hl=en" type="application/x-shockwave-flash" width="425" height="344"></embed></object>[/youtube]


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## 1Kenny (Jun 22, 2008)

Thank you,Tmuir :bow:

A very good point is made. Everyone should watch this.

Kenny


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## Bogstandard (Jun 22, 2008)

Very good video T. Imagine what would have happened with something a little larger.
A good case of not taking safety seriously.

I think on this one, everyone there needed a pants change.

John


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## Divided He ad (Jun 22, 2008)

*HOLY [email protected]%* That was just damn scary.... People should just not play with things that they know nothing of!

Did you hear.... 'We've tweaked the pressure release valve' ... 'the valve of death as it is also known' They really do/did have no idea what they were doing!!!!!!

I'd be amazed if no one got injured.


This should be shown to every newbie from day one.



Ralph.


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## PTsideshow (Jun 22, 2008)

From the abrupt ending one or more got a least scalded or hit with the boiler when the end closet to the torch came off or let loose and the rest took off like a rocket. 
Looked like a school, or community hall of some kind. I hope no one was injured. 
The draino bombs are currently making the rounds in the area with graduation. Somebody will get hurt or screw their life when they take out a mail box. And video tape it, a couple of geniuses did that last year and made sure their faces were nice and clear for the close ups.
As has been said time and time again. A little knowledge, is a dangerous thing.


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## raym 11 (Jun 22, 2008)

On another thread ...I said (Don't forget the most important things.... Hydrostat finished boiler....calculate the proper size and pressure of the PRV (Pressure Relief Valve).

There were no replys or comments. Hopefully it was read and understood.
Ray M


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## LCT (Jul 23, 2008)

Mcgyver  said:
			
		

> good advice Rick, you don't want to mess with boilers. Unless you are very comfortable with the engineering, build to published designs.
> 
> In fact its not the pressure that you need to be afraid of, its the drop in pressure - that's what causes the explosion.
> 
> ...



Thank you for this!
I assumed boiler explosions were from over pressure (too much heat, too little steam drawn off). I was gonna fix that with a simple pop off. Now I see that may not be enough. You may have kept my children off welfare.


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## kvom (Jul 23, 2008)

WRT to the question about popcorn, I found the following via Google:

"Before you start cooking popcorn, the pressure inside and outside the kernel is the same. 

As the kernel heats, the moisture turns to steam, and the internal pressure of the kernel rises. When the temperature inside the kernel climbs above 100 degrees C., you might expect that all the water would turn to steam.In fact, only a small amount vaporizes, because the tough pericarp acts like a pressure cooker. 

The high-pressure steam penetrates the starch granules and transforms them into hot, gelatinized globules. 

Finally at about 175 degrees C., *when the pressure inside the kernel is about 9 atm*, the pericarp explodes. "

So popcorn pressure is ~130 psi.


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## Mcgyver (Jul 23, 2008)

LCT, its a fine point which some might consider academic - as the most common reason for a sudden drop in pressure is a rupture brought about by high pressure or other mechanical fault many take the rupture and the explosion one.....and the safety valve is a line of defence against this happening so for sure you want one (or two). I don't think its academic because if get it, you understand why they are dangerous and how dangerous they are, the sudden release of all the latent heat blah blah blah. If I've kept your kids off welfare its a good days work (tongue planted in cheek) but please read read read before building a boiler. irrc the standard is a 8x safety factor and everything has to be engineered, thickness, construction method (rolled, tube, riveted etc) stays etc plus right material for fittings, pressure relief valves, site glass etc


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## raym 11 (Jul 23, 2008)

kvom;
thanks for digging into the popcorn 8) ;D
Ray M


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## Bernd (Jul 23, 2008)

Dose anybody here remember the traction engine explosion that happened in Ohio a couple of years ago?

