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Boiler certification in a launch

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mick H09/11/2018 20:12:31
723 forum posts
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Posted by SillyOldDuffer on 09/11/2018 17:47:56:

For example, if someone died after a boiler accident, the charge would be manslaughter, not failure to produce a Boiler Certificate.

Almost certainly not manslaughter Dave but almost equally certainly liability in civil law.


Sam Longley 109/11/2018 20:50:05
751 forum posts
26 photos
Posted by Paul Kemp on 09/11/2018 20:09:02:

Posted by Ron Laden on 09/11/2018 16:52:03:

I know very little about steam engines and boilers etc but how anyone can operate one at any scale with an untested boiler is beyond me. I would keep looking at the boiler thinking "is it safe" maybe its just me.

Edited By Ron Laden on 09/11/2018 17:07:15


Anyone operating a boiler ought to be capable of making an informed judgement if the boiler is in acceptable condition - if that is not the case then I respectfully suggest they stay well away from one! The real danger from boilers is a lack of understanding by the operator.

I regularly volunteer on a heritage railway and before anyone is allowed to light a loco up, let alone fire one they have to learn and demonstrate competence in the principles of operation and safety and carry out their own visual examination of the boiler for any signs of water leakage externally or within the firebox including stays and fusible plug(s) and the smokebox tube plate / tubes which is a daily check, to an assessor. Once in steam and before going off shed the safety valve should be observed to be operating correctly according to the pressure gauge and methods of water feed proved functional as well as a proper test of the gauge glass(s) or try cocks. Granted that is not a full trousers down inspection of the whole boiler but roughly once a month at wash out all fittings are inspected as well as an internal exam and integrity of stays checked, among other things. This is in addition to the annual formal boiler test by an independent inspector.

Things worth considering are; boilers rarely fail catastrophically without some prior indication like steam and water leaks - hence the importance of the operator having a full understanding of the implications of warning signs. A boiler inspection is a bit like an MOT, happens once a year and a lot of damage can be done to a boiler in a year by the operator running with low water, rushing into steam (unequal expansion damage), failure to wash out or in hard water areas descale so hot spots develop stressing the plates, etc etc etc!

The real risk of a miniature boiler exploding is small unless it has been made from a baked bean tin held together with chewing gum by someone with no knowledge or appreciation of the potential issues - in which case return to paragraph one! The relative level of risk is further evidenced by the low cost of insurance, if boilers were exploding left right and centre the premiums would be massive. Even the black museum of sectioned boilers parts showing quite serious weld defects and constructional issues which used to appear on various stands at exhibitions in a perverse way show the level of risk as they came from boilers that had been operated for years with those defects present before they were cut up and none of them failed catastrophically as far as I am aware?

As far as the OP question goes there is not enough information on the proposed boiler itself to make any reasonable assesment of risk - is/ was it being made to an established design? What are the materials? Builder competence? The question focused on a lack of intent to follow a formal independent inspection and certification regime because of a belief it wasn't required - that doesn't necessarily on its own make the boiler dangerous. It may be the owner is perfectly capable of making his own assesment and is confident in his abilities. It is interesting perhaps and seemingly little understood that it is the owner / operators responsibility under the regulations to appoint a competent person and be confident of his competence in so doing, to inspect a pressure system. It remains the owners liability for the safe operation unless it can be proved the person issuing the certification was negligent the owner / operator will carry the can. Having boiler certification means nothing 11 months after the test if the boiler has not been operated and monitored correctly by the operator.


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

DMB09/11/2018 23:10:39
999 forum posts

Worthing model engineers have a compressor and is tested by the boiler testers.

Paul Kemp10/11/2018 00:30:28
480 forum posts
18 photos

Posted by Sam Longley 1

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


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 Olsen10/11/2018 05:28:45
1039 forum posts
91 photos
1 articles

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 H10/11/2018 07:38:19
1637 forum posts
108 photos

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 Olsen10/11/2018 09:02:49
1039 forum posts
91 photos
1 articles

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 India10/11/2018 09:44:29
213 forum posts

Small boilers are covered in the 2018 Boiler Regulations

They are really easy to test.

Why not just test them?

Tony Wright 110/11/2018 11:05:31
3 forum posts

Just be sensible.

Harry Wilkes10/11/2018 11:38:37
893 forum posts
61 photos

Here is a link to the SFMES current small boiler regs link


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