Welding versus brazing

[gmensing]

Hi,

I am looking to find a way to improve the seems of ducts. These ducts are for example used for airconditing. Currently these seems are welded but the quality is not that great. The sheet metal of which these ducts are made are about 0.6 mm to 1.0 mm thick. The length of the seem is about 1 m. to 2 m.
Would brazing be a good option?
I know that brazing is difficult for longer parts (because the sheet metal has to be heated so that the filler material will melt.
Also, brazing requires quite a lot of work and accuracy.
What is best?

Regards,

Gert

 

[pardal]

Hi Gert, as far as I know the longitudinal duct join is doing by a mechanical way ,because welding will burnt out the galvanized bath and heat will deform its shape, furthermore, if I would have to think in welding I would use electrical resistance welding as it is used in pipes or vegetables can.
Please feel free ask more if you want.

 

[gmensing]

Hi DesignerAtOrder,

Thanks for your reply. I know that joints for ducts in general are mechanical, but we have some ducts which need to be "leak-proof" on the sides. This means that I have to use other means of joining the seam, and that means either adhesive bonding or welding. Welding is currently used (MIG), but the quality is overall not good enough. I realise that this partly due to the welder, but to achieve a consistant quality (almost) every time, I would like to de-skill the work. I have already looked at electrical resistance welding (seam welding) but I still have doubts because of the lack of accessibility on the inside of the duct.
As for the welding effects on the galvanised sheet metal; we do a "cover-up" job which means we paint it....

Regards,

Gert

 

[pardal]

Hi Gert, please refer to

http://www.smacna.org

Gbariel

 

[sbc]

If you are trying to weld galvinized sheet metal
you will not get good results unless all of it
is removed prior to heating. The fumes are poisonous
and so is the grinding dust. I hope you can find
some sort of sealant for your application before
your liver shuts down.