The main product of Kherson State Plant «Pallada» is composite floating docks with the lifting capacity up to 30000 t. But the developed by the plant technology of caisson free longitudinal and lateral joining of hulls afloat makes it possible to build floating docks practically of any dimensions. Generally world shipbuilding plants build metal floating docks. But the metal is corroded in the water. So to the effective thickness of dock’s hull elements the extra thickness of the metal is added to guarantee the full lifetime of metal dock. This thickness must be consumed for the corrosion during all the operation life. Thereby the effective thickness metal of hull increases to 30-50% more. It results accordingly into the excessive metal consumption and high labour coefficient for the hull manufacturing of such docks.
The metal hull is coated by the protective paint for the slowdown of corrosion process. During the maintenance the metal docks bottom is repaired periodically for the renewal of protective coating. It relates with a necessity of docking the dock itself or the separate parts of its pontoon. During overhaul the metal dock proper usage is excluded partially or fully.
The advantage of the composite construction docks lies in the fact that reinforced concrete, which the dock pontoon part is made of, works good itself in compression and the work in tension of its pontoon is provided with reinforcing steel, which is protected by the concrete layer against corrosion. In this case the rolled iron is consumed less, than in case of the steel hull building. In addition reinforcing bar is cheaper than the structural stock and flat. So far as the reinforced concrete is not corroded in the sea water, the composite dock pontoon does not require painting and docking. The sidewalls of the dock can be painted and repaired if it is necessary without removing the dock out of service for its docking, in other words, in parallel with the vessel overhaul in the composite dock. An operation of composite docks without removing them out of service during the whole lifetime term brings many economical advantages to their owners.
Elements of reinforced concrete pontoon of the composite dock have a greater thickness which extends, considerably, service particulars: in this dock the vessels can be placed, which lost longitudinal strength or the vessel can be parted without concern of the dock damage by the load impact; the vessels can be placed on the stocks of dock in any place without concern of the dock or vessel damage.
The building of the first composite dock project 1760 with the lifting capacity 8500 t was an important step in building practice of the new generation docks. These docks are designed for the docking of vessels with the deadweight 10000-20000 t. These vessels are included into 50% of total amount of the world fleet vessels. So there is a regular demand for docks of this lifting capacity at the world markets with the rising tendency. The plant built totally 39 docks of this project and its modifications, which operate practically in all regions of the world.
But the docks of this project could not dock the considerable quantity of vessels with dock mass 8500 tons because of the insufficient breadth between entrance fenders. And so in 2005 the plant together with projectors of Central Design Bureau «Izumrud» worked out the new project 1760KP of the dock with lifting capacity 8500 t, which satisfies completely all requirements of «Regulations of classification and sea vessels hull construction» and «Regulations of hull constructions for sea vessels and floating facilities with usage of reinforced concrete» of Russian Maritime Register of Shipping. An increased breadth of the dock, the project 1760KP between entrance fenders provides the docking practically of all vessels with the dock mass 8500 t. The dock maintenance warranty period without overhaul is 50 years. In 2006 the main dock of this project was submitted to the customer and now it operates successfully in Qatar (port Doha). The other similar dock is now in the last phase of building.
The development and mastering of technology of caisson free longitudinal and lateral joining afloat of docks with big lifting capacity from the separate parts, which were built on the different stocks and launched independently, became an outstanding event in production activity of the plant. At present time the plant makes underwater longitudinal joining of docks by caisson free method, and joining of docks afloat in lateral direction from separate parts-units is realized by the above-water joining of its sidewalls by welding.
Implementation of longitudinal and lateral joining afloat of docks with big lifting capacity makes it possible to create the floating docks with lifting capacity from 13500 to 50000 tons. And the joining of docks with lifting capacity more than 30000 t from the separate part-units, made at Kherson State Plant «Pallada», can be executed in the customers own water areas.