I believe a write up was in Live Steam giving the cause of the explosion. There were several factors. I don't recall all of them. After reading this thread I've only come across the fact that a rupture can cause an explosion. From what I remember of that write up there are several factors that need to happen for such a fracture to occur. One is corrosion of the stays over the fire box. Another is water below the crown sheet. When the water sloshes around in the boiler and hits the hot crown sheet, instant steam and a sudden rise in pressure. These I believe were only a couple of the things that caused the explosion.

I'll try and find a link to that if I can.

Bernd


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## Bernd (Jul 23, 2008)

Found the link to that boiler explosion. It happened in Medina, Ohio on July 29, 2001. Here's the link to the report. http://www.doli.state.mn.us/boilerohio.html

Bernd


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## bretk (Jul 23, 2008)

I knew the guys through mutual friends. Terrible incident, but that's what happens when you let a crown sheet that is corroded to less than 1/8" thickaround the stays go dry over a fire and 100+ psi of steam. Also when you are using old safety plugs in your crownsheet that have so much scale over the lead that it doesn't melt out. I have been silent on all the boiler threads up to now but here goes my 2 cents. I have worked with a large group of livesteamers that have built their own boilers for their engines www.lakeshorelivesteamers.com their experience rances from ex steam locomotive engineers and certified asme welders to hobby folks. They have a very good boiler test procedure and certification process set by the club, as do many of the live steam clubs around the country, and have been operating safely and successfully for years. Yes the boilers are something to be respected, yes their care and maintinance are crucial, but they aren't ticking time bombs. and I would feel safe firing any of the clubmembers engines. most are steel shells with rolled in copper tubes, and if a leak occurs, we do as the prototypes do, plug the tube until the next teardown. the leaks arent explosive by any means. and as far as too large a safety or valve, at the end of the day, when you aretrying to blow the mud out of the mudring, you open the biggest valve you have on the boiler (can be up to 3/4" on a 6" dia boiler. to blow the crud out of the boiler. and the boiler doesn't explode. the boiler has been holding that energy in check all along, so there is no reason that it won't hold it as it is venting, as long as itis not from a tearing seam like the Case 110 in Medina.

-Bret


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## raym 11 (Jul 23, 2008)

yup,
 In my other life the main plant ran 3 or 4 horizontal Cleaver Brooks horizontal fire tube boilers of sizes 100 to 250 horse power. The crown valves were 2 to 4 inches. We had a maintenance program of blowing the mud out of the drum on a weekly basis.This consisted of opening a '1" to 1 1/4" Quick Open' valve located on the bottom of the shell for 5-10 seconds.Even though they were low pressure boilers(250#), the blow down would definitely get a passerby 's attention. Mucho noisy volume. 

Ray M


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## rake60 (Jul 23, 2008)

Bernd I know of that incident far too well.

It was a friendly, family oriented exposition where people were hurt because
a rusty relief valve malfunctioned.

The WRONG relief valve in a smaller boiler will offer the same results.

Sometimes I feel like I'm talking to a blank computer screen.
I guess in reality I am...

I just don't want to see ANYONE get hurt by a _little knowledge_.

Now I'm PISSING MYSELF OFF again! 

Unless you are properly trained in the physics of a steam boiler
DON'T F*%K with it!!!!

Was that out of line?
Do I care it it was?

If you want to build a bomb I can tell you how to do that with the 
contents of your home kitchen supplies.
Will you survive the aftermath? Probably not.
That's not MY problem, all I did was offer the how to.

And Then............

Rick


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## Bernd (Jul 24, 2008)

Rick,

I'm not advocating building a boiler as a team project. It just seemed to me that a bit more information could be gotten from that info on boiler explosions. 

Didn't mean to piss you off. I understand your stand on this. I don't think your out of line on anything you said.

Would I or will I ever build a boiler? The answer to that right now is yes. I have plans for both the Clishay and a three truck Shay. Will I ever get to to it, well that remains to be seen.

And yes I've built a couple of kitchen type things that go boom. Ever hear of an air-fuel (leaving off the last word here). 

