On 23 October, 1989 at approximately 1:05 PM Central Daylight Time, a series of explosions occurred at Phillips Petroleum Company's Houston Chemical Complex in Pasadena, Texas, near the Houston Ship Channel. The initial blast registered 3.5 on the Richter scale, and the resulting fires took 10 hours to bring under control, as efforts to battle the fire were hindered due to damaged water pipes for the fire hydrants from the blast. The initial explosion was found to have resulted from a release of extremely flammable process gasses used to produce high-density polyethylene, a plastic used for various consumer food container products. The US Occupational Safety and Health Administration fined Phillips Petroleum Company $5,666,200 and fined Fish Engineering and Construction, inc, the maintenance contractor, $729,600. The event killed 23 employees and injured 314. Prior to the disaster The HCC produced approximately per year of high-density polyethylene (HDPE), a plastic material used to make milk bottles and other containers. Approximately 1500 people worked at the facility, including 905 company employees and approximately 600 daily contract employees, who were engaged primarily in regular maintenance activities and new plant construction. Cause The accident resulted from a release of extremely flammable process gases that occurred during regular maintenance operations on one of the plant's polyethylene reactors. More than of highly flammable gases were released through an open valve almost instantaneously. During routine maintenance, isolation valves were closed and compressed air hoses that actuated them physically disconnected as a safety measure. The air connections for opening and closing this valve were identical, and had been improperly reversed when last re-connected. As a result, the valve would have been open while the switch in the control room was in the "valve closed" position. After that, the valve was opened when it was expected to stay closed, and finally passed the reactor content into air. A vapor cloud formed and travelled rapidly through the polyethylene plant. Within 90 to 120 seconds, the vapor cloud came into contact with an ignition source and exploded with the force of 2.4 tons of TNT. Ten to fifteen minutes later, that was followed by the explosion of the isobutane storage tank, then by the catastrophic failure of another polyethylene reactor, and finally by other explosions, probably about six in total. Explosions The incident started at approximately 1:05 PM local time on October 23, 1989, at 1400 Jefferson Road, Pasadena, Texas. A powerful