HRP Welding Steel Boilers

For obvious safety reasons it is definitely stressed that no one other than a competent welder should attempt to weld up a large scale model boiler. However, the job will present little difficulty to the skilled man; it may be that you wish to prepare your boiler for someone else to weld, and therefore the drawing No. 4 clearly shows practical ways of achieving good sound welds in the less accessible places. The side firebox stays should be flush or only very slightly proud before welding, so that no slag trap will be present on the underside of the stay as welded. The difficulty here is that the rod must lay at an acute angle. Any blind bushes should be finished with a very flat bevel, which with the countersink of the boiler plate will give easy access for welding.

Always remember, it is not sufficient to only seal a boiler but to achieve a thickness of weld at stays, plate junctions, etc., which will give ample life of the boiler; it is little use using y thick boiler plate and then having a 1/16" thickness of weld sealing the stays. Therefore, build stay ends up into a nice large radius and if countersunk make sure your weld has penetrated through, or nearly through, the boiler plate. (See also drg. 5.)