1999 - Multitank Ascania

Year 1999
Vessel Multitank Ascania
Location North of Scotland
Cargo type Bulk
Chemicals VINYL ACETATE inhibited

Summary

On March 19, 1999, at around 3.00a.m., a distress call was received by the Pentland Coast Guard station in northern Scotland from the Tuvalu registered 4,050 chemical tanker "Multitank Ascania". The vessel was en route from Merseyside to Teesport through the Penland Firth, carrying 1,750 tonnes of vinyl acetate, as well as 70 tonnes of heavy fuel and 20 tonnes of diesel, when the fire broke out in her boiler room. The vessel had suffered a fire in the engine room as a result of which she had lost power. The engine room was sealed off and flooded with carbon dioxide. All the carbon dioxide had been released and the systems were shut down. The vessel now drifted helplessly in winds of force 8 approximately 7km west of Dunnet Head, located at the northern tip of Scotland. The Coast Guard immediately scrambled a rescue helicopter and lifeboats with rescue teams from various locations in the area. The helicopter lifted the 14 crew members to safety leaving the master on board.

A salvage contract was signed by the ship's managers. At 5.45a.m., the salvage tug arrived on the scene and attempted to pick up a line from the stricken tanker which she did and tried to pull the vessel away from the land but the line parted a little while after. The master managed to drop the anchors by a lee shore and turned on the emergency pumps to fill the cofferdam (space) between the engine room and the cargo tanks with sea water. He was then winched to safety. By this time, the ship was less than 1km from the shore but with the anchor holding.

The main potential hazard posed by the incident was the risk of explosion. When exposed to heat, vinyl acetate polymerizes (turns solid) in a controlled fashion, but this process generates more heat which, as well as keeping the polymerization going, would also help to "boil off" some of the vinyl acetate through the vents, probably burning and contributing to the smoke. If there was an uncontrolled release, the vinyl acetate which meets the sea would almost instantly be hydrolyzed to acetic acid and acetaldehyde. Acetaldehyde has some toxic properties but is also extremely flammable. If the cargo exploded, there would be thick black smoke consisting mainly of carbon dioxide, carbon particles, some unburned vinyl acetate and a small amount of acetaldehyde.

Narrative

On March 19, 1999, at around 3.00a.m., a distress call was received by the Pentland Coast Guard station in northern Scotland from the Tuvalu registered 4,050 chemical tanker "Multitank Ascania". The vessel was en route from Merseyside to Teesport through the Penland Firth, carrying 1,750 tonnes of vinyl acetate, as well as 70 tonnes of heavy fuel and 20 tonnes of diesel, when the fire broke out in her boiler room. The vessel had suffered a fire in the engine room as a result of which she had lost power. The engine room was sealed off and flooded with carbon dioxide. All the carbon dioxide had been released and the systems were shut down. The vessel now drifted helplessly in winds of force 8 approximately 7km west of Dunnet Head, located at the northern tip of Scotland. The Coast Guard immediately scrambled a rescue helicopter and lifeboats with rescue teams from various locations in the area. The helicopter lifted the 14 crew members to safety leaving the master on board.

A salvage contract was signed by the ship's managers. At 5.45a.m., the salvage tug arrived on the scene and attempted to pick up a line from the stricken tanker which she did and tried to pull the vessel away from the land but the line parted a little while after. The master managed to drop the anchors by a lee shore and turned on the emergency pumps to fill the cofferdam (space) between the engine room and the cargo tanks with sea water. He was then winched to safety. By this time, the ship was less than 1km from the shore but with the anchor holding.

The main potential hazard posed by the incident was the risk of explosion. When exposed to heat, vinyl acetate polymerizes (turns solid) in a controlled fashion, but this process generates more heat which, as well as keeping the polymerization going, would also help to "boil off" some of the vinyl acetate through the vents, probably burning and contributing to the smoke. If there was an uncontrolled release, the vinyl acetate which meets the sea would almost instantly be hydrolyzed to acetic acid and acetaldehyde. Acetaldehyde has some toxic properties but is also extremely flammable. If the cargo exploded, there would be thick black smoke consisting mainly of carbon dioxide, carbon particles, some unburned vinyl acetate and a small amount of acetaldehyde.

