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Up Topic Welding Industry / Technical Discussions / Air Arc Gouging
- - By Richard V. Roch (**) Date 10-26-2007 11:11
Does anyone know if preheat is a requirement when you back gouge on a double sided weld in accordance with AWS D1.1? The welding procedure states air arc gouging is an essetial variable. AWS D1.1 does not specifically mention preheat during gouging operations.
Thanks in advance
Parent - - By G.S.Crisi (****) Date 10-26-2007 18:18
Of course, carbon arc gouging is an essential variable.
To answer your question, I've never used preheating before carbon arc gouging. However, as I may be wrong, ask the "kings" of carbon electrodes for arc gouging:
www.carbonelorraine.com  (there's a French and an English section) 
There's also their Great Britain affiliate:
www.lecarbone-gb.co.uk

Giovanni S. Crisi
Sao Paulo - Brazil

Parent - - By darren (***) Date 10-27-2007 00:28
the only reason you would preheat for gouging is if there would be no back welding. i.e. removing fitting attachments on a pressure vessel envelope or other materials or situations that would require preheat to weld on.
when one is back gouging to prepare a joint for welding then any haz created by gouging will be annealed by the subsequent welding, and of course any determined pre or post heat treatment that might be applied.
having said all that if the metal is below 50 degrees f then it sure wouldn't hurt. I've always thought on very critical welds it would help in some way to maintain a good grain structure and if done in a timely fashion then the piece is prepared for welding immediately after the gouge is done.
but hey this is just my opinion and the reason i render them here is because my wife constantly reminds me they are of little value in her world ;)
darren
Parent - By Tommyjoking (****) Date 10-27-2007 06:38
very nice reply Darren!!
Parent - - By pipewelder_1999 (****) Date 10-27-2007 10:14
I am interested in this reply. Is the time and temperature high enough to cause problems from gouging when it is not welded over? Are there any studies or references you could point me too?

Thanks for any information you have

Gerald
Have a nice day
Parent - - By 803056 (*****) Date 10-27-2007 12:32
I believe there is something in D1.1 with regards to thermal cutting, of which, carbon arc gouging is a member of. I believe the preheat requirements are the same for thermal cutting as for welding. Both processes, welding and thermal cutting, can result in a HAZ, and both can result in martensitic microstructure in the HAZ.

I also believe AISC requires preheating for heavy sections in specific groups.

Best regards - Al
Parent - - By pipewelder_1999 (****) Date 10-28-2007 00:08
I know oxygen gouging could be a problem. I just never would have thought the thin HAZ with carbon arc gouging would be an issue on say a removed weld in which some of the metal was left.  The preheat requirement could be a pain for people using CNC plasma tables for cutting thick sections.

I'll have to look into it further. I appreciate the info.

Gerald
Parent - - By cwi-cws (*) Date 10-28-2007 02:50
fema 353 requires preheat for heavy sections when oxy-fuel cutting is done .we also preheated for arc gouging, it is an arc process therefore you should preheat! i would for d1.1 ,aisc or fema. i hope this helps.
Parent - By pipewelder_1999 (****) Date 10-28-2007 09:55
Does the FEMA 353 require it for Air Carbon Arc gouging or PLasma cutting?
Parent - By makeithot (***) Date 10-29-2007 00:33
Well thougt out Darren, I have the same problem with my wife.
Up Topic Welding Industry / Technical Discussions / Air Arc Gouging

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