Pressure Test (December 2014)
Following the manufacture of the front wheels, my attention was drawn to fact that if this model is to be publicly steamed and probably more importantly ever steamed safely, then the boiler will to be tested and certified. The best option I found to do this was to join the local model engineers society as part of the privilege of being a member was access to experienced boiler inspectors. Beyond this it was also a good way to meet fellow model engineers, which I'm sure will come in handy as I tackle a build like this for the first time. The club I joined:
Bristol Society of Model and Experimental Engineers
To complete the test the engine had to be stripped down to the boiler, which was something i was meaning to do anyway to continue with the inspection and now was as good a time as any! The main difficulty I experienced from here was the shear number of holes that needed to be secured in order for the boiler hold pressure. The majority could be completed using 5BA screws and nuts with a little dob of gasket sealer. Whereas all the major steam fittings required brass bungs to be turned up:
Following the manufacture of the front wheels, my attention was drawn to fact that if this model is to be publicly steamed and probably more importantly ever steamed safely, then the boiler will to be tested and certified. The best option I found to do this was to join the local model engineers society as part of the privilege of being a member was access to experienced boiler inspectors. Beyond this it was also a good way to meet fellow model engineers, which I'm sure will come in handy as I tackle a build like this for the first time. The club I joined:
Bristol Society of Model and Experimental Engineers
To complete the test the engine had to be stripped down to the boiler, which was something i was meaning to do anyway to continue with the inspection and now was as good a time as any! The main difficulty I experienced from here was the shear number of holes that needed to be secured in order for the boiler hold pressure. The majority could be completed using 5BA screws and nuts with a little dob of gasket sealer. Whereas all the major steam fittings required brass bungs to be turned up:
Once all the holes were filled, I bought a small locomotive hand pump and mounted it in the base of a baking tray and made up a flexi hose assembly to join pump to the boiler. Whilst the pump was summered in water I primed the boiler, then capped it of using a suitable fitting and pressure gauge threaded into the steam chest hole, as is was effectively the highest point. I then slowly raised the pressure in the boiler, taking it up in small stages and waiting between continuing up. I must admit it tool several goes to, 1) get the clack valves in the pump to hold and 2) to the stop all the 'plugs' from weeping. However, after a bit of fettling the boiler was tight.
Now, this was a pretty nervous few minutes. My father believed the boiler had been tested when it was built, but there was no written evidence. The boiler is 30 years old and I had no idea of any issues that might have been found or worked around when it was silver soldered, and for obvious reasons if it was to fail then it would be a turning point for the project, as I was not mined to build another one, or to spend near to £1500 buying a new one. So I took a deep breath and cracked on to 200psi.
Now, this was a pretty nervous few minutes. My father believed the boiler had been tested when it was built, but there was no written evidence. The boiler is 30 years old and I had no idea of any issues that might have been found or worked around when it was silver soldered, and for obvious reasons if it was to fail then it would be a turning point for the project, as I was not mined to build another one, or to spend near to £1500 buying a new one. So I took a deep breath and cracked on to 200psi.
As I had hoped the boiler held fine and the pressure gauge needle sat quite still at the double working pressure hydraulic test. I took the opportunity to carefully inspect all the joints, rivets and seams with torch and mirror but could find no evidence of leakage - happy days. One thing the boiler didn't have was any identification marks or numbers so with a set of punches I permanently added these to just below the foundation ring. The numbers I chose were my grandfathers initials followed by 01, as at the end of the day it was his graft that built this boiler!
This bench test was only really the trial run, in preparation for the 'real' test which was to be completed in front of the boiler inspector. So now knowing that the boiler was sound I made the necessary arrangements with one of BSMEE's boiler inspectors and took the boiler for inspection. Thankfully after a careful few minutes of checking the drawings and presented boiler the inspectors were content, so pressure was built, held for the required 10mins and the certificate was written. This really was turning point for the project as it now gave me added enthusiasm to carry on with the build, safe in the knowledge that the boiler is sound.
This bench test was only really the trial run, in preparation for the 'real' test which was to be completed in front of the boiler inspector. So now knowing that the boiler was sound I made the necessary arrangements with one of BSMEE's boiler inspectors and took the boiler for inspection. Thankfully after a careful few minutes of checking the drawings and presented boiler the inspectors were content, so pressure was built, held for the required 10mins and the certificate was written. This really was turning point for the project as it now gave me added enthusiasm to carry on with the build, safe in the knowledge that the boiler is sound.