ME and Captive Valve Spindles

[peterseager]

The latest issue of ME contained a letter stating that "... club testers recently held discussions with the Southern Federation (SF) to clarify [the issue of captive valve spindles on existing boilers] and were advised that at a recent federation meeting it was confirmed that the ruling applied to all boiler valves and there was no retrospective immunity."

The only relevant document I can find on the SF web site is the minutes of the Boiler Test Group:
www.southernfed.co.uk/PDFs/091104BoilerGroupMinutes.pdf
Their recommendation after discussing the issue was:

4. Screw operated valves on previously tested boilers.
The meeting recommends that screw operated valves should have captive spindles.

This is as the Blue book states now. Can the SF unilaterally change the rules changing should to shall? As a club our reading of the blue book was that should means "desirable" not "mandatory".

Having spent a lot of time preparing a newly acquired loco for a full test, passing the hydraulic last week and thinking the steam test on Saturday would allow me to start using the loco it now looks like my hopes are dashed by a couple of suddenly non-compliant blowdown valves (another grey area - are they valves within the meaning of the Blue Book?).

I think I'll go fishing instead.

Peter

I like bashing my head against a brick wall - its so nice when you stop.

[alanstepney]

It is very unusual for laws to be made retrospective, and therefore I would question whether such guidelines can be made so.
However, SFQ7 in the document refered to, appears to show that they so intend.
( I disagree with them doing so, but that is a personal opinion.)

But, "The meeting recommends " doesnt make it compulsory.


( I also disgree with their comments re CE making under SFQ6, as I believe there is a major error there.
I will contact the boiler test group regarding this.)

[Nigel Bennett]

Captive blow-down valves, if operable only by a tool such as a spanner, could in my opinion be non-captive.

How would such a non-captive valve differ from (say) a safety valve? I can unscrew that with a spanner with the loco in steam and it isn't captive...

[mutley]

Who's side are the Southern Fed on? My engine hasn't been out now for nearly a year and I was considering getting it retested. With the additional work I would have to do to pass a test it can sit in the workshop for another year.
Its for reasons like this that the traction engine I am building will not be going near the club for boiler testing.

Andy

[peterseager]

I was lucky. The Boiler Inspectors attitude was that he had had no communication from the Southern Fed changing the rules so the current Blue Book rules.

He has had indications that changes are on the way though. As mutley says this is going to put many locomotives out of use because of the work involved. In my own case the blower valve on my Simplex, which comes up for test soon, could be outside any new rules. Before I know where I am the loco could end up in pieces because the blower valve is the type that screws into the boiler and passes steam through a tube in the boiler. I don't believe the mod suggested by the Southern Fed will work reliably over time. From my experience the so called captive spindle valves are not immune to the whole spindle assy screwing out.

So it looks as though the only effect of the ME letter for me has been to raise a lot of stress that I could do without but I can see some people having trouble from Boiler Inspectors who believe everything they read in magazines.

Peter

[russell]

I do believe that imposing such regulations retrospectively is rather silly. Most new safety legislation is non-retrospective. You are still allowed to drive a vintage car without safety belts and air bags and the result of an accident could be fatal. So why are the rules being applied retrospectively to our hobby by the very people who should be supporting it? How many instances have there, been over the life of the hobby, of serious injury being caused by a valve unscrewing? Is there any evidence that such an event is really dangerous, I suspect not.

(end of rant)
Russell.

[weldsol]

Will it now be that suppliers should only sell items with captive spindles ?
That would mean a lot of scrap units lying on their shelves.
I have three items on my traction engine which now will have to be sorted or changed
The blower valve can be made into a captive spindle
The blow down valve can be done by turning a groove and putting a pin in the body
But the biggest challenge is the water gauge blow down as it is such a small spindle to start with it may have to be replaced "Bummer" !!!

Paul

[peterseager]

Will it now be that suppliers should only sell items with captive spindles ?

From my experience at Guildford - No. To be fair, I checked before I bought but the seller had to refer to others to find out. In fact they were OK.

One item was a water gauge. The existing one has a very small spindle covering a very small hole, hard to see a problem. Safety valves must be far more dangerous, are they going to be banned? I postulated at the club that the Southern Fed could end up taking risk reduction to the point where they ban steam engines. Those present thought this may not be too far from the truth.

