Stolt Groenland, 2019: styrene polymerisation and cargo tank rupture
The 28 September 2019 cargo tank burst and fire at Ulsan, and the MAIB findings on heat transfer from adjacent heated tanks and unmonitored cargo temperature.
On 28 September 2019 a cargo tank aboard the Cayman Islands-flagged chemical tanker Stolt Groenland burst at Ulsan, Republic of Korea, as a result of runaway polymerisation of a styrene monomer cargo, and the released vapour ignited. The emergency response ran over six hours and involved more than 700 personnel with 117 fire trucks, pumps and fire tugs.
The UK Marine Accident Investigation Branch investigated on behalf of the Red Ensign Group and published report 9/2021 on 20 July 2021. Its safety issues were that the styrene monomer was affected by heat from other heated cargo tanks, that the heat transfer to adjacent cargoes was not fully appreciated, and that the styrene monomer temperature was not monitored. Styrene is inhibited with an oxygen-dependent additive whose effectiveness falls as temperature rises, so an unmonitored temperature is an unmonitored inhibitor.
The recommendations went beyond the operator. The Branch recommended to the Cayman Islands Shipping Registry, the Chemical Distribution Institute and Plastics Europe that the guidance carried in inhibitor certificates and styrene handling guides be made consistent and achievable given the limitations of shipboard equipment and testing facilities. The full article will cover the casualty sequence, the findings, the recommendations and the connection to IBC Code paragraph 15.13 and the certificate of protection.