REMOVING STEEL BOILER TUBES

Gentlemen, A dear friend has a foster 3" or 4" traction engine he built about 25 years ago. He is not in the best of health and needs the boiler tubes replaced and to that end I have offered to help or do the job. The plan is to machine up a fitting which will fit inside the old tube with a slightly larger diameter to sit on the end of the tube to be removed, though just smaller than the tube o/d. A length of 16mm threaded rod with a nut on it passes through the tube into the smoke box where a section of tube of just larger than the o/d of the tube to be removed is used as a spacer and a hollow hydraulic cylinder on the end retained by another nut is used to pull out the fire tube. The hydraulic cylinder will develope about 5 tons pull. My fear is that if the tube does not move then damage may occur to the tube plate, though there is a pressure gauge on the cylinder so the applied force can be read. Or how else can I get the old tubes out .I have oxy/ propane and am skilled in it's use. Any advice on this job will be a great help. Noel.

Hello, not really any help but there was a write up in one of the ME magazines a short time ago.

i cannot remember which edition it was but i am sure someone will know.

If i remember correctly is was over 2 editions.

Don't confuse me with someone who has actually done this but the full size boys drill them out I think. As far as I can see the principle is the tubes are expanded into the hole in the tubeplate so the holes are larger than the tube diameter to start with. Once the tube has been drilled nominal diameter they should pretty much fall out. I assume they are not welded in otherwise your plan will fail anyway.

Don't just take my word for it but ask the full size boys.

regards Martin

The difficulty is getting a drill into our size fireboxes and not having a decent size manhole.

As Brian says there was a good 2 part article in ME though I think it was a bit more than a short time ago, can't find them at the moment.

In ME vol 196 (2002) issue 4267 Dennis Herbert of the Elmdon MES describes the retubing of a 7 1/4" gauge Highlander locomotive with a steel boiler which may help.

Edited By Nick Clarke 3 on 18/09/2020 19:57:57

[This posting has been removed]

First part was in 4396 by Chris Gunn, second part in 4401

Edited By JasonB on 18/09/2020 20:19:32

Well found, was a very interesting read.

Having done the full size version on several locos, I can assure you that the tubes do not "just fall out" after drilling. There is a small matter of scale on the tubes and they can be a swine to get out!

Andrew.

Quarter or Third scale isn't all that smalll Jason. Just a little concerned about the strain on the plates particularly as less and less tubes remain. It must be possible to come up with some rig to drive a cutter in the firebox from the smokebox end a but like counterboring on the underside of a plate with the mandrel passing through the hole. Once most of the tube thickness has been removed it must make it easier to pull out.

As I said I haven't done it but it sounds like Noel hasn't either. He is brave to volunteer in my book, but sensible enough to find out all he can first. Best of luck Noel.

regards Martin

Noel, I hope you can get a copy of the 2 articles I wrote longer ago than we all think, but to answer your question, I ground the ends of the tubes back to the firebox back plate, so any swelled tube ends were removed. I could get in with a 4" disc grinder to get most of the corner ones. Today i would use a power file as well to get in the corners. At the front I made a bar to fit the tubes, and fitted a boring tool to it, and adjusted it to remove most of the material in the bore just about 1/2" in. I was surprised how easily it cut using a power drill. then I used 16mm studding to pull the tubes out, and they came out OK. However it is easy to strip the studding if you get a tight one. If I were to do it again, like one of my fellow club members this year, I would use a hydraulic puller. It has been a bad year for tubes in our club, a 3" McClaren, a 3" little Samson and a 3" Allchin have all been done more or less this way.

Chris Gunn

Agreed

H

That's why some of them have the front end swaged a bit bigger so that once you've got them clear of the firebox end and a few inches out it becomes a lot easier

Edited By duncan webster on 18/09/2020 21:29:18

Would it be a good idea to de-scale the inside of the boiler first ?

Getting the old tubes out of the boiler can be a real pain. Done it on a couple of full size engines with 1 1/2" and 1 3/4" diameter steel tubes.

The end of the old steel tube was cut from inside of the tube and just behind the tubeplate at the smoke box end with a plasma cutter (or oxy cutter) taking care not to damage the tubeplate. (suggest using a Dremmel with a cutter disc for small tubes). The stub end than removed by crushed with a chisel and hammer.

A length of pipe then inserted thru the smokebox tubeplate and boiler tube to sipport it while the tube end in the smokebox was also crushed with chisel and hammer and the tube withdrawn thru the smokebox end. The pipe used to guide it thru the hole.

Holes in the tubeplate are normally a clearance fit with the tube and with a bit of pushing and pulling it is possible to scrape off any scale on the tubes and remove them from the boiler.

A possible problem which you could have with just trying to remove the tubes with a hydraulic puller is not only the force on the tubeplate but if they buckle behind the tubeplate inside of the boiler.

When I built my boiler, I added a large inspection hole in the tubeplate at the firebox end. Then all I have to do is to cut the tubes at both end inside of the tubeplates and slide the old tubes thru the inspection hole. And remove stubs in the tubeplates.

Paul.

I'll bow out now there are commentators with more expertese than me posting.

(Whilst it seems they won't just fall out after drilling just trying to hydraulic them out is fraught with danger).

regards Martin

I had a couple of tubes crumple as they came out, if one uses a mandrel that is as good a fit as possible in the bore this stops the tube crumpling. Then one must make a drift and knock the bent tube back in the boiler, and hook it out of the mud hole, and cut bits off it untll you can get it all out.

Noel do not be put off, it can be done with patience. However if you are not happy to have a go there are folks out there who will do it for you, at a price of course.

Chris Gunn

Quick question for those that have replaced tubes. Does the boiler then need a 2 x WP test and if so do all fittings need to be removed for that and plugged? Then the usual 1.5x WP with it back together and an accumalation test or just the 1.5x?

Jason - as I am neither your, nor the OP's, boiler examiner I cannot give an authoritative answer but the current test code states -

"Any structural modifications shall invalidate the initial shell test and necessitate a re-examination and re-test at TWICE Working Pressure (2xPW) for both copper and steel boilers"

and subject to another opinion from your tester I should consider re-tubing a structural change as the tubes will provide support to the smokebox and firebox tubeplates.

I was wondering how you might repair any accidental damages the tube plate holes ?