Peter

[maunsell]

I find it a matter of concern that some Boiler Inspector's are deciding that non captive valve spindles are not acceptable therefore making this a mandatory requirement in some clubs. The current edition of the Examination & Testing of Boilers book quite clearly states that "All screw operated valves should be checked to ensure that they cannot be screwed out while under pressure" etc. The operative word is SHOULD which does NOT mean that it is mandatory, in fact quite the reverse.
In a previous comment I have stated that in 1" scale and above I see no problem with making captive valve spindles, but in the smaller scales such as 1/2" and 3/4" I do not believe that the risk levels can justify a mandatory requirement.
I believe some clubs of already require a locking arrangement to safety valve adjusting nuts.
I agree with Peter Seager's thoughts on risk and ban on steam engines.

[houstonceng]

Trouble is that it's a very badly worded rule in that, the SHOULD applies to the tester not the valve. Effectively, it means that the tester can decide to check or not.

If, however, he/she does check, then ENSURE requires that, as far as my experience of Specification writing goes, it is mandatory that the valves have captive spindles.

The wording needs changing to say either "All valves shall have captive - - -" = Manditiory OR "All valves should have captive - - - " = Recommended.

Better yet, make it Manditory for locos built after a certain date and Recommended for any that were built before that date - same as Seat Belts, Two dipping Headlights, Day-light Running Lights, etc, etc, etc on motor vehicles and changes in wire colours, sizes, etc, for domestic and industrial mains wiring.

[kwil]

Daylight Running Lights are required to be a part of newly manufactured cars but their use in the UK is not mandatory and you can prevent their automatic function (at least on some cars).

[maunsell]

I agree with the comments that the wording of this clause in the "Blue Book" is not just poorly worded, but extremely ambiguous in that by inference use of the word "cannot" implies that the inspector having checked the valve spindle must refuse to accept a non captive spindle.
I feel very strongly that should captive spindles become mandatory that there must be a cut off point for scales below 3/4" to 1'-0" as it is in my opinion not only unreasonable, but the practicality is dubious for the average model engineer. We are not all gold medal standard folk!

[davidm]

I agree with houstonceng, and especially

Better yet, make it Manditory for locos built after a certain date and Recommended for any that were built before that date

David

[peterseager]

Trouble is that it's a very badly worded rule in that, the SHOULD applies to the tester not the valve. Effectively, it means that the tester can decide to check or not.

If, however, he/she does check, then ENSURE requires that, as far as my experience of Specification writing goes, it is mandatory that the valves have captive spindles.

Andy, that exactly how I read it.

The problem with the blue book is that it tries to be a requirements document and a test procedure. Normally you have a requirements specification to define requirements and a test procedure to state how you are going prove you comply with the requirements. To do requirements management properly you then have a Verification Cross Reference Index (VCRI) into which you capture your requirements, rank them (mandatory etc) and show which test procedure will demonstrate compliance. Ultimately you include the test results and if all is well the contract gets signed off.

This is obviously over the top for our purposes but is such a well used way of doing business worldwide that the principles will be applied to our situation like it or not. The point is that there are only three words ranking/defining a requirement - "shall" (Mandatory), "should" (Desirable) and "must" (required by law). "Will" is a fact that can be relied upon but the requirement is specified elsewhere. These words are always defined in a section at the front of the document. Unlike the Blue Book, the definitions section should not include requirements. The above quote is therefore all one requirement. The word "ensure" only defines the scope of the requirement. Test procedures do not contain requirements.

One important use of the VCRI is to get agreement between the customer and contractor as to what are the requirements. It may even be that some descriptive text is recognized as a requirement at this stage but its inclusion in the VCRI ranked "Mandatory" gives it validity while the source document is updated.

There are some indications that the next update of the Blue Book will be two documents. Lets hope they use a simple VCRI to get it right.

Peter

[houstonceng]

Careful Peter.

You might be talking yourself into an unpaid job writing the new version of the "Blue Book".

[maunsell]

It is now essential that the National Federations and Boiler Group quickly clarify the situation as if the word "should" is being interpreted as the Boiler Inspector, and in the event that he dcides to examine screw operated valves then he has no choice but to fail any boiler with non captive screw operated valves based on the wording "ensure that they cannot be unscrewed" etc.
Inevitably there will be a very high failure rate!!!