Our Sites

Aluminum Workshop: The real deal when welding aluminum and steel

Q: We fabricate small pressure vessels to ASME code. Up until now we have fabricated only steel tanks, but recently we’ve been given the opportunity to fabricate similar pressure vessels from aluminum. A few people have told us that we shouldn’t attempt to fabricate aluminum and steel components in the same building because the steel grinding dust can contaminate the aluminum. Others have told us that this should not be a problem. What’s the real story?

A: This is a myth that gets passed around regularly. First of all, most aluminum alloys contain about 0.50 percent iron, so it would be difficult to “contaminate” the aluminum. Second, in my younger days I worked for many years in a shop that fabricated both steel and aluminum pressure vessels. I will personally affirm that we never had any issue with iron contamination. So, the short answer to your question is that yes, aluminum and steel can be fabricated successfully in the same building, and even in the same bay of the building.

However, this isn’t to say that you shouldn’t take certain precautions. I think it is safe to say that aluminum is less tolerant of foreign contamination—not including iron—than steel is during welding. When I say “foreign contamination” I am referring to the particulates in your shop air, like oil mist, as well as the residue of oils, greases, and lubricants on your parts. In many shops the amount of contaminants floating around in the air, which might not cause a problem in welding steel, may cause a problem in welding aluminum. You must ensure that the aluminum is clean when you weld it, whether or not you are welding steel in the same plant. Here are a few ways you can do this:

  • Clean the aluminum properly before welding. This usually means removing oils and greases with a degreasing solvent followed by wire brushing to remove oxides.
  • Once the weld area is clean, perform the weld as soon as possible so that dirt or other contamination doesn’t infiltrate the weld area.
  • If you can’t weld the joint right away (say, within 8 hours or so), cover the weld seam with heavy brown paper and tape it down so it doesn’t blow off.
  • If you leave an unfinished weld over a weekend, cover it with brown paper.

If you take sensible precautions, you can weld steel and aluminum in the same space. If you are careless, you will have problems welding aluminum even if you aren’t welding steel nearby.

About the Author
Aluminum Consulting Inc.

Frank Armao

President

Aluminum Consulting Inc.

440-479-0239

Frank Armao was an active member of the AWS D1 Committee, chairman of the AWS D1 Aluminum Subcommittee, and member of the Aluminum Association Committee on Welding and Joining. He also was the author of The WELDER's "Aluminum Workshop" column from 2001 to 2020.