Hi Keith
I have a very nicly made scotch boiler that i am completing that was built by an experanced model engineer who has since passed away. I am confident that it has been built well and I have been able to presure test it sucessfully. I have been unable to find any published boiler plans so cannot prove its design performance for getting a boiler certificate. Any advice on plans or how I prove the boilers performance would be great.
Thanks Rob

Hi Ron
Thankyou for your responce. In the UK the exemption as far as I understand is pressure vessels over 3 bar litres need to be tested if I want to run it anywhere other than my own property. This boiler is way above that being 7" diameter and 6" in length and a working pressure of 100 PSI. As prevously recomended I will read K&N Harris model boiler making to see if this explins things. I will also have another chat to club boiler tester to see if I can get some more clarity. I will try to document how l get on so others can learn as this information is not readily available.
Rob, as a place to start look for boiler exemption regulations in the jurisdiction of your residence. For example, I live in Alberta, Canada and the province of Alberta has a Boiler Exemption Act that describes what boilers are subject to regulation and inspection. You have a Scotch Marine Boiler. That is a fire tube boiler surrounded by a "hydropneumatic" tank. Today the word "hydropneumatic" is almost Old English but a hydropneumatic tank contains a liquid (water) and a gas (steam) at the same time. In Alberta, Canada hydropneumatic tanks with a diameter under 610 milimeters are exempt from inspection or regulation. Check your local regulations.
As a next step I would make a list of the dimensions and material the boiler is made from. Make a list of all of the fittings on the boiler and their pressure ratings. Then look at the completness of the information. The more blanks you have the harder it is going to be to qualify the boiler.
Like Keith I am not an engineer but I did spend 20 years working for EPC companies (Engineering, Procurement and Construction) and understand the process to qualify a pressure vessel.
Ron in Calgary, Canada
Hi the book by KN Harries mentioned in another post will be a good staring point so you can do the calculations yourself. If you are going put the boiler into a boat then my first advice still stands go and talk to the club who's pond you will be using.
My my my, two water glasses? That boiler looks stunning! I hope you can pass inspection, sadly now a days they hardly even inspect- all they want are papers.
Hi Mike, Yes plan to build a boat and run it in public. Ive been struggling to get a strait answer so thought I would ask here incase anyone had seen plans or could advise how to calculate the answers.
do you need to have a boiler certificate, are you planning to run it in public. As always talk to the clubs boiler inpector.
That is a beautiful boiler. Hope to see it in action soon.