Western Railroad Discussion > Thermite Welding of Rails

Interesting video on the Veritasium channel showing
Thermite welding of rails showing the complete
process including alignment of the rails, placement
of the molds, and the actual thermite welding. This 
includes a special cutaway shot through a glass
window. Also shows laboratory testing of finished
welds to failure for quality control.

Agree - it's an excellent video:

https://youtu.be/Rdj5-6t6QI8

Good video. Things have changed a bit since I first was around this process. 

Dec 1978 on the ICG Amboy District near Hayworth IL, just south of Bloomington (track is long gone now). The DE had come up with some second hand welded rail to replace very old 90# jointed rail. The "new" rail was 127# that probably had come off an ex-PRR property as it was an odd ball cross section called "Dudley" that only PRR used (if I remember right). This rail was pretty badly worn, but still better than the 90# jointed rail coming out, just. I was just on a survey crew but the DE asked me to come along to learn some stuff and help fill out the crew.

The welding kits we were using were similar to what you see in the video but not as nicely packaged. The molds and shoes were very similar. The crucible for heating the charge was a reusable one with a tin hat not the nice pre-packaged can in the video. The charge (the mix of metal and aluminum to be made into molten metal) came in a plastic bag you poured into the crucible.

The video shows packing the sides of the mold with a sand mixture. Our kit came with a clay to do the same thing. This is where I learned how to pack Thermite molds. Given the large amount of wear on the rail we were installing, getting a good fit of the rail ends was tricky to say the least. That's why we had to have a ball of the molding clay on a stick handy when the crucible opened to drop the molten metal into the mold in case our packing blew out. 

This is really a very simple process. All you have to do is follow this recipe, especially for safety sake. That is the key--Follow Directions!

One key safety item is where to put the slag pans when you take them off. Many years later there were incidents where they were not handled safely and started grass fires (summer) or exploded when dropped in snow (winter).

Our welder had not used this process too many times before and did not like how the heating reaction bubbled and spit out the top of the cover of the crucible. He decided to cut down on the amount of charge he would put in the crucible to reduce the mess. 

Consternation ensued when the head of the weld tore out when we sheared the upset. (we did this by hand with a chisel and sledge, not have a fancy hydraulic shear)

Complaints were lodged with the weld provider and they sent a rep out to see what happened. 

You can guess the result when the rep asked to welder to take him through the steps he did to make the weld. DUH!

I have helped pack a few more welds over the years and have seen the improvements made to the "recipe" but it is still basically the same, just better tools and tighter QC steps along the way. 

Nice story xrds72 !

There has been much knowledge gained in the installation, welding and maintenance of CWR since the early days for sure.

As fyi, 127 DY (Dudley) rail was the product of the fertile mind of Dr. P.H. Dudley of the New York Central RR. 127 was the standard on main lines and lesser lines got 105DY.
Both good sections, and quite a few miles of it still out there in places (although not on high density main lines anymore).

Thanks train1275, I couldn't remember which road used the Dudley, PRR or NYC.