Hi rbohlsen. You have a couple of good thoughts there. The top...

Hi rbohlsen. You have a couple of good thoughts there. The top sleeve welding technique you propose sounds a stronger approach than just a straight single-welded termination.

I don't see where it helps to contain the large compressive forces further which the whole case is subject too. Not sure I have fully grasped your idea.
Wouldn't it be nice to be able to draw sketches here.

The second suggestion sounds like you are proposing a form of telecopic expansion mechanism with the final bore case tube sliding inside a slightly larger outer casing that is cemented into the granite. Sounds good to that point. Have I got that right?

If so some mechanical means has to effect a final dynamic seal between the two tubes.
In commercial type expansion units a convoluted steel 'bellows' is usually employed.
a. The amount of travel per unit is small, say 50mm, they just use more units to get the compressive distance required.
b. The bellows is usually stainless steel but this component has a life and needs replacing. Not easy in our case.
c.Could seals be achieved with O-Rigs or packings? Doubtful and again are not maintenance free.
d. Have I completely missed something in your idea? 'Cos
in essence it sounds good.I just can't see the 'seal'.

This has reminded me of a thought I had on first contemplating this (GDY) report. It's a real bitch as in steam or HP hot water systems they always provide plenty of isolating valves so you can turn off the flow to service something. Even in your domestic water supply you have some like at the hot water heater to make replacing an element easier.


GDY don't have the luxury of this. Having one at the bottom of the hole would be great.
Can't even shut the boiler down and leave it cool off. Nope. The God given heat is just gonna keep on comin'.

geojac