A bit below the racehorse, I found this. So it's a corrosion-resistant copper-based alloy – I suspect the next issue would be finding a supplier.

Rob

Edit – must type faster!

Links to https://dl.asminternational.org/alloy-digest/article-abstract/5/5/Cu-38/438/TOBIN-BRONZE-452Corrosion-Resistant-Copper-Base?redirectedFrom=fulltext

Edited By Grindstone Cowboy on 02/11/2022 19:11:44

The AMBSC code allows the use of Tobin bronze brazing in boilers. You may use an unflagged joint between the throatplate and barrel, so long as the throatplate is set inside the barrel opening, not butting onto its outside. The reason is obvious. This saves a double flanged throatplate and is what I always do. Bronze brazing isn’t much fun as the copper must be glowing orange before the rod will flow and I find it hard to see what’s going on. The Code states that only those experienced in bronze brazing should use it, but how do you get experienced?
I have wondered about dezincification. Presumably that 1% tin makes all the difference.

The AMBSC code does not permit TIG welded copper joints except by suitably certified welders.
A beginner should do quite a few practice joints when beginning to silver solder. This is especially so for bronze brazing where you risk overheating the copper. You really need oxy-propane/acetylene for bronze brazing, although propane will do the job for an isolated assembly such as foundation ring section to inner firebox wrapper as a first operation. I would always prefer high temperature silver solder if I had it in stock.

Is that actually weld on the first photo, colour of filler rod looks more like it was TIG brazed?

Would be interesting to see if the other side was a better "weld" as access may have been a bit tight from the side where the photo was taken depending on scale of job.

Edited By JasonB on 04/11/2022 07:22:39

Its a big job, those bent plates are 10mm thick. Other side looks like this…

The paint is for specific testing.

I have made my thoughts on this clear before ! BUT there are good and bad professional welders as there are good and bad amateur welders. Luker says it all when he mentions his club inspector and him being a practical man !

where or how do you draw the line ? Noel.

I agree; as with anything there is a standard distribution, my sample set is very much skewed to one side (if there was any doubt, amateurs win!).

The line should be drawn by the boiler inspectors. It’s their job to determine if the boiler is fit for purpose by testing etc. I think the same onerous criteria for welding qualifications should apply to the boiler inspectors. In other words, they should be highly qualified and/or certified, with practical experience in building boilers. Let’s just peg it to a few tertiary engineering degrees and they must have, at least, completed 5 boilers to qualify! Seems a little ridiculous?

In ME 4702 21 oct-2 nov pgs 569-571 there are drawings for the Ballaarat copper boiler. In my copy, all the object lines in the views are coloured light grey, along with the crosshatch. This essentially makes the object in the views invisible and the drawings are completely useless. The dimension lines are black as expected.

ME editors – are you aware of this error in some or all copies? will you be publishing usable drawings in future?