welding over old weld?

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how many of you guys will weld over an old weld, you did not do, when fixing or rebuilding something ? I find that I try to clean all old weld off as I don't know what it was welded with or by who. unless I find it had a good penitration and looked to be an exceptional factory weld.  I thought of this the other day when I had to change the hitch on the tounge of a trailer that someone home made. It had been welded with a stick and had flux deposits and porous holes in the welds.Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Grind/cut it out.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:We are a repair shop and we see broken/crappy/questionable welds everyday.We always remove the old stuff.
Reply:ARC AIR!  Nuttin cuts off old welds better.  Especially bird dropping welds.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Visual inspection is accepted by every welding code and spec I've heard of.  Therefore, it's reasonable to believe that it can be inspected and a good decision made as to whether it should be ground out.Also, the application has a lot to do with it.Proud to be a UNION worker.  Better pay, better benefits, better work environment.  UA Unions = working for the working class!!
Reply:Originally Posted by asemasterhow many of you guys will weld over an old weld, you did not do, when fixing or rebuilding something ? I find that I try to clean all old weld off as I don't know what it was welded with or by who. unless I find it had a good penitration and looked to be an exceptional factory weld.  I thought of this the other day when I had to change the hitch on the tounge of a trailer that someone home made. It had been welded with a stick and had flux deposits and porous holes in the welds.
Reply:Always cut or grind it out.  Worse ones to clean up are those done with stainless rods.  Hate them.
Reply:When in doubt, cut it out. Always remove the old stuff. You never know if that weld you did a visual on is a dress weld over one thats full of porosity.
Reply:Originally Posted by EngloidVisual inspection is accepted by every welding code and spec I've heard of.  Therefore, it's reasonable to believe that it can be inspected and a good decision made as to whether it should be ground out.Also, the application has a lot to do with it.
Reply:Turn up the heat and go for it
Reply:I've made a career out of repairing stuff that broke. If it failed it needs to be gone anyway and start from base metal. I prefer to get rid of the old weld as I have no way of knowing what electrode was used to begin with, and if it's all gone I know exactly what's there when I am done. In the last 10 years I have had to repair two of my repairs that cracked out and both were on 100+ year old cast iron and that is always hit or miss.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:No way.  Old weld has to go.  There is no way you can properly repair a cracked joint by welding over the top of the existing broken weld.  Grind it out run a fresh root, and finish it out as required...I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......