High-strength truck frame welding violations

General principle illustration. NHTSA-prohibited welding on HSLA tractor-trailer ladder frames; aftermarket welds cause failure at ~100k miles.

If you look at the frame of a tractor-trailer going down the road, that's a big plate of steel made into a C-channel. The steel frame is ladder-frame construction — a C-channel here, another over here, those are the two ladder rails. Usually a high-strength steel, eighty or ninety ksi. You are not allowed to weld on that. National Highway Transportation Safety Authority — you're not allowed to weld. Some old boy comes along, wants to add a little bracket to the bottom of his truck. He puts a little weld down there, and 100,000 miles later — which is not a lot on a truck — the frame falls apart. You can't weld high-strength steels and keep the strength. You can bolt on it, they put drilled holes in for that, but you don't weld on it.