On 28 September 2019, a cargo tank containing styrene monomer on board the MAIC (Maritime Authority of the Cayman Islands) registered chemical tanker Stolt Groenland ruptured due to runaway polymerisation. The catastrophic rupture released a large quantity of vapour to the atmosphere, and it subsequently ignited. Fire-fighting efforts by the emergency services took over six hours and involved more than 700 personnel and 117 units of fire trucks, pumps and fire tugs.
The rupture of the styrene monomer tank resulted from a runaway polymerisation that was initiated by elevated temperatures caused by heat transfer from other chemical cargoes. The elevated temperatures caused the inhibitor, added to prevent the chemical’s polymerisation during the voyage, to deplete more rapidly than expected. Athough the styrene monomer had not been stowed directly adjacent to heated cargo, the potential for heat transfer through intermediate tanks was not fully appreciated or assessed. Critical temperature limits had been reached before the vessel berthed under the road bridge in
Ulsan. The tanker’s crew did not monitor the temperature of the styrene monomer during the voyage, and therefore were not aware of the increasingly dangerous situaution.
Safety Issues
– the styrene monomer was affected by other heated cargo tanks
– heat transfer from other cargoes was not fully appreciated
– the styrene monomer temperature was not monitored
Recommendations
– A recommendation (2021/122) has been made to Stolt Tankers B.V. aimed at ensuring the wider marine chemical sector benefits from the lessons learned from the Stolt Focus incident and research initiatives that were carried out as a result of this accident.
– The Internantional Chamber of Shipping and INTERTANKO have been recommended (2021/118 and 2021/119) to promulgate our report to their members.
– Recommendations (2021/117, 2021/120 and 2021/121) have also been made to the Cayman Island Shipping Registry , the Chemical Distribution Institute and Plastics Europe (Styrene Producers Association). These are intended to assist in ensuring that the guidance provided in certificates of inhibitor and styrene monomer handling guides is consistent and achievable given the limitations of equipment and testing facilities on board ships.
You can read the report here: Stolt Groenland Report
Read another cargo related report: Are your containers fit for purpose?
