Can we weld on aluminized or stainless tubing?

[dibbons]

It seems the aluminized and stainless steel aftermarket exhaust systems are held together by clamps. Is that because welding destroys the rustproofing? I want to make a custom exhaust that exits in front of the rear tires but also want it to be as rust proof as possible. If I use the above tubing choices, I don't want to destroy it in the process. Is welding off limits? Thank you.

 

[CultClassik]

Yes. I always sand the aluminizing off at the joint, weld and coat with paint. The seam on rolled tubing usually rusts too, aluminized or not. I just paint everything with black BBQ paint.

Stainless is another story. It really needs to be TIG welded and backpurged or you'll contaminate it with the carbon in mild steel from MIG wire or from the adjoining metal, if it's not stainelss also. If you weld stainless without backpurging, it will make black crusty nasties (google stainless sugaring) inside the pipe which will weaken the weld and cause corrosion. This is because the backside of the weld will draw in carbon from the air (carbon dioxide). I don't backpurge but I do use Solar Flux on the back. Works great for me.

 

[Leadfoot]

We weld stainless pipes all the time. In the food service industry. I honestly don't know if there's a difference in the grade of stainless used for muffler pipes or not but our plumbing spends years in a wet environment with no hint of rust. We tig with a stainless filler rod and polish with a scotchbrite wheel. From past experience I've seen rust on stainless caused by impurities in the grinding/sanding wheels used to clean up the weld.

 

[2 Darts]

It seems to me that aftermarket systems use clamps because the average garage does not have inert gas welding equipment rather than concern over welding.

If the car in you avatar is the one that is to receive the new exhaust system, you may want to check routing of a dual system. The TB X-member on the passenger side is not notched for pipe clearance. Running a pipe underneath it usually results in a crushed pipe.