Exothermic welding issues

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kbsparky

kbsparky

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Location
Delmarva, USA
Today, I was able to install a couple of exothermic welds on a grounding grid for a new building.

We have one of those graphite molds that fits over the top of the ground rod, and allows a #2 wire to pass-thru. The end weld forms a "T" ....

I was having problems getting the starter powder to ignite (using a torch). I didn't have a flint striker handy. We finally got it going by "stirring" the starter powder with a scrap piece of wire while the torch flame was shooting into the side slot.

I figure that I could use some July 4 sparklers the next time for better results....
 
When you pour the powder into the mold do you get the fine starter powder out of the bottom of the charge tube? If you don't or you mix it into the charge you will have a hard time lighting it. Is it dry? I stop using the pour shot. I use the electric starter now. It keeps me from getting burned.
 
kbsparky said:
Today, I was able to install a couple of exothermic welds on a grounding grid for a new building.

We have one of those graphite molds that fits over the top of the ground rod, and allows a #2 wire to pass-thru. The end weld forms a "T" ....

I was having problems getting the starter powder to ignite (using a torch). I didn't have a flint striker handy. We finally got it going by "stirring" the starter powder with a scrap piece of wire while the torch flame was shooting into the side slot.

I figure that I could use some July 4 sparklers the next time for better results....
Click to expand...

As hot as that stuff gets, I would highly recommend a starter unit: http://www.erico.com/products/CADWELD_PLUS_Control_Unit.asp

I have a nice scar on my leg where that stuff burnt through at the bottom and spilled out. Amazing how fast you can get out of a pair of pants when you and them are on fire!
 
Hv&Lv said:
As hot as that stuff gets, I would highly recommend a starter unit: http://www.erico.com/products/CADWELD_PLUS_Control_Unit.asp

I have a nice scar on my leg where that stuff burnt through at the bottom and spilled out. Amazing how fast you can get out of a pair of pants when you and them are on fire!
Click to expand...

Sorry to hear about you getting hurt. I was doing a cell tower site one fall day and I overlooked all the leaves in the trench................
Boy did that make a big fire!

(sorry still don't know how to make the dunce head thing) ;)
 
kbsparky said:
Today, I was able to install a couple of exothermic welds on a grounding grid for a new building.

We have one of those graphite molds that fits over the top of the ground rod, and allows a #2 wire to pass-thru. The end weld forms a "T" ....

I was having problems getting the starter powder to ignite (using a torch). I didn't have a flint striker handy. We finally got it going by "stirring" the starter powder with a scrap piece of wire while the torch flame was shooting into the side slot.

I figure that I could use some July 4 sparklers the next time for better results....
Click to expand...
It doesn't sound like you read the instructions about the fine powder in the bottom of the container. If you did, and still have a problem, I have experienced problems with an old batch that has gotten shaken up, or a tube that is left open to moisture. In that case, you can throw it away and try again, or you can use the powder from the bottom of another container. I discourage you from stirring the powder with a piece of wire. No matter how careful you are trying to be, I can smell disaster. As others have stated, do you have any idea of just how HOT that stuff is?
 
Yes, I did read the directions, thank-you-very-much. Several times. :rant:

This is why I was so frustrated in trying to get that dang thing to ignite.

Maybe it was old -- sitting on the shelf at the supply house? I just bought the stuff the day before, so it was brand-new to me.

I poured the metal powder mix into the mold very carefully. At the bottom, the starter power appeared to be embedded in the base. Directions said to re-cap the tube, and tap it to loosen, then pour 1/3 of it on top of the metal powder, and then the rest on the top of the mold after the top was set in place. I did exactly as directed. The stuff just would not get started, even with the MAPP gas flame directly on the pile of starter powder. Not until we stirred it with a piece of tie wire .... :ashamed:

I got some July 4 sparklers today, so those should do the trick when we go back next week to complete the grounding grid in the foundation. I'll light the sparkler with the torch, and then stick the lit end into the top chamber ....

The surprising part of the whole thing is the speed in which the exothermic process takes place. While I have read 15-20 seconds, that must include attempting to light the dang thing. Once lit, it's over in 1-2 seconds!
 
kbsparky said:
The surprising part of the whole thing is the speed in which the exothermic process takes place. While I have read 15-20 seconds, that must include attempting to light the dang thing. Once lit, it's over in 1-2 seconds!
Click to expand...

I made some thermite "just for kicks" many years ago when I was working around a welding shop. Set it on a piece of 3/8 steel plate thinking we were going to see something cool. Once I got the Mag. strip started, the whole thing started burning, and burnt a hole in the 3/8 steel plate. It dripped onto the concrete floor below... You ever had a torch too close to concrete...:ashamed:
 
I switched over to the Cad Weld plus, its a sealed unit with electric ignition. The shot cost is the same. I sent my old shots back and I got credit for them. The CAD weld plus is much safer.

On another note, the shot material in CAD weld was used in WWII called a thermite bomb to burn thru concrete. I know an electrician who cad welded a one million copper to rebar for a nuclear power plant. they tied the ignitor to a 2x4 and stood way back.
 
UPDATE: Using sparklers

UPDATE: Using sparklers

I got some sparklers from the fireworks tents this week, and they work GREAT in getting the exothermic welds going!

I just stuck the tip of the sparkler into the mold slot, and lit the back end.

Then just stand back, and watch it like a slow fuse burning its way to the mold.

Then WHOOSH! It lights the stuf, and the exothermic reaction takes place welding my ground wire(s) to the ground rod.
 
copper chopper said:
that craps old school, we dont use it anymore for all those reasons, we only use crimp lugs, hell on most of our jobs its not even allowed in the spec book.
Click to expand...

We use it for every underground connection in a substation for our grounding grid. Most POCO's do the same.
 
tom baker said:
I switched over to the Cad Weld plus, its a sealed unit with electric ignition. The shot cost is the same. I sent my old shots back and I got credit for them. The CAD weld plus is much safer.

On another note, the shot material in CAD weld was used in WWII called a thermite bomb to burn thru concrete. I know an electrician who cad welded a one million copper to rebar for a nuclear power plant. they tied the ignitor to a 2x4 and stood way back.
Click to expand...


Cad plus is the only way to go. Just make sure you have extra batteries and leads for the electronic igniter.
 
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