Davidson Enterprises, Inc.: OSHA inspections and violations

Incident on Jan 28, 2002: Oil tank truck explodes, injures worker

On January 28, 2002, Employee #1, a worker with a tank overhaul and repair compa ny, was cleaning a truck tank used to haul crude oil for a company that overhaul s tankers used by trucking companies to haul liquids on the highways. Employee # 1 was using a "spinner" (an electromechanical device that uses steam under press ure to clean the inside of the tank) and was standing on top of the tank when va pors ignited and exploded inside the tank. He was thrown into the air and landed several feet away from the tank. He suffered no serious burns, but had a separa ted shoulder, twisted ankle, and facial lacerations. He was transported to the h ospital in a coma, but recovered consciousness and was discharged three days lat er. The spinner would set on top of the tank. It was powered by a 24-volt motor, which was not intrinsically safe and was located on top of the tank. A rod pass ed through a rubber stopper into the tank. Steam was forced through the rod at 8 00 to 1,000 lbs per square in. (PSI), and it rotated to direct the water in all areas of the tank. The usual procedure was to initially monitor the tank with a calibrated meter to measure lower explosive limits (LEL), and, if any flammable vapors were found, the tank was flushed with water or air as needed until the in terior of the tank was inert. Records were kept of LEL measurements. If the tank did not show any LEL concentrations, it was not rechecked until the next time t he tank is worked on or in. Employee #1 stated that he followed the procedure. I t was a cold and wet morning, and he has previously observed that as the steam h eats the tank, vapors come off from the residual crude oil. When he removed the spinner from the tank section, he saw sparks coming from it and then the explosi on occurred. The employer was cited for a serious accident-related violation of 8CCR, section 5420 (a) (2), namely (1) the spinner was not intrinsically safe, t hus, was a source of ignition introduced to the explosive zone, and (2) the empl oyer did not require frequent tests of the LEL to determine if the environment w as changing (especially with the introduction of heat) and if the quantity of ga s released was rising to the point that the LEL was reached.