Ok, enough said about this subject. Let's just hope that anybody building a boiler follows the spec's of the plan or buys one ready made by a professional.

Bernd


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## Cedge (Jul 24, 2008)

Brend
I think see a consensus forming, of sorts. I don't think anyone has said building a boiler is a bad thing. BretK's post contained a lot of important keywords. Words like experience, testing procedures, certification, due respect, maintenance, and regular inspection. Granted... The boilers he's talking about are usually larger than the average table top variety, but most of them are just as applicable. No... a boiler is not a ticking bomb, but neither is their stored potential something one should take for granted. 

Building a boiler can be a very rewarding project. I've been around quite a few home built versions with no problems of any kind. As long as one uses proper materials and building techniques are used there shouldn't be any problems with building one's own boiler. The consensus seems to be that getting well educated on the subject is the key to doing so.


I hope boiler discussions will always be a staple on the board. The information we get from experienced builders can only add to the chances that those who do attempt to build one will have a better shot at doing so safely and successfully.

Steve


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## Bernd (Jul 24, 2008)

Cedge  said:
			
		

> Brend
> I think see a consensus forming, of sorts. I don't think anyone has said building a boiler is a bad thing.



You are correct. I also agree with what you are saying.



> BretK's post contained a lot of important keywords. Words like experience, testing procedures, certification, due respect, maintenance, and regular inspection.



Again I agree whole heartily with that. 


From reading the posts on this subject it seemed to me there were two extreme points brought up. I couldn't see were it was explained why a boiler explodes other than poor materials and poor workmanship. I didn't see anybody explain the maintenance needed on a boiler, which wasn't done on the boiler on the Case engine. Even though that engine was build by professionals it exploded due to poor maintenance and basically old age too.

From what I read in the previous posts was that a rupture can cause an explosion. I think Bret explained it best when he described the blow down of a boiler by opening a valve. Usually a blown down is done after the fire is out. Although I have seen it done with the boiler under fire.

I don't think some of members here fully understand the workings of a boiler. Show of hands of those knowing what a crown sheet is, were it's located, and why you keep the water level above the crown sheet. Also how many know that boilers of the locomotive type have what are called soft plugs and know what they do or where they are located. That was one of my reasons for posting the report of that Case explosions. It talked about the how's and whys of a boiler explosion.

Bernd

(edited)

I went back and looked at the video. Two things puzzel me. One, I saw no relief valve open and I didn't see the engine start to turn. I heard something to the effect of opening up a valve to start the engine running, I think. Also I question the solder used to hold the end cap on the boiler. Was it silver soldered or did they use a soft solder. To me that video is a good example of people not knowing anything about boilers getting hurt. It's also a poor example for newbies. Their first thought is that they all will explode and hurt you. They're right, but will they learn why that happend? I doubt it. Problem is you can't fix stupid.


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## Bogstandard (Jul 24, 2008)

Bernd,



> Their first thought is that they all will explode and hurt you.



If you take that attitude you will work safetly.
If you have to think about anything untowards while you are making a boiler, you shouldn't be doing it.

Thoughts like, have I got enough solder on there, is that tube thick enough, is that too much of a gap. All these arising questions show you are not yet up to boiler making. It has to be done correctly or not at all. No lash ups or quick fixes, good workmanship should be the only thing you think about. If you are not up to very good standards, don't even contemplate it.

John


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## bretk (Jul 24, 2008)

RE: blowing down to clear the sediment with a fire in the fire box: It was routinely done at marked locations during regular operations while the train was at speed and with a full firebox of fuel. It is still done today, if you get a chance to take a ride on the Cumbres and Toltec railroad in Chama New Mexico, you will get a chance to see them do it on a 120' tall curving trestle, truly a spectacular sight! Also, if you get a chance to look at some of the 4449 videos (Southern Pacific Daylight 4-8-4 you will usually get a shot of them blowing down over a trestle during their run. 

