Cool. I saw it on a wheel widening website... I think... Wondering if it made a difference.
I've never done it myself. But, I don't do a whole lot of aluminum tube work to begin with.

 

I'll do a little demo piece tonight after getting this fuel cell mocked up.

 

I will post some new work soon, my lap top took a dump, so my new ones on the way! Then ill post some.

 

Wow Toxic fabrication^ , long time, did you check the post your best welds topic its huge lol

 

ive purged aluminum heads before when welding way, way down in one of the ports after a broken valve stem rips out the guide and the aluminum around it. its not done to remove o2, but its a must when your tig angle is so steep you must cut the side out of the cup and bend the tungsten to get to the spot. very tedious work.

 

9bells

This is why I asked if anyone back purges aluminum...

Found the link to the guy back purging his wheels
http://www.autocrossforum.com/forums...pic=7910&st=15

Any reason why one would do this?

 

No. I've done this on a testing block, and the results were the same. I checked the purge with ti and it was better colour than the top as is expected.
I still have to try the tube, but his weld inside looks like most of mine on my aluminum exhausts which I do not purge.
Maybe he does it so he can charge more? Has he tried it without? He just might not know any better so he errs on the side of caution.

 

Ive seen it done at my old aerospace job. It was somewhat rare to see but the part had a decent value. I think it was a fuel cooler for an F22 and it was a repair job. I rememeber asking why on the back purge but cant rememeber the answer, lol. I also recall a very high pulse rate being used and I remember him saying it was in an effort to 'boil' or bring the contaminants to the surface?? In fact that might have been a combined answer for both, who knows..it was a loong time ago..

Bottom line is it certainly wouldnt hurt the part, just your wallet if you pay for your own gas.

 

thanks for the info , would you back purge mild steel ?

 

In aerospace everything is backpurged, from what I've seen.

 

I thought it was self explanatory but only the part about backpurging Al was sorta rare to see. Of course with every other material its mandatory. If you didnt, it was either scrap or a lot of rework.

As for the purging on mild steel, if its an important part then yes you'd want to. If its something of no real signifcance, why bother?

 

No. Pressure and boiler code does not require it.