[R-390] Thermite welding

[Tisha Hayes]

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