-Bret


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## Bernd (Jul 24, 2008)

Bogstandard  said:
			
		

> Thoughts like, have I got enough solder on there, is that tube thick enough, is that too much of a gap. All these arising questions show you are not yet up to boiler making. It has to be done correctly or not at all. No lash ups or quick fixes, good workmanship should be the only thing you think about. If you are not up to very good standards, don't even contemplate it.
> John



I agree with you 100 percent on that John. Trouble is though I've seen some soldering jobs were the person doing the job thought he was good and it was a good solder joint. Luckly it wasn't on anything dangerous. 

Bernd


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## steamboatmodel (Sep 11, 2008)

One thing that has not been mentioned, is NEVER ADD WATER TO A BOILER THAT HAS RUN DRY, extinguish the fire and wait untill the boiler is cold. You should then retest Hydrostatically.
Regards,
Gerald


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## BobWarfield (Sep 11, 2008)

Thank you Gerald for providing an actual actionable tip on how to operate a boiler more safely.

I love to learn more about how to do things more safely. The more practical tips I can get, the happier I become!

Cheers,

BW


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## steamer (Sep 11, 2008)

One thing that has not been mentioned, is NEVER ADD WATER TO A BOILER THAT HAS RUN DRY, extinguish the fire and wait until the boiler is cold. You should then retest Hydrostatically..."

Personally, I would pull the fire altogether, but the point is exactly the same.

Not a good situation to be in regardless!

That situation would result from violating the first three rules of operating a boiler.
You will rarely see them written down formally, but everyone abides by them.
You ready, here they are, pay attention, 

1.  Keep WATER in the boiler.

2.  Keep water IN the boiler.

3.  KEEP water in the boiler.

*I am not kidding.*

Additionally, ( and even more seriously) you should have at a MINIMUM two ways to GET water in a boiler. One should be a hand pump. ( I'm talking about the boilers the average ME will run here.)
My boat has three, BIG Hand pump, engine driven feed pump, and injector, all on separate circuits with separate checks and separate stop valves.  
Don't forget plumb a stop valve between the boiler and the check. Checks fail!

Sub section rules for the above three are listed but not limited to the following:

Make sure your gauge glass is clean and it can be blown down and/or isolated, and you know how to blow it down.

Make sure you have trycocks for WHEN the gauge glass breaks ( it will ). know how to use them.

Put a Guard on the gauge glass so when it breaks you are not wearing it in your forehead.
I make no claims to my good looks, but I have grown rather attached to my face and would like it to stay there.

Make sure your lowest gauge cock and the bottom of your glass are suitably above the crown sheet/drum tube connections. How much depends on the boiler design....I can't help you there.

Make sure you have the tools to draw a fire if things go catiwampus on you. If you burn wood or coal, that would be an appropriate shovel. In a boat it's over the side. In other situations, any safe place other than the fire box.

Running a boiler is not a day at the beach. Dress appropriately. Wear jeans and full sleeve shirt and boots with socks, not flip flops.  A fool runs a boiler bare handed. Gauntlet gloves are a must. OK miniature boiler valves may restrict your glove wear...make sure the handles are thermally isolated then. Safety glasses would not be amiss.

ANTICIPATE!  This is important and can be the most stressful and difficult part for an operator to learn. Think about where you want the boiler conditions to be 10 minutes from now. Look at where the pressure is going, not necessarily what the gauge is reading right now ( is it rising or falling and how fast). Firetube boilers react to firing rate much slower than watertube boilers generally. Learn how your boiler behaves. Every one is a little differant.

Think ahead and soon you will be letting it run, instead of making it run......there's a difference and it takes practice and experience to learn it.

Have fun and be safe.

Dave


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## Dhow Nunda wallah (Sep 16, 2008)

Gentle folk of this site, will any of you, outside of Oz, please let me know if your model engineering (etc) societies, require you to pay for information?

