Just a few details, say like a firebox.
Rest assured that if the big three were still in business building steam locomotives, they would have welded, fabricated frames. Steel castings were state of the art in the 1930's, but are completely obsolete today for complex steel shapes.If over 3/4" thick, I believe that stress relief is required.

Does anyone know if they are building her with a belpair Firebox or not?

Yes it will have a Bellpaire. They have CAD drawings on their FB page and their website of boiler.

Kelly was correct, In one of their newsletters they talked about Continental Fabricators having an oven big enough to stress relieve the whole boiler when completed. That is one of the reasons they went with Continental.

They also said they were going with all fillet welded staybolts. Can someone explain the difference between fillet welded and regular staybolts? Kelly?

Here is a shot of the 1385's boiler in Continental's oven. I realize at this angle the perspective is a bit hard to catch but there was plenty of room.



As far as stays, besides the fillet attachment there is full penetration weld and threaded/upset. Which flavor is what you were thinking of as regular stays?

Beyond that I'm going to step back, pop some corn & start melting the butter....mld

Fillet-welded staybolts are staybolts attached to the boiler sheets with a fillet weld. In many parts of the world, these have been the "regular" type of staybolt for many decades. There has also been quite a bit of study on the stresses of the rear boiler which led to conodial profiles along the shaft with enlarged heads to distribute bending stresses more evenly and provide an enlarged attachment area by the increase in circumference.

There are a number of locomotives already operating in the U.S. with staybolts attached by fillet welds. Additionally, ASME locomotive boiler code allows their use and relates this design methodology.

Sincerely,

Matt Janssen

Found this lomg series in the archives regarding threaded vs welded stay bolts

viewtopic.php?f=1&t=28659

Found this long series in the archives regarding threaded vs welded stay bolts

viewtopic.php?f=1&t=28659

Interesting input on both sides of the fence

Rather than trying to filter through all the arguing and personal attacks and other BS on the previous thread, for the beginner the simple version is this: welded staybolts use a straight bolt that's welded to the sheets - either with a fillet or a full penetration weld, and traditional staybolts are threaded through both sheets and traditionally the ends are peened over to seal them against the sheet. A later development was seal welding the threaded bolts rather than peening. Boilermakers today use any/all of the methods, although full penetration welds have unsatisfactory flexing problems in locomotive boilers and fillet welded is acceptable for long-life service when a specially designed bolt is used. Welded bolts are somewhat quicker to install but require high quality welding work, traditional threaded bolts take a little longer but are a little less finicky.
Full penetration on the left and fillet on the right (weld is the shadowed areas) in this illustration:

Of course if you're a masochist or have the desire and time to spare, by all means dive into the other thread...

Thank you for the discussion above re stress relieving. Also, "that other thread" on stays is quite interesting and filled with useful information.
Back to the T1 boiler. How will the heads be stayed?

How about building the rest of the locomotive first? The tubes will be one of the last things installed.

I believe that has already been cleared up here that tubes won't go in for many years until it is sitting on the frame and close to being finished. They are building the exterior firebox and don't expect it to be finished until late next year.

The staybolt heads will be fillet welded and not peened over from their FB page.

Thanks for posting picture on the oven with 1385 boiler in it. That is pretty cool to see. Would the Big 3 stress relieved their riveted boilers back on days of steam?

Sorry, should have asked, how will the tube sheets (heads) be stayed?
Thanks.

Stress relieving is usually done on structural weldments. When weld metal cools, it shrinks. If the base metal is restrained then that stress created from shrinking wants to break the weld or distort the weldment. Correct stress relieving releases that stress.

Traditionally, the tubes themselves stay the tube bundles and the remaining flat bits are stayed with diagonal braces back into the barrel. In the firebox, stays for the throat and braces between the bottom of he bundle and bottom of the barrel as necessary.

Which is why you don't want to stress relieve a riveted boiler. The tension stress on each rivet is what clamps and seals the joint. Release that tension, and you turn your boiler into a large lawn sprinkler.