Hi all
Just to try and explain to Colin Bishop and Bunkerbarge and others, the principles of a high pressure rotary coupling, which, has been around from day blonk.
This setup is very much on the same principle as a gland on a steam valve. The only difference being is the spindle in the valve is actually a machined pipe, which is represented by A in the drawing below. This can rotate 360 degrees and the graphite packing is quite capable of taking higher pressures than 10 bar (1 bar = 14.6 psi approx (if my memory serves me correctly). This type of application of swivelling joints has been used, and is used, in areas that use super-heated steam as well.
I do suspect that the main boilers on the General Havelock would have operated in the region of 80 psi and something like 120 psi. She would have carried what is known as 'Donkey Boilers' smaller boilers to supply steam for deck machinery, therefore avoiding draining too much steam from the main boilers.
Hope this is of some help.
Aye
John E
Bluebird