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Up Topic Welding Industry / General Welding Discussion / Aluminum Dye Penetrant Test
- - By 52757 (**) Date 08-04-2009 12:17
  Print requires Dye Pen. test of all welds (5356 filler). Initial testing showed porosity. Operator runs a scotch brite wheel across the surface face of the welds. Will this  seal the porosity holes to where dye pen will not show them? If so, will wire brushing (stainless) open them  back up so that I can retest? Or are there other options to do before retest. Any help would be appreceiated. Thank you.
Parent - - By jrw159 (*****) Date 08-04-2009 13:14
52757,
  Yes this has the potential to "mask/hide" the indications. A wire brush may or may not open them back up. The best, and proper option, since the initial test showed porosity indications, is to grind the porosity out, re weld, then retest. Smoothing over, or welding over only traps the discontinuity in, it does not fix it.

jrw159
Parent - - By eekpod (****) Date 08-04-2009 15:34
I would agree,  The object of the game is to have a good quality weld that will pass PT inspection.  Not to just pass the PT inspection.  Do you have a certain code you are working with?  make sure they are intrepreting the acceptance criteria correctly. 
Parent - By flamin (**) Date 08-04-2009 15:41 Edited 08-08-2009 15:01
When ever I find indications, I usually have the welder grind out and re-weld, as previously mentioned. More times than not, the small indications will reveal much more beneath the surface once the indication is ground out.

EDIT: I've been working on a project for the last couple of months peforming visual and preliminary PT NDE on the parts. Thus far, porosity has been a non issue, but the big issue has been crater cracks. These particular parts have intermittent fillet welds all over the place, and so far 90-95% of all the fillet welds have the crater cracks. The welds look beautiful visually, but once the penetrant is done, it changes the whole story. I guess what I am trying to say is, I think that porosity would be the least of you worries when it comes to aluminum.

Jason
Parent - - By ravi theCobra (**) Date 08-04-2009 15:59
The first  question  is  WHAT  CODE / STANDARD  are you  welding  to  and  WHAT IS  THE  ACCEPTANCE  CRITERIA  ?  ?  ?  ?
Parent - By Lawrence (*****) Date 08-08-2009 02:12
I'm with Ravi

What is the criteria...  How much, how large,  is there a minimum size of pore to measure?

The porosity that shows up with FPI should be seen and verified fairly easily with a 10X loop unless they are very small pores indeed..
Parent - - By 52757 (**) Date 08-10-2009 13:25
  Sorry it took so long to reply been gone for a few days. Welding to D1.2, but our company policy is NO porosity allowed. The porosity that I am seeing is intermitent and would meet code acceptance the problem being our company standard. Porosity is small and very hard to see even with a magnifying glass, when I do dye pen. test it shows up. On the earlier mentioned part we removed and rewelded the part becaause of the grinding that was done.
Parent - By jrw159 (*****) Date 08-10-2009 13:30
52757,
  Ravi and Lawrence are correct. I jumped the gun on part of my response to you without asking the important parts first. You know what they say about ASSuming. LOL

Glad everything worked out.

jrw159
Parent - - By bozaktwo1 (***) Date 08-10-2009 16:52
I want to meet the welder who can make 100% welds in aluminum with absolutely zero porosity.  There's a reason it's allowed by the code.  I'm not saying it's impossible, just highly unlikely.  IMHO.
Parent - By 52757 (**) Date 08-10-2009 18:28
  I agree. I am working with engineering now to see if I can get this changed. Aluminum is not our standard product. All welding in the past has been to D1.1 with the exception of a 0 tolerance for porosity. Eng. just carried this over to the D1.2.
Parent - - By ravi theCobra (**) Date 08-10-2009 21:16
It  is very  easy  to produce porosity  free welds  in  aluminum  -  just use  110 %  TO 125  %  helium  shielding
Parent - - By ssbn727 (*****) Date 08-10-2009 22:52
Ravi, do you really mean 10 to 25% helium - balance Argon shielding???

Respectfully,
Henry
Parent - - By ravi theCobra (**) Date 08-10-2009 23:37
Just kidding, Hank -

We  used to  put  1  to  2   %   Freon  12   into  our  pure Helium  shielding gas  and  that's   why  we called  it " 110   to  125  %

helium  " -  The  freon  would   decompose  into  chlorine and  fluorine  and  it  would  verry agressively  seek   out  hydrogen  which

was   in   the  casting  -   we had castings  with  1"  to  2"   walls   and  this  was quite  an  aid  when  we would  end  up  with a

particularly  gassy   ( H 2 )   area  in  a  casting  -   we  would  have  a  mass  of  porosity   1/16    to   1/8   inch   diameter  -

You  cannot  economically  get  F - 12   now  so  another  trick  is  gone  .  .  .  .

By  the  way  good  health  and  godspeed  -
Parent - By ssbn727 (*****) Date 08-11-2009 02:05
Well now, that is most interesting, and good of you to share this unconventional approach to solving the problem! ;)
Thank you for your kind words. :) :) :)

Respectfully,
Henry
Parent - - By DaveBoyer (*****) Date 08-11-2009 04:58
Isn't R12 extremely toxic when exposed to high temperature? Turns into something like agent orange ???? I guess at those small % it doesn't ammount to much, or You wouldn't be talking about it now.
Parent - By ravi theCobra (**) Date 08-11-2009 20:10
If  you  look  at  the  chemicals  in  COMMON   usage  between  1966   and   1985  it  is  a  wonder any of  us  are alive  -

The Freons , Trochlorethylene , perchlorethylene ,methylene chloride,benzene, 111 trichlorethane   - need I go  on  ?
Up Topic Welding Industry / General Welding Discussion / Aluminum Dye Penetrant Test

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