mark s
Thanks for the info. I have the McQueen book but have not yet absorbed all of that detail. I may also have the Trains article on the 3100 and 3101-will have to look.
On NYC, the RR tried double riveting and even triple riveting on the J-3's that originally ran at 275 psi and were reduced to 265 psi. The welded J-3 boilers were 1/2 inch thicker than the original boilers based on drawing references such as the arc for the sand dome listed as a separate drawing group. It seems that almost every RR had problems with at least one class of power, the PRR Q2 comes to mind.....
I also enjoyed the information provided in this thread. Thanks to all.