Boiler testing and regulators (ie throttles)

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Boiler testing and regulators (ie throttles)

This topic has 14 replies, 8 voices, and was last updated 21 June 2013 at 15:25 by ay dee.

Viewing 15 posts - 1 through 15 (of 15 total)

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12 May 2013 at 14:36 #119621
John Billard
Participant
@johnbillard11913
I am hearing that some club boiler testers are including the regulator as part of the hydraulic test and are failing boilers as a consequence. It seems to me that this is quite wrong as the regulator is not part of the pressure system. Some regulator designs are also quite diifficult to make pressure tight for this procedure.

Fortunately my club testers in their discretion do not include the regulator but if they did I would be quite concerned if a carefully maintained boiler could not be cerificated for this reason.

I believe that it should be made clear that the regulator is not to be included in the test. If it leaks it shold be blanked off.

Kind regards

John Billard
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12 May 2013 at 14:36 #1180
John Billard
Participant
@johnbillard11913
12 May 2013 at 15:20 #119624
Steambuff
Participant
@steambuff
I am not going to comment what fittings should be part of the hydraulic test and which ones should not.

But in my opinion the Regulator is part of the pressure system …. as one side of it is either in the boiler or off a bush connected to the boiler and will be at full boiler pressure.

Dave
12 May 2013 at 17:17 #119637
John Baguley
Participant
@johnbaguley78655
Under the new boiler regs (Green Book) – Following the initial 2x WP hydraulic test on the boiler shell, all subsequent hydraulic tests to 1.5x WP should be carried out with ALL fittings attached to the boiler shell. This will include the regulator if it is an integral part of the boiler and, if possible, the superheaters. If the regulator leaks slightly (as most of them do!) I would think that simply blanking off the steam pipe from the regulator should satisfy the test. The object is to check the integrity of the boiler with the fittings attached rather than whether the fittings themselves leak.

Section 10.8 of the Green book refers.

John
13 May 2013 at 18:02 #119723
John Billard
Participant
@johnbillard11913
Thank you both for your comments so far. Regarding John's comments that most regulators leak albeit slightly I believe that some testers are failing the boiler for this reason and it seems not permitting blanking off.

I can't believe that is the intention of the regulations and this is what I am seeking to clarify.

Kind regards

John
13 May 2013 at 18:09 #119724
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
So why isn't there a requirement to pressure test the cylinders – is it that it's not nescessary or just that the idiots haven't thought of it yet ???

MikeW
13 May 2013 at 18:29 #119725
Steambuff
Participant
@steambuff
All,

Quote from the Green Book

10.13 Any loss of pressure shall be fully investigated. Slight loss from blanking plugs and fittings may be allowed. The boiler fittings should be examined for integrity, thread quality and dezincification to eliminate any risk of subsequent detachment.

10.14 Pressure loss which cannot be accounted for or which is at an unacceptable level shall lead to the test being declared a failure.

10.8 For all further hydraulic repeat tests, i.e. subsequent to the initial hydraulic shell test, the boiler shall be fitted with the working components attached to the boiler shell to prove the pressure and structural integrity of the interface and the boiler fittings. This includes the pressure gauge. If the gauge is not of the full range required by the test (1.5 x PW) it shall be disconnected and a blank fitted. On completion of the test (1.5 x PW) the blank shall be removed, the gauge shall be reconnected and a pressure applied equal to the full range of the pressure gauge. The pressure is to be applied for a sufficient length of time to prove the structural integrity of the gauge fitting.

10.9 If practical, the superheater should be included in the hydraulic repeat pressure test. This requires a blank to be fitted on the outlet of the superheater. It shall be removed on completion of the test and the pipe reconnected. The regulator shall be in the ‘Open’ position for the test. For superheaters the Boiler Inspector shall assess the testing requirement on an individual basis and annotate the Written Scheme of Examination accordingly.

Edited By Steambuff on 13/05/2013 18:30:51
13 May 2013 at 18:58 #119727
David Jupp
Participant
@davidjupp51506
As someone who works professionally with pressure systems, it seems to me that there is some confusion between 'leaking' and 'passing', one indicates a flaw which may become dangerous, the other is more of an inconvenience in most cases .

