Quality control of coating anti-corrosion engineering.

Introduction
Anti-corrosion coating project is a complex process, its quality and coating selection, substrate surface treatment, defect treatment, construction personnel skills, construction environment and other factors are closely related. In the coating process, the quality of coating anti-corrosion engineering can not be guaranteed due to some negligence, affecting the anti-corrosion life of the project. Therefore, we must pay attention to the coating anti-corrosion engineering of all aspects of the construction of strict control

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1, anti-corrosion construction process overview
before the construction must pay attention to the construction of the design plan to confirm. In the course of operation, the operation methods of each link are fully mastered to understand the construction process and construction characteristics of each link. Before construction, we should obtain the necessary work guidance and standardize the operation according to the construction requirements. In general, the following procedures are required during the construction of anti-corrosion works:
first of all, the surface is cleaned, the required level of surface treatment is reached, and the coating is completed within a specified time limit. Apply a layer of primer and paint the second layer of primer. After the completion of the primer painting, the coating of the middle paint, need to apply two layers of intermediate paint, after the completion of the middle paint, the paint coating. In the construction process to complete the construction of each coating according to the prescribed time interval, the quality of each process in accordance with the "construction work instructions" to carry out strict control, to ensure that the quality meets the requirements before the follow-up process operation. All links should carry out the necessary monitoring and measurement, rating in line with the specification requirements, and do a good job of recording.
2, anti-corrosion coating project construction control
2.1 reasonable choice 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. Anti-corrosion coatings are usually divided into 3 layers, i.e. primers, intermediate paints, and finishes. Primer and metal substrate direct contact, so it is necessary to ensure that in the actual application of the process has a strong adhesion, in the process of painting primer, it is recommended to add a certain amount of impermeable filler, intermediate paint belongs to a transition layer, in the application process is very important, play a role in the up and down.
In the actual operation process needs paint and primer to meet the following requirements: First, between the two and the medium coating should have a certain adhesion, and secondly, need to ensure that both have a strong shielding effect, because the paint will be directly in contact with the surrounding environment, so we must pay attention to the actual construction process, the surrounding environmental climate characteristics and environmental factors analysis, in the selection of anti-corrosion coating process needs to pay attention to the following points.
(1) paint should be stable in nature. In the chemical and physical properties must pay attention to ensure that anti-corrosion coating curing 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 stronger chemical reaction; The resulting coating should have good tightness. Because the corrosion of steel is mainly due to water and oxygen through the coating contact with the metal surface caused by metal corrosion,
(3) to choose a strong adhesion coating, an important factor affecting the anti-corrosion effect is the adhesion of the coating, the coating adhesion needs to be fully considered, as far as possible to choose some materials that can prevent the spread of corrosion media, to avoid engineering corrosion. Makes the coating have a long service life.
2.2 Blast Rust removal
in the process of surface pre-treatment at the engineering interface, the main use of blasting rust removal materials. Engineering substations often have some problems, such as bump inequality, and need to be polished for subsequent coating. In the process of blasting the surface of the body, the size selection and requirements of the abrasive need to be operated in accordance with the specific requirements of the technical specifications of the anti-corrosion engineering of the steel oil storage tank, and it is also necessary to ensure that the abrasive conforms to the method of steel surface treatment, the specific requirements and regulations of the abrasive injection cleaning before coating.
also can not appear some of the more corrosive or affect the coating of the substance, in the actual operation process to reduce the number of re-use of abrasives.
the metal surface after the completion of the blasting work needs to be coated, before coating must pay attention to the metal surface dust for effective treatment. Since dust can cause the adhesion of the coating to decrease, the dust pollution index is evaluated according to the obtained dust standard map distribution and particle size to analyze, the relevant national regulations set the dust pollution index to 5 levels, the smallest is 50 m, the largest is More than 2.5 mm, and foreign in the dust pollution index control than the domestic leading, such as the United Kingdom in the construction process of a project to provide for surface treatment dust pollution index, need to be controlled within the second level, but domestic projects have not paid attention to the dust pollution index related requirements.
2.3 Coating process control
after the completion of the metal surface treatment needs to be completed in accordance with the prescribed time, the prescribed environmental conditions, in accordance with the standard method of painting the primer. If not operated in a timely manner, it may cause moisture to appear on the metal surface and cause repairs. In the process of coating, we must be clear about the specific requirements, in accordance with the specifications for coating. For example, in the prescribed high-pressure airless spraying process, it can not be modified without authorization, changed to brush.
in the coating process must pay attention to the metal surface temperature control, need to exceed the field dew point temperature of more than 3 degrees C, but not more than 50 degrees C. In the process of coating operation must pay attention to forced ventilation, to ensure the safety of the operation of construction personnel. In the process of painting the primer needs to cover all metal surfaces, for some important locations need to use putty to find flat treatment, according to the specific characteristics of the paint reasonable choice of coating equipment, can not be in pursuit of cost and arbitrarily change to coating equipment, to prevent coating defects and cause rework.
