IMT North Andover hot isostatic press explosion

World's largest HIP at the time. 60-inch ID, 300-ton forged vessel, 200-ton cylinder with 50-ton plugs top and bottom, holding 20,000 psi argon at 1500°F for jet engine disc and rotor consolidation. Japanese-forged vessel (no U.S. capability in 1980s). Brittle fracture initiated outside at a threaded stress concentration; top piece flew a quarter mile; one 5-ton fragment crushed the operator's chair (vacant by ~3 feet, 2 AM shift change). Three-factor teaching case: material deficient (renormalization without prolongation, substitute test piece cooled wrong), stress higher than predicted (transient thermal stress on outside, not the steady-state inside max from the supercomputer model), environment corrosive (phosphate water-treatment chemistry pitting the outside like a Dalmatian). Critical flaw size went from a predicted 15 inches to a measured half-inch initiating fatigue crack. Pratt Whitney, GE, Rolls-Royce all dependent on this furnace for aircraft engine disc HIP; fortunately a sister vessel was under construction.