Saturday 10 May 2014

Another day of superheater element removal, a bit easier this time round as we knew what we were up for. The last two rows of seven (a total of 14 elements) were removed and now onto the small tubes.

To explain how to remove the small tubes its probably best to explain how they were originally put in. Basically its like this;

1. Each tube is cut to the correct length allowing for the correct amount of overhang at both ends.
2. They are inserted into the boiler from the smoke box end and starting from the bottom row inserted through the tube plate. The far end of the tube is pushed through its corresponding hole in the firebox tube plate. This is repeated until all tubes are fitted.
3. The tubes are then set with the correct amount of overhang at the firebox end to allow for beading.
4. Each tube is then expanded until its tight against the tube plate. Regular checks to ensure the tube has not moved whilst expanding upsetting the beading allowance. Repeat until all are expanded at the firebox end.
5. The smoke box end is then expanded.
6. The fire box end is then beaded over to form a smooth rounded edge.

   

   Beading The Tubes

7. The tube is then sealed with a bead of weld.

To remove you basically do the reverse. The bead/weld is removed, the inside of the tube is warmed up which allows it to shrink when it cools down and then the tube is punched out with a special drift or punch. They are removed from top to bottom so the tube can rest on the ones below as your sliding them out.

Sounds easy doesn't it, but again its hard work.

We removed some of the top rows before we called it a day.