pressure vessel testing

[michael howarth 1Participant @michaelhowarth1]

I am of the opinion that the PSSR is a piece of catch-all legislation (which I think was a consolidation of various European directives) which has caused unintentional consequences. It is true that there are references to "schools" and "minor systems" but nowhere does it exempt the operation of any model locomotive boiler of whatever size from the requirements of the regulations. There may be a concession to "proportionality" but this is left vague. It seems to me quite disproportionate that a Mamod traction engine should be subject to the same written scheme of examination etc as a piece of major industrial plant. It is probable that officialdom would not be overly interested in model boilers………..until something goes wrong.

Mick

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mick H on 15/01/2016 19:43:46:

… but nowhere does it exempt the operation of any model locomotive boiler of whatever size from the requirements of the regulations.

.

Forgive me if this sounds confrontational, Mick; I don't mean it that way:

Why should it "exempt the operation of any model locomotive boiler of whatever size from the requirements of the regulations" ?

MichaelG.

.

[quote]

This Code has been approved by the Health and Safety Executive, with the consent of the Secretary of State. It gives practical advice on how to comply with the law. If you follow the advice you will be doing enough to comply with the law in respect of those specific matters on which the Code gives advice. You may use alternative methods to those set out in the Code in order to comply with the law.

However, the Code has a special legal status. If you are prosecuted for breach of health and safety law, and it is proved that you did not follow the relevant provisions of the Code, you will need to show that you have complied with the law in some other way or a Court will find you at fault.

[/quote]

Edited By Michael Gilligan on 15/01/2016 20:01:59

[Cabinet EnforcerParticipant @cabinetenforcer]

Posted by Neil Wyatt on 15/01/2016 17:06:53:

One interesting thing about the Code of Practice is it make its clear that the USER of a model steam engine not the OWNER is the responsible person. This suggests that clubs who, as long as they make reasonable efforts to ensure members using a club engine are competent, could then argue they were not responsible if the member caused an accident . I can't see it as licence to just hand an engine over to an unsupervised beginner.

Neil

Neil, in the case of PSSR, the terms "owner" and "user" are defined in the interpretation section and their meaning is restricted to that definition, and should not be interpreted as the "common" meaning.

For example, when you get your tyres changed on your car, the chap who inflates them is not the "user" of the system, it's the business who employs him. Similarly, the person who is operating a model steam engine may not the "user" of the model.

Schoools are the most obvious example, students may well use a model, but the school is the "user".

I'm surprised at the lack of facts in this thread, given how long the legislation has been around.

[michael howarth 1Participant @michaelhowarth1]

Posted by Michael Gilligan on 15/01/2016 19:56:48:

Posted by mick H on 15/01/2016 19:43:46:

… but nowhere does it exempt the operation of any model locomotive boiler of whatever size from the requirements of the regulations.

.

Forgive me if this sounds confrontational, Mick; I don't mean it that way:

Why should it "exempt the operation of any model locomotive boiler of whatever size from the requirements of the regulations" ?

MichaelG.

.

[quote]

This Code has been approved by the Health and Safety Executive, with the consent of the Secretary of State. It gives practical advice on how to comply with the law. If you follow the advice you will be doing enough to comply with the law in respect of those specific matters on which the Code gives advice. You may use alternative methods to those set out in the Code in order to comply with the law.

However, the Code has a special legal status. If you are prosecuted for breach of health and safety law, and it is proved that you did not follow the relevant provisions of the Code, you will need to show that you have complied with the law in some other way or a Court will find you at fault.

[/quote]

Edited By Michael Gilligan on 15/01/2016 20:01:59

No reason at all Michael. The thing that I find bizarre is that some of the people that I speak to on this subject seem to be in total denial or ignorance of the PSSR which have been around since 2000. Quite clearly, boilers used in public should be subject to some sort of testing regime (and as far as I can establish have been so for some considerable time) under sensible rules drawn up by the relevant clubs bodies and associations. These practices were overturned by PSSR in favour of a far more rigid testing regime but there are still people in the model engineering world, in denial, talking about the 3 Bar/litre rule. Nevertheless, the regulations would appear to only affect public or workplace use and those using their boilers in private….me included ……are exempt from its requirements.

Mick

[duncan webster 1Participant @duncanwebster1]

As we've now moved on to boilers for model locos let me refer to the Southern Fed publications, obtainable from **LINK**

which cover exactly this topic. As mickH says, if you are making the boiler yourself and will never operate it in public, there are no relevant regulations, do your own thing. If you are making for your own use, but want to operate in public join your local ME club, whose boiler inspector will advise and eventually test and certify if you make a half decent job of it. As usual the requirements are not onerous.

