In this C&NW #1385 update, we get a glimpse of the process of installing tubes in the boiler.
The tubes are installed by sliding them into the holes on the tubesheet. Their outside diameter is just slightly smaller than the holes in the tube sheet. However, in order to have a water-tight and steam-tight seal, there can’t be any gap. This is achieved through a process called rolling.
In the rolling process the tube is actually expanded from the inside using a roller. The roller presses the end of the tube against the hole in the tubesheet tightly enough to form a steam-tight seal. The end of the tube actually sticks out of the hole a specified amount. The portion that sticks out is then curled outward and back until it touches the tubesheet in a process called beading. If the end of the tube were left hanging out by itself it would soon overheat and burn off or crack. Since the beaded end of the tube is touching the tubesheet it will transfer some of the heat back into the tubesheet and not get hot enough to burn off or crack.
A Continental Fabricators employee trims excess tube material from the front of the boiler. Additional employees are on the firebox-end rolling and beading the tubes. Photos courtesy Continental Fabricators.
Additionally, the arch tubes have now been installed. Arch tubes provide increased firebox heating surface area and allow better circulation of water in the areas surrounding the firebox. The arch tubes also serve to support the brick arch, a series of firebricks that help direct heat from the fire more evenly throughout the firebox.
Arch tubes inside the 1385’s firebox as viewed from firebox door. S. Roudebush photo.
Wrappersheet around the firebox showing the stays, arch tube plugs and the external combustion air inlets S. Roudebush photo.
Detail view of wrappersheet showing the stays, arch tube cleanout holes (with plugs removed) and the external combustion air inlets. S. Roudebush photo.
With the tubes now installed, a countdown clock has begun to tick. A boiler must be disassembled for extensive Federal Railroad Administration mandated inspections every 15 calendar years or 1,472 days of operating – whichever occurs first. Once the first tube was installed, the FRA gives a 1-year grace period in which to complete work before the 15-year time limit begins. If the locomotive is completed in less time, the 15-year clock starts once the FRA accepts the locomotive for service. If the locomotive is not accepted for service within the 1-year grace period, then the 15-year clocks starts anyway. This greatly incentivizes owners of locomotives such as Mid-Continent to not install tubes unless they feel confident the locomotive will be ready for operation in one year or less.
The next step for C&NW 1385’s boiler is the hydro test. Stay tuned!
The busy bees at Continental Fabricators have been making excellent progress on C&NW #1385’s new boiler. By late August work on staybolt installation was wrapping up. The next few photos show that work taking place.
The first shot is looking from inside the firebox at the firedoor ring and we can see the finished welding.
In this second picture we’re looking toward the front of the firebox at the crownsheet and rear tubesheet. The small group of staybolts not yet welded in are the flexible stays and the larger holes in the firebox sheets will accept the arch tubes. The arch tubes have a dual purpose in that they will form a structure to hold the arch brick in the firebox. They will also promote much better water circulation around the firebox while the locomotive is in operation.
This third shot shows the outside of the staybolts yet to be finished and with the boiler rotated on its side. We’re looking at the top of the vessel in the center of the picture.
This fourth picture is looking down through the steam dome inside the boiler at the braces welded in place to support the rear tubesheet. Those braces were discussed in an earlier update and this is a look at the finished product.
With the structural welding completed, as people across the nation were getting ready to fire up their grills for Labor Day weekend cookouts, the folks at Continental Fabricators were preparing a roast of their own. C&NW 1385’s boiler was moved inside Continental’s enormous heat treating oven for its Post Weld Heat Treatment (or PWHT). This process helps to relieve stresses built up during the welding process. The following two photos were taken while the boiler was cooling off after completing the heat treatment.
Next up, the boiler will get sandblasted and painted. The interior will receive Apexior paint which will help protect the steel from corrosion as it boils the water for steam.
August has arrived and with it is a new update on 1385’s boiler as it progresses toward becoming a finished vessel.
The fire door ring has been fitted to the firebox and backhead sheets and will be welded in place. The firemans’ shovel will pass through this opening many, many times feeding the fire that will keep 1385 running.
Looking at the other end of the firebox we can see where the rear tubesheet braces will be installed. Those are the wider-spaced holes below the field of closely spaced 2” tube holes. The braces are necessary because the holes in the tubesheet are above the top of the throat sheet so the braces are welded to the inside of the belly of the boiler. The braces are shaped like an elongated and squished “Z” so they can enter the hole in the tubesheet at a right angle and also lay flat on the boiler shell belly as they are welded in place.
The shot of the top of the boiler shows that just a ‘few’ stays need finish welding. You can also see that the steam dome base has been finished. The holes that do not have stays inserted are going to be some of the flexible stays and are awaiting the installation of the sleeves on the outside of the shell before the bolt itself can be applied and welded in place.
We do not have an anticipated return-to-service date for the 1385 but every weld is one step closer. Stay tuned to this webpage or our official Facebook and Instagram pages to keep up with most up-to-date information on 1385’s progress.
We appreciate the public’s enthusiasm to see the 1385’s progress first-hand; however, the contractor shops where the #1385 work is taking place are not open to the public. Anyone showing up at our contractor’s locations requesting to see the locomotive will be turned away. Please help #1385 return to operation as expeditiously as possible by respecting our contractors’ wishes.
Chicago & North Western #1385’s boiler continues to see steady progress. Since the last update, the boiler has been moved across the Continental Fabricators shop floor and is now on the positioner. With the boiler now on the positioner, it can be rotated to allow workers to put it into the best position for welding and assembly in areas that would otherwise be difficult to access.
C&NW #1385’s boiler on the positioner at Continental Fabricators. The positioner allows the boiler to be rotated. June 11, 2019. Photo courtesy Continental Fabricators.
C&NW #1385 left side wrapper sheet. Continental Fabricators. June 11, 2019. Photo courtesy Continental Fabricators.
C&NW #1385 right side wrapper sheet. Continental Fabricators. June 11, 2019. Photo courtesy Continental Fabricators.
Installation of the crown stays is also in process. Crown stays are the staybolts that connect the wrapper sheets – which wrap around the firebox – to the crown sheet (i.e. the top of the firebox). The crown sheet is directly above the fire and is the hottest part of the firebox.
The crown stays (shown in green) support the crown sheet at the top of the firebox, preventing it from bowing inward from the immense pressures.
Work on Mid-Continent Railway Museum’s Chicago & North Western #1385 locomotive during the month of May has consisted of stay installation, stay installation, and more stay installation. With over 900 staybolts to be applied, this process represents one of the more time-intensive portions of the new boiler production. Each weld must be made with great care and precision to avoid leaks and ensure proper strength when the boiler is under operating pressure.
Continental Fabricator’s Tom G. peered into the belly of the beast on May 29th to take these photos of stay installation progress on the inside of 1385’s firebox.
View of the interior of the 1385’s firebox on the fireman’s side. May 29, 2019. Photo courtesy Continental Fabricators.
View of the interior of the 1385’s firebox looking toward the front of the boiler. May 29, 2019. Photo courtesy Continental Fabricators.
View of the interior of the 1385’s firebox on the engineer’s side. May 29, 2019. Photo courtesy Continental Fabricators.