It all begins from either recognized line drawings or customers sketches which we draw onto our CAD program and convert to G Code. This then allows our CNC plasma to cut the flat sheets including wrappers and barrel, leaving only weld prepping before forming and welding.
We follow BS EN ISO 15614-6:2006 welding procedure, and as our process is different from the conventional silver brazing technique, we do not require flanging of plates, so nothing needs annealing.
We use copper filler wire which is close to the parent material, including extra deoxidizing elements.
This allows us to construct the boilers in a way that other methods cannot due to the local heat input. Already TIG welded joints; we will not undo any of the existing work through overheating.
Stay arrangements are followed from recognized designs, but we also have safety guidelines in which we can cross-reference with to ensure adequate safety factors are met for the intended design pressure at that shape/size of the vessel.
We still braze the bushes in. These are machined from ‘PB1’ phosphor bronze, which, although with a high content of copper are capable of being welded to the boilerplate. However, we opt for brazing to BS EN 13134:2000 with 55% silver allowing the option of replacing bushes if threads are stripped later in its life.
Of course, with the rest of the vessel being welded, we do not find ourselves chasing cracked silver joints around as most of our customers will be all too familiar with.
Conforming to 2014/68/EU pressure equipment directive, all our boilers go out the door bearing CE marks (where required) and conformity and hydro test certificates to twice working pressure which is valid for the life of the boiler unless modifications or repairs that are integral to the vessel occur.