MSC Napoli Report
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Explosive Separation of MSC NAPOLI MSC Napoli is a UK flagged container ship built in 1991. Some 275 metres in length, with a beam of 37 metres, she weighs 53,409 gross tonnes. On Thursday 18 January 2007 she suffered flooding to the engine room during force 8 gales, whilst 40 miles south of Cornwall. The 26 crew abandoned ship and were safely rescued from their lifeboat by helicopter, whilst the vessel grounded off the south coast of England. Working in challenging conditions, SMIT salvage removed over 2000 shipping containers and pumped out the majority of the 4 000 tonnes of bunker oil on board in an attempt to salvage the vessel. On the morning of 9 July 2007 SMIT Salvage re-floated the MSC Napoli, and brought her to deeper water, where she was dewatered and inspected. Once re-floated however, it became apparent that the damage she had sustained would prevent her from being towed. After being continuously pounded by bad weather, cracks on both sides of the ship worsened and the stern of the ship gradually started settling lower in the water. With the risk of the vessel sinking, the Secretary of States Representative (SOSREP) for Marine Salvage, made the decision to ground her again. The stern section was grounded and ballasted down with 30 tonnes of sand, east of Sidmouth to minimize any environmental impact or risk to other vessels. At this stage it was decided to separate the stern and bows section of the vessel, at the vessels shear point, immediately forward of the superstructure. SMIT contracted Ramora UK (As always, late on a Friday afternoon!) to establish if the main supporting structures between the superstructure and the forward section of the vessel could be explosively separated in a safe and controlled manner. This process included liaison with external agencies including the SOSREP, MCA, MOD, police, insurance representatives, and on site support personnel. An initial survey was conducted by Ramora, the SMIT naval architect and Senior Salvage master. The forward section of the vessel weighed 11 000 tonnes and the stern some 8 000 tonnes. The initial damage was allowing 2 of the holds to flood to a depth of 8 metres despite internal patches being welded to the hull. These factors were compounded by the fact that the forward part of the vessel was moving significantly with the rise and fall of the tide. The motion created by the swell resulted in the vessel being severely damaged elsewhere, with steel structures buckling and spliting in the vicinity of the sheer point. Allied to the fact that most areas were covered in oil, and large metal structures were fracturing under the stress, this meant that working conditions were particularly interesting. Following a survey of the shear points from zero deck down to the ships hull, it was agreed that a controlled 3 phase operation would be implemented with the emphasis being entirely on safety. The main objectives were to explosively segregate the vessel in 3 controlled phases, ensuring that that when separated the 2 sections remained upright, the fore and after bulkheads were not penetrated and environmental damage was minimized. The initial phase required access holes to be cut through 44mm of steel deck plate in order to allow access to the longitudinal supporting beams that were providing the structural strength to the vessel. In accordance with Bureau Veritas classification the metal was Grade A, high tensile steel, with a yield point of 355 N/mm 2. Before any of this work could be conducted, the appropriate risk assessments and method statements for the project had to be completed. This process addressed a range of the project management issues, including cordon sizes, RADHAZ, initiation methods, transport and storage of explosives, Notice to mariners and airmen, identification and mitigation of secondary hazards, casualty evacuation plans and so on. On Monday 16 th July preparatory works were conducted to provide access, load equipment, vent spaces and apply fire suppressants below the area being cut. The naval architect specified the size and location of the access holes required and marked the area to be cut. On Tuesday 17 th July the first phase of the explosives operation began. The intention was to cut seven holes simultaneously, immediately above the recognised shear point, just forward of the ships superstructure. This required 3 rectangular holes to be cut on the port side and 4 on the starboard side, each measuring 1000mm x 600mm. This was done using copper sheathed linear cutting charges, with a core load of 3200 grains per foot. A one inch stand off was employed and the cutting effect was supported by PE4 punching charges being initiated on each plate, 50 milliseconds after the cut to assist in removing the deck plates. Once the charges were fitted the cordon was confirmed with the MCA, Police and Secretary of States Representative (SOSREP). Only when the cordon confirmation was received, were detonators fitted and initiation conducted. Following every initiation a 30 minute soak time was applied to ensure the vessel stability had not deteriorated, before boarding to conduct the confirmation phase. All seven of the initial cuts worked perfectly as illustrated in the photographs. The second phase was conducted on the following day and required the longitudinal beams running fore and aft to be cut in the same way. The beams were 44mm thick and 700mm deep. Three beams were located on each side of the vessel and again had to be cut simultaneously. This was successfully completed at 1400 on the Wednesday 18 th . On completion the intention was to pull the forward part of the vessel to starboard, throughout Thursday 19 th hoping to part the remaining fittings from the bulkhead. Despite applying 140 tonnes of pull via the tug, this proved unsuccessful and the 3 rd stage of the operation was implemented to explosively cut the remaining structures. This phase required cutting through a range of metals of varying thicknesses but without the application of punching charges (some 15 metres of cuts were completed) on Friday 20 th July. Immediately following initiation of the 3 rd phase cuts, the port side of the vessel dropped 2 feet below the stern section and 30 seconds later the starboard side fell away to the same level, and an 18 inch gap was evident between the 2 sections. At this stage the concern was for the stability of the bow section and after waiting for the vessel to settle, the tug began to take up the strain and pull the bow section directly forward. Within minutes the two sections were over a hundred metres apart and both perfectly stable. Containment booms were immediately placed around the vessel to contain the minimal amounts of oil that appeared. This environmental control concluded a highly successful explosives operation conducted in the glare of the media on a considerable and precarious target. Andy Pearce MIExpE Operations Director Ramora UK .