Quality control of anti-corrosion engineering of t

2022-08-13
  • Detail

Quality control of coating anti-corrosion engineering

Quality Control of coating anti-corrosion engineering

September 24, 2020

Introduction

anti corrosion coating engineering is a complex process, and its quality is closely related to the selection of coating, the surface treatment of substrate, the treatment of 4 sampling quantity defects, the skills of construction personnel, the construction environment and other factors. During the coating process, the quality of the coating anti-corrosion project can not be guaranteed due to some negligence, which affects the anti-corrosion life of the project. Therefore, we must pay attention to strictly control the coating in all construction links of the coating anti-corrosion project

1. Overview of anti-corrosion construction procedures

before construction, we must pay attention to the confirmation of the construction design scheme. During the operation, fully grasp the operation methods of each link, and understand the construction technology and construction characteristics of each link. Obtain necessary operation instructions before construction and operate in accordance with the construction requirements. Generally speaking, in the process of anti-corrosion construction of the project, the following procedures need to be followed:

first, the coated surface needs to be cleaned to reach the required surface treatment level, and the coating should be completed within the specified time range. Apply one layer of primer and the second layer of primer. After the primer is applied, the intermediate paint is applied, which requires two layers of intermediate paint. After the intermediate paint is applied, the finish paint is applied. In the process of construction, the construction of each coating should be completed at the specified time interval. The quality of each process should be strictly controlled according to the "construction operation instructions" to ensure that the quality meets the requirements before subsequent process operations. Necessary monitoring and measurement shall be carried out for each link, and the evaluation grade shall meet the specification requirements, and records shall be made

2. Construction control of anti-corrosion coating engineering

2.1 reasonable selection of anti-corrosion coating

in the process of engineering practice, in order to meet the needs of anti-corrosion, we must pay attention to the structural form of anti-corrosion coating. The anti-corrosion coating is usually divided into three layers, namely primer, intermediate paint and finish paint. The primer is in direct contact with the metal matrix, so it is necessary to ensure strong adhesion in the process of practical application. In the process of painting the primer, it is recommended to add a certain impermeable filler. The intermediate paint is a transition layer, which is very important in the process of application and plays a role of connecting the upper and the lower

in the actual operation process, the topcoat and primer need to meet the following requirements: first, both of them should have a certain adhesion with the intermediate coat, and second, it needs to ensure that both of them have a strong shielding effect, because the topcoat will directly contact the surrounding environment of mechanical property tests: tensile, zigzag, contraction, shear, Charpy impact, hardness (Rockwell, Brinell, Vickers, micro Vickers), etc, Therefore, we must pay attention to the analysis of the surrounding environmental and climatic characteristics and environmental elements in the actual construction process, and pay attention to the following points in the selection of anti-corrosion coatings

► (1) the properties of the coating should be stable. In terms of chemical and physical properties, attention must be paid to ensure that the cured coating of anti-corrosion coating can effectively exist in the environment. It is not easy to decompose and dissolve under the conditions of acid, alkali and other corrosive media, and there will be no strong chemical reaction

► (2) selected coating. The formed coating should have good compactness. The corrosion of steel is mainly caused by water and oxygen contacting the metal surface through the coating

► (3) choose coatings with strong adhesion. An important factor affecting the anti-corrosion effect is the adhesion of the coating. It is necessary to fully consider the adhesion of the coating, and try to choose some materials that can prevent the diffusion of corrosive media to avoid engineering corrosion. The coating has a long service life

2.2 sand blasting derusting

in the process of surface pretreatment of engineering interface, sand blasting derusting materials are mainly used. There are often some defects in the engineering matrix, such as uneven concave and convex, which need to be polished for subsequent coating. In the process of sandblasting on the body surface, the size selection and requirements of the abrasive need to be operated in accordance with the specific requirements of the technical specification for anti-corrosion engineering of steel oil storage tanks. In addition, it also needs to ensure that the abrasive meets the methods of steel surface treatment before coating, and the specific requirements and regulations of abrasive jet cleaning

in addition, there should be no substances with strong corrosivity or affecting the coating, so as to reduce the number of repeated use of abrasives in the actual operation process

painting is required after the completion of sandblasting on the metal surface, and effective treatment of dust on the metal surface must be paid attention to before painting. Because dust will cause the adhesion of the coating to decline, the evaluation method of dust pollution index is based on the obtained dust standard map distribution and particle size. The relevant national regulations set the dust pollution index to grade 5, with the minimum of 50 µ m and the maximum of more than 2.5 mm. However, foreign countries are ahead of China in controlling the dust pollution index, For example, during the construction of a project in the UK, the pollution index of dust after surface treatment needs to be controlled within grade II, but domestic projects have not paid attention to the relevant requirements of dust pollution index