I require information, specifically, for a welded carbon steel boiler.
Aforementioned boiler will be:

1:	welded by a coded welder (AS3902, ASME 9, pressure vessels, etc)
2:	pressure tested and certified by a competent (ISO 9002) engineering company
3:	supervised for first steaming by a combustion engineer (ex British Gas, among others)

Does any other country require one to part with credit card details, simply to comply with "model" boiler standards?

The AMBSC (Australian Miniature Boiler Safety Committee) requires coin of the realm, before they will tell me, just how safe my boiler must be.
Not insurance or audit trail, just "standards".

I can understand, and would welcome, recommendations.
I cannot understand witholding information.

Surely, it would make sense to freely publish these standards?

Any other Au modellers care to comment?


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## Maryak (Sep 16, 2008)

I know where your coming from mate but I am curious as to what your engineering company will be certifying without a standard against which to certify.

I have contacted a mate in Sydney as I am in the same boat as you. If I have any joy will let you know. ???


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## steamboatmodel (Sep 16, 2008)

"The AMBSC (Australian Miniature Boiler Safety Committee) requires coin of the realm, before they will tell me, just how safe my boiler must be.
Not insurance or audit trail, just "standards".

Is this Committee a Government agency?
Regards,
Gerald.
PS In Ontario, Canada the regulations are on the web
http://www.tssa.org/regulated/boilers/boilersSafety.asp?loc3=act


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## Dhow Nunda wallah (Sep 16, 2008)

Maryak, you understand the quandary.

Steamboat, no, AMBSC is a private organization.
Largely organized around model steam locos, as far as I can tell?

And, for what it's worth, my plan is for a "steamboat".
A harbour tug of 19XX vintage.


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## steamer (Sep 16, 2008)

The ASME code cost ( I bought Section 1) quite a bit.

No it was not given to me even though I am a member...

Dave


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## steamboatmodel (Sep 17, 2008)

If it is a private organisation can you not ignore them and find out what the Government regulations are?
Regards,
Gerald


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## tmuir (Sep 17, 2008)

I could be wrong on this issue but I think this private body is the organisation that writes the standards on model boilers for Australia and it's their standards that are required to meet to get public liabilty insurance etc.


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## ianjkirby (Sep 18, 2008)

Hi all,
 I would like to ask for a bit of latitude here. I am the current chairman of AMBSC, and I would like to state up front that it is most certainly not the case that AMBSC demands money for any of its services.
 In brief, in Australia most model engineering clubs are affiliated with the Australian Association of Live Steamers (AALS). A sub-committee of AALS is the Australian Miniature Boiler Safety Committee (AMBSC). This committee has been operating since 1965, and in 1968 published the first of its small boiler codes. This effort was undertaken when the Australian statutory authorities began to take an interest in us, and checking to see that we complied with full-size code practice. When it was agreed that we could not, the authorities "allowed" us to write our own code, sensibly based on the full size codes, but within the practicalities of model practice. Since then the first code (which was for copper boilers only) has developed from the original 16 page A5 booklet into a fairly thorough A4 book of some 56 pages, and is now in its 7th revision. About 1975, after significant demand from modellers, a steel code was published. This is now in its 4th revision, and is currently being revised. (We need to revise both codes on a roughly 5-year cycle; another story!)
 These codes each have upper limits of volume and pressure, designated by the authorities many years ago, which keeps our boilers in a particular "hazard level" in the big picture. Within that hazard level, we are allowed to be self-regulating, and can use club boiler inspectors to approve designs, inspect during several stages of construction, test and issue certificates periodically after completion. This authority to be self-regulating is granted to us in the legislature, and our codes are referenced in Australian Standards.
 AMBSC sells its codes for about $20 each. This is the only time money is mentioned. There are ongoing costs for the periodic revisions, and of course there are printing costs. I consider the cost to members is very reasonable. They are not in the public domain, and I know of no similar organisation which gives its codes away freely. Perhaps one of our US members will let the group know the cost of the ASME pressure vessel code.
 All hobby boilers registered with AMBSC are completely traceable. The registered number stamped on a boiler (this is in fact done immediately after the hydraulic test is complete, whether the boiler passes or fails the hydro-test) indicates the club where the boiler was approved, inspected and tested, the year of first registration, and the running number in the club's boiler record book. These books are subject to random audit by the executive of AMBSC. Whenever a boiler changes owners, copies of all it's records go to the new owner, and the new club inspector is notified, whence the details are recorded in the club record book of the new club.
 Boilers will not be allowed to operate at an affiliated club without a current boiler certificate.
 All club boiler inspectors are registered with the executive, and we meet annually at the national convention.
 All club inspectors are volunteers, and charge nothing for their services to their members. They are protected by our national insurance scheme which most clubs pay into, and there are specific clauses covering boiler inspectors.
 I have no idea of what our friend is referring to when he makes such allegations, but I have asked him privately to provide me with specific details, and I will investigate the matter.
 I am sorry this is a little long-winded, but I think the organisation (AMBSC) has been a bit unfairly charged. AMBSC does not withhold information, indeed, club boiler inspectors go out of their way to advise and help members build their boilers safely.
 It also needs to be said that a small number of clubs have chosen to remain outside the affiliation umbrella for their own reasons, and that is their choice, but AMBSC has been chartered to operate within AALS.
 It further needs to be said that building a boiler, of any size or material, is not a cheap exercise, but AMBSC does not add to that cost!
 Rather than take up more space/time/??, I will leave it there. If anyone has specific queries, I will be pleased to respond to them.
Regards, Ian Kirby.