Edited By duncan webster on 15/01/2016 22:21:16

[IanTParticipant @iant]

I'm sorry Mick – but I'm a little confused about your comment;

"These practices were overturned by PSSR in favour of a far more rigid testing regime but there are still people in the model engineering world, in denial, talking about the 3 Bar/litre rule…"

I thought that the current Green Book (2012 Southern Feb guidance) still did differentiate between "above 3B/L" and "Small Boilers" (e.g. < 3B/L) – or have I missed something? .

Regards,

 

IanT

Edited By IanT on 15/01/2016 23:21:29

[michael howarth 1Participant @michaelhowarth1]

IanT……..quite my point Ian, although probably not very well made by me. The Blue Book does indeed differentiate between < or> 3Bar/litre but PSSR 2000 does not. If I may go back to my post of yesterday at 0953 I asked whether I was missing something as well. Has there been an exemption made by HSE under Reg 17, for small boilers? If it has it does not seem to have been very widely published. If not then surely PSSR 2000 must apply in all its requirements?

Mick

Edited By mick H on 16/01/2016 07:15:23

[Michael GilliganParticipant @michaelgilligan61133]

Gentlemen,

Please forgive the pedantry [it is not gratuitous]:

I believe that the unit of measure is 'bar litre' not 'bar/litre'.

This appears trivial, but that 'division' slash changes the meaning.

MichaelG.

.

P.S. .. For my defence; I have just located this useful page.

Edited By Michael Gilligan on 16/01/2016 07:55:45

[michael howarth 1Participant @michaelhowarth1]

Michael…….I do believe that you are absolutely correct!

Mick

[V8EngParticipant @v8eng]

Posted by Michael Gilligan on 16/01/2016 07:54:38:

Gentlemen,

Please forgive the pedantry [it is not gratuitous]:

I believe that the unit of measure is 'bar litre' not 'bar/litre'.

This appears trivial, but that 'division' slash changes the meaning.

MichaelG.

.

P.S. .. For my defence; I have just located this useful page.

Edited By Michael Gilligan on 16/01/2016 07:55:45

Good morning Michael.

Your link just seems to take me to a page labelled:- about:blank.

Not sure if it is just my system?

Thanks. V8.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by V8Eng on 16/01/2016 09:14:07:

Posted by Michael Gilligan

P.S. .. For my defence; I have just located this useful page.

Your link just seems to take me to a page labelled:- about:blank.

.

Sorry, V8 … don't know how that happened

It should have linked to this

http://www.healthandsafetytips.co.uk/forums/viewtopic.php?f=1&t=24765

MichaelG.

[Russell EberhardtParticipant @russelleberhardt48058]

You have to be careful with reading internet forums (fora?) including this one.

From that link:

"Barlitre is a measure of the potential energy stored in a pressurised system.
A litre at one bar has only the potential energy of the mass of fluid"

Think about what that means!  e = mC²

Russell.

Edited By Russell Eberhardt on 16/01/2016 10:38:33

[Michael GilliganParticipant @michaelgilligan61133]

Yawn

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Russell Eberhardt on 16/01/2016 10:36:13:

You have to be careful with reading internet forums …

.

Russell,

Does this [non forum] source meet with your approval?

MichaelG.

[bodgeParticipant @bodge]

It seems there must be some regulation somewhere for Garrys op, found this on one site

Walther LP 300 air cylinder 300 bar – Reduced from £140 to £40 due to "time expired" .

Would have thought it would come under the same regs as a diving bottle,

b.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Michael Gilligan on 16/01/2016 11:38:10:.

Does this [non forum] source meet with your approval?

MichaelG.

Well, at least it seems to be correct as opposed to talking about the potential energy of the mass of fluid!

Russell.

[Michael GilliganParticipant @michaelgilligan61133]

Russell,

I know [or at least believe] that you are just being provocative 'for the sport of it', but I would just like to make a couple of points before we let the thread get back on track:

1. "A litre at one bar has only the potential energy of the mass of fluid" might reasonably be thought to have a subtly different meaning to "A litre at one bar has only the potential energy in the mass of fluid" …

2. If you insist on interpreting 'of' as 'in' … then the substance of the boiler would have rather more 'potential energy' than its contents.

MichaelG.

