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AN EMERGING HAZARD INCIDENT REPORT • REGULATORY CHANGES ARE BEING ADVISED AFTER THE MAERSK HONAM INVESTIGATION POINTS TO IMPROPER CLASSIFICATION OF SDID THE DISASTROUS FIRE aboard the containership Maersk Honam on 6 March 2018, which caused the deaths of four crew members and left one missing, was most likely caused by the spontaneous self-decomposition of a large consignment of sodium dichloroisocyanurate dihydrate (SDID), according to a report into the incident by the Transport Safety Investigation Bureau (TSIB) of the Ministry of Transport, Singapore. The ship, carrying 7,860 containers, was en route from Singapore to the Suez Canal when the fire broke out when it was in the Arabian Sea, some 900 nm west of the Indian coast. As the fire took hold, the crew attempted to fight it by boundary cooling and the release of carbon dioxide into the cargo hold, but these attempts failed and the crew abandoned ship
less than three hours after the first sign of fire. TSIB subsequently engaged Dr JH Burgoyne & Partners to undertake a very thorough inspection of the vessel, once it was secured and moored off Dubai. Due to the nature of the incident and the severe fire damage to the ship, it has proved impossible to determine with certainty what caused the fire to break out. However, it started in a hold that had 54 containers of SDID, as well as 11 containers with dangerous goods of Division 5.1. The crew all reported smelling chlorine and their boiler suits were bleached, strongly suggesting that a chlorine compound was involved. RULE OUT THE IMPOSSIBLE The investigation team considered other
causes. It was thought unlikely that another dangerous cargo had been misdeclared: there was no evidence found during the forensic examination of the hold where the fire started of anything that would indicate another source. The crew had not noticed any smell indicating combustion and no black or grey smoke was seen during the initial phase of the incident. The investigation team also ruled out the possibility of an electrical fault or that the heated fuel tanks had caused the fire. TSIB says that the most likely explanation is that the integrity of the SDID consignment, carried in block stowage, had been compromised and that the heat generated by spontaneous self-decomposition worsened. Although the crew demonstrated “good efforts” to take care of each other during the emergency, TSIB notes that the fire alarm was not raised at the onset of the fire, which led to a delay in the closure of magnetic fire doors in the accommodation block, immediately aft of the fire, and exterior ventilator vents. As a result, toxic smoke spread through the accommodation areas. HAZARDS NOT RECOGNISED TSIB also looked at the current classification of SDID, which has a chlorine content of 56 per cent, under the International Maritime Dangerous Goods (IMDG) Code. Shipping SDID under UN 3077 environmentally hazardous substance, solid, nos, in Class 9, permitted by special provision 135, does not properly reflect the potential secondary hazards of decomposition and instability, its report says. SDID displays similar chemical properties to some substances assigned to Division 5.1. In particular, the lower chlorine level in SDID compared to dichloroisocyanuric acid, assigned to UN 2465, Division 5.1, may have been deemed less risky when it was added to the IMDG Code. Test results for SDID, which formed the basis of its classification, had been derived from relatively small package sizes; in the Maersk Honam incident, the SDID was packaged into flexible intermediate bulk containers (FIBCs), each with around 1 tonne of product. In effect, this created a block of containers, each with around 20 tonnes of SDID, amounting to a cuboid of more than 1,000 tonnes.
HCB MONTHLY | NOVEMBER 2020
