|mick H||09/11/2018 20:12:31|
|686 forum posts|
|Sam Longley 1||09/11/2018 20:50:05|
|718 forum posts|
Please accept that I agree with you entirely & with some of the comments within this thread. I just am surprised that no one can come up with a statutory instrument to stop people having what would be quite a large boiler without having any sort of test during its lifetime
I suppose it is a bit like all the cheap air compressors that are sold to the public. I expect that once sold none are ever tested, but many sit in sheds collecting water in the tanks, never drained, & rusting gently away.
Still as one never hears of one exploding I suppose it is a non event, thus not requiring attention from the authorities
|901 forum posts|
Worthing model engineers have a compressor and is tested by the boiler testers.
|Paul Kemp||10/11/2018 00:30:28|
|284 forum posts|
Accepted, lol. In terms of being quite a large boiler though, would it? 16' steam powered launch is likely to have something like a Stuart Compound as a prime mover and the boiler would be between 12 and 18 diameter probably and the water space maybe 24" high. Operating pressure as its a compound may be in the region of 150psi. So in terms of volume or bar/litre classification maybe towards the top end of the 'club' testing regime. In the grand scheme of things that isn't a large boiler. Yes if it went pop it has the potential to do a fair amount of damage and cause some pretty nasty even fatal injuries but if properly designed, manufactured and maintained the risks are pretty low.
My concern would be more the design, materials used, welder competence if steel etc than if it is subsequently regularly tested by an independent examiner. There was an incident with a steam boat a few years back in Beaulieu involving a fatality, the boiler had been inspected! I can't direct you to the info at the moment but I am sure a bit of Internet surfing will bring it up - if I remember correctly there is an HSE report on it.
Personally I think there are more than enough Statutory Instruments already, they tend to apply to those that abide by them, those that don't want too continue not too and bad things still happen! Codes of best practice can be just as effective and still carry weight in law, they are not statutory but you have to have a good argument why you didn't comply when things go wrong.
|John Olsen||10/11/2018 05:28:45|
|977 forum posts|
Not being based in the UK I have no idea what the law is there, but I know that here in New Zealand the situation is ambiguous to some degree. Apparently the marine people have responsibility for boilers in vessels, but they are apparently not interested in small steam boats. So people generally get their steam launch boilers tested and certified as if they were a stationary boiler, or if they are small enough to qualify, under the model engineering club system, which is OK for boilers up to a cubic foot and 100 psi if I recall correctly.
My own 30 foot launch has a boiler much bigger than that. and the intended working pressure is 170 psi, or about 11 Bars if you go that way. So it has so far had a hydraulic test from SGS M&I and will have a steam test with them once I get the burner operating reliably and with enough power to make such a test meaningful. So it will actually have the same certification it would have if it was bolted to the floor in some factory. It was also built with fully traceable materials, and the welder was done by a firm certified for pressure vessel work. The safety valve was set and sealed for me by the supplier. The boiler design is actually certified for a working pressure of 250psi, but I don't feel that the white metal bearings in my engine would be very happy with the sort of loads that would lead to so plan to operate at the more moderate pressure.
If I was in the UK, I would approach the Steam Boat Association and get my boiler certified through their system. They are accustomed to the types of boilers used in amateur steam launches, and it will be possible to get insurance and all that.
Even if there was really no official scheme available, I would want to make sure that any boiler I had anything to do with was inspected and OKed by someone other than myself, and with no emotional ties to the project. If you can't find an independent inspector who thinks it is OK then maybe it isn't!
It is also important to bear in mind that the real danger with steel boilers, provided they are reasonably competently made in the first place, is corrosion due to neglect. A boiler that is not used often can corrode just as fast and maybe even faster than one that is in regular use.
|Brian H||10/11/2018 07:38:19|
1171 forum posts
I suspect t hat rusting inside a small compressor air tank wold not result in an explosion, just a small leak at the most rusted point that would prevent the pressure from rising.
|John Olsen||10/11/2018 09:02:49|
|977 forum posts|
You are right, when a compressed air container fails there is likely to be a bit of a bang but not the kind of disaster that a boiler can create. This is because the water in a boiler is at an elevated temperature, so that as the pressure drops due to a rupture, more of it flashes into steam. I've read somewhere about domestic radiators being tested with compressed air just by putting them into a bit of a cage and putting the pressure on. They would go with a bit of a bang if they failed, but not break out of the cage. With water and steam, the water flashing into steam will keep the pressure up long after the air would have dissipated.
|Clive India||10/11/2018 09:44:29|
179 forum posts
Small boilers are covered in the 2018 Boiler Regulations
They are really easy to test.
Why not just test them?
|Tony Wright 1||10/11/2018 11:05:31|
3 forum posts
Just be sensible.
|Harry Wilkes||10/11/2018 11:38:37|
686 forum posts
Here is a link to the SFMES current small boiler regs link
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