Transport Malta’s Marine Security Investigation Unit has issued an investigation report right into a failure of a prime cowl bolt of a cargo manifold blind flange valve, leading to an oil spill on deck, throughout cargo operations within the port of Genoa, Italy 21 August 2023.
The Incident
On 21 August 2023, FT Sturla was moored on the port of Genoa, Italy, to unload a cargo of low-sulphur gasoline oil (LSFO). At 0700, a ship-shore security assembly came about between the chief officer and the loading grasp, throughout which it was agreed that the utmost strain to be maintained on the vessel’s manifold, all through the unloading interval, can be 7.0 bar.
Following related checks and preparations, the unloading operation commenced at 1030. The cargo was being pumped out from cargo tank nos. 5 port and starboard, by way of the widespread pipeline manifold valve on the starboard facet. Following a affirmation that every one was so as on board and ashore, the unloading strain was step by step elevated to six.8 bar on the vessel’s manifold. At 1230, nonetheless, one of many in a position seafarers – deck (A/B), observed an oil leak from the widespread pipeline on the port facet. He instantly notified the cargo management room (CCR) through his transportable radio, following which, he pressed the emergency shutdown button on the port facet manifold.
The chief officer, who occurred to be within the CCR at the moment, instructed the crew member stationed on the vessel’s manifold to close the starboard manifold valve. He then suggested the grasp and the terminal in regards to the oil leak and activated the overall alarm.
The grasp notified the vessel’s managers (the Firm) and related authorities, whereas the crew members carried out oil spill contingency measures. A number of crew members rigged up an oil growth across the vessel, to limit the unfold of the oil, within the occasion that any of it was spilled overboard. Within the meantime, different crew members started to comprise and gather the leaked oil on board.
Reason behind the Oil Spill
Throughout their investigation on the supply of the oil spill, the crew members discovered that one of many prime cowl bolts of a blind flange valve of cargo tank no. 5 starboard, on the port facet manifold, had failed. Consequently, the cargo being pumped out, leaked from the highest of the valve. The bolt was noticed to have fractured at first of the underside threaded portion.
Conclusions of the Laboratory Evaluation
The laboratory evaluation report concluded that the fracture could possibly be related to stress corrosion cracking (SCC) phenomenon, in a chlorides-containing humid setting (marine). SCC is often associated to synergistic components, equivalent to an aggressive setting, a static stress discipline utilized to a part and prone fabrication materials.
Chlorides-induced SCC phenomena in austenitic chrome steel, are sometimes within the type of transgranular and considerably branched cracks that may propagate at a comparatively quick charge (30 mm, or extra, per yr), particularly in extreme aggressive environments. The fabrication materials of an AISI 303 (sulphur-rich) austenitic stainless-steel bolt was not enough to withstand corrosion and SCC in humid marine environments.
Security actions taken in the course of the course of the security investigation
Following the incidence, the Firm renewed the highest cowl bolts of all blind flange valves on the manifolds.
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Supply: Transport Malta
