The application of an anticorrosive project must be aimed at the care of natural resources and the protection of structures, always promoting reliability for the safety of living beings.
by Duván Chaverra Agudelo
For all members of the surface protection and corrosion sector it is important to keep up to date the knowledge about the strategies that must be implemented in an anticorrosive project for the industrial sector.
The execution of an efficient plan of this type is based on the analysis of the project, conditions, costs, specialized personnel and countless requirements that we will analyze with the advice of an expert in auditing, training and contracts for the control and prevention of corrosion.
This is Juan Manuel Álvarez, specialist in corrosion control designs of Nace International, certified inspector in coatings, member of the astm corrosion committee and specialist in metal structures and composite materials, who will reveal details to perform a correct anticorrosive industrial maintenance.
INPRA: What is the analysis of an anti-corrosion project for the industrial sector?
Juan Manuel Álvarez: The analysis starts of course from the type of industry and the materials that it has at the structural level for the equipment and machinery; within this analysis, parameters such as the following must be taken into account:
- Working, tolerance, rest and emergency temperatures.
- Humidity, either of fluids (transport for example) or of the environment.
- The pH of the environment (generated by gases for example) or of the products of raw material (storage), process (by reaction), or finished product (handling and storage).
- Pressures, working or atmospheric.
- Structural load or mechanical work.
- Vectors (means of transport of contaminants that may cause corrosion problems).
INPRA: What are the most notable differences between an industrial anti-corrosion project and an anti-corrosion project of another type?
JMA: With respect to the items listed above, none. But with respect to the parameters of each particular industry, the aggressiveness of these items can be very diverse, which is why they can be classified according to the variables of the environment and therefore present typical or frequent types of corrosion by industry. This has a direct relationship with the different materials that are used according to the project. Keep in mind that the aggressiveness of each industry at the union level and its geographical position presents different problems. In the diagnostic work it is easily appreciated that each industry is a world apart in terms of work and environmental variables.
INPRA: What are the types of anticorrosive coatings ideal for industrial projects and what are their main characteristics?
JMA: The ideal anticorrosive coatings are those that have the greatest compatibility with the materials to be protected and the greatest resistance to the environment where the structure or surface is located, either from the purely environmental perspective or that of mechanical work.
The compatibility characteristics are directly related to the adhesion or protection time, while the resistance to the environment must present properties such as resistance to ultraviolet light (exposure to sunlight), chemical resistance (by pH of the chemicals present, whether liquids, gases and even solids), resistance in the saline chamber (for maritime areas or where this vector is present). As for the resistance by mechanical work requires characteristics such as hardness or flexibility, resistance to abrasion (when elements or particles that come into contact with the surface requires a good resistive behavior), resistance to events that mechanically affect the integrity of the coating there are several.
The most important feature fulfilling the compatibility with the surface, and after adhesion and elasticity, is that the coating protects 100% of the surface. For this, the porosity inspection or determination of microorifices is a test that should be required at the maintenance level.
INPRA: What is the average time that an industrial anti-corrosion project lasts before having a new inspection to coat again?
JMA: The time can be estimated quite approximately through the assessment of specimens made or worked in similar conditions in parallel during the application to the surface or structure; specimens where the accelerated tests and determination of resistances are carried out that in their analysis of results is analyzed under the perspective of similarity of the working environment of the surface.
On the other hand, periodic inspections will be subject to the type of environment to which the coating is exposed according to its classification. For example, every five years, a detailed inspection could be done considering a change of coating according to the condition in which it is located. Every year, basic inspections can be performed by analyzing porosity, dry film thickness and hardness; frequency that may vary if you are outdoors. If the environment is more aggressive due to the presence of gases as polluting vectors to the surface of the coating, the inspection can be carried out every three years. On the other hand, it must be executed a preventive maintenance must be executed every six months.
INPRA: What are the environmental conditions that most affect industrial processes? Do environmental conditions modify the maintenance or protection process?
JMA: The chemical aggressiveness or pH of the environment is the most demanding and is a selection parameter through the chemical resistance offered by the paint for purchase. The temperature according to the range as working temperature would be in second place, since it is a characteristic that ages the coatings; if these two variables are presented simultaneously they are a limit for many paints, without counting the mechanical work that the coating must respond according to the mobility of the surface. Humidity is considered as a selection parameter but is more manageable in the aspect of its maintenance.
INPRA: In an industrial project, what are the materials that deserve the most protection?
JMA: Those materials that have greater structural responsibility should correspond to those with greater protection, in this way accidents, catastrophic failures, human losses and even environmental damage would be avoided.
INPRA: What are the most recommended paint application techniques or methods for industrial installations?
JMA: The most recommended methods would be related to variables such as performance in the application, access to surfaces, the amount and type of paint to be applied, and logistics in field work (for example, in high-performance application procedures, limited to weather conditions).
INPRA: Do you think that industrial companies invest what is necessary in anti-corrosion projects?
JMA: The concept of corrosion control is an issue that has cultural interference, and therefore if we talk about countries or regions, or types of company, it is visualized that there is no real assessment from the preventive point of view.
In the depreciation of assets, it is not considered in the dimension that the impact of corrosion or aging should be. Budgets in preventive maintenance or in investment of hours dedicated to inspection or predictive maintenance are not estimated as part of production and reliability, but as an expense.
I believe that the particular issue of corrosion control is in progress and will be demanded in the future in greater quantity and quality; and therefore it will end up being valued at the budget level. Corrosion costs will be increasingly necessary and valued as the environments and the expectations of durability of the structures are increasing.
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