60007 (4498) Sir Nigel Gresley Overhaul

Let me explain. A tube expander is a series of hardened rollers around the periphery of a steel 'cage'. This is inserted into the tube end (with plenty of oil) right up to the flange on the expander and a tapered mandrel pushed into the expander. There is a square drive on the end of mandrel which can be turned, slowly, by a hand ratchet or a windy drill. As the mandrel turns it screws its way down the expander pushing the rollers out as they turn. This pushes on the inside of the tube wall which expands sealing it in the tube hole. You can see the tube deforming as the expander is turned so tubes are best annealed first. Sometimes the tube may be swaged down and/or jumped up for several inches at the end. IIRC the ones on a Jinty were 1 3/4" dia swaged down to 1 5/8" at the firebox end and jumped up to 1 7/8" at the smokebox end. The idea being that the tube is easier to remove when covered in scale. The expander must be long enough to expand the tube for the full thickness of the tubeplate which is why tubes are trimmed to only leave 3/8 - 1/2" sticking out. The whole process is easier to do than describe, and if doing it by hand, one gets arm muscles like Popeye.
On firebox tubeplates (and on some smokebox tubeplates) the tubes are beaded over onto the tubeplate using a beading tool - the "hook shape" you described. This can be done by hand or machine.
The idea of beading is two-fold, to stop the tube end burning away and to protect the tubeplate. Hope this helps.
Ray.

 

More or less. Rolling is the term used in the US; we tend to say expanding in the UK but it is the same thing. The sealing of the tube to the tubeplate is done in the expanding process. The beading of the tube ends is to prevent them burning away. In the US beading is still quite common on industrial boilers but rarely happens in the UK where we tend to go for welding. You can't do this with a copper firebox on a loco boiler so it has to be by means of beading. Fitting of ferrules to protect the tube end is an alternative to beading but it is a long time since I saw this done with a loco boiler.

Edit, Marshall5 just beat me to it.

 

Thanks to you both marshall5 and steve for that explanation on this subject. I've been looking all over Google sites to see if I could find anything about tube fitting. I came across a few You Tube vids on demos. Mainly Yankee boiler smithies fitting tubes and showing how rolling and beading is done.

 

Thanks for the very interesting technical explanations above.

 

More on tubing. You've mentioned tubes being swaged up and tubes being swaged down. Main line loco practice is generally for the tubes to be swaged down at the firebox whilst industrial loco practice is generally for tubes to be swaged up at the smokebox end, although, as you say, both can be applied. The advantage of the former is that the ligaments between the tubes are larger, making them less liable to fracture whilst the advantage of the latter is that the tubes are generally easier to remove when covered in scale. The diagram below shows the difference between two otherwise identical tube arrangements.

 

Like Kylchap, thank you all for the explanations, tis so good for me to be able to increasingly understand the technical side of our passion.

Chris

 

The advantage to "mainline practice" is increased heating surface, as for a given size of tube holes one gets to use tubes which are a size larger.

There are also locos about which have the tubes swaged down at the firebox end, and swaged up in the front tubeplate (the front tubeplate is often very thick, which then permits a certain amount of reduction in the ligaments size) - to some extent this arrangement is a "best of both worlds".

 

From the SNGLT website (members area) today...


Update 24 April:

The overhaul of our locomotive achieved a significant milestone yesterday when the boiler successfully passed its formal hydraulic test to the satisfaction of our insurers. A steam test will follow shortly. The superheater needs to be re-fitted after which the boiler will be moved to York and reunited with the frames. It is envisaged a further in-frames hydraulic test will be conducted during the re-assembly process to reset the clock on the ten year boiler approval.

 

Thanks for spotting that, good progress for a much needed A4 working presence.

 

Any news on when a move of 60007,s boiler is moved back to N.R.M.? Then early to mid summer im presuming if a out of frames steam test is to take place.
Good news on the hydraulic test.

 

Not yet. Be patient!

 

Ok john.

 

Snap! Got my 5" gauge LNER V1 2-6-2 tank loco boiler hydraulically tested successfully today by the local model engineering club.

 

update from rail advent 28th/5/2019 written by jamie duggan issue 40 engineering update on A4 60007 S.N.G. latest restoration work of tender and middle valve gear components and more......
Check the link above Davo 56F.

 

A fire was lit this morning to warm up the boiler in readiness for its steam test.

Bob.

 

Boiler steam testing has started at Llangollen, this is part of a series of tests leading to the formal insurance test when the superheater header has been fitted. The fire was first lit on 23rd May 2019, 60 years after 60007 set the post war speed record.

 

Just one quibble with this. From my experience isn't it more of a case of the tube being initially rolled and expanded so that it is in contact all round with the hole in the tube plate, then being squeezed between the rollers of the expander and the tube plate, which results in the circumference of the tube being stretched and thus made larger in diameter to effect a seal? A bit difficult to find words to describe the procedure, but hope you understand what I mean.

 

Reaming the tube ends?

 

Expanding a tube to fit a hole in a tube plate is not reaming as I understand it, which is finishing a hole to a precise size

 

Do you mean beading-over?


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