Introduction to anti-corrosion technology of petrochemical storage tanks
Storage tanks for petrochemical products, as an important device for storing petrochemical products, play an irreplaceable role in the refining and storage of petrochemical products. However, through long-term practice, it can be found that after a period of use, the storage tank will be corroded by the petrochemical product itself or certain substances in the atmosphere, which may cause oil leakage. In severe cases, it may also cause a major safety accident, which will cause huge losses to the enterprise, and cause immeasurable harm to the environment. Therefore, it is imperative to improve the anti-corrosion ability inside and outside the oil storage tank.
Based on years of actual production and construction experience, the following analysis and discussion are conducted on the anti-corrosion products of petrochemical storage equipment.
1. Causes of corrosion inside the storage tank:
Gas corrosion: There are places in the storage tank that are not in direct contact with petrochemical products, such as tank tops and tank walls that are not in contact with petrochemical products. These parts are attacked by acid gases such as sulfur dioxide and hydrogen sulfide, and sometimes they are affected by gases such as oxygen and carbon dioxide entering the tank during the filling process. If these gases are collected in the tank, a corresponding chemical reaction will occur, which will lead to a deeper corrosion of the tank top;
Liquid corrosion: The parts of the tank that are in direct contact with the petrochemical product are subject to corrosion by certain chemicals, especially at the bottom of the tank. The moisture and other impurities in the petrochemical product may settle due to gravity. The liquid not only has the effect of chemical corrosion, but also has the effect of electrochemical corrosion.
2. Anti-corrosion technology for corrosion inside the storage tank:
Reasonable use of anti-corrosion coatings: Coating protection can be used to protect the inside of the tank. This is the most economical and simplest and most convenient protection. When selecting anti-corrosion coatings, we must not only ensure that the coatings have good water resistance, chemical resistance and adhesion, but also have strong resistance to bending and impact, like epoxy coatings.
Adding a corrosion inhibitor: As the name implies, it is an additive that can effectively delay the corrosion. Applying it to the surface of the anti-corrosion coating can further protect the oil storage tank.
Increase the thickness of the steel: combined with practical experience, special treatment can be carried out on the parts of the storage tank which are easily corroded and have a deep corrosion degree, that is, the thickness of the steel in these parts can be appropriately increased, thereby effectively extending the service life of the storage tank. In addition, enterprises should check the corrosion of storage tanks regularly or irregularly, and effectively deal with the problems found in order to ensure the efficiency of the enterprise.
3. Causes of external corrosion of petrochemical tanks:
The external corrosion of the tank mainly comes from atmospheric corrosion. This is closely related to the environment in which the tank is located. For example, if the tank is placed closer to the coastal area, the deeper it is corroded, because the air humidity in these areas is greater than that of other inland areas, and it is easy to form a water film on the outer wall of the tank. When some substances in the air fuse with the water film, the polarization reaction is carried out under the action of oxygen. In addition, when the tank is in use, the surface of the bottom plate is most corroded because it is in direct contact with water or soil.
4. Introduction of common anti-corrosion technology for tank outer wall:
The most typical and most commonly used method is to apply different anti-corrosion coatings on the tank top, tank wall and tank bottom of the tank. The selection of the paint should be combined with the position of the tank to make the best use. And the choice of the coating should be combined with the location of the tank and match well with the environment to maximize the positive effects of anti-corrosion coatings. At the same time, in order to further extend the service life, the outer wall of the oil storage tank can be coated with a primer with excellent rust resistance (such as epoxy zinc-rich primer), a middle layer paint with good shielding performance (such as micaceous iron epoxy middle layer paint), and a finishing coat that can be coated repeatedly, with good gloss and color retention performance.
For the bottom of the tank, asphalt or epoxy coal tar paint can be used as