Well, the way to get the post back on topic is to get it back on topic. Here is a first question, the report says this:

Since no decision could be made regarding the future
of either the inner or outer firebox crown sheets until the
box was removed, it was necessary to perform this work
in a manner to minimise damage to the plate or stay
holes. The simplest way was to remove the nuts as in
the previous image and wind the stays out with an air-
powered impact wrench.

(I don't know if Australians spell minimize differently than we do, like labour or colour, or if that was a typo).

Anyway, the question is, was this a logical way to proceed, or is it actually possible to tell if the inner or outer firebox crown sheets need replacement without the above labour-intensive process?

Not sure if NDT procedures are permitted in Australian code. Here, we'd usually do a visual from inside with tubes removed and through washout holes and external visual combined with ultrasound thickness readings. Areas that were still questionable would be examined more closely with radiographic or other means before heavy disassembly.... but considering there's much more of a history of copper inner fireboxes down under it may be an artefact from that era? One thing for sure - there will be no question about the quality of the boiler when they are done.

Kelly Anderson can tell us just how short this procedure might be when using the 'death ray' - unless I'm mistaken, all that's necessary to demonstrate that the inner or outer sheets are bad is to find excessive defects in the gridded ultrasonic scan, before you have to waste any time pulling tubes, working borescopes and light sources around in cramped quarters, etc.

PMC,
No, it's not a typo. Americans call it "zee', we call it "zed".
Australians (or at least those who haven't been totally captivated by American culture) tend to follow the English spelling of most words, but that's slowly changing, unfortunately. The English spelling tends to use an "S", whereas Americans use "Z"
There's quite a bit of dialectic difference between us. Many years ago, I worked for Borg Warner and we had a supplier who's name was Randy Root.
Now I don't know how much mirth that will cause in America, but over here, it has people falling off their chairs with laughter every time I mention it!
Cheers, Bob

Yes, a little mirth here in Connecticut this morning!

As for "Zed", over here it's probably best known from "Pulp Fiction"-- "Zed's dead, baby."

Take it easy,

Howard P.

Howard, scary to realize that we think the same way. "Baby, honey, we've got to hit the f***in' road!" is from the same scene. I often invoke that line when my wife is delaying our departure from the house.

Regarding removing the firebox for inspection, that does seem extreme, but as mentioned above, they know it will be right when completed.

I donno, Howard. You guys have a Central Vermont single sheathed boxcar in your collection, right? You know you can't properly repair a Canadian boxcar with Zee bars; you have to use Zed bars.

I would be interested to hear a line of reasoning for dumping all the known advantages of an all-welded firebox and their plan to revert to the antiquated, all riveted firebox seams.

"September 7 at 10:00 PM ·

This weekend, Transport Heritage NSW completed the first steam test of locomotive 3801's repaired boiler.

This was the first time 3801's boiler had been fired up in more than a decade, with its original full working pressure restored to 245 psi.

Here's a look at our team at work over the past few days during this historic milestone."

https://www.facebook.com/TransportHerit ... tion=group

I can ALMOST make out the wheel arrangement of the 3801. Either a 4-6-2 or 4-6-4. Can anyone advise?

Les

Pacific 4-6-2. See https://en.wikipedia.org/wiki/3801

Great news - beautiful job.

This was a cautionary tale on so many levels. I only hope the 'true' history can be documented so that organizations can avoid many of the 'situations' that led up to this. That doesn't take away from the triumph of success, and perhaps the retention of original fabric and technology.

The 3801 is a lovely engine.
Not to derail this thread, but there is an older thread with talk on welded boilers:
viewtopic.php?f=1&t=37786
Has anyone found Canadian Pacific mechanical or engineering notes on the success of the two welded-boiler G-5 Pacifics, numbers 1216 and 1231 built in 1946. It would seem that CPR must have been up to something to try the welded boilers. One assumes they kept notes. It was too late in the game to be replicated, however.
Incidentally, there is some concern with early deterioration of welded boilers in traction engine service. In the longitudinal seams, especially on boilers where the seam is placed at the bottom for cosmetic reasons, the metal is showing inside the boiler wastage on both sides of the seam from the change in the metal structure during welding.
Also, new boilers had to be stress relieved until recently. This is evidently no longer required - is that advisable? The stresses inherent in welding steel are self evident if you have ever welded.
Riveted boilers will gain small leaks from operational stresses, but can be easily repaired without need of professional services. Welded boilers will always need certified repairs. Repairing, maintaining, and preserving the original boilers, when possible, seems like a better long-term solution.
Thank you for any information.

Even riveted long seams were usually placed above center line - preferably above water level - to avoid just that issue of wastage at the bottom of the barrel. Given a riveted seam was not as efficient as the metal. good practice, but with welded seams being able to be at 100 percent efficiency, unless heavier than necessary metal is speced, any wastage becomes an issue (consider PRR Belpaire wrapper sheets as a non welded example) so....... your mileage may vary and you damn well better maintain your water chemistry and washouts perfectly. Puffing Billy did this sort of experimentation unintentionally a couple decades ago I understand - they had been replacing whole riveted boilers rather frequently, but when they started installing new welded boilers instead of riveted found they only had to replace fireboxes but could keep the rest - very favorable comparison. I think it comes down to careful engineering, construction, material selection, and of course maintenance.