Know what Forest Gump would say about welding?
It’s like a box of chocolates. You never know what you’re gonna to get.
The I-40 bridge into Memphis found out. The weld separated on the box beam, and the bottom member fatigued. Notice that it didn’t fail in the highest stress area where the beam meets the gussets. No weld there, only bolts. Read the Associated Press article here.
Subject to many variables.
Besides weakening the metal, welding is subject to many variables. Too many. The results are connections that are never the same. Temperature, contaminants, weld speed, weld position, gases, etc. all make the strength of the connection impossible to predict. That leaves a good chance of a failure down the road.
Welding is a last resort. It is easy to hold two components together and weld them. Mechanically fastening (bolting or riveting) requires more engineering and assembly time. But, the metal isn’t weakened and the variables for quality are minimal. Good thing they didn’t weld the gussets and beams on this bridge. It would have failed a long time ago.
Nobody would drive over a bridge assembled by welding. Nobody would drive a truck with a welded frame. Next time you buy an aluminum dump trailer, consider the only one built without welds; an entire body constructed with Huck bolts and rivets. You’ll know what you’re getting.
Check out our bolted vs. welded demonstration.