Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Steam => Topic started by: pipercub1772 on April 28, 2010, 11:52:53 am

Title: boiler testing
Post by: pipercub1772 on April 28, 2010, 11:52:53 am
ok, its 50years since i left school never was much good at maths then !certainly not now ,i have got a 3/1/2 inch horizontal boiler from maccsteam just 2 years old  its capacity is 675ml i have the safety valve set at 30 psi  apart from the important visual and obvious safe operation of the boiler under the current legislation do i need a new test certificate , dont seam to be able to work out this new bar rating thanks guys  allan
Title: Re: boiler testing
Post by: wideawake on April 28, 2010, 12:23:24 pm
Quote from: pipercub1772 on April 28, 2010, 11:52:53 am
ok, its 50years since i left school never was much good at maths then !certainly not now ,i have got a 3/1/2 inch horizontal boiler from maccsteam just 2 years old  its capacity is 675ml i have the safety valve set at 30 psi  apart from the important visual and obvious safe operation of the boiler under the current legislation do i need a new test certificate , dont seam to be able to work out this new bar rating thanks guys  allan

Basically to work out whether you need a test certificate you need a figure in Bar-litres.  that is to say the safety valve blow off pressure times the capacity of the boiler.   1 Bar is approximately 15 pounds per square inch so your safety is set at roughly 2 Bar.  Multiply that by the boiler capacity of 675ml amd you get 2 x 675/1000 = 1.35 Bar-litres (Say 1.5 Bar-litres)

The legal "small boiler limit" is 3 Bar-litres so if all the above is true then you're OK.

Two cautionary thoughts.  First I may not be right in assuming that the presure figure used is the sfaety valve blow off, not the boiler test pressure and second some clubs and insurance companies are still insisting on boiler teast certificates even though they're not a legal reqyuirenment for these small boilers.


At least a couple of other people have far more knowledge of this topic than I do so expect further comment!

HTH

Guy
Title: Re: boiler testing
Post by: SteamboatPhil on April 28, 2010, 02:03:54 pm
Guy is correct, some clubs do require a test cirtificate regardless of the bar litre chart, and the MPBA do require a cirtificate as we have not adopted the bar / litre chart.
Hope this helps, shout if you need more info   :-))
Title: Re: boiler testing
Post by: Bunkerbarge on April 29, 2010, 08:50:48 am
Just to add a bit to what has already been correctly quoted.

There are two sets of regulations out there, the first set are according to the The Examination and Testing of Miniature Steam Boilers (Revised Edition 2008), better known as the "Blue Book"

distributed by:

Midlands Federation of model Engineering Societies

Northern Association of Model Engineers

The 7 ¼” Gauge Society Ltd.

Southern Federation of Model Engineering Societies

and the second set of rules are the rules as laid down by the Model Power Boat Association (MPBA).

The first set of rules do not require pressure tests for manufactured boilers below the three bar-litre limit but do recommend annual steam tests and the second set of rules does require pressure tests of all boilers.  To ensure you can run your model everywhere you would need a current (Dated) numbered pressure test certificate but if you were only going to run it at a club that used the “Blue Book” you would only need a steam test certificate.

As for the 3 bar-litre rule your 3 ½ inch Macsteam boiler has a working pressure (design pressure, not safety valve lift pressure) of 4 bar and a capacity of 750ml so that puts it slap bang on 3 bar-litres.  If you want to avoid the pressure test requirements I would ensure that the capacity is measured as 740 ml. %)

Assuming the “Blue Book” is being used the safety valve can be set at any pressure below 4 bar but during the steam test the pressure must not rise above 10% of the working pressure with the flame on full and the safety valve fully lifted.

The pressure gauge must also be checked against a calibrated and certificated test gauge.
Title: Re: boiler testing
Post by: Circlip on April 29, 2010, 11:40:23 am
Allan (Pipercub1772), If you have a current bit of paper certified to twice the pressure you're working at for the boiler (yes, I know the 1 1/2 times in subsequent) NOBODY can argue perviding the Safety is set correctly. Hmm, why don't you have to have a cert for THAT one??   %%

  Regards  Ian.
Title: Re: boiler testing
Post by: pipercub1772 on April 29, 2010, 12:51:15 pm
thanks for  you're replies i am a lot clearer and take on board all your comments its just great to find so much knowledge in this great forum once again thanks allan
Title: Re: boiler testing
Post by: Bunkerbarge on April 30, 2010, 07:44:08 am
Glad we could help.  It is always worth checking before any steam related event just what rules are being used by the club and hence just what certification is required.  For instance any event being run under the "Blue Book" rules will require a current and numbered steam test certificate however some clubs may well offer the opportunity to complete a steam test on the day.

