Tornado

Anyone remember this?

"80135 was withdrawn from service in July 1965 and sold to Woodham Brothers for scrap. It entered the scrapyard at Barry in January 1966 and stayed there until April 1973 when it left to go to the North Yorkshire Moors Railway (NYMR) at Pickering.

It was bought by Jos de Crau, who financed its restoration in the NYMR workshops.

As part of the restoration of the locomotive a new firebox was made of steel which subsequently proved troublesome and was it was later replaced with a conventional copper firebox."

 

I wonder what the records say about the ten Stanier Class 5s fitted with steel inner fireboxes (44718-44727) All were allocated to Scottish Region sheds because of the soft water in Scotland.

 

80002 had similar problems in preservation with its new steel inner firebox.

 

Since when have stays been expanded?

 

From Arthur Cook's 'Raising Steam on the LMS' (1999) RCTS ISBN 0 901115 85 1:

As part of the programme of experiments made in the post-war Class 5 4-6-0s, engines 44718-27 were fitted with welded steel inner fireboxes, and, as a further experiment, five spare G7S boilers for 4F 0-6-0s had all-welded copper inner fireboxes. By this time the SR had demonstrated that welded steel fireboxes presented no insuperable difficulties under British conditions, although unusual care had to be taken over water treatment if the fireboxes were to achieve reasonable lives. The SR had made provision for keeping the fireboxes hot whilst the engines were standing in sheds, to reduced the stresses caused by changes of temperature, but this provision had been found to be unnecessary. Annealing of the welds had also been found to be unnecessary, as the temperatures reached when the boiler was in steam had proved to be sufficient to achieve the necessary stress relief. Some of the uncertainties which LMS engineers had felt about welding as an alternative to riveting in boilers had thus been dispelled by Bulleid's experience. Furthermore, Crewe had gained considerable experience during the war of building large welded assemblies, for which manipulators were needed to allow the welders always to work downhand. The construction of welded steel fireboxes thus presented few problems, and I C Forsyth, the Crewe Works Superintendent, said at a meeting that "the welding of the complete steel inner box caused no difficulties whatever, and may be regarded as a straightforward job. The fixtures and manipulator proved entirely satisfactory...X-rays of the first box revealed slag inclusions, which had to be chipped out, but once the welders had established the correct technique .... there was no further difficulty".

Although ordered by the LMS, these ten boilers, 12928-37, were completed between December 1948 and March 1949. To ensure that the boilers had water of uniform quality for the experiment, the engines were stationed in Scotland. The fireboxes had Monel water-space stays, which were caulked on the inner ends and fitted with nuts, in accordance with current practice. Star-shaped fractures developed around the stay holes, and when it became necessary to renew three-quarters of the firebox sides, the stays were riveted over without caulking. The firebox ends of the tubes were beaded over and welded, and cracks developed around the tube holes. The replacement tubes were welded without beading. These two modifications solved the problems of cracking, but it was decided that the steel fireboxes had brought no economic advantage, and after nine years' service eight of them (and possibly the other two also) were replaced by copper boxes.

 

Very expensive.. anything with copper, as prices are soaring due to China hoarding it at the moment. Difficult to machine..you can say that again and it tends to work harden too. Very similar to Inconel, another nasty...

 

Difficult to repair but not impossible, two locomotive have had a repair effected recently. One Merchant Navy boiler was built without syphons, last fitted to 35017

 

I was wondering that, too.

 

Thanks for that.

 

Mandrel expanded stays are a thing on the continent - we did a narrow gauge boiler with them recently. The design we used started with a long 6mm hole and a short 14mm hole in the stay ends, and you drive a succession of tapered tools into them with a rivet gun until the 6mm hole tapers out to meet the 14mm section. No idea on the longevity, but they were quick and easy to fit.

 

Sorry I was referring to tubes, , but saying that it would appear on the continent,, some stays are expanded, i'm not a boilersmith by trade, so I'm interested to hear from people that have done this, Is it a temporary fix to keep an engine , in traffic until it can be shopped ?

 

This is very revealling. Some notable lines give a lot away.

Water treatment is always the prefered path, if its available. Notable that someone thought thermal cooling of the inner versus outer would create issues. Hold that thought.

This would be true on the inner wrapper, however the heat affected zones on the outer wrapper would not be subject to the same temps, and so residual thermal stresses would still be present.

Traditional stay practice, and we still get these fractures in current boilers without welding the stays.

Yes, you dont need to bead and weld, one or the other will suffice.

A happy benefit in a time where copper did not cost what it does now, they could just go backwards.

In summary, its fine, but its using traditional staying practice, whereas Tornado has welded stays inner and outer, is that right? The inners will bake out the weld stresses, but the outers wont. The cracking on a welded box is going to be worst around the stays and the found rings. The seams to the barrel and in the wrappers are less worry-some.

In theory, could the box be fully welded up, minus barrel, put in an oven, and then assembled to the barrel later? Baking out the welds to the barrel could be done with blankets. Thinking out loud here.

The other option is to move to traditional staying practice, but that's a change in design and would require whatever design authority to go back and re-do the analysis. £££££

The other aspect we haven't yet mentioned, is mechanical support. The large nuts used in traditional staying practice provide considerable mechanical support to both wrappers. On a welded stay, that isn't there, and worse still, there are residual thermal stresses right in the region of where more mechanical support would be helpful to the wrappers.

It only adds to the argument of trying to get as much of the residual thermal stresses out of the box as possible of longevity is the primary motive.

Indeed, Inco and Monel are nightmarish to machine. Asking someone for quotes immediately makes them think how many more carbide tips they will need to buy.

Global copper demand is set to rise, check the demand over the previous century, it goes up in fits and spurts, not in a linear fashion.

 

Bulleid's design was somewhat different from the international standard for steel boxes, the steel stays being thinner (5/8" dia. between the 7/8" x 11tpi threaded ends) and more numerous than the norm (3 1/4" centres) and the water legs wider (and of coure the A1 boiler is round top) which Bulleid thought would provide the flexibility. He did not use standard Flannery-type flexible stays save around the lower connection of the syphons but experience of stay failures led to monel stays (which I assume were threaded) being introduced into the breaking zones. U channels were I believe only used on the WC/BBs. There are extensive and very interesting commentaries on the Bulleid design in Bulleid's own paper (to the IMechE I think, in 1945) and Burrows and Wallace' paper of 1958 to the ILocoE on experience with the boilers in service.

 

The largest component of monel is nickel of course which is around twice the price of copper.
It is strange we don't hear much in the way of appeals to finance monel stays. Perhaps they don't need replacing very often?

 

There seems to be progress at last.

https://mailchi.mp/a1steam/a1latest?e=49fa2d19c7

 

Great colour choice.

 

I can’t add any technical knowledge to the steel firebox debate, but IIRC the N2 currently has a steel firebox with welded stays, fitted during its previous overhaul.

 

"In October 2021 it was announced that the Gresley Society had launched an appeal for £100,000 after discovering that an exceptional number of items required replacement. The items included the pony truck tyres, crankpins, safety valves, superheater header and both smokebox and firebox tubeplates. In addition the firebox wrapper also needs to be replaced due to cracking around the crown stay holes.

The total cost of the overhaul at Northern Steam Engineering at Thornaby was forecast in April 2024 to be £650,000. Hydraulic and steam testing was anticipated to be undertaken in May before the locomotive returned to service in the summer of 2024."

 

So £600k for lots of stuff, only some of it is firebox-related.