Abstract: At approximately 10:30 a.m. on June 14, 2007, Employee #1 was leak testing a 4 foot long, 4 inch diameter titanium duct tube by applying 420 psi air while the tube was in an enclosed water tank. Employee #1 released the air pressure after one minute and the pressure gage reading was at zero air pressure. Employee #1 then placed the titanium duct tube on the adjacent work bench and began removing the cover plugs from the ends of the titanium tube when it suddenly exploded. Two coworkers immediately came over to help Employee #1. The supervisor called the city fire paramedics when informed of the accident by the coworkers. Employee #1 was taken to Saint Joseph Hospital and was diagnosed with a right hand fractured thumb, lacerations to the stomach, and right wrist. Employee #1 was admitted to the hospital for three days. The coworkers did not observe the accident when it occurred. The employer was Senior Aerospace, a manufacturer of aircraft ducting.