Shipbuilding is a very complicated process, which goes through segment manufacturing and pre-outfitting, dock or docking, launching, quay outfitting and mooring test, sea trial, etc.; while the painting of the ship has to be adapted to the whole shipbuilding process, and the corresponding painting work is determined at each stage of the shipbuilding process. The painting work of newbuilding ships is usually carried out in sections, especially for the construction of large ships, so that the steel can avoid premature rusting and be carried out indoors or on flat ground.
Ship painting process procedure is as follows
Raw material shot blasting line pretreatment → painting workshop primer → steel drop, processing, assembly → segment pre-outfitting → segment secondary rust removal → segment painting → platform closing, outfitting → platform secondary rust removal → secondary painting → ship launching → terminal secondary rust removal, painting → dock painting before delivery.
It can be confirmed from the painting process of the ship that the painting operation runs through the whole process of shipbuilding, therefore, the quality of painting operation must be paid attention to.I. Tips and precautions when painting ship segments
(1) Before painting, the pre-treatment of steel plate should strictly reach the relevant standard of secondary rust removal, remove oil and dirt, wipe the surface with solvent, and apply paint as soon as possible to avoid the steel from oxidizing and rusting again.
(2) According to different parts of the ship and different usage requirements, choose reasonable paint varieties and matching schemes. Each course of paint should be constructed according to the requirements of the product instruction manual. Before painting, check whether the paint varieties, colors, specifications and models meet the technical requirements of painting, check the quality and storage period of the paint, and the paint that exceeds the storage period must be re-examined by the unit with inspection qualification and can be used only after passing.
(3) Thinner must be used in accordance with the requirements, generally not more than 5% of the paint dosage, no harmful solvents or pigments are allowed to be added to the paint, which should be evenly blended before use and filtered according to the requirements of the painting method. For two-component paint, add curing agent in proportion and mix evenly, have a certain activation period and use up within a certain time.
(4) The construction unit can adopt the suitable coating method according to the nature of the coating, the surface state of the painted object and the environmental conditions, which is generally brush coating, roller coating, air spraying, airless spraying and scraping coating and other construction methods. In order to improve efficiency and get beautiful coating film, high pressure airless spraying is generally used. But for the narrow compartment painting, roller coating or manual brushing is still used. Pre-painting is done with brushes and bending off brushes for the flowing holes, the reverse side of angle iron, and the parts that are not easy to spray to. For the contact parts of different metals and rivets, welds and corners should be brushed once and then sprayed.
(5) The coating film should reach the specified dry film thickness. During the painting process, keep measuring the wet film thickness to estimate the number of spraying channels to reach the specified dry film thickness. Before spraying and coating, test spraying should be carried out to choose a suitable nozzle and adjust the proper pressure.
(6) When painting antirust coating, it is better to use the same variety of paint with different colors for each channel*** to prevent leakage and facilitate quality inspection. After the coating is completed, the total dry film thickness should be checked and the coating leak test should be conducted according to the corresponding standard.
(7) It is forbidden to paint the surface which is not suitable for painting such as sacrificial anode, insoluble auxiliary anode, reference electrode, receiver and transmitter thread of depth gauge, sign, rubber seal, valve, steel cable and active friction surface. When spraying or using other methods of painting, cover with tape paper.
(8) It is strictly forbidden to paint antifouling paint or waterline paint directly on the bare metal surface or the interior of the compartment.
(9) When painting in sections, open flame operation is strictly prohibited. High-pressure airless spraying must strictly adhere to the operating procedures and prevent environmental pollution from spraying. Install proper ventilation equipment to avoid the poisonous effect of solvent evaporation on human body and possible fire, and to ensure the quality of construction. For painting in small compartments, manual ventilation is necessary, and workers should wear gas masks and work continuously for no more than half an hour.
(10) The painting construction is usually carried out in an environment where the temperature is 5-30℃ and the relative temperature is less than 85%. When it is raining, foggy or the hull is covered with water vapor and frost and snow, it should not be painted outdoors. It is also not suitable to paint when there is high wind and dust. The temperature of steel plate should be more than 3℃ above the dew point, and the temperature should not be lower than the *** low temperature specified by the paint drying.
(11) Aluminum, galvanized surface or other special material surface should use special paint, such as zinc yellow primer, and primer containing copper, mercury and lead pigment is not allowed to be painted.
(12) The welds and rivets of the hull part shall not be painted within 10mm around before the watertight test; the weld side shall not be painted within 50mm before welding. Apply paper or plastic film to cover up when painting, and remove it in time after painting.
(13) In order to ensure the quality of the coating, after the coating film is fully dry, the section can be moved. Avoid scratching and wearing the coating film when moving.
(14) Before the coating construction, the construction unit should estimate the required coating amount and make a detailed construction plan according to the actual situation such as the coating area of each part of the ship, the construction method and the substrate material and refer to the previous construction data and other factors.