Failure to have correct certification in place will result in the clubs insurers refusing to cover such a model so you may well find yourself operating entirely at your own risk. Hence be cautious of advice that may suggest that you don't need certification as you could end up either not being allowed to steam your model or operating it without insurance.
Title: Re: boiler testing
Post by: Underpressure on May 01, 2010, 07:06:58 am
I think this is the most factual and concise explanation I have seen regarding current boiler testing.

Thanks everyone, even I understand  :embarrassed:

Neil
Title: Re: boiler testing
Post by: Bunkerbarge on May 01, 2010, 08:10:59 am
I have just attended a boiler testing seminar put on by the Northern Federation, which I found extreemly interesting and informative so I now feel a liitle bit more comfortable with the 'Blue Book' and it's contents.  The biggest problem however remain those steam modellers who have enjoyed a very flexible and easy going regeime in the past which simply cannot continue in this day and age of our litigation hungry society.
Title: Re: boiler testing
Post by: Underpressure on May 01, 2010, 08:38:05 am
It seems to be going full circle, which is no bad thing.

Title: Re: boiler testing
Post by: TAG on May 07, 2010, 12:42:26 pm
Having attended the same seminar as bunkerbarge I fully concur with his comments on boiler testing.
I think our club rules are in need of a bit of updating.
Title: Re: boiler testing
Post by: Canopus on August 13, 2010, 02:18:03 pm
Just as an observation, I have never been asked for a test certificate at any meeting I have been to in the last 5/6 years. In terms of club insurance it may or may not respond if there is no test certificate but have look at your houshold insurance as you are covered for hobbies without restriction (unless you build a boat over a certain size or fly a plane over a certain size) so there may be dual insurance.

I also seem to recall an article which advised that boilers under a certain bar/litre size no no longer need a pressure certificate - EU rules and interestingly that EU rules superceed club or local rules to the extent that its illigal to impose rules in contravention of EU law.

Not trying to stir things up but just curious as this all seems to be a grey area.

Also has anyone ever experienced a steam problem? I confine the request to model boats and not steam engines/traction engines which are typically beasts of a different order. We once had a member of a steam railway club lecture us on regulations etc and pressure testing - basically he was so severe it was a question of either ignoring him or cease sailing any steam models as he would refuse to certify even a Cheddar boiler with out an authenticated piece of copper plate to test first. Something of an overkill I think but perhaps more relevant with a 12 foot long steam train running at god knows what pressure whilst pulling children!

Yes we all live in a litigeous society but a little common sense goes a long way but lets not tie our hobby into knots and choke it on regulations which are really not that relevant to our hobby just because we can. It just turns people off the hobby.

Just my thoughts and I expect to get shot down - but lets all be sensible!

G
Title: Re: boiler testing
Post by: Circlip on August 13, 2010, 02:35:28 pm
Only problem with trying to apply "Common Sense" to any application is that everyone has the same hymn sheet. Look what happens when you apply a flame to PTFE or "Silicon" O-rings. Easy with a flaring burner.
Title: Re: boiler testing
Post by: Canopus on September 16, 2010, 01:25:21 pm
Just to follow up with my original question there are always possible accidents with a steam plant but has anyone ever seen one with a model boat, and what happened?

I have never had an issue with a flaring burner but perhaps that's because my cheddar puffin has the piezo ignition system so all contained in the boat.

Thinking about it I did see an incident about 8 years ago when there was a small gas leak in an open launch and it burned through the servo wire, but that's all!

Just curious as its far to easy to scare ourselves
Title: Re: boiler testing
Post by: Circlip on September 16, 2010, 02:33:06 pm
Gee, you ain't half tempting providence Canopus, but, if s**t happens and you can prove that you've taken every possible avenue to ensure it shouldn't, that surely kills off possibility of litigation? If you've attended a steam meeting in a public park like the Spen gathering was (and a classic example of preventative safety undertakings), given that someones little darling can be within close proximity of an "Occurrence", trying to explain why you haven't got bits of paper to show the safety precautions you have taken while their Dad has his hand gripping your windpipe cos it's gone spheroids up is not to be reccomended.

  Preventon and cure spring to mind.