In the coating needs to be in accordance with the specific requirements of the thickness of the coating design construction, to avoid the appearance of work-stealing material reduction and other conditions on the thickness of the coating, in the coating needs to timely understand the specific parameters of the coating equipment, especially the speed of the gun movement distance and spray bonding, as well as the viscosity of the spray process, to avoid uneven thickness, flow hanging and other defects. It is strictly forbidden to add some flammable volatile organic solvents to the coating during the coating process, so as to avoid large amounts of volatilization during drying, resulting in hazards.
2.4 paint film thickness control
we must pay attention to strengthen the paint film thickness inspection. Paint film thickness is an important index to identify the quality of coating, paint film thickness evaluation design requirements are also an important indicator to ensure the anti-corrosion function of the coating. In accordance with the specific regulations and requirements of various industries, strict control of the thickness of the paint film, at any time on the thickness of the paint film testing, divided into dry film thickness detection and wet film thickness detection. Under normal conditions, it is necessary to ensure that 5 test points are distributed within 1 m2, with 3 tests each, and the average is taken to obtain standard data.
In the process of total thickness testing mainly to dry film thickness, in general, it is necessary to ensure that the average thickness of dry film control in the standard value of more than 90%, if the dry film thickness is not reached, need to be handled in strict accordance with the standard. If the pass rate is less than 80%, it needs to be re-coated. Pass rate between 80% to 90% of the need for local re-painting in accordance with the requirements, if the paint film is too thick may also appear some problems, will cause paint loss and waste of funds, wrinkles on the paint film, hanging and other paint diseases. Too thick paint film will affect solvent volatility, resulting in problems in the subsequent coating process, if the thickness of the paint film exceeds 10% of the thickness of the dry film, we must pay attention to grinding treatment.
2.5 Coating Interval Quality Control
In the process of construction of the composite coating system, it is necessary to ensure the time interval of each coating, and require that under the conditions of change in construction conditions and construction environment, operation should be carried out in accordance with the requirements of the coating supplier to prevent coating quality problems.
2.6 Adhesion Control
adhesion test is required after coating, as adhesion test is a destructive test that needs to be repaired after the experiment is completed. Chemical equipment needs to be used in a more harsh environment, if the construction program or construction operation is not proper, there may be a direct impact on adhesion, so we must do a good job of adhesion testing.
3, coating anti-corrosion engineering other quality control measures
3.1 strengthen the management of the construction team
need to pay attention to the paint anti-corrosion construction quality strict control, not only need to be in accordance with advanced testing equipment control, but also pay attention to strictly in accordance with the acceptance norms for operation, pay attention to strengthen the management of the team. Construction units must hire some professional construction personnel, to ensure that construction personnel in the operation process certified on duty, with a certain degree of anti-corrosion knowledge, each corrosion process to refine, in accordance with the requirements of rust removal grade, coating process control, in the construction process of quality and quantity. Construction units need to be equipped with coating leak detector, coating thickness meter and other related tools for key process self-test, strict construction quality control, to avoid rework after the construction operation.
3.2 Strengthen technical management
In the process of coating construction must ensure the professionalism of staff, for some key processes must be assigned with professional knowledge, skilled personnel to operate, in order to carry out strict control of the quality of construction, according to specifications for painting
Must be strict records of the construction situation, do a good job of related construction preparations, to prevent the construction of unexpected situations can not be dealt with, in the process of construction operations for comprehensive evaluation, if found that the construction did not operate in accordance with the specifications, we must promptly make corrections to prevent the impact of the overall quality. Technical personnel in the operation process must be the whole process of coating, control every detail and construction node, in the report and optimize the construction, in strict accordance with the coating requirements for operation.
3.3 Strengthen quality control in the completion phase
During completion, we must actively strengthen the quality testing experiments, organize technical information, only in this way to ensure the traceability of construction quality, the construction side needs to prepare documents, and give a withdrawal plan. In the process of inspection must be covert construction quality strict control, in accordance with the requirements of professional norms for acceptance, if the quality of non-conforming places must be timely requirements for the construction party to rework.
Conclusion
Good protective construction is an important basis for safe operation, in order to carry out strict control of the quality of anti-corrosion construction of the project, we must strictly and standardized from all aspects of the synthesis of the impact factors to consider, do a good job in every link of the control work, for the project to provide qualified anti-corrosion coating.
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