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## steamer (Sep 18, 2008)

Thank you Ian for setting it straight.


Regards,

Dave


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## tmuir (Sep 20, 2008)

Thanks Ian for some of the history and the facts.

Tony


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## Steam4ian (Sep 21, 2008)

G'day all.

Read, mark, learn Ian Kirby's post. The AMBSC boiler codes (copper anyway) are a good read and very instructive. If you are building subminature boilers you will need to get the supplementary code as well. 

As Ian K has said, the codes are prepared by volunteers whose only aim is to keep the model engineering hobby below the radar of the industrial inspectors and panicy insurers. You may have to forego a slab of beer or two bottles of sound Ozzie wine but the codes are good value for the read and learning experience.

To the non Ozzies (poor fellows) the codes are still soundly written and would prove very useful.

Professionally I have to read and interpret many codes, most (if not all) are not as helpful as the AMBCS codes.

Off soap box.

Regards,
Ian


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## steamer (Sep 21, 2008)

Thanks Ian,

How does a non-oz builder get a hold of said code? ;D

Can I buy an electronic copy?.....I have heard many good things about it, so I would like the good read.

Dave


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## Steam4ian (Sep 21, 2008)

G'day Dave et al.

I bought my codes through Australian Model Engineer, their web site has a catalogue of good books including the codes.

You could also try Plough Books and Minitech.

All the sites can be found on Google.

Regards,
Ian


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## ianjkirby (Sep 21, 2008)

Hi all,
 As well as the suggestions offered by Steam4ian, the AMBSC codes may be ordered from the AALS treasurer, Ross Walker, at <[email protected]>. From memory they are about $20AUD.
 Please note that the codes are not legally binding outside Australia and New Zealand, and may in fact not comply with local regulations where you live. In all cases, consult your local boiler inspector, whether s/he be a club inspector, or a professional, for guidance before planning any boiler.
Regards, Ian Kirby.

...and Ian, just fyi, our codes are not meant to get below the authorities' and insurers' radar, rather they are approved and endorsed by both, and we are properly delegated to be legally self-regulating. Any change(s) we make to the codes are approved by both before we publish and operate with them. It is a completely open process.


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## 1Kenny (Sep 25, 2008)

The information and resources being posted is wonderful. I can't speak for anyone else, but I am learning a lot. It is great to be able know that people all around the world are serious about boiler safety. I thank each and everyone of you for sharing your knowledge. Please keep it up.

Kenny


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