On 9 August 2024, a major explosion occurred aboard the container vessel YM Mobility at the Beilun Second Container Terminal in Ningbo-Zhoushan, China. The explosion originated from a container near the bow, loaded with dangerous goods. Although declared by the shipper as a reefer container used as a substitute for a dry container, it was not connected to a power supply. The incident resulted in an estimated economic loss of approximately CNY 90 million (US$13 million).
According to the China Maritime Safety Administration (CMSA), the container held tert-Butyl peroxybenzoate (TBPB), a thermally unstable compound capable of self-decomposition at room temperature, releasing significant heat and gas. The unplugged reefer, which lacked adequate heat dissipation, allowed heat from the TBPB’s self-decomposition reaction to accumulate. This triggered a thermal runaway, leading to the explosion and subsequent fire.
The CMSA also linked the incident to extreme summer temperatures. When TBPB was packed in Shanghai on 25 July, the ambient temperature was around 35°C. From that date until the explosion on 9 August, both Shanghai and Ningbo experienced sustained high heat, with daytime temperatures reaching up to 40°C.
Containers stored outdoors would have been exposed to even higher temperatures, exacerbating the risk by raising the internal temperature of the unplugged reefer, increasing the chance of decomposition and explosion during transport.
The investigation revealed that the operator failed to perform a thorough safety assessment. No consideration was given to the compound’s thermal sensitivity, seasonal temperature extremes, or the heat retention properties of an unplugged reefer. By approving the use of this container type for TBPB, the operator overlooked the serious temperature-related hazards.
Both the shipper and operator were found responsible for the incident. They jointly chose to use an unplugged reefer for a thermally unstable substance without adequately assessing risks tied to heat, cargo chemistry and container insulation. Their failure to conduct a proper evaluation of the transportation plan and packing conditions directly contributed to the disaster.
Implications
The YM Mobility explosion highlights the critical importance of accurate cargo declarations and strict compliance with dangerous goods regulations. It underscores the severe risks of improper handling and packing of hazardous materials, risks that can endanger vessels, crews, port facilities, and the environment.
The incident serves as a powerful reminder that a proactive safety culture, thorough risk assessment and emergency preparedness are essential to safely managing dangerous goods.