Sunday, 2 November 2014

Blue Circle: Boilers And Tubes...

Hi all. Today was a quiet and chilly day at Shackerstone Loco Shed. I spent a few hours on this bracing afternoon helping Mick with his engine: "Blue Circle". The 2-2-0 Aveling & Porter Single, built in 1926, is now going through what would be a 10-year overhaul for a 'normal' railway loco. However, with "BC", things are easier to do. The boiler doesn't have to come out of the frames unlike a railway engine variant, as the boiler is pretty much the frame, with the cylinder block and water tanks being bolted to it. The engine therefore only has to be stripped as far as the boiler, with the tubes then having to be removed for the internal barrel inspection and retube. Today, myself and Mick were removing some tubes. The tubes had already been cut in the middle, with this process being made easier by the typical traction engine asset of a large 'manhole' door in the side of the barrel. The forward halves of the tubes had already also been removed via the smokebox. I think Mick said there were 37 tubes in his boiler, which actually originates from Aveling road loco types. The tubes are expanded into the tubeplates at both front & rear, and beaded to prevent burning away the ends. The tubes were removed today by forcing them through from the firebox into the barrel and then they were brought out via the manhole door. The best way we found was to grind away the beading gently, then use a bar in the end of the tube to gently (with good force!) wiggle it free. You have to be careful as you don't want to damage the tube plate but, with plenty of up & down motion projected by myself through the inspection door, the job went slowly ahead. Here we see a tube end being ground; the square shape is the firebox which you don't normally see as this is taken inside the barrel...
Here are some tube ends following removal. These are the rear ends of the tubes. The clean ends are where they were expanded into the tubeplate. The damaged ends are where they were cut in half...
Six half tubes following removal...
I tell you what, boiler work on standard gauge is hard work. I know we're only talking 37 tubes here but they are still tough. Its such a shame as well as the tubes we removed were not in very bad condition at all considering how long they've been in service for. The loco is very well looked after and treated correctly, therefore the boiler has lasted well. Unfortunately though, the internal barrel inspection does call for all tubes out and, naturally, they can't go back in once they're out...new ones are needed! Ahh well, such is life. I left today feeling like we'd done some good work and it was good to have Mick as company with his Aveling. All the best guys, Sam...

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