Thank you George, I find this all fascinating ! Am I right in thinking this would have to be engineered to withstand & supply full line (tube) pressure ?? I would also note this rating is for "seamless" s/s of adequate wall thickness tube, which is of course temperature dependant (see Table 24—Elevated Temperature Factors).. I've taken the liberty to add some data below...
http://www.swagelok.com/downloads/webcatalogs/EN/MS-01-107.PDF
One of the problems with most people when they think about flash steam is to try and calculate all the different possibilities some of which I think are impossible to do and you can get bogged down in theory rather than cutting metal..
When I started out I went to the Mitchell Library in Glasgow which has the finest ref section in Europe and hunted out all the articles that were highlighted in EXPERIMENTAL FLASH STEAM and could be found in back copies of M.E..
Eventually I arrived at R.KIrtley's write up on his boat PISCIS 11 which at that time was doing 100 mph. all my work has been empirical and following what Bob and others before him had accomplished, All the varying metals that had been used were listed so I followed on their footsteps.
Some of the metals on my first engine were not available in small quantities so I had to improvise.
For instance I tried all sorts of materials to make the Poppet valve and seat, I found that Silver Steel oil hardened worked reasonably well but eventually softened as the high temperatures hit it and I had to constantly make new valves and seats.
When I made the new bigger bore engine I used Bob's method of machining the valve and the seat from the exhaust valve of a Cummins Diesal Engine and to date , as I and Bob has found it has been totally satisfactory.
I have never tried to calculate the steam pressure in the Stainless Steel coil I only know that Bob has used this for years and if it's O.K. for 120 mph it's O.K. for me.
It really is hard enough to get the steam plant working but the challenge was just too much for me to ignore and as when I was in business I never had much opportunity to do machining, only design work, so this was the challenge to make some thing and make it work.
Flash Steam is the most infuriating subject and there have been many break downs and repairs, it is not for the feint hearted but when you here that roar of the burners and the boat takes of it's worth it.
I have loads of pics but have not found out how to resize them so if you are interested have a look on my club web site and you will see some of the pics of the new engine (
www.glasgowrichmondmbc.co.uk )
George.