Tuesday, 17 June 2014

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Hydrolysis of water during underwater fire cracker welding with AC current

In My previous article, I have explained the working of Fire Cracker welding.

Now I am trying to make a joint underwater by using it underwater variant. I used E6013 electrode for that purpose.    The question is" Why I want to make a joint with the Firecracker welding. Because it is an automatic process. Means operator has nothing to do after the establishment of arc. If we use SMAW process then vision is not clear so a lot of Problem comes. 
that's why i choose firecracker welding to make a bead on plate. 

I used an AC ESAB power source. I took a tub filled it with water. Put the work-piece in the tub. I put the welding electrode holder with holding E 6013 electrode such that electrode starts touching the surface of work-piece(17.5 cm X 5 cm X 8 mm mild steel plate). Now I switched on the power supply. at that time current is 150 A. At that current due to hydrolysis hydrogen & oxygen starts forming in the form of very small bubbles due to hydrolysis.

 Now I used a bare electrode tip to establish the arc. But I was not successful to establish a good continuous arc with ease as in case of simple firecracker welding. So I increased the current to 175A. More Bubbles were formed. But again I was not successful. So again increased the current to 200A.  Now bubbles were formed not only at the tip but on whole electrode length.I think This is due to the penetration of water in flux coating.
I was doing this experiment till 250 A. But arc was not established.

Also when I took the work-piece outside the water, I was 
surprised to see that whole work-piece and electrode was corroded. 
I studied in school that hydrolysis is possible with DC current only. But here I saw that situation is different. I don't know why.

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