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What Welding Rail Repair is This?

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What Welding Rail Repair is This?
Posted by rjemery on Friday, January 06, 2012 1:20 AM

The January, 2012, issue of National Geographic has an article on Northern Montana, part of which describes the Great Northern Hi-Line.  A photo that accompanies the article is that of a welder working on the railroad near Rudyard, MT.

See photo at http://tinyurl.com/6wlyeht

Exactly what is this welder doing?  What is the equipment he is using?  What are what appears to be two yellow pneumatic jacks laid horizontally on either side of the rail being repaired?

RJ Emery in NJ near ex-LV, PRR, RDG, CNJ & DL&W
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Posted by ericsp on Friday, January 06, 2012 2:11 AM

It looks like a thermite weld. I do not know what the yellow things are for unless they are used to pull the ends of the rails toward each other.

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Posted by cacole on Friday, January 06, 2012 5:44 AM

It's a Thermite welding apparatus, which uses the heat generated by the burning of thermite to melt and fuse the rail ends.

Here's a You-Tube video of thermite welding --

http://www.youtube.com/watch?v=EpOJE-mkWmw 

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Posted by Paul_D_North_Jr on Friday, January 06, 2012 5:47 AM

Yes, a thermite weld - pretty much done in the field/ at the site only - to join or re-join 2 lengths of rails together.

The yellow cylinders are hydraulic, and used to hold the close ends of the rails in correct alignment and most importantly, at the precise distance apart as specified by the weld manufacturer - usually about 1 inch or so.  Once you've got them properly aligned, about the last thing in the world you want to have happen while you're preparing or making this kind of a weld is for the rails to decide to expand or otherwise move closer together or farther apart, as well as sideways or up and down with respect to each other - but with daily temperature changes, the heat from the weld, vibrations from passing trains on another track, the release of stress in the rail from creating the gap for the weld, etc., that can easily happen.  That will displace or rupture the mold, allowing the molten steel to leak out and ruin the weld and one or both rails.

I've got to head out for an appointment now - let me know if you have any other questions. 

- Paul North.   

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by mudchicken on Friday, January 06, 2012 7:41 AM

Ditto what Paul said: Thermite/ Boutet Weld...looking at the crucible that has been lit off, the boutet charge has been lit off and it appears the liquid molten metal is about ready to pour into the clay mold. After the molten metal is poured, the crucible pot will be swung out of the way, the clay cast will be removed and when the metal cools enough (though still visibly red hot), the hot cut chisel and the grinder will come out to shape the outside of the casting down to finished cross-section.

(They should have shown it right after they set the boutet charge off - quite a light show!)

The hydraulic rail puller appears to be holding the rail in place to keep it from pulling apart/running. (The rail most likely is about 100 degrees cooler than when it was laid in summer)

Edit: molten metal has already poured, excess metal has flowed into the rectangular steel pan on the field side of the rail (making a red-hot ingot in a mold in the picture)

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by tree68 on Friday, January 06, 2012 8:23 AM

Given that they're welding the rail, versus replacing sheared bolts in a joint, the hydraulics are certainly more predictable than the technique I saw CSX using a while back - lighting a fire on both sides of the rail on both sides of the joint to expand it so the joint closes back up...

I've never seen rail welded as such first hand, but I've seen some smaller thermite-type welding done to bond grounds to towers, etc.  Pretty impressive.

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Posted by mudchicken on Friday, January 06, 2012 9:35 AM

Watch'em do it in the middle of a 5000 ft tunnel. Except for the acrid smoke & fumes, pretty neat.Cool

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by rjemery on Friday, January 06, 2012 9:52 AM

Working with molten metal would appear to be a dangerous task.  Also, aside from the photographer, the track worker/welder pictured appears to be working alone.  For this and other tasks, I am curious about the injury rate among employees working in the field, especially in remote areas.

-----

I've seen human track welders at work along the Northeast Corridor but never with a thermite apparatus.  A crew seems to be no less than four in number -- at least two to work the rail, and two some distance away on either side of the repair site to sound air horns when oncoming trains are sighted.  The Northeast Corridor in my area is 4 to 6 tracks wide with a train at least every ten minutes.

It is possible thermite is used at night when there is less train traffic.  The area being worked is brightly lit by floodlights attached to the poles supporting the catenary system plus auxiliary lighting.  It is bright as day.  Most work seems to occur at switching complexes.

Every time an inbound train I am on emerges from the Hudson tubes west of Penn Station in Manhattan, I see track welders at work, but no thermite.  That is one huge complex of switches and crossovers operating at near capacity.

RJ Emery in NJ near ex-LV, PRR, RDG, CNJ & DL&W
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Posted by mudchicken on Friday, January 06, 2012 10:23 AM

Hot , dirty job that requires a certain amount of skill, hard work and patience. Most railroads out west use a welder & welder helper (2 men) supported by  a track section gang if needed. They are in constant demand and roadmasters never can have enough. One of the better paying jobs in the track department. Wimps need not apply.