Resume

In view of the grave risk of a major pollution incident should the vessel founder or a serious explosion if the fire succeeded in spreading to the cargo tanks, the Coast Guard established a total exclusion zone for maritime traffic of 5km around the tanker and a temporary danger area for aircraft at 8km radius and 30,000 feet. This necessitated evacuating around 600 people from nearby villages. The evacuation was co-ordinated by local police. The Marine Pollution Control Unit (MPCU) of the Maritime and Coast Guard Agency (MCA) was also activated which in turn called upon their contractors to provide a Chemical Strike Team and aerial support to move personnel and MPCU's equipment to the scene. An operation officer from the MPCU, a press officer and MCA's aerial contract manager also flew to Scotland. The MCA's Director of Operations was to control the operations invoking powers of intervention under various legal acts. He also issued a directive to the salvors that they must submit salvage plans to him for approval before proceeding. Meanwhile, the ship's managers appointed salvors which in turn brought in sub-contractors specialized in marine chemical emergencies.

By 9.10a.m., a coast guard helicopter was deployed to monitor the fire on board the vessel and, using an infrared camera, found that the engine room and funnel area were very hot and smoke was still coming out from the engine room vents. Further overflights carried out later indicated that the risk of explosion was subsiding and the cofferdam appeared to prevent the fire from spreading. At 14.00, a coast guard emergency towing tug took up station on the edge of the exclusion zone whilst a communication schedule was set up with updates of the casualty being passed every hour. Broadcasts warned ships in the area that an exclusion zone was in force. A scientist was also sent to the scene ready to set up vapour monitoring, if necessary, for reasons of public health and safety. An expert from a clean-up contractor was also deployed on the shoreline to consider the terrain for clean-up options in case there was to be an oil spill.

On March 20, at 7.10a.m., a Coast Guard helicopter was deployed to check for hot spots on the vessel using the thermal imaging camera. It was confirmed that the fire had not spread to the accommodation unit and that the starboard anchor was holding in place. The salvage master and the MCA's contracted manager of the Chemical Support Team were winched down onto the tanker's deck by 10.10a.m. and they inspected the casualty using a digital laser thermometer, satisfying themselves that the fire was extinguished and there was no further risk of explosion or pollution. A meeting was held, involving all those from the response entities and the ship's master, to gather as much information as possible and outline a strategy.

The plan was to tow the vessel the 30km to Scapa Flow, Orkney Islands, a designated safe haven for ship-to-ship (STS) transfer operations with pollution cover as well as engineering and electrical support and the provision of work boats. A temporary exclusion zone of 2km radius around the casualty was put in place for the tow. At this point, the exclusion zone was lifted and roadblocks removed, allowing local residents back to their homes. The air exclusion zone was also lifted and the Chemical Strike Team and other experts contracted by the Coast Guard stood down. The vessels was safely moored in Scapa Flow by 17.30 hours of March 20.

On March 21, the Highlands and Islands Fire Brigade inspected the tanker in Scapa Flow and gave the all clear that she no longer presented an immediate danger to those on board, allowing the salvor and the specialized response team contracted by them to make a full assessment of the ship. The ship's machinery was found to be totally out of action and the engine room and accommodation unit were heavily damaged by smoke. The salvor began investigations into the ship's condition and the necessary repairs whilst the specialized response team studied the best options for the transfer of the product. They prepared a method statement for the STS transfer of the cargo from a "dead ship" to a standby vessel, the first such operation involving a chemical cargo in European waters. It was critical that the vapour emission control methods used would ensure that there was no release of the highly flammable and noxious vapour to the environment since the local authority would not permit the STS operation until it could be shown that it could be carried out safely and without an environmental impact. Meanwhile, personnel on board the vessel were busy cleaning her up and preparing the machinery and safety systems for transfer operations. The tanker's own pumps were available for the transfer but additional equipment had to be brought in.

By the end of the week, the weather had improved and the Orkney Harbour Authorities, who now assumed control since the operation was to take place within harbour limits, gave permission for the vessel to be towed into Lyness Harbour for the STS transfer. The receiving vessel, Rodenbek, arrived on March 29 and the transfer completed the same day (Figure 1). By the following morning, the Multitank Ascania's tanks had been cleaned and gas freed and on March 31 she departed under tow for a repair yard in Rotterdam.

last modified 2020-12-09T12:11:32+00:00