HRP Important Points

Created by: Administrator, Last modification: 05 Aug 2008 (15:06 UTC)

If your boiler has hollow stays for attaching the horn-plates, locate these hornplates on the boiler sides (preferably as a unit) and drill pilot holes for each hollow stay, using the hornplates as a drilling jig. Open up and thread through both sides of the boiler plates, making and fitting threaded hollow stays to suit the hornplate securing bolts. The boiler plates should be well countersunk and the hollow stays left protruding. (See Drg. 3.)

The hollow stays each side (where applicable), become a means of accurately locating the hornplates to the boiler. After brazing the hollow stays, accurately align the boiler on a large milling machine and end-mill over the top of these stays on one side; then turn over and clamp down, locating on the machined surface of the first side; whilst machining the stays of the second side, to the final width of the boiler firebox. (From your drawing.)

The drain plug bush may be left out until the final stage, making it possible to remove copper swarf.

After finally brazing up, carry out an air test with the boiler under water, pressure being applied by mouth through a rubber tube; this will show most leaks. Chalk mark these and seal with Sifcupron or silver solder (not forgetting to pre-heat). After a final satisfactory air test, carry out a hydraulic test to twice the working pressure. A suitable pump for this test is a hand pump of the type used in fruit spraying, or in fact, any suitable pump that will handle water. Of course, in this category are model boiler pumps and in fact the mechanical crankshaft driven pump of the model for which the boiler is intended. Having satisfied yourself that your boiler is mechanically strong, neatly made and free from leaks, you may then wish to apply for boiler insurance, and the following notes below will be of assistance. However, one should remember that often small boiler pressure gauges are not always constantly accurate and therefore, when you make your own hydraulic test it is always best to use a large gauge of known accuracy.