Equipment safety is critical to a company's life and property; it must never be taken lightly.
Accident Retrospective: On January 7, 2010, at approximately 17:24, a severe explosion and fire occurred at Tank Farm No. 316, located within a local petrochemical subsidiary of a major national oil and gas corporation. The accident ultimately resulted in six fatalities and six injuries, one of which was critical. In the immediate aftermath, it was widely believed that the accident was caused by a cloud of leaked butane gas igniting. However, subsequent investigations revealed that the deeper underlying cause was an Equipment Integrity Failure. The investigation determined that the accident originated at the R202 spherical storage tank, which was used to store butane. A welded elbow on the tank's outlet piping suffered a brittle fracture within the Heat-Affected Zone (HAZ) of the weld seam due to metallurgical defects in the material. Following the rupture of the pipe, a large volume of highly flammable C4 hydrocarbons (butane) leaked rapidly. As the combustible vapor cloud spread across the tank farm, it drifted toward the heating furnace area of a nearby acrylonitrile unit; upon encountering an open flame there, it ignited, triggering a violent Vapor Cloud Explosion (VCE) that subsequently escalated into a massive fire. One of the most critical lessons drawn from this incident stems from the investigation report's revelations regarding maintenance management deficiencies. As early as 2007-three years prior to the accident-inspectors had already identified severe corrosion and wall-thinning issues in the inlet and outlet piping of several spherical butane tanks, including R202. Consequently, the company initiated a replacement program for the piping associated with several of these spherical tanks. However, according to the investigation findings, the piping replacement was ultimately completed for only one of the tanks; despite the known severe deterioration of its associated piping, the R202 spherical tank remained in active operation. Therefore, this incident should not be viewed merely as a simple "leak-and-ignition" event, but rather as a textbook example of a Major Process Safety Failure resulting from Deferred Maintenance. Key Process Safety Lessons Learned: Issues identified during inspections must be addressed with timely corrective actions and fully rectified. A Mechanical Integrity management system is truly effective only when recommended corrective measures are thoroughly implemented. Under the prolonged effects of corrosion and degradation, the heat-affected zone (HAZ) of a weld seam may become the most critical site of failure. Risk assessments for hydrocarbon storage facilities must take into account potential ignition sources located at a considerable distance from the point of leakage, rather than focusing solely on the immediate vicinity of the leak source. From the perspective of Process Safety Management (PSM), the Lanzhou Petrochemical accident shares a common characteristic with numerous other major industrial disasters-such as the Texas City Refinery explosion in the U.S. and the Bhopal disaster in India: the hazards had long been identified, yet the necessary corrective measures were never fully implemented. Many disasters do not stem from unknown risks, but rather from known problems that have remained unresolved over a prolonged period.
