Took this pic in Roanoke yesterday afternoon.
Reminds me of the FB meme about Amish Christmas lights…
That is “SOP”… (Standard Operating Procedure)
The KIT for doing a Thermite weld comes in a cardboardbox. It has two halves of a mold to fit on each side of the gap in the rail to be welded and a bag of Thermite.
They bolt the mold halves on each side of the rail and afix a crucible atop on a pivot so that it can be filled and then swung over a hole in the mold. Packing material is tossed into the box and the Thermite bag is emptied into the crucible and the bag is also put in the cardboard box.
Then they stick an acetelyne torch in the hole on top of the mold to heat the ends of the rails.
After a few minutes of heating they swing the crucible over the hole in the mold and then touch the torch to the top and put a vented lid over it.
The Thermite FLAMES something fierce for a few seconds (nice “rocket-engine” blast out the top!) and the metal portion of the thermite melts and pours down into the mold, between the rail ends. It soon solidifies and the workers using a set of long tongs remove a small pan on the side where the excess molten metal overflowed and they dump it into the cardboard box. While they are then breaking up the mold with hammers and preparing to grind the weld smooth on the top (as is pictured above) that cardboard box bursts into flame and is consumed by the fire caused by the red-hot metal overflow that was tossed into it.
The reusable parts of the crucible are put back on the MOW truck (after an appropriate cool down!). The broken parts of the mold are kicked away from the track and become part of the ballast rock. The ash of the “kit” box and packing blows away in the wind. Less stuff to haul away and dispose of when you are done.
Marshmallows optional, I guess.
“Never mind Frank, keep welding, it’s probably nothing.”
And so the Normandie was lost…
“+1” to Semper Vaporo’s description above - nicely done ! [bow]
- Paul North.
+2 (and don’t you dare throw water at the crucible!)
+3, and some additional photos to expand on it.
The crucible and overflow, and whats left when the clay/ceramic mold is removed.
I’ve never seen rail welded as such, but I have seen the very similar process used to bond ground wires to radio towers and the like. Even that is pretty spectacular.
To add to Mudchicken’s comment about water, also don’t throw the hot slag into an adjacent waterbody. It will shatter explosively (and fatally in one case).
[oops]
Watch your signal guys place bond wires in jointed rail territory (same process, just smaller)…rarely is a signalman allowed to drill a post into the top ball/ field side of the rail anymore…
Ed’s photos are darn good and detailed - thanks !
One more that’s needed is the sometime “4th of July” / giant sparkler effect when the thermite charge is first ignited, and a huge plume of sparks comes out of the top of the crucible. Unfortunately, you have to be ready and right there to catch it when it happens !
EDIT: Here’s a link to a typical example: http://web.mta.info/lirr/News/2008/images/TrackProgramAhead7.jpg
For more of same, do a Google Image search for “thermite weld track”.
- Paul North.