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    Home > Coatings News > Paints and Coatings Market > Coating Process Control of Epoxy Ballast Tank Coating under PSPC New Specification

    Coating Process Control of Epoxy Ballast Tank Coating under PSPC New Specification

    • Last Update: 2020-12-27
    • Source: Internet
    • Author: User
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    China Paint Online News Information
    Li Song, Jin Xiaohong (Xiamen Shuangrui Ship Coatings Co., Ltd., Xiamen, Fujian 361101)
    Abstract: This paper combines 82000t bulk carrier ballast cabin coating, introduced in the implementation of PSPC specifications encountered in various problems and solutions, including coating inspectors, testing equipment, fully enclosed sand blasting room, coating room establishment, as well as steel surface treatment, coating process control.
    key words: ship coating; Surface treatment; PSPC
    : TQ630 Document Identification Code: A Article No:1003-1545 (2012) 04-0073-03
    With the gradual implementation of the Ship Ballast Cabin Protection Coating Performance Standard (PSPC Standard), paint manufacturers have introduced to meet PSP PC standard ballast coating, Xiamen Shuangrui Ship Coatings Co., Ltd. has also specially developed 725-H53-201 epoxy ballast coating for the implementation of PSPC standard ships, the coating obtained the China Class Society (CCS), Lloyd's Society (LR) accreditation certificate, applied to Fujian Province's first implementation of PSPC standard 82000t bulk carrier.
    The ship was built by Ningde Shunda Shipping Co., Ltd., as the shipyard for the first time to meet PSPC standards of the ship, therefore, commissioned by the China Class Society, Xiamen Shuangrui Ship Coatings Co., Ltd. as the ship's chief coating inspector unit, responsible for the ship's construction process PSPC implementation supervision, guidance, including ballast cabin coating inspection tripadcade agreement, and ballast cabin corrosion prevention plan preparation.
    1. Coating inspectors and testing instruments
    In the integration of modern shipbuilding shellcoating, coating is a very important part, ship coating is the whole process of ship construction. Paint as a semi-finished product, must be through scientific and reasonable on-site construction, in order to achieve the expected protection, decoration or other functions. In order to effectively ensure the quality of ship coating, it is essential that the coating process is equipped with qualified coating inspectors and corresponding testing instruments.
    of the coating inspector is to ensure that the ship coating is constructed in accordance with the approved coating support and process technology requirements and that the results of inspection and observation are properly and objectively reported. Ship coating inspectors should understand the principle of corrosion and cathode protection, coating characteristics, coating supporting systems, surface treatment methods, relevant codes, national regulations and standards, inspection of the use of equipment, safety protection and other related knowledge.
    in accordance with PSPC requirements, coating inspectors should have the same qualifications as NACE Inspector Level 2, FROSIO Inspector III, or recognized by the competent authorities. China Ship Coating Inspector Level II (CMMCIC II) is the only qualified ship coating inspector recognized by the Ministry of Transport of China. Xiamen Shuangrui Ship Coatings Co. , Ltd. sent qualified inspectors, the whole process of participating in the ship coating inspection work, to assist the shipyard with the relevant instruments, including rocking table, dew point calculation table, steel plate surface thermometer, wet film thickness meter, dry film thickness meter, roughness meter, pinhole detector, destructive dry film thickness detector PIG instrument, adhesion detector, etc., and on-site practical operation and demonstration. Before the official start of the 82,000t bulk cargo ship, it passed the inspection and approval of the China Class Society.
    2. Surface treatment
    2.1 steel requirements
    steel surface grade by reference to ISO8501 (equivalent to GB8923) standard evaluation. Steel surface corrosion grade, according to the high to low into 4 levels: A, B, C, D. Before the official start of the 82000t bulk carrier, the shipyard's steel plate was mostly C-grade steel plate, a small number of D-grade steel plate, and PSPC standard requirements for ballast cabin steel plate original grade can not be D-class. On the advice and requirements of the Chief Coating Inspector Unit, all ballast plates of the ship were replaced with class A and B steel plates.
    2.2 Surface pretreating
    82000t bulk cargo ship steel plate using blast treatment method for steel plate pretreating, the approximate process is: steel plate leveling →seating→ de-oiling→ preheating→→ blasting workshop primer →heating workshop primer→ after heating→ → roller transport→ lifting. Before the official start, the site test results are: processing grade up to Sa2.5, roughness is: 30-100 m; Surface dust: "3", "4", "5" level of dust distribution up to 1 level; Water-soluble salt content of 72mg/m2 on the surface of the steel plate.
    the above test data can be seen that the surface roughness of the steel plate after treatment, surface water-soluble salt content exceeds the standard requirements (PSPC standard requirements: roughness range is: 30-75 m; Water-soluble salt content on the surface of the steel plate ≤50mg/m2).
    for the phenomenon of excessive roughness, the chief coating inspector unit recommends that by adjusting the ratio of old and new sand and sand pressure, the roughness meets the requirements of PSPC. For the individual roughness exceeding the standard after the official start of work, it is required to make up by increasing the thickness of the coating film.
