Abstract: This company uses a pressure vessel to test oil drilling tools under conditions of pressure and temperature. The tool is attached and activated in the pressure vessel using an assembly which is attached to the top of the cylinder with four long rods. The rods are secured to the vessel with 2-in.-long bolts. The design specifications of the vessel components show that holes in the rods were to be 1-in.-deep leaving 1 in. of bolt to extend into the plate on the top of the vessel. The holes in the rods were drilled to approximately 1.75 in. deep. During the assembly it appears that the bolts screwed themselves into the rods only leaving 0.25 in. of the bolt to hold the assembly in place. During the test, the assembly separated from the pressure vessel at approximately 12,000 PSI. Employee #1 appears to have been struck by an unknown object, probably the top assembly. Employee #1 was killed.