Abstract: At approximately 9:30 a.m. on January 19, 2005, Employee #1 and Employee #2, of the Kern Oil & Refining Co., were isolating and cleaning a series of three pumps at the Kern refinery in Bakersfield, California, while Employee #3 observed the cleaning operation from a distance. The three workers were starting up the refinery's crude unit. They were experiencing screen plugging from crude unit particles inside the crude unit's prefractionator reboiler pump (pump). The screens commonly become plugged during start-up operations. After the charge pump is isolated, workers clean the pump body by injecting pressurized steam into it. Normally the mix of residual crude oil and pressurized steam is removed through a small outlet in the valve body. Employee #1 connected a 40 psi steam line to the top of the pump body. The flexible removable steam line connects to a Chicago fitting on the top of the pump. Just before the explosion, Employee #1 had cracked open the steam line, letting steam into the pump. An uncontrolled pressure event immediately ensued. The overpressurization of the pump body assembly caused the pump suction flange, strainer outlet flange, and flex connector to blow out violently. The spraying hot oil and the fire started by the explosion caused burns to Employees #1, #2, and #3. Employee #1 sustained third and second degree burns over 50 percent of his body and later died. Employee #2 suffered first and second degree burns over his back. Employee #3 suffered first degree burns on his face. Employees #1 and #2 were treated at the Grossman Burn Center at Sherman Oaks Hospital. Employee #3 was treated locally in Bakersfield.