 
Quote
I have never had an issue with a flaring burner but perhaps that's because my cheddar puffin has the piezo ignition system so all contained in the boat.

  Hopefully, you'll never have a gas leak and fill yer bilges.

Quote
has anyone ever seen one with a model boat, and what happened?

 Yep, a meths burner overflowed inside the hull,(metal)really singed the paintwork and an absolute b****r to put out.

   Regards  Ian
Title: Re: boiler testing
Post by: steamboatmodel on September 16, 2010, 05:56:44 pm
I had a fuel line come partially lose with a butane burner. The gas was coming out the side of the burner and scorched some wood work. Looking back it was quite funny, my launch had picked up some weeds on the prop. One of the other modellers was using his model to push mine in. He bumped his model into mine this caused the fuel line to loosen and the gas coming out light up. When he started to push my launch in we were both on the dock, with about 20 other modelers and spectators on the shore. Just before my launch was within reach I looked around and there was no one with in 15 feet of me. I evaluated the situation and reached over and turned the gas off ( If the flame had been nearer to the fuel tank I was going to push the launch underwater). When I got the model home I rebuild the burner Silver Soldering the line in. It had originally been soft soldered in by the manufacturer. I have since designed my own burner which works better.
Regards,
Gerald.
Title: Re: boiler testing
Post by: knoby on September 16, 2010, 10:46:21 pm
whilst i am fully aware of the inherent dangers of model steam plants & don't wish to spread complacency, has anyone actually witnessed or even heard of a major accident involving a model steam boat?  i am just curious, i am not trying to start an argument.  having been around model steam boats most of my life, i am not aware of any major injuries caused to people. Whether this is down to pure luck or good engineering practise i don't know. Maybe it goes to prove how effective the testing regulations are ?

cheers Glenn
Title: Re: boiler testing
Post by: Colin Bishop on September 16, 2010, 11:02:25 pm
I would think that a lot of it is down to taking sensible precautions. When you think about it, a boiler is essentially a regulated potential bomb!

Earlier this week 17 people were injured by a coffee machine blowing up in a Sainsbury branch due to over pressurisation of a boiler according to the company.

There is always a risk if you have a lot of energy concentrated in a small space, whether it is a steam vessel or a Lipo battery. It is managing that risk that keeps people safe. Time spent on safety precautions is never wasted.

Colin
Title: Re: boiler testing
Post by: Bunkerbarge on September 16, 2010, 11:46:10 pm
There is probably quite a bit less energy contained in a boiler under pressure than there is in a 7ah 12v battery or even some of the high capacity 7.2 packs and lipo packs.  To be honest I consider them to be more of a potential hazard but at the end of the day any form of stored energy requires treating with respect as Colin suggests.

I also think that gas is a bigger hazard than the boiler and it's handling and use needs to be thought about very carefully.
Title: Re: boiler testing
Post by: Canopus on September 17, 2010, 01:39:11 pm
The responses are interesting, kind of what I expected. Clearly whilst there are inherent dangers in operating a steam plant, thankfully no one appears to be aware of a major incident and long may that continue. It is interesting and good to note that no one here knows of an explosion which is what we are all really concerned with.

I remember reading an article some years ago which aired some concerns about the availability of commercial steam plants for models. The gist of it was that when you had to build them yourselves you had to have a good understanding of engineering so there was an inherent understanding of what you were doing and therfore a ready appreciation of the risks so kind of self regulating. If you wern't intelligent enough to build one you wern't intelligent enough to operate one!. Once they were commercial then a complete novice could operate them with an increase in exposure as there was no inherent understanding of the mechanics and what the issues were.

I also seem to remember an article which did a steam test to destruction on a Cheddar boiler and apart from the phenominal pressure it took the actual rupture was a suprisingly tame affair. My belief is most good commercail boliers are vastly over engineered as if just one of their products exploded they would be ruined.

My only experience is a Cheddar Puffin unit which I purchased about 15 years ago so at that time I fell into the novice catagory but I was able to construct my own detailed models so hopefully not "stupid". I have since learned to design and machiine my own engines so feel reasonably confident at my abilities and understanding.

I recall an incident many years ago when I was at the model engineering show Alexander Palace in London when Canopus opened fire with blanks and a fireman went nuts, completley ignoring the fact the model was surrounded by water in the middle of the pond whilst ignoring the fact that there was a jet turbine reving up 30 feet away at 130,000 rpm surrounded by people!