Clause 10.9 as shown in Steambuff's post should be clear enough, passing of the regulator is not a concern – leaking may be.

As for cylinders, yes they are part of the pressure system, but the probability of catastrophic failure is low, and likely consequences less severe than a rupture of the boiler or of items close coupled to it.

All recent UK/EU led directives are 'risk based' – most effort / testing / inspection is concentrated where there is highest risk of harm to people ot the environment. Cylinders would have to be very large for a model to become subject to PED, boilers very easily fall within PED.
14 May 2013 at 16:59 #119807
John Billard
Participant
@johnbillard11913
Yes, all great stuff but the question is still not answered clearly. If a regulator has what I would call a fairly minor leak (and is quite usable in service) and the boiler is otherwise sound does that amount to a fail? Some testers are saying yes and I would say no.

I guess the answer is in 10.19 and whether the pressure loss is "unacceptable" How is that word measured? Even a panel of High Court judges probably could not agree! And we arre placing that onus on our amateur testers.

Best wishes

John
14 May 2013 at 18:52 #119827
David Jupp
Participant
@davidjupp51506
Pleas calrify by 'leak' do you mean not tight between inlet and outlet, or do you mean leaking to atmosphere?

If former I agree, a blank on the outlet should adequately check system integrity.

If leaking to atmosphere – maybe OK from gland (though as a tester I would wonder why you couldn't be bothered to fix the gland for the test), if leaking elsewhere to atmospehere I'd say unacceptable.
14 May 2013 at 19:13 #119830
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
A regulator which leaks to the extent that it can never be shut is a possible source of danger in that under working conditions engine could move off on its own or be slow to stop in an emergency .

But arguably that is really a matter of a functional test not particularly a pressure test .

Cylinders rarely fail in any major way but its not unknown for cylinder covers to blow off or sudden big leaks of steam to occur when gaskets blow out . Again a matter of inspection and not particularly a pressure test .

What to test / inspect on a boiler or indeed a complete engine is a matter that should be thought through from basics .

Trouble is that a surprisingly small band of people seem to have decided for themselves that it is their life's work to tell the rest of us what we can and can't do .

Michael Williams .
14 May 2013 at 21:21 #119854
Sub Mandrel
Participant
@submandrel
A cylinder failure wouldn't result in a catastrophic emptying of the boiler, the consequences would be no worse than having a drain cock open.

Neil
6 June 2013 at 00:18 #121637
julian atkins
Participant
@julianatkins58923
hi john,

ive made quite a few boilers and quite a few locos and lots of injectors and even made a pressure gauge but ive never yet made a loco with a regulator that didnt leak on a hydraulic test! as jopn baguley correctly observes the correct way is to blank off the regulator where it connects to the steam pipe. this also pressure tests the superheaters which is no bad thing in my book. unfortunately a lot of the published designs make blanking off the steam pipe difficult.. a bit of inginuity and forethought is often required.

cheers,

julian

Edited By julian atkins on 06/06/2013 00:18:35
7 June 2013 at 18:36 #121812
John Billard
Participant
@johnbillard11913
Thanks, Julian

Yes, you are right (though I think that the screw down type is possibly more easy to make steam tight.) That is why I think that a leak at the regulator valve should be allowed within the spirit of reasonableness.

To blank off the regulator on my Martin Evans Manor design would require the removal of the superheater.

I do not wish to critisise the authors of the boiler code who have done a good job. It is the wide band of interpretation by testers that I think might be an issue.

Kind regards

John
21 June 2013 at 15:25 #122842
ay dee
Participant
@aydee34131
I guess sometimes common sense is lacking – if the regulator allows too much water past to hold hydraulic pressure without pumping like mad, the inspector should fail it. Not so much because of the regulator, but because frantic pumping, water pouring out of the blast cap into the smokebox, and probably back down the tubes and out the ashpan once the smokebox fills up are not conducive to examination of leaks in the boiler. Blank off the regulator wherever you can for a hassle-free test. Not many designs allow for easy hydraulic tests, and most models need some dismantling for blanking off.
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