Abstract: At approximately 11:30 p.m. on May 24, 2000, Employees #1 through #12 were working in the #3 ammonia plant. Employee #7 was vacuuming desiccant from inside mole sieve vessel #109D-B, which was adjacent to vessel 109D-C. The 109D-C was one of three identical vessels at the facility that removed moisture and carbon monoxide from a synthesis gas used in the manufacture of ammonia. The 109D-C, which had been taken off line to replace its desiccant material, had been online for approximately 11 1/2 hours when the vessel exploded into flame. Employee #7 was killed instantly in the explosion. Employees #2 through #4 and #8 through 11, who were working as his attendants or were conversing with the client's representatives, all suffered severe burns. No information on injuries was provided for Employee #5. Employee #12, a forklift driver, was thrown during the blast and suffered injuries to his neck and back. Employee #6, a crane operator for the permanent maintenance contractor, suffered from severe burns and was hospitalized for several weeks before he died. Employee #1, an ammonia operator, was standing on the catwalk above the 109D-C when it exploded. He also suffered severe burns and died several weeks later. Subsequent inspection of the vessel revealed a cracked weld. Apparently, an inadequate repair job had been made to the weld two days before the accident.