New York Central’s Niagaras suffered a malady I had never heard about. To quote Wikipedia: “failure of the highly-expensive firebox-wrapper metallurgy to withstand the conditions of actual operation. (reference: pages 172 ~ 173 The Great Book of Trains, Brian Hollingsworth and Authur Cook (Bedford Editions, Salamander Books, 1987).”
Firebox-wrapper metallurgy is a new one on me. How did the Niagara’s metallurgy differ from other modern steamers and why did it fail; how did it fail; why wasn’t it repairable?
Does anyone out there have some insight?
I presume they are talking about an Embrittlement of the Crownsheet and the upper parts of the the side waterlegs around the firebox. With the advent of what are called “Superpower” steam locomotives, problems showed up in the design of boilers and the metals used to construct them that weren’t a problem with older lower powered locomotives. With the high evaporation rates, dissolved oxygen in the water was causing the steels used to fabricate the crownsheet to become brittle and develop cracks. Quality control in the production of the steel used to construct the boilers wasn’t keeping up with the stresses produced in the newer more powerful boilers.
Edit: I mean the wrapper sheet not the Crownsheet, the dissolved Oxygen forms bubbles of pure Oxygen at the point of steam formation which then impinge on the surface of the wrappersheet embrittling the steel there.