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In the previous article we learnt what is exactly meant by ship scrapping or ship breaking. 80% of the ship breaking process involves manual labour. Unique technical knowledge with physical labour is required for this task. Technical knowlege is required to dismantle the parts with utmost safety and precaution and to avoid accidents due to handling of hazardous materials and heavy sections of steel from the ship's body. And Physical labor is required because most of the work is done with the help of hand held cutting tools.
Let's take a look at the various methods that are used to carry out ship breaking and also the different hazards and problems attached with the whole process.
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The Ship Breaking Process: Methods
There are mainly two methods that are used to carry out the ship breaking process.
- Afloat method
- Dry dock method
In the afloat method, the dismantling starts while the ship is in water. This is a more difficult method because the scrapping of the interior has to be carried out in the water itself before the actual dismantling can began. The workers remove the insides of the ships, from doors to machinery, and dismantle the rudder and propeller from inside while the ship is still in water. After that, the superstructure and the deck components are removed before cutting of the main and lower deck commences. As the ship become lighter, it is pulled to the shore with the help of high tides and the rest of cutting is carried out after that.
In the dry dock method, the ship is docked at the shore and the whole scrapping is done at the same place. This is a faster process as the workers can start dismantling immediately after the ship is docked. This process is easier because the ship is not in water when the breaking is done. But at the same time, it is more expensive than the other method. The ship is first broken into large pieces, which are then shifted to other areas to cut them into smaller pieces.
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Removing the Interiors
The engine room of the ship consists of a variety of machinery such as mechanical, hydraulic and electronic equipments. Mostly, all these equipments are in proper working condition and thus have a potential resale market. Therefore all the salvageable equipments are removed with utmost care which mainly involve manual labor. Once it is done, the hull structure is cut apart. Pipes, cables, partitions and furniture are also removed or gas cut. The heavy steel of the hull is cut with the help of gas torches and saws.
Many equipment that are used to the cut the steel are more than 10 tons in weight and thus special cranes and lifting equipments are used to lift them. Equipments such as grinders, abrasive cutting wheels, hand held shears and plasma torches are also used for the cutting purposes.Diagrams of compartments, cargo tanks and storage areas are used to make the process easy. It is of extreme importance that hazardous materials such as fuel oils, asbestos and discarded waste are handled with utmost care.
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Cutting the Exteriors
After the interiors are dismantled, the scrapping of the main structure begins. The ship is towed to the main scrapping site or dry docked, if the scrapping is done by afloat method. The scrapping is mostly performed at slips, which are openings on the banks for the ships to slip over. They are of 400- 700 feet long and 100 - 120 feet wide. Winches and cranes are used to pull the ship on the slips.
Before the main process starts, the diagrams of the rooms and tanks are properly studied in order to understand the structure of the ship. Oils, dangerous cargoes or any other hazardous materials are drained out of the tanks and collecting areas. As gas cutting is used, care is taken to see that none of the combustible material remains in the ship in order to prevent explosions and spills. All the cutting torches and saws abide by the regulations of hot permit work approval. Anchors, chains or any other fixtures are also removed prior to dismantling. All the Asbestos Containing Materials (ACM) are removed with utmost care from the areas where the cutting is to be done. Paint of the surfaces to be cut are also removed.
The cutting process starts by cutting the superstructure and the upper decks, followed by the main and lower decks. Oxygen fuel cutting torches are used for metal cutting. The structure is first cut into large parts which are then carried by the cranes to the areas where they are cut into small pieces. As the cutting process continues, the ship is pulled gradually over the slips with the help of winches.
In the next article we will learn about the metal cutting of the hull structure and the hazards related to it.
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