Being a Mechanical Engineer, I have a lot of curiosities about stuff. Last evening I wondered about the techniques used to attach flue tubes to the firebox and smoke box boiler sheets. My thought was that one end of each flue tube would be fixed to a sheet, and one end would be an attachment that enables axial thermal expansion of the tubes and thermal distortion of the sheet to which it is attached. Today I found this:
Near the end of the document in the link, there are sketches of various flue tube connections.
So I am asking, what is the flue tube attachment techniques used in later steam locomotives like the 4014, the 765, the N&W J, etc?