According to the hull structure of tankers, tankers can be divided into two types: double-hull tankers and single-hull tankers. Only double-skin oil tankers are introduced here.
Double hull tanker refers to a special ship with double bottom, double hull and engine room at the tail, which is engaged in the transportation of crude oil or petroleum products. Its special structural features are mainly manifested in the following aspects:
1 cargo oil tank layout
1) Tail-type aircraft, double hulls, professional ballast tanks, medium and high decks, and deck machinery and equipment such as winches, windlasses, cranes, diversion ladders and gangways are mostly operated by hydraulic or pneumatic, which has a high degree of automation.
2) Adopt advanced navigation instruments and communication equipment, such as satellite locator, electronic chart, collision avoidance radar, automatic ship identification system and satellite communication equipment.
3) Equipped with advanced life-saving and fire-fighting equipment, such as automatic fire detection system, large foam fire extinguishing station, satellite position indicator, fully enclosed lifeboat, helipad, etc.
4) Set crude oil tank washing system (COW), inert gas system (IGS), sewage monitoring system and cargo oil loading and unloading centralized control room to realize remote control of loading and unloading operations.
5) The deck, bottom and inner bottom of cargo oil tank area are all longitudinal frame structures. When the length of the ship is greater than 190m, the side, inner shell and longitudinal bulkhead are generally also longitudinal frame structures.
6) In order to facilitate isolation from engine room, dry goods room and living room, isolated empty cabins are set at the front and rear ends of cargo oil tank area. The isolated cabin can cover the bulkhead area at the end of all cargo oil tanks, and the bulkhead spacing is not less than 760 mm The pump cabin, ballast cabin and fuel tank can also be used as isolated cabins.
7) Cabins adjacent to cargo oil tanks, including passages and tunnels passing through or adjacent to cargo oil tanks, all of which can directly lead to the open deck.
2. Double bottom
1) In order to ensure the integrity of the double bottom, there is no manhole on the bilge (inner bottom plate) of the cargo oil tank (the same is true for the double bottom in the engine room), so it directly enters the entrance and exit of the double bottom to the open deck.
2) The box beam or pipe tunnel is isolated from the engine room, and at least two exits lead to the outdoor deck with the largest horizontal distance.
3. Waterproof wall
1) bulkhead types mainly include: plane oil-tight transverse bulkhead and longitudinal bulkhead, trough oil-tight transverse bulkhead and longitudinal bulkhead, non-oil-tight bulkhead and swing bulkhead, etc.
2) The transverse bulkhead is generally equipped with a low stool and a high stool. Tankers with captain 190m and above generally do not adopt grooved longitudinal bulkheads.
3) The opening area of transverse non-oil tight bulkhead or surge bulkhead should not be less than 10% of the total bulkhead area, and there should be a passage opening not less than 600 mm× 800 mm ..
4. Cargo oil tank hatch
1) When the same cargo oil tank is separated by one or more surge bulkheads (or non-oil-tight bulkheads), at least two hatches are far apart and not within the same rib distance.
2) The hatch is round or oval, and the long axis of the oval hatch is arranged along the captain's direction.
3) The size and position of the hatch are determined on the basis of considering the maintenance of the oil tank, the entry and exit of personnel wearing breathing apparatus and the overflow of unconscious injured personnel (possibly on a stretcher) from the oil tank. The basic principle is to keep the minimum size under the condition of meeting reasonable access and ventilation requirements.
4) The height and thickness of hatch coaming shall not be less than 600 mm and 10 mm, and the thickness of cover plate shall not be less than 12 mm. ..
5) The hatch cover is provided with a measuring hole and an observation hole, the diameter of which is not less than 150mm, and the oil tightness is guaranteed.
6) The hatch is provided with a steel fixed escalator to the bilge, and the gradient of the escalator is not more than 70. And when the actual length exceeds 9m, there is a rest platform.
5. Characteristics of oil tankers
1) The design and construction of oil tankers are pushing towards super-large and super-large, with the deadweight from tens of thousands of tons to 200,000-300,000 tons now. The transportation speed is not fast, and the speed is generally around 15 knots (28km/h), so it belongs to a relatively slow ship.
2) It is easy to distinguish from the general dry cargo ship in appearance and layout. The superstructure and engine room of the tanker are located in the longitudinal middle of the stern and upper deck, and there are oil pipelines and footbridges running through the whole ship. Oil is packed in every sealed oil tank. When loading and unloading cargo oil, the tanker uses special oil pump and tubing to load and unload all cargo oil in a few hours to one day and night, so there is no need for cargo oil boom and cargo oil winch on the deck, and there is no need to open the cargo port.
3) As a liquid tanker, the oil tanker has its particularity. Because the goods it carries are basically inflammable and explosive dangerous goods, it is difficult to repair the structural defects found for the purpose of fire prevention and explosion prevention, and they must be repaired after washing the cabin and measuring the explosion. Compared with ordinary ships, tankers have high requirements, strict management and the highest safety factor.