    For the phenomenon of water-soluble salt exceeding the standard, the chief coating inspector unit recommends: (1) controlling the salt content of the abrasive and replacing the abrasive in a timely manner; The water-soluble salt content reached 28-35 mg/m2, which met the requirements of PSPC standard.
    2.3 segmented secondary surface treatment
    in order to avoid theinstallation of the coating damage, before the secondary surface treatment, the firstparts of the installation, including manhole cover, straight ladder, corrosion-resistant zinc block, outer plate signs, lines and pipe cable carriers.
    Because the workshop primer used for the pre-treatment of the steel plate did not pass the compatibility test with the 725-H53-201 epoxy ballast coating, the secondary surface treatment required the removal of all the original workshop primers, reaching Sa2.5 level.
    Before the official start of construction, the shipyard does not have a second rust blasting room and segmented coating room, therefore, the chief coating inspector unit suggested that the shipyard built a new fully enclosed blasting room, coating room. Blast room equipped with: high-power screw air compressor, vacuum sand absorber, sand punch tank, local dust exhaust fan, for local blasting transformation vacuum gun and other equipment. Coating room equipped with: explosion-proof fan, fan delivery, wheel refrigeration combination dehumidifier and refrigeration units and other equipment. And in the blasting room and coating room near the installation of deionized water equipment, high-pressure water flushing equipment.
    82000t bulk carrier ballast cabin site, after secondary surface treatment to: steel surface defect treatment and weld polishing, treatment to P2 level, free edge grinding to a radius of ≥2mm; Sa2.5; Roughness reached: 30-75 m; Surface dust: "3", "4", "5" level of dust distribution up to 1 level; The water-soluble salt content of steel plate surface ≤ 50 mg/m2, which meets the requirements of PSPC standard.
    3. Segment coating
    82000t bulk carrier ballast cabin coating design in accordance with PSPC requirements, designed into two coatings, each coating dry film thickness of 160 m, the total dry film thickness of 320 m. For the purpose of coating inspection, the bottom layer is coated with red ballast cabin paint and the surface is coated with light gray ballast coating.
    -stage coating process for: unified coating once and pre-coated two degrees and unified coating once the process. The application is carried out by high-pressure airless spraying, and the pre-painting is carried out by the brush coating process (only the process of roller coating is used for flowing water holes and mouse holes).
    Because the construction team responsible for coating for the first time to undertake PSPC ship paint construction, therefore, the chief coating inspector unit organized a training of construction personnel, the main contents of the training are:
    (1) before construction must do a good job of safety protection, construction personnel should be equipped with the necessary protective tools, such as: gas masks, static work clothes, hard hats, steel head protection of work shoes; At the same time, the construction site should do a good job of ventilation, explosion-proof work.
    (2) in the surface treatment to meet technical requirements, temperature, humidity and other factors to meet the construction requirements, can be carried out paint construction. Before construction, first check: paint packaging barrels are normal (e.g. whether there are breakages, loopholes, etc.), record the batch number, paint name, color and other parameters; After opening the barrel, check that the paint is OK (e.g. bottoming, peeling, etc.). Construction can only be carried out after the coating has been qualified.
    (3) in the paint construction process, should be in accordance with the requirements of the coating package, pay attention to control the coating of film thickness, uniformity, and at any time pay attention to detect changes in environmental factors (temperature, humidity, dew point temperature). After the completion of construction, we should do a good job of cleaning and cleaning the site to prevent waste from causing pollution to the environment.
    4. After the stage coating
    is closed to the platform, the chief coating inspector unit requires the shipyard to carry out the necessary protective measures for ballast cabin coating, specifically: (1) first of all, the channel of the area that does not need to be worked on, to avoid damage to the coating caused by the entry and exit of personnel; Through the above measures effectively avoid the damage of the coating, the area of the damaged coating is controlled at about 0.5%, avoiding the sand blasting rust removal method when the coating is repaired after boarding the platform (PSPC standard requires that when the damage area exceeds 2%, the surface treatment should be carried out by sand blasting rust removal). The ship's platform coating takes the method of spraying and brushing, the way of spraying for large welds and large parts of broken area, and the way of brushing and repairing for small area areas.
    5. Conclusion
    In October 2010, the ship completed the close-up of four ballast module coating test sections, and passed the on-site inspection and approval of the China Class Society, and the ship was officially successfully launched in November 2011. The successful implementation of the 82000t bulk ship PSPC project has accumulated valuable experience for small and medium-sized shipyards in China to deal with PSPC practice.
    Reference:
    Wang Guoping. Ship Coatings and Coating Technology, 2nd Edition, Beijing: Chemical Industry Press, 2007:132-137.
    Resolution IMO-MSC.215 (82). Protective coating performance standards (PSPC) for all types of marine ballast compartments and bulk carriers.
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