Injury susceptibility is slightly (but not much) elevated above that of a normal trackman. What does remoteness have to do with the equation? I'd rather be working away from a congested area (the operating department is a bigger threat for welders than the work IMHO [coming from a former Los Angeles roadmaster])

In an optimum situation, you can shoot welds in about two hours, start to finish. You don't do this in the rain/ averse chemical reaction with water and molten metal. About $1200 covers the material costs per boutet. Most places don't have an electric arc flash but welder just sitting around for day to day maintenance. The only faster way to get a track back into service is to bar the joint.

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
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Posted by Paul of Covington on Friday, January 06, 2012 10:34 AM

    I remember watching this process on streetcar track about 20 years ago.    The blinding, bright light from the process was almost painful to watch from about 30 feet away.

________

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Posted by Paul_D_North_Jr on Friday, January 06, 2012 3:55 PM

" '4th of July fireworks' on the track" is what I call it !  Smile, Wink & Grin

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Posted by Rader Sidetrack on Friday, January 06, 2012 5:36 PM

mudchicken

In an optimum situation, you can shoot welds in about two hours, start to finish. You don't do this in the rain/ averse chemical reaction with water and molten metal.

During new construction at the Port of Seattle a few years ago I saw temporary rain shelters (similar to those portable picnic shelters) erected over thermite weld joint work areas.  As I recall it wasn't raining right then, but they were obviously prepared for that possibility.

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Posted by cx500 on Friday, January 06, 2012 11:11 PM

As Mudchicken says, it is safe unless you do something really stupid, like tossing the red hot excess slag or mould (not sure exactly) into the pond beside the track.  On hitting the water the thermal stress caused the material to shatter violently.  At least the flying debris only hit the guilty party, but I think it was a fatality.  That would have been perhaps 15 years ago.

John

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Posted by Semper Vaporo on Saturday, January 07, 2012 12:57 AM

I am not sure if what I am about to relate is exactly what happens, but I watched several thermite welds being done a couple of years ago.  The process involved two major components,  One, a set of clamps and a crucible of sorts, with a funnel like lid, and the other a cardboard box that apparently contained the consumables; a pair of mold halves and a bag of thermite and maybe some other items, but I could not see all of it from my vantage point.

After removing the consumables from the box, they tossed it not too far away and then placed the mold halves on each side of where the joint was to be made and used the clamps to hold them in place.  Then they sat the crucible on top and dumped a bag of thermite (I assume that is what it was) into the top of the crucible top and tossed the bag into the cardboard box.

After another man inspected the whole setup, then he tossed a match into the top of the crucible.  It smoldered a few seconds and then gave off a large flame out the top with a shower of sparks.  The space between the crucible and the rail smoked heavily and I could (from quite a distance) tell that something "flowed" from the crucible to the area below and a small amount of overflow went into a shallow pan they had hung from the side.

A minute or two after that they began to dismantle the whole apparatus, and after some banging on the shallow pan they used some tongs to toss its contents into the carboard box.  The carboard box almost immediately began to smolder, and burst into flame, completely consuming the box, bag and all the other stuff they had tossed into it.

While the box was burning they knocked the mold pieces off, breaking them into lots of small rocks.

Then they attached a second machine to the rail a couple of feet away.  This had an air operated grinding wheel on the end that was suspended directly over the place where the weld had been done.  By pivoting the grinder where it was clamped to the rail, they swept the grinding wheel from side to side.  It appeared that the grinding wheel would not go lower than the top of the surounding rail but I could not tell how that was controlled.

The total time to do all this was about 30 to 40 minutes and most of that time was spent in attaching and removing the equipment.  The actual thermite burn was less than 45 seconds and the grinding time was no more than 2 or 3 minutes.

This was during the summer months.  I also saw a similar operation in the winter time and it took comsiderably longer as they had to setup a set of gas burners on both sides of the rail for about 10-ft in both directions from the point where the weld was done (nearly continuous flame for the whole 20-ft on both sides with only a 2-ft gap in the middle).

They heated the rail for about 10 minutes before even starting to attach the crucible.  This was done for two reasons.  One is to get the rail warm such that the thermite weld would not chill too quickly and form a bad weld, and the other reason was to stretch the rail to the correct length to provide the proper tension for thermal expansion and contraction throughout the year.  This was also near dusk and the thermite burn was absolutely spectacular!  The whole joint glowed a deep red up until they started grinding on it.

 

Semper Vaporo

Pkgs.

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Posted by Paul_D_North_Jr on Saturday, January 07, 2012 5:11 AM

Pretty good summary of the process, from a layman's perspective !  Thumbs Up 

Links to some photos and information on "rail puller - expanders", the general name for this kind of equipment, some of which show it in use for thermite welding: 

http://www.hollandco.com/equipment/flash-butt-rail-welding-equipment/in-track-welding-equipment/puller-lite 

http://www.railway-technology.com/contractors/track/railtech/railtech2.html 

http://www.wbequipment.com/simplex/pdf/RR_Rail_Pullers.pdf 

- Paul North. 