Note the fireman was there because earlier a fast electric had slashed the side of the pond with its prop and nearly flooded the entire show on day one - not good if your at Ali Pally as its a steel  frame structure with electrical wires all over the place!



Title: Re: boiler testing
Post by: Circlip on September 17, 2010, 03:44:33 pm
Quote
I recall an incident many years ago when I was at the model engineering show Alexander Palace in London when Canopus opened fire with blanks and a fireman went nuts,

  But was his wrath vented because of "Gunshot" sounds? Never seen a panic evacuation?  (WTFWT?)

  The main thrust of the safety exercise is NOT to do an Elfin job on our hobby, the general public think we've not grown up anyway but to save "Normal" people getting injured. Toy gliders were considered safe until a member of the public was hit by one and died, we then lost the Keil Kraft Supersonic spinners due to a requirement for a minimum of 6mm (Or whatever) radius on spinners and A/C noses.

  But you have hit the nail on the head with
Quote
when you had to build them yourselves you had to have a good understanding of engineering so there was an inherent understanding of what you were doing and therfore a ready appreciation of the risks so kind of self regulating.
Wonder who buys boilers from the "Flee" bart a certificate??

   Regards  Ian.

 
Title: Re: boiler testing
Post by: gondolier88 on September 17, 2010, 07:44:54 pm
The reason for the bar-litre rule is that it is the VOLUME of stored water at 100 deg.C + is the real hazard- you could store 50ml of water at 500 deg. C @ 300psi and have it explode and it would do far less damage than 100L of water stored at 180 deg. C @ 120psi-

Steam expands at 1600 X it's volume under pressure at a rate appertaining to it's stored energy potential (latent heat)

Water stored at above 100 deg. C under pressure will flash into steam under conditions of any pressures and temperatures less than it is stored at- this rate is again controlled by it's stored potential

On the stroed LPG side-

LPG- specifically 70/30 Butane/Propane mix- has an explosive window of between 2% Gas to air and 9% Gas to air ratio, below that and it will 'flash' or 'pop' off, above that and it will catch fire making a smoky yellow flame.

Like water in a boiler it will flash into an explosive gas when subjected to atmospheric pressures and temperatures above it's boiling point (due to the rapid temperature increase this time, as opposed to rapid temperature change in the case of steam).

Usually this event would be caused by a rupture in the gas tank (EXTREMELY rare, I have never heard of it happen, I don't know about anyone else on here?)

A rupture in a supply pipe would vent the gas, and is potentially explosive- but the conatainer it fills- the boat hull- being usually very small in volume compared to the volume of evaporated stored LPG in the tank itself would pose a very real, however fairly low-risk, explosion hazard.

Greg
Title: Re: boiler testing
Post by: steamboatmodel on September 18, 2010, 05:18:11 pm
"Usually this event would be caused by a rupture in the gas tank (EXTREMELY rare, I have never heard of it happen, I don't know about anyone else on here?)"
There were some problems with some of the Gauge 1 Live steam trains. The original fuel tanks were designed to be used with straight butane, and some of the modelers were using the butane/propane mix and filling the tanks completely, some were even using water bathes containing boiling hot water. When the fuel warmed up it expanded and ruptured. The tanks were all recalled by the manufacturer who replaced them with a stronger and better design. If the original tanks had been used with the proper fuel and filled proper there would have been no problem.
Regards,
Gerald.
Title: Re: boiler testing
Post by: Canopus on September 20, 2010, 02:05:01 pm
The fireman was upset at the percieved danger of blanks. I think he was concerned at the explosive potential. I take your point about gunshot panic but at Ali Pali all knew what was happening and enjoyed it and typically a large noise would attract people rather than repel them. Also with a jet engine at 130,000 rpm only feet away the noise was quite modest in comparison. Those were the good old days when you were allowed to have fun.

Just for the record, did I ever have an accident with the working guns, yes three times, the first two were when the guns fired when they weren't intended - signal interfearance/swamped but cured completley by inserting a micro switch at 90 degrees so guns can only fire when abeam so ignition takes two full actions, one to turn the turrets thriough 90 degrees and the other to operate the fire control table.. The other accident was much earlier when I got cocky and tried multiple shots per gun. The test piece worked fine - three shots - but the production pieces blew up - sympathetic detonation. I have some very good Jutland type pictures of burnt out gun turrets. This accident happened about 20 years ago and whilst I now know the causes and the solution I haven't tried it again due to safety concerns and because I'm working on a safe system which should give me 100 shots per barrel.

Geoff