2.3 coating process control

after finishing the surface treatment of metal, it is necessary to finish the coating of primer according to the standard method within the specified time and under the specified environmental conditions. If the operation is not timely, it may cause the metal surface to be affected by moisture and cause repair. In the process of painting, we must clarify the specific requirements and paint according to the specifications. For example, in the specified high-pressure airless spraying process, it cannot be modified without authorization and replaced by painting

in the process of coating, we must pay attention to the control of metal surface temperature, which needs to exceed the dew point temperature on site by more than 3 ℃, but not more than 50 ℃. Pay attention to forced ventilation during coating operation to ensure the operation safety of construction personnel. In the process of painting, the primer needs to cover all the metal surfaces. For some important positions, putty needs to be used for leveling treatment. The selection of coating equipment should be reasonable according to the specific characteristics of the coating. It is not allowed to use coating equipment at will in pursuit of cost, so as to prevent rework caused by coating defects

when painting, it is necessary to construct according to the specific requirements of the design thickness of the coating, so as to avoid the influence of Jerry built materials on the thickness of the coating; During coating, it is necessary to know the specific parameters of the coating equipment in time, especially the moving speed and distance of the spray gun, the lapping of spray, and the viscosity in the spraying process, so as to avoid the defects such as uneven thickness and sagging. It is strictly forbidden to add some combustible volatile organic solvents to the paint during the coating process, so as to avoid a large amount of volatilization during drying and cause danger

2.4 control of paint film thickness

we must pay attention to strengthening the inspection of paint film thickness. The thickness of paint film is an important index to identify the coating quality, and the evaluation design requirements of paint film thickness is also an important index to ensure the anti-corrosion function of the coating. According to the specific regulations and requirements of various industries, strictly control the thickness of the paint film, and test the thickness of the paint film at any time, which is divided into dry film thickness test and wet film thickness test. Under normal conditions, it is necessary to ensure that five test points are distributed within 1 m2, and three tests are carried out respectively, and the average value is taken to obtain standard data

in the process of total thickness testing, the dry film thickness is mainly used. Generally, it is necessary to ensure that the average dry film thickness is controlled at more than 90% of the standard value. If the dry film thickness is not reached, it needs to be treated in strict accordance with the standard. If the qualified rate is less than 80%, it needs to be repaired. If the qualified rate is between 80% and 90%, local touch up coating shall be carried out according to the requirements. If the paint film is too thick, some problems may also occur, which will cause paint loss and waste of funds, and paint diseases such as wrinkles and sagging on the paint film. Too thick paint film will affect the solvent volatilization, resulting in problems in the subsequent coating process. If the paint film thickness exceeds 10% of the dry film thickness, you must pay attention to grinding

2.5 quality control of coating interval

during the construction of the composite coating system, it is necessary to ensure the time interval of each coating, and it is required to operate according to the requirements of the coating supplier under the conditions of changes in construction conditions and construction environment, so as to prevent coating quality problems

2.6 adhesion control

adhesion test is required after coating, because adhesion test is a destructive test, and repair work needs to be done after the completion of the test. Chemical equipment needs to be used in a harsh environment. If the construction scheme or construction operation is improper, it may directly affect the adhesion. Therefore, the adhesion test must be done well

3. Other quality control measures for coating anti-corrosion engineering

3.1 strengthen the management of the construction team

we need to pay attention to the strict control of the construction quality of coating anti-corrosion, not only according to the advanced testing equipment, but also in strict accordance with the acceptance specifications, and pay attention to strengthening the management of the team. The construction unit must employ some professional construction personnel to ensure that the construction personnel work with certificates in the operation process, have certain anti-corrosion knowledge, refine each corrosion process, control the rust removal grade and coating process according to the requirements, and ensure the quality and quantity in the construction process. The construction unit needs to be equipped with coating leak detector, coating thickness gauge and other relevant tools for self inspection of key processes, strictly control the construction quality, and avoid rework after construction operations

3.2 strengthen technical management

in the process of coating construction, we must ensure the professionalism of the staff, and for some key processes, we must assign professional knowledge and skilled personnel to operate, so as to strictly control the construction quality and paint according to the specifications

other objective conditions and factors will also affect the resilience LS PVC material. The arithmetic mean value of the measured diameter at three places has good flame retardancy, high transparency, high reflectance and uniform metal color effect, which affects the quality of the project. It is necessary to strictly consider the weather factors, surface treatment and personnel quality, arrange the construction personnel, control the construction time, and prepare the construction process. The construction conditions must be strictly recorded, and the relevant construction preparations must be made to prevent the inability to deal with emergencies during construction. A comprehensive evaluation should be carried out during the construction operation. If it is found that the construction is not carried out in accordance with the specifications, it must be corrected in time to prevent affecting the overall quality. Technicians must paint the whole process during the operation, control every detail and construction node, write it in the report, optimize the construction, and operate in strict accordance with the painting requirements

3.3 strengthen the quality control in the completion stage

during the completion period, we must actively strengthen the quality inspection experiment and sort out the technical data. Only in this way can we ensure the traceability of the construction quality. The construction party needs to prepare documents and give the demobilization plan. In the process of inspection, the construction quality of concealed works must be strictly controlled, and the acceptance shall be carried out according to the requirements of professional specifications. If there is any quality problem

Copyright © 2011 JIN SHI