Quality control and promotion method in cargo tank coating

Since china entered
21st century, Chinese ships have occupied a growing share of the world shipping market. The number of repairs and maintenance of finished oil tankers in China is increasing. The special coating of the cargo tank is the biggest difficulty in the repair of the tanker, the delay and poor quality are common phenomena in the industry, which brings great trouble to the shipowners

. However, how to solve the current problems in the process of coating the cargo tank, which needs to comprehensively strengthen the quality control in the coating operation process, improve the current problems and shortcomings, the implementation of fine management of various production processes, improve the aesthetics of the surface of the cargo tank, while minimizing the potential risks and hidden dangers caused by coating failure.
Cargo tank coating treatment
cargo tank coating treatment refers to the surface painting work carried out after the internal blasting of the cargo tank at the time of ship repair, after meeting the requirements of rust removal and de-contamination. From the point of view of the process, cargo tank coating often needs to go through tedious treatment works, from scaffolding, chemical cleaning treatment, sand blasting rust removal, cleaning, coating, demolition, sea water experiments and other processes. How to maintain ventilation, dehumidification and lighting in the construction process have high requirements. When the cargo tank is repaired, the coating is selected by the shipowner, the shipyard needs to be in strict accordance with the paint company prepared surface treatment standards, spray equipment model, construction methods, coating thickness range and other guidance programs for construction, but also pay attention to the coating process of the protection of the external environment, personal protection, ship spray equipment maintenance and other work.
cargo tank coating operation will go through a lot of tedious steps, ship repair cycle is very tight, coating process is cumbersome, paint storage and pre-construction temperature control is very high, making coating operation management very difficult.
main step of the coating operation process
01 scaffolding operation
suitable scaffolding is very important for the whole special coating process. The scaffolding material used must be cleaned, the surface must not be oily, rusty, sand ash, etc., the spacing between each scaffolding is strictly controlled at 1.8 to 2 m, and the vertical distance between the scaffolding surface and the surface of the cargo tank is strictly controlled between 25 and 35 cm, both Convenient construction, but also to ensure safety, all grooves must be set up work surface platform to ensure that construction personnel easily access to any work surface, foot tube two ends using rubber plugs closed, mesh (or springboard) and steel pipe contact with the surface to add rubber, to prevent friction during the construction process sparks, causing safety problems.
02 in-cabin dehumidification to meet the specifications
cargo tank special coating process, the need to use heating (cooling), dehumidification of the air conditioning to meet the blast rust removal, coating construction, coating curing during the requirements. In some cases, fan should also be used to ensure the amount of ventilation in the cabin, to ensure the safety of construction.
03 LightingIn strict accordance with the requirements of the operating instructions, the use of wireless explosion-proof lamps, first, lighting is an important guarantee to improve the construction safety factor, second, lighting for paint construction has important significance, construction to acceptance of the whole process needs to use different brightness explosion-proof lamps, check different degrees of defects.
04 Blast rust removalThe most important step before coating construction is sand blasting and rust removal, not only to remove rust, oxidizing skin, paint, but also to deal with clean surface pollutants. Sand blasting is divided into pre-flushing sand and restructing sand, the former in order to solve structural defects, the latter used for coating construction. Surface treatment requirements strictly comply with the specifications, usually surface treatment grade ISO 8501-1 Sa2.5, abrasives need to be hardness of more than 6HM copper ore, and salt testing meets the specifications. In particular, in the blasting process, it is important to maintain the relative air humidity in the cabin <50%, and even some shipowners (specs, coating companies) will require less than 40%, lower relative air humidity environment can ensure a better surface after sanding treatment.
05 Paint constructionPaint construction, must choose a professional qualified construction personnel, the performance of the paint and construction program is familiar with, paint preservation, mixing, paint pump, paint belt, nozzle and so on should be in accordance with the requirements of the paint company construction;06 coating inspection each degree coating construction is completed, need to strictly check, film measuring personnel need to be in accordance with SSPC-PA2:2004 standard dry film thickness measurement, the use of the instrument must be in a calibration state, inspectors should be strong responsibility, meet the requirements of the specifications, and labeling;
07 Seawater testSeawater immersion tests are required prior to completion of the tank (as required in the specifications) to detect defects in the coating. The way, time and materials of immersion should be carried out in accordance with the requirements of the specifications.
A effective measure to comprehensively strengthen the quality control of cargo tank coating
In the face of some problems existing in the process of cargo tank coating operation, it is necessary to strengthen quality control and improve the quality of cargo tank coating, we can make efforts from the following aspects:
(1) to expand the training of talent. Coating professional and technical personnel is the basic guarantee of technological innovation and efficiency upgrading. The marine industry is growing day by day, coating technology is constantly updated, whether in the construction process, or in the upgrading of coating raw materials, need to inject a large number of professionals. Construction personnel engaged in ship coating operations must master the corresponding basic coating theory, but also proficient in the operation skills of various construction equipment, the training of coating inspection should be updated regularly. The internal management personnel of the ship enterprise also need to master the technical level of the current construction personnel, carry out the operation training in due course and appropriately, and
improve the business level of the construction personnel; The most important component of coating operation is site construction, at the same time to strengthen the construction process of inspection, improve the three-level inspection system, do a good job in the construction team self-inspection, factory mutual inspection work, as well as the final shipowner representative of the special inspection work. The three-level inspection system is a practical scheme to improve the quality of cargo and oil tank coating operations. At the same time do a good job on-site records, clear to the responsible person, record the construction conditions and construction personnel, all registered in the process record form;
(3) to strengthen the construction environment to further improve. Cargo tank in the coating construction, the construction of environmental conditions have very high requirements, can use advanced recording equipment, strict monitoring of real-time environmental conditions in the cabin. The construction party should first understand the changes in the environment in the area, and then take targeted corresponding solutions, such as temperature, relative air humidity and wind and sand and other environmental factors, will affect the quality of coating, the temperature is too high easy to cause dry cracking of the coating, and the temperature is too low will cause the coating dry slow, or the coating corrosion conditions. In this case, the environment should be effectively examined and asserted to ensure that the surrounding environmental factors are suitable for coating operations.
in the coating process, once there is windy weather, easy to cause dust and debris flying, then it will affect the adhesion of the coating, so in the above-mentioned environment to stop coating construction. If it is in the summer high temperature environment under the coating operation, easy to appear bubbles or bone cracking phenomenon, so to take certain cooling measures. By combining the climatic conditions to carry out the construction, to ensure the quality of coating, to avoid the overall quality of the construction greatly reduced
; In the process of coating will inevitably appear a certain problem, which requires a series of defects on the surface to do a good job of handling. For example, to the site of construction personnel to carry out strict inspection and foreint inspection, to ensure that the interval between painting is more reasonable, if the coating has leakage brush or inadvertent collision phenomenon, to be timely treatment, to avoid the phenomenon of rust. In short, it is possible to deal scientifically and rationally with the phenomenon of hanging, virtual spraying or brush marks in the process of coating, through timely remediation and treatment, the selection of correct and better quality tools for construction, to avoid affecting the later use and aesthetics.
A conclusion
in the process of coating the cargo tank, whether before or after coating there may be quality problems, in the face of this phenomenon is necessary to strengthen quality control, on the one hand, should do a good job of surface treatment, but also to strengthen the paint performance of the familiar, but also to the construction environment requirements and restrictions, but also to improve the application of the implementation process of a series of defects, and finally improve the professional quality of construction personnel, so as to truly improve the overall quality of the oil tank coating.
(slightly)
author Dai Jiangxiang
(Shanghai COSCO Shipping Heavy Industry Co., Ltd., Shanghai 201913)