Hi Charles,

I am not sure if there is actually a spec laid down over here for
metal thickness versus boiler size. However, the 'standard' seems to be :

barrel, wrappers, and crown stays - 16swg (1.6mm)
Smokebox tubeplate, throat plate, backhead, firebox plates - 13swg (2.5mm)
Tubes - 18swg or 20swg (0.9/1.2mm)

For a small boiler you can get away with 16swg for the throat plate,
firebox tubeplate and firebox door plate. Makes flanging the plates
much easier as well. I've read that the only reason for using 13swg
for the backhead was that LBSC used to thread his fittings straight
into the copper without using bushes and the thicker metal gives more
thread. I would not recommend that practice nowadays though!

John




--- In halfinchlivesteamforum@..., "charles"
<mortimer@...> wrote:
>
> what is the british standard of boiler thickness to obtain a
> certificate on 2.5 gauge is it 2mm thick or code l 3mmthick tube just
> checking before i buy some copper
> charles australia
>