P2 Locomotive Company and related matters

Why would a stay on the RHS of the firehole be easier/harder to replace than the same stay on the other side? The reason for the asymmetry is probably much simpler - for whatever reason, they didn't have sufficient flexibles and placed the five stays required away from the corners.

 

Er..... I hope that no inner firebox ever gets near 600C, even for a short time. If it does, its time for serious panic. The plates are kept relatively cool by the boiler water. Even allowing for a temperature gradient between the flame side and the water side I wouldn't expect it to exceed 250deg.
I do wonder whether the number of flexible stays being installed on this boiler is overkill. I can understand the need for them where copper fireboxes are in use but the differential expansion between steel inner and outer fireboxes is going to be a lot less. I doubt that there has been any FEA carried out (although happy to be told that's not the case) and I suspect it is a jerk reaction to the problems casued by the effectively short stays of the original boiler.

 

I really hope boiler makers are not making design changes on the fly like this because they haven't ordered the right parts. If they are, a great deal else comes into question.

 

We are talking about five stays difference!

 

I'm talking about the underlying engineering practices - if changes are being made on the fly like that, it makes me ask what else I should worry about.

 

Flexible (socketed) stays with a copper firebox? The nearest you get to that is a copper stay. Most likely, the copper firebox is the flexible part.

 

That's something I've never thought about and, when I do, the only flexible stays I've had any involvement with have been on steel fireboxes. Is there a reason why they wouldn't be used on a copper box?

 

I would be utterly gobsmacked to hear that an ISO9001 registered boilermaker had changed the specification unilaterally because they were a piece short.

 

A copper firebox is much more malleable than a steel one. HBSS make their copper firebox sections with a former and a (large) hide hammer!