Ted,
315 was built in 1895 and had a steel lap seam boiler when delivered by Baldwin. In 1923 she was rebuilt with a new firebox that used a different crown stay design, removal of two tubes, installation of two new front flue sheet braces, new front and rear flue sheets, installation of a steam dome reinforcement ring, reinforcement plates on the longitudinal lap seams new and rear door sheet braces. After the modifications 315’s boiler pressure was raised from 145 psi to 160 psi with the required factor of safety of 4.
When we tested the steel barrel I ran carbon and sulphur tests. I was surprised at how low the sulphur content was in her barrel plates, indicative of relatively clean steel. The carbon content was about where we expected.
As far as I can tell the two cylindrical boiler courses and the outer firebox wrapper sheet and the outer door sheet are original to the 1895 construction. The front and rear flue sheets and all the inner firebox sheets were replaced by the D&RG.
Scott