[R-390] Thermite welding

[Cecil Acuff]

The days of the little blue shot cartridges are going away.  They have a new 
one now that is cone shaped with a metal tab sticking out of it.  You 
connect a yellow ignitor box to it and it uses batteries to fire off the 
shot.

I like them...they are sealed and more impervious to moisture.  Quicker and 
easier to handle as well.

Those are the ones I used here.

The Cadweld folks have a new one size fits all mold system as well that 
looks really neat.  Probably could have used that to do the copper strap to 
ground rod welds but didn't have access to one of those.  I borrowed all the 
molds for the work I did...just had to buy the shot.

Cecil...
----- Original Message ----- 
From: "Tisha Hayes" <tisha.hayes at gmail.com>
To: <r-390 at mailman.qth.net>
Sent: Thursday, July 30, 2009 5:25 PM
Subject: [R-390] Thermite welding


> It is a thermite compound (one of many) that has powdered copper in the 
> mix.
> Once it arcs and sparks and finally cools you open the mold or crack open
> the unishot ceramic shell and it looks like you melted down five or six
> pennies into this formed blob that has attached the wire to the ground 
> rod.
>
> There is no special permitting required, it is not an explosive device.
> Using the quantity of materials in one of the little plastic containers 
> you
> would not melt through the hood of a car (had that idea once in the middle
> of a divorce). How you pour the powder into the mold is important as the
> finer granules are at the bottom and need to be at the top of the pile.
> There is a thin metal disc that keeps the powder in a nice pile and it 
> also
> contributes to the metal blob as the thing melts down.
>
> We used to fire these off on steel pipelines that were 5/16" thickness 
> with
> an internal pressure of up to 1170 PSI. The corrosion guys tried to attach
> to a flange but didn't seem to mind making this miniature volcano on a
> pipeline full of gasoline. I have never heard of a pipeline failing during 
> a
> exothermic weld, that would be a "bad thing".
>
> Bunches of places sell the same product. Tessco, Talley or Harger. Harger 
> is
> very into the grounding world (you can say they are well grounded <pun>).
> They explain the ultraweld process pretty well at;
>
> http://www.harger.com/products/ultraw/up/up.cfm
>
> Their library has quite a few useful references including a more graphical
> presentation (death by powerpoint).
>
> http://www.harger.com/library/slides.cfm?maingroupnbr=183
>
> -- 
> Ms. Tisha Hayes
>
> ----------------
> "I will not recant the truth. I am corn, not chaff; I will not be blown 
> away
> with the wind or burst by the flail. I will survive both."
> -Walter Milne, 1558
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