Forty-one people died when a road tanker exploded in the Boksburg suburb of Johannesburg in 2022. Process safety specialist Motlatsi Mabaso asks whether the lessons learned will ever be made public
ON CHRISTMAS Eve 2022, in the Boksburg suburb of Johannesburg, South Africa, a road tanker carrying liquefied petroleum gas (LPG) exploded killing 41 people in what is thought to have been a boiling liquid expanding vapour explosion (BLEVE) event.
The major incident took place in a residential area close to Tambo Memorial Hospital after the tanker became wedged under a bridge.
At the time of writing, no incident investigation report is available. A dangerous goods supply chain national task team has been assembled, coordinated by the Department of Transport, but the leader of the task team could not confirm the progress of the investigation.
However, from information available in the public domain, this is what I have been able to piece together:
Using my own knowledge to join the dots between point 4 and point 5, I believe that due to the heating effect of the torch fire on the shell of the vessel, the LPG began to boil. The boiling resulted in an increase in pressure inside the vessel (due to more vapour being present as the LPG boiled). When the pressure inside the tanker exceeded the design pressure of the tanker shell, an explosion took place. It is highly likely that this explosion was a BLEVE.
Amateur video footage after the incident shows victims who had their clothing either melted on to their skin or burned away to reveal damaged skin beneath. According to the Netherlands Organisation for Applied Scientific Research (TNO) Green Book, this indicates exposure of thermal radiation greater than 50 kW/m2 over a short period of time. The injuries and fatalities observed on the day were likely a combination of exposure to high thermal radiation levels as well as a significant amount of explosion overpressure.
The Boksburg tanker explosion differed from other recent industrial incidents in South Africa in so much as it occurred very publicly. There were a number of eyewitness accounts, and extensive amateur video footage of the incident detailing the largest explosion and the aftermath. The accounts and footage captured the attention of the entire country and brought several issues into public focus, including transportation of dangerous goods on public roads, process safety in general and the state of municipal infrastructure.
Companies are legally required by the Promulgation of Major Hazard Installation Regulations to report major incidents or near-misses to the Department of Employment and Labour, the local government in their area, and the supplier of the substance involved. At present companies are not legally required to publicly release incident reports or lessons learned related to major incidents which occur at their premises.
Below are just three of the major industrial incidents that have occurred in South Africa since 2004:
It has, unfortunately, become commonplace for the companies involved to conduct their own internal investigations, resulting in lessons learned often failing to reach the public domain. A legal compliance and vehicle route audit was conducted after the Boksburg incident by Transheq, an independent road transport safety system auditor based in Johannesburg. In a television interview with South African news channel eNCA, Transheq director Richard Durrant confirmed he had studied documentation provided to him by the trucking company. “My scope was more on legal compliance and whether the driver and the vehicle were legally compliant and whether the driver was on the legal route,” said Durrant. “After studying the information, I found that there were no issues or variations of the route by the driver.”
However, Transheq’s audit was remote and not a forensic investigation and the report is not publicly available, leaving us with questions that still need answering.
Because the tanker in the Boksburg blast was en route to its destination, the investigation falls under the remit of the Department of Transport (DoT) and the police.
The worry is that the investigation will only focus on criminal culpability. And while a criminal investigation is important, especially to the families who lost loved ones, without a proper technical investigation we risk not knowing exactly how and why the incident occurred. Trying to extract lessons from major incidents based on media reports, eyewitness accounts and amateur video footage is far from ideal. That lack of knowledge opens us up to the risk of a similar tragedy in the future, perhaps with even more devastating consequences.
It is clear South Africa needs to instigate a body similar to the US’ Chemical Safety and Hazard Investigation Board (CSB), which has a legal mandate to investigate major chemical incidents, providing publicly available reports, simulations, and recommendations for industry consideration. Only then can we be sure the lessons of Boksburg, and incidents like it, will truly be learnt.
Catch up on the latest news, views and jobs from The Chemical Engineer. Below are the four latest issues. View a wider selection of the archive from within the Magazine section of this site.