Boeing 747-400 titanium catalytic converter welding (Englehard)

Extended teaching case. Boeing's general spec required x-ray inspection of titanium welds with no flaw larger than ten thousandths of an inch. Englehard, accustomed to stainless steel cleanliness practices, was failing 25–50% of welds from hydrogen porosity caused by hydrocarbon contamination. Tom's diagnosis: reagent-grade acetone degreasing and white gloves. The case recurs: Englehard succeeded, then reverted to non-reagent-grade acetone and failed again. Tom flags an identical case at GE Lynn with electron beam welds in titanium.

Boeing's aircraft — I remember when the 747-400 came out, twenty-five or thirty years ago. I'd been over in the Far East for a couple of weeks, and when I came back I got an emergency call from Englehard Metals. They were making the platinum catalyst for the 747. Do you know why you have a catalyst in a 747 for the air you breathe? Up there there's lots of ozone, and if you breathed that much ozone for a trip all the way across the Pacific, you would have a very bad headache. Ozone gives you a headache. So all the air coming into the cabin has to go through one of two catalysts, just like the catalyst on your car that gets rid of carbon monoxide. This gets rid of the ozone and converts it back to oxygen so you don't get a headache on your flight. Plus ozone is not good for your heart and other things, supposedly, medically.