Tube Oxidation

[jonfilipa]

I have been working on bending in the fuselage sides to form the tail by the recommended method of heating the tubes up at the bend location per the Sonerai construction manual and Fred's newsletter tips. Worked pretty well, except one of the tubes developed some oxidation/scale on the surface per the attached picture. Not exactly sure what happened as the other bend locations don't exhibit this surface condition, but am suspicious that I may have heated it up with an slightly oxidizing flame instead of a balanced neutral flame.

I'm looking for feedback on whether:
(1) This is still acceptable and can be cured by sanding/benching off the surface oxide/scale material before final welding
(2) There is a significant issue here that may require tube repair or replacement.

Looking for input from some of the more experienced welders out there. Naturally don't want to have to repair/replace if possible, but also don't want to have a compromised airframe either. Any feedback and advice is appreciated.

Jon

Attachments:

[4trade]

You just heated that tubing little too much. It happen always when add too much heat. When it happen, small metal particles and carbon start to burn at that surface. It weaken that tubing little, but that tubing should be fine when i look at photo.

There is only so little amount of that surface, what is burning away that you don´t need to replace tubing.

Next time avoid too much heat. When surface start to "sparkle" you go too far with heat.

....and don´t put that torch too close to tubing when work....it help.

[raceair]

I agree......most of the scale comes off with 150 grit sandpaper, and/or a fine file....does not take too much to remove it.....Ed F.

[jonfilipa]

I realize this is a bit late, but thanks for the feedback. I've got the bending done and am closing in on the getting the horizontal tubes done too. Starting to look like an airplane!

PS - Ed, big congtats on getting elected to the Homebuilders Hall of Fame. Very cool honor, and you're an inspiration to the rest of us. ;D