[JonParticipant @jon]

Posted by bodge on 17/01/2016 05:29:35:

It seems there must be some regulation somewhere for Garrys op, found this on one site

Walther LP 300 air cylinder 300 bar – Reduced from £140 to £40 due to "time expired" .

Would have thought it would come under the same regs as a diving bottle,

No regulations for removable cylinders below 500cc as what Shaun stated 3 days ago.
Time expired on that one is because its aluminium though no law its an understanding of European manufacturers covering themselves in the event of a failure. This came to light around 2006 with Anchutz and a recall of certain dated cylinders.
ie send back an in date cylinder with visible stress cracks, its brushed aside and new cylinder might be sent out.

Therefore the scuba IDAS testing wont apply but can be done as a one off if you supplied the fittings to go on to their test equipment.
Generally make cylinders and any component able to withstand 1 1/2 times the operating pressure as a minimum. Some producers go by the tube rating ignoring any threads, pins, breakouts or weak points.
Used to take mine round to Shaun 20 odd years ago operating pressure 232bar, pressure test took one cylinder with end plugs to 6600psi where the off the shelf 1/8"BSP hydraulic grease gun nipple sheared. Likewise last year good to know the European producers using 1mm pitch threads around 10mm long are fine, Shaun will tell the length of thread in cylinder where thread sheared out, substantially less than 10mm.

[garrygunParticipant @garrygun]

Thank you guys, didnt expect to get this much response this has been of great help.

as you can see, bodge has found a walther unit £140. thats probably the price of a 7ltr diving cylinder

very expensive, thats why i started to make these cyls, until the testing obstacle arose, think i might get there now with the forum help.

Cheers..

[David JuppParticipant @davidjupp51506]

Re the 'don't use beyond' date on some Aluminium pressure vessels.

For those not familiar with fatigue life charts, whilst steels will show infinite fatigue life if stress is below some minimum value, this is not the case for aluminium where fatigue will proceed even at very low stress levels. Basically you can't totally design fatigue out of an aluminium item that is subject to cyclic loading.

Where monitoring number of pressure cycles is impractical, inspection is difficult (or expensive compared to replacing the item with new), a rate of applying pressure cycles will be assumed and used to calculate an end of useful life date.

I've recently seen such expiry dates on hydrogen cylinders (fuel tanks) for fuel cell powered vehicles.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by David Jupp on 18/01/2016 07:54:12:

Re the 'don't use beyond' date on some Aluminium pressure vessels.

For those not familiar with fatigue life charts, whilst steels will show infinite fatigue life if stress is below some minimum value, this is not the case for aluminium where fatigue will proceed even at very low stress levels. Basically you can't totally design fatigue out of an aluminium item that is subject to cyclic loading.

Where monitoring number of pressure cycles is impractical, inspection is difficult (or expensive compared to replacing the item with new), a rate of applying pressure cycles will be assumed and used to calculate an end of useful life date.

I've recently seen such expiry dates on hydrogen cylinders (fuel tanks) for fuel cell powered vehicles.

.

That's a VERY useful summary, David

Thank You.

MichaelG.

[Martin ConnellyParticipant @martinconnelly55370]

Jon, the most recent interpretation of the PED that I have seen is that the 1 1/2 times test pressure should be applied to the safety valve release pressure not the operating pressure. This makes the test pressure higher than just using expected working pressure as your starting point so is a more rigorous test. It is because it is possible for the operating pressure to be at fault at higher than nominal pressure and the system can still work as normal.

Martin

[Neil WyattModerator @neilwyatt]

> Basically you can't totally design fatigue out of an aluminium item that is subject to cyclic loading.

Such as a DeHavilland Comet

I do worry about the first generation of alloy mountain bike frames… I wouldn't hurl myself down a hillside on one from the early 1990s.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

The move by SodaStream [10 or more years ago], from Steel to Aluminium cylinders is of some interest. There was presumably some clear business advantage to this, but the safety aspects are a little worrying. …

The company makes it reasonably clear that the cylinders are rented, not sold, and that they should not be unofficially re-filled … but that does happen.

I would be grateful for any comment from the wise … Does SodaStream individually test the returned cylinders, or scrap them when time-expired, or what ?

MichaelG.

.

P.S. I have a sufficient supply of the old Steel cylinders to meet my needs; but the question is generally relevant to this discussion.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 18/01/2016 10:48:48:

Such as a DeHavilland Comet

**LINK**

MichaelG.

.

P.S.  Follow the hyperlinks … there are some great pictures.

Edited By Michael Gilligan on 18/01/2016 11:23:30

[Author]

Posts