Welding anodized aluminum pipe

By jman Date 10-22-2002 01:29

hey, i happen to build t-tops and towers for a living so i may be of some use here.
first know the anodizing does not conduct electricity and has actually contaminated the material, but not to worry this is how we do it.
this is done in 2 passes. 1pass looks like crap if youre really good and much worse if youre not. the 1st pass we call BACK FILL and is put in backwards reative to a normal TIG weld (oh by the way you can only do this with TIG because you need the high frequency to break up the anodizing.) do this one drop at a time like a series of tacks or a backwards pluse weld. be sure to let the drops melt in or FAN OUT. you control your heat by triggering your torch off longer than on. you will do the oppsite when you start. hint, do NOT let your heat get out of control. ok, now you will BUMP OUT the weld. start where you finished and trigger the torch on and off in a pulse fashion with no filler rod to flow out the filler rod when you are done it should be shiny in the middle mostly flat (not much crown but NOT concave.) and dull on the sides with really even edges and good definition.
you should use a heat range of 172 to 212 amps. start closer to the bottom, trust me. 1/8" RED 2% thoriated tung + a #8 nozzle for a #18 TIG torch. ESAB 5356 1/8" filler rod works best but just make sure its 5356. any questions? i know it looks like english but i dont under stand a word. but really if i can help post a question to jman in this forum. be well and good luck.

By warreneaton Date 10-22-2002 18:02

jman,

Thanks for your suggestions I will give them a try. The only other question I can think of is what type of gas you are using? Are you using pure Argon or some other mixture and at what flow have you had the most success?

warreneaton

By jman Date 10-26-2002 03:48

hey,straight argon is the sheild of choice. i have never heard of any one even trying a mix or helium. remember dont give up. you will have to practice a lot to just get an ok bead. what we do is backwards from anything you have been taught. myself included. ask questions and dont give up. be well and good luck.

By Proarc Date 11-14-2002 14:12

Jman, Saw your post on welding anodized Al. pipe. Have not used your technique, but am going to try it. Do you use foot control or remote switch? When your "bump out" the weld will the contaminated anodizing flow to the edge of the welds? Also by pulsing with out rod, I guess you are make a pretty cover pass? Thanks for any help you can give me, I am a aircraft mechanic, and do mostly stainless and Al. aircraft parts. I live on the Gulf Coast of Florida and have built a couple Tee tops for my own boats. With out any knowledge of anodized Al. pipe welding or advice, the start of the process was very frustrating. I saw great welds on other boats, but had a hard time duplicating them. Presently run around area to be welded with the High freq. to clear out the anodizing, then come back and weld. Have make a lot of progress, but still not satisfied with appearance. One top has been in use 3 years with no cracks, so I must be getting good penetration. Thanks for any help or advice you can give.