Report on the investigation of a marine accident Clipper Sund LAIR6 occupational accident Antwerp 6 September 2011

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Description

At 01.15 on Tuesday 6 September 2011, an explosion occurred on deck on board the Norwegian chemical tanker Clipper Sund at quay in Antwerp. One man died from injuries sustained in connection with the explosion.

The explosion occurred as the result of a reaction between two incompatible cargoes.

The vessel was loaded with mono nitrobenzene, nitric acid and aniline. After the discharging operations had finished, there was aniline in the vessel's port drip tray and nitric acid in the vessel's drainline, only separated by a single ball valve.

The investigation concludes that the factors that triggered the explosion were that the able seaman who was alone on deck at the time of the accident caused the opening of the ball valve separating the aniline and nitric acid. The incompatible cargoes reacted immediately and caused heat and gas generation. In all probability, the able seaman understood that something was wrong and reacted by closing the valve in order to limit the extent of the damage. On the contrary, this made it impossible for the gases in the drainline to escape. The pressure in the pipe increased rapidly and caused an explosion.

The purpose of the investigation was to identify the underlying causes of how the opening of a single valve could lead to an accident of this kind. The investigation has focused on design, operational factors and regulations.

The applicable regulations, relevant industry standards and the classification society's interpretation of them permitted the vessel's drip tray to be directly connected to the vessel's drainline, only separated by a ball valve. In the case of the Clipper Sund, the drip trays were not just connected to the drainline, but, through them, also to cargo tank 5C. The AIBN submits a safety recommendation to Det Norske Veritas and the Norwegian Maritime Directorate in this connection, proposing a change in the current classification regulations and the interpretation of the IBC Code.

The shipping company had not carried out vessel-specific risk assessments of loading and discharging operations that should have formed the basis for the introduction of risk reduction measures, including the drawing up of necessary plans, procedures and instructions. The shipping company states that it has implemented a number of measures on four sister vessels in order to prevent similar accidents in future. The AIBN nevertheless submits a safety recommendation to the shipping company relating to the carrying out of risk assessments of loading and discharging operations and the establishment of necessary operational procedures based on such assessments.

The current regulations give the shipping company a great degree of freedom to choose how to conduct its risk management. No specific requirements apply to how risks on board are to be identified and how risk assessments are to be carried out. The regulations thereby provide the shipping company with little support for conducting satisfactory risk assessments that, in turn, put the shipping company in a position to implement relevant measures.

The AIBN is not aware of the quality of risk management work in other shipping companies, but, given that the same requirements for this work apply to small and simple shipping organisations as to large shipping organisations, the AIBN cannot exclude the possibility that the quality of this work can vary considerably. A safety recommendation is submitted to the Norwegian Maritime Directorate to the effect that it should map the status of the shipping companies' risk management work with a view to further targeting the work on guidelines/guides to help the shipping companies to establish satisfactory risk management.

Safety recommendation

Safety recommendation MARINE no 2013/10T

The shipping company had not carried out or documented risk assessments of the loading and discharging operations on board. This resulted in inadequate plans and a reduced focus on the safety aspect of stripping operations. 

The AIBN recommends the shipping company, through a risk assessment of the overall cargo handling on board and on the basis of the uncovered risk, to assess existing plans, procedures and checklists and carry out necessary measures. This work should be carried out in close cooperation with the crews on board.

Safety recommendation MARINE no 2013/11T

The current national and international regulations do not set specific requirements for how risks on board are to be uncovered and how risk assessments are to be carried out. Guidelines to official requirements could have contributed to ensuring that the shipping company carried out risk assessments of the loading and discharging operation. The Norwegian Maritime Directorate is working both nationally and internationally on the preparation of guidelines to risk assessments.

The AIBN recommends the Norwegian Maritime Directorate to map the status of the shipping companies’ risk management work with a view to further targeting the work on guidelines/guides to help the shipping companies to establish satisfactory risk management.

Safety recommendation MARINE no 2013/12T

Drip trays are not described in much detail in the existing regulations and are not assessed by DNV with regard to segregation. In the case of the Clipper Sund, the drip trays were connected to the vessel’s drainline. This led to the opening and closing of a ball valve, which resulted in an explosion in the vessel’s drainline. The drip trays were connected to cargo tank 5C through the connection to the drainline, which meant that the tank was not segregated in accordance with the intentions of the Code and that it represented a latent risk.


The AIBN submits a safety recommendation to DNV that it amend its regulations and practice so that open systems, such as drip trays, must be designed for segregation on a par with closed tank and pipe systems.

Safety recommendation MARINE no 2013/13T

Drip trays are not described in much detail in the existing regulations. In the case of the Clipper Sund, the drip trays were connected to the vessel’s drainline. This led to the opening and closing of a ball valve, which resulted in an explosion in the vessel’s drainline. The drip trays were connected to cargo tank 5C through the connection to the drainline, which meant that the tank was not segregated in accordance with the intentions of the Code and that it represented a latent risk.

The AIBN submits a safety recommendation to the Norwegian Maritime Directorate that it work towards the adoption of an interpretation of the IBC code through the IMO to the effect that open systems, such as drip trays, must be designed for segregation on a par with closed tank and pipe systems.

Location
Antwerp, Belgium
Occurrence date
06.09.2011
Accident category
Personal injury
Area
Other Nation's Territorial Waters
IMO number
9375977
Name of vessel
Clipper Sund
Accident type
Fire/Explosion, Fatal Accident, Occupational accident, Technical failure, propulsion or auxiliary engines
Vessel type
Tanker
Register
The Norwegian International Ship Register
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