A younger member of our club had been given a rather nice stationary steam plant manufactured by ‘Doll et Cie’ of Nüremburg, Germany. The trouble was the boiler was ‘shot’! This is the story of the repair I put together with him.
The barrel is of very thin gauge brass with a rolled and soft soldered seam on the bottom.
The fittings screw into brass nuts soft soldered on the inside.
The coloured finish is effected by being dipped a chemical compound.
The barrel end where the water gauge fitted had perished with age and split. An earlier attempt at repair had failed.
The split can be seen running across the top of the lower hole for the water gauge. It also ran up the left hand side of the indent for the gauge glass.
An alternative solution to replacing the end was to produce an insert.
A brass disc was machined up to be a tight fit inside the endplate. A bush was made to replace the nut that held the drain cock, the bush end was soldered into the insert and the insert was then fitted inside the endplate and soldered.
The whole assembly was then pressed onto the barrel and the seam with the barrel was then soldered. This then meant that effectively the insert is the new endplate and is holding the pressure.
The bush projected through the front of the endplate and was soldered there too. This means the bush / insert combination isolated the original end plate from the contents of the boiler.
Again you get a clear view of the crack. A dummy water gauge and protector can be fitted to complete the external appearance.
The boiler was hydraulically tested to 40 psi with no problems.
Working pressure is to be set at 15 psi.
The safety valve will be set under steam.
The final job is to run the boiler with the steam plant so that the exact amount of fuel to use can be judged to ensure the boiler does not run dry and spring the soldered seam.
If we were in the least doubt about the safety of this boiler then we would scrap it and make another from copper. Safety first at all times.
Here is a recently added video of the ‘Doll’ in steam: