Acetylene Service Company Gas Explosion

On 25 January 2005, a powerful explosion destroyed a portion of the Acetylene Service Company (ASCO) plant in Perth Amboy, New Jersey. ASCO was a manufacturer and packager of acetylene gas, used primarily for welding. The blast originated in a small, unventilated wooden "lime shed" that housed pumps and piping for the facility's waste-water recycling system. Three workers were killed instantly or shortly after, and another was severely injured by a supersonic pressure wave (detonation) that hurled debris as far as 450 feet.

The Chemical Safety Board (CSB) and OSHA investigations revealed a "perfect storm" of mechanical failure and procedural negligence. Because it was a freezing winter morning, workers had left a drain valve open in the lime shed to prevent water lines from freezing. When the plant's acetylene generator was started, a critical "gumdrop" check valve—designed to prevent gas from flowing back into the water supply—failed because its stem became snagged, sticking the valve in the open position. With no water pressure in the line to counter it, high-pressure acetylene gas flowed backwards from the generator, through the open check valve, and out of the open drain valve directly into the lime shed.

The shed had no mechanical ventilation and contained a propane-powered space heater used to keep the pipes warm. The accumulated acetylene reached its explosive limit and was ignited, likely by the heater's hot surface or an electrical spark. The CSB noted that the company had no formal Process Safety Management (PSM) program and had a history of smaller fires that had gone unaddressed by rigorous safety audits. Furthermore, the check valve used was found to be an older design that was prone to exactly this type of "hang-up" failure.