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Posted by ccltrains on Saturday, January 07, 2012 7:58 AM

Thermite welds were great sport for college boys when I was in school.  I never participated but saw the end results.  The bad boys would "liberate" some powdered magnesium and powdered aluminum from the chemistry lab.  Then during the night they would pour a mix of the two elements into the space where a manhole cover mates with the base.  With a spark the mix is ignited and poof the lid is welded on.  For some reason the city fathers frowned on this sport.

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Posted by ccltrains on Saturday, January 07, 2012 8:05 AM

There was a "sport" practiced by some college students with thermite welding while I was in college.  I never participated in the execution of this game but saw the final results.  The boys would "liberate" some powered magnesium and powered aluminum from the chemistry lab.  The elements would be mixed and in the middle of the night be poured into the space between the cover and base of a manhole.  A spark to the mix and poof:  the cover is welded to the base.  For some reason the city fathers frowned on this game.

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Posted by ccltrains on Saturday, January 07, 2012 8:08 AM

Excuse the double posting.  For some reason when I tried to post I got an error message.

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Posted by aegrotatio on Sunday, January 08, 2012 9:20 PM

tree68

Given that they're welding the rail, versus replacing sheared bolts in a joint, the hydraulics are certainly more predictable than the technique I saw CSX using a while back - lighting a fire on both sides of the rail on both sides of the joint to expand it so the joint closes back up...

While I'm as quick to take jabs at CSX as the next guy I would suspect that the fire was to heat the rail to the average temperature for that climate so it wouldn't expand/contract and break the weld whenever the seasons changed.

 

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Posted by BaltACD on Monday, January 09, 2012 9:13 AM

Even in welded rail territory bolted up rail joints still exist - Insulated Joints for signal purposes if there are no others.  What you witnessed was a crew repairing a pull-a-part where the bolt sheared from the shrinking nature of rail at temperatures below it's 'normalized temperature' at which it was laid. 

Using cotton 'rope' to heat 100 feet or so of rail on either side of the joint will cause the rail to expand back together so the joint can be re-bolted thus completing the repair.

Sometimes for emergency broken rail repair, joint bars will be applied and a speed restriction will be issued over the point.  No ever trackman responding to a broken rail is a equipped Thermite welder.  Depending on the characteristics of the break using joint bars may not be a option and a complete segment of rail must be welded in place....needless to say when it is necessary to weld in a segment of rail it will take longer to complete the repair.  A Thermite weld takes approximately 2 hours of track time for the welder - setup - the welding process itself - the clean up and finishing grinding of the weld contour and then getting off the track.

tree68

Given that they're welding the rail, versus replacing sheared bolts in a joint, the hydraulics are certainly more predictable than the technique I saw CSX using a while back - lighting a fire on both sides of the rail on both sides of the joint to expand it so the joint closes back up...

I've never seen rail welded as such first hand, but I've seen some smaller thermite-type welding done to bond grounds to towers, etc.  Pretty impressive.

Never too old to have a happy childhood!

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Posted by Paul_D_North_Jr on Monday, January 09, 2012 9:41 AM

The pull-apart could also have been caused by / resulted from either a weld breaking, or the rail itself, due to contraction from cold temperature.  Even when fully anchored, a few hundred feet will spring or retract back.  Heat the rail up a little bit and vibrate it (hammer on the tie plates) to encourage the rails to close up the gap, and either make the weld or apply the temporary joint bars and drill bolt holes for same, pending the permanent repair.

It's not cotton rope, by the way (though it does look like it) - that would burn up too quickly.  It's a woven fiberglass rope, soaked in kerosene or diesel fuel, laid out, and ignited with a fusee (flare) or cutting torch - see under "Rail Bender* Accessories" about 1/3 of the way down this webpage: http://www.westernsafety.com/aldon2010/aldon2010pg9.html and "close to home", this from North Baltimore, Ohio: http://nbnewsxpress.com/viewnews.php?newsid=2379&id=1   

Smelly and messy, but effective, and warm, too, on those frigid bitter cold days . . .  Coffee  Headphones 

(*Absolutely no relation to the "Bender" = "Bending Unit 22" robot character from the "Futureama" animated TV show - see: http://en.wikipedia.org/wiki/Bender_(Futurama - although after reading that description of his capabilities . . . Whistling  Smile, Wink & Grin  )

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Posted by cefinkjr on Monday, January 09, 2012 9:23 PM

mudchicken

Watch'em do it in the middle of a 5000 ft tunnel. Except for the acrid smoke & fumes, pretty neat.Cool

Oh, that DOES sound like fun.  I've often described the process as a miniature, man-made volcano.  In a tunnel would almost make it like being in the volcano.

 

Chuck
Allen, TX

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Posted by cefinkjr on Monday, January 09, 2012 9:26 PM

Paul of Covington

    I remember watching this process on streetcar track about 20 years ago.    The blinding, bright light from the process was almost painful to watch from about 30 feet away.

Pittsburgh Railways (and I imagine other streetcar lines) simply tossed a bare wire over the trolley wire and, presto!, an electric arc welder.  I remember seeing this done several times in downtown Pittsburgh, always at night to minimize interference with automobile traffic.

Chuck
Allen, TX

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