testing water tube boilers

[Metatsteam1Participant @metatsteam1]

Can anyone advise on testing water tube boilers, hydraulic and steam test. Specifically what a club track would want to see before allowing it to run. I am building LBSCs Rose a 2.5in great eastern 2/4/0. Also any advise on making blower and gauge glass valves captive as I seem to think this is a requirement now. The boilers working pressure is 80 psi.

Matt

[Metatsteam1Participant @metatsteam1]

[IanTParticipant @iant]

Hi Matthew,

As far as I am aware the general guidance for testing a water tube boiler would be exactly the same as a 'locomotive' fire tube one. Most (all?) MES will be affiliated to either Southern Fed or Northern and I believe their boiler test requirements will be pretty much the same.

I run Gauge '3' (2.5" gauge but scenic) live steam and the G3 Society use SF guidance for their testing, so I'm more familiar with their practice.

The first thing to establish is the physical capacity of the boiler (by filling it completely with water) and the water tube boiler on 'Rose' may be just under the 3 bar/litre boundary (which is capacity in litres x pressure in bar). If so then it would be viewed as a "small" boiler and tested as such.

In G3 (but not SF) a small boiler only requires an initial 2x hydraulic shell test (and not the second x1.5 hydraulic after fitting out. Thereafter, there are no further hydraulic tests required for small boilers but there are annual steam tests/checks. This will also involve checking the pressure gauge against a calibrated gauge at least (very minimum) every other year.

If the boiler is >3B/L then the full SF guidance (Green Book) will apply to the boiler – but you might well just sneak under with this one.

In terms of captive fittings (e.g. cannot blow out when unscrewed) – this is very good practice and would be expected/required on any new build. One other thing to note is that the water gauge (where fitted in a small engine) must be capable of being blown down.

I think that just about covers it. 'Rose' is a very nice little engine and we don't see too many of them at our Garden GTGs – but if you find it's not a "heavy hauler" with yourself in tow – then you might like to come along to one of our garden events and try it with a train of wagons or coaches. We've just had a our main 'boiler testing' day of the season but you can probably arrange to have something done at one of our GTGs through the year.

I've said this before here – but my advice to anyone building a new boiler is to talk to the boiler tester who is most likely to be testing the boiler – BEFORE you start to build. It can save a lot of time and effort to do this. So join your local MEs or the National 2.5" Gauge Association or The Gauge '3' Society and talk to their boiler testers about your plans.

Regards,

IanT

[Metatsteam1Participant @metatsteam1]

Hello Ian

Thanks for your reply and advice, my nearest club track with 2.5 track is Clitheroe so i guess the northern fed guidance is the one i need to work to. I intend to pay a visit to Clitheroe over the Easter holiday so i will seek there advice. Thanks again.

Matthew.

[FMESParticipant @fmes]

Hello Ian,

The 3 bar / litre exemption no longer applies to small boilers **LINK** section 1.6, and then refer to section 14 for small boiler testing.

Regards

Lofty

[IanTParticipant @iant]

Hi Lofty, I'm not sure you understood my posting correctly.

I was explaining that the Gauge '3' Society (G3S) do require testing of small boilers but use a slightly different regime for <3 B/L boilers than that given in the SFed Green Book – in that a second (x1.5) hydraulic test is not required by 3GS on "small" boilers (whereas it is in Sect 14 of the Green Book). The G3S also observe all Green Book requirements for >3 B/L boilers, which most G3 engines probably still are at the moment.

A year or two ago, G1MRA & 16mm Assoc. decided to use a different boiler test regime for their small boilers than that proposed by MERG (e.g. it's not SFed). The G3S looked at these 'new' test policies but decided to broadly stay with SFed for <3 B/L with some small changes. The G3S felt this was a good compromise between the two systems. It's a somewhat complicated subject but (for instance) G3S do not allow a "buddy system" and we still use SFed test documentation (which has a trackable serial number).

Matthew – if you want to run at Clitheroe MES, then I believe you will need to meet the full Green Book requirement for <3 B/L boilers (I think the spirit boilered Rose will be <3B/L – but you need to check the capacity). The G3S will accept your NFed boiler test certificates if you want to come to a G3S GTG – but MES may not now accept a G3S one for a small boiler.

The question you asked about "how" to make a valve 'captive' – I failed to answer but it is very simple in concept. The valve stem must have an end cone (or other part) that cannot pass through the gland nut – e.g. you have to take the nut off to fit the valve stem and then it's not possible to have the valve blow out by unscrewing it too far.

If you follow the link that Lofty has provided you will find the SFed 2012 boiler test regs I've been referring to (commonly known as the "Green Book" – because that's the colour of the book cover if you buy the printed version).

Good luck with your engine build.

Regards,

IanT

[IanTParticipant @iant]

I seemed to remember that the late Peter Jones had built an engine based on 'Rose' so I got his book "Building Small Steam Locomotives: A Practical Guide to Making Engines for Garden Gauges" down off the shelf this morning.

He describes an engine called 'Wirral' which is a 2-4-0 tank version of Rose (which LBSC designed as a tender engine). A very simple single cylindered engine, Peter built his version with a gas-fired boiler. He devotes a whole chapter to Wirral, describing what is a charming (scenic) 2.5" live steam locomotive that would be a good starting project for live steam in Gauge '3'.

I'd forgotten what a nice book this is. Peter had a gentle style and the illustrations and photographs are first class. Some might want a little more step by step 'build' detail but generally a very good intro & overview to building small steam engines for anyone interested in 16mm, G1 or G3.

Regards,

IanT

[Author]

Posts