It isn't often that you see the inside of a steam locomotive boiler. Usually, we see their innards only once a year as part of their annual inspection (by law) for the Federal Railroad Administration.
After removing the decorative sheet metal housing over the steam dome, we undo about two dozen big nuts that hold the thick steel cover in place, and keeps the steam inside the boiler. Once the cover has been lifted off by our hoist, it is possible to wiggle down into the steam dome, past the throttle valve and end up laying on your back or belly on top of the boiler tubes and flues to begin inspecting the inside of the boiler.
We look for build ups of scale (residue from minerals in the water) and for pitting, especially on the tubes and flues (from oxygen in the water). Occasionally, corrosion from stress and/or impurities in the water might also be found. Inside is where you can really tell whether or not our boiler water treatment program is working or not (it is!).
The upper photo is No.3025, quite clean after 295 days in service since we finished rebuilding it in 2010. The lower photo is No.40, showing a bit of scale buildup (but little pitting) after 1338 days running over the last 14 years.
We are allowed (by law) to operate a steam locomotive only 1472 days within a 15 year time period. Then we must remove the boiler tubes and flues so we can clean and inspect the entire interior of the boiler. Once inspected, tube and flues are installed and we start the cycle over again.
One of the reasons that railroads stopped using steam locomotives was that they are very labor intensive machines. But we love them and care for them and use them to teach a new generation not only about their beauty, but also about the skills needed to keep them running.
J. David Conrad