"Vintage" C Channel welding

[BOWTIEGUY]

I was given a nice collection of 4" C Channel that has been outside for years, are there any concerns welding the channel with MIG? I understand that it has to have the rusty surface ground off before welding but are there any special considerations other than good surface prep?

Thanks

[kevin]

instead of grinding, try using your torch to clean off the rust, just heat it where the weld will be, cuz, badly rusted steel is usually pitted, and grinding it takes off too much steel

[Aeronca41]

instead of grinding, try using your torch to clean off the rust, just heat it where the weld will be, cuz, badly rusted steel is usually pitted, and grinding it takes off too much steel

Right on. The old timers used the same principle in a process they called flame priming prior to painting. Even had special torch heads to cover about 4" or so at a time. Theory is there's always a minute amount of moisture under the rust in the pits. Hit it with a very hot flame and the instantaneously generated steam will make the rust literally explode out of the pits. I did it on a very old badly pitted I-beam before paint about 15 years ago. It's been out in the weather ever since and is not rusting yet. Wear eye protection!

[nfinch86]

Yes, I agree !
A flap disk will remove the excess rust then put a torch to it !

As you said - Wear a Mask for sure + Safety Glasses , it will pop & get in your eyes !

Norm

[ryanjones2150]

And a hat. Blobs of molten metal on your scalp will make you sad.

[MAC702]

If you get good surface prep, nothing wrong with MIGging old steel. If you don't get it as nice as you like (or it will take too long) then switch to FCAW to help burn through it.

[ryanjones2150]

Or stick it.

[BOWTIEGUY]

Thanks guys ..wasn't aware of the torch technique and just filled my acetylene bottle. Haven't used my AC/DC stick in at least 10 years but it could be an option.

[BOWTIEGUY]

Just thinking..I have a portable sand blaster....maybe clean the weld areas that way?

[Oldgrandad]

Sand blasting is a great option, that will get into all those divots and clean them out. Remember clean the dust off before welding.

[Aeronca41]

Agree-I've done that and it works great. I just find the torch method so much less messy. Just use a REALLY good respirator or supplied air with that sandblaster.

[nfinch86]

Depends what you have to hand grinders or bottles, i carry a battery grinder so smash it of and weld it

What ???????????????

[tackit]

I use a 3" cup brush on my 4.5" grinders to remove rust. it does a great job.