Facing the challenge of finding a way to weld fully welded body Ball Valve.
The matter is that, ones the valve is opened and the seat replaced, the body must be welded again without damaging the seats with high temperature welding.
As it can be seen from the attached pictures, the welding is supposed to be really close to the seats.
There is bound to be some low thermal conductivity gel or fluid that can be put in through the bleed port(s) and then either flushed or solvent washed out.  Maybe just mineral oil.  Or possibly a cooling water/fluid circulation in the cavity while welding, with the valve standing on end and the welding taking place at the lower end.
mention any size,pressure class, fluid or size, but as seen from the picture it ssems to be a valve of some size and probably a higher pressure class? Depending on details some possible solutions could be suggested,
Some questions are obvious:
How was the sealingsa protected when originally welded into the pipeline?
Possibly other solutions than the obvious 'cooling down'? (other materials, other sealings,mother product within practical and economical limits?)
Dry-ice? (Frozen CO2)

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