Step 3: Chop the top off
If you can get a spanner around your valve I would recommend heating the bottle where the valve connects, they seal these valves with a liquid weld which will return to liquid when heated up, this will make it a little easier to get off. I would also recommend using a length of steel pipe on your spanner to give you extra leverage.
ok back to the cutting, you need to allow enough on the top of the bottle for about 2 inches of refractory, I measured up 5 and a half inches from the top of the centre seem and marked them with a mark pen.
cut along the marked line using your angle grinder with a cutting disc, I managed to con my brother in to doing most of the work for me while I cooked him dinner ;-)
once the top has been cut off grind off the sharp edges with a grinding disc
here is by brother grinding the sharp edges off.