zboss:Th reason HP steel tanks need 300 bar valves (i believe) is because the 1st stage regs need to be able to handle this high pressure and the 200 bar valves don't have enough threads to securely tighten the reg to the valve. It was found that the yoke connection made to a 300 BAR valve using an adapter had a high rate of failure.
A yoke will not fit over a 300 bar valve as a safety measure. Also, as far as a mechanical fitting, the two extra threads don't make much difference in HP tanks used here. For true 300 bar tanks (4350psi), it would provide more safety.
I have no problem putting 3500 psi throught my 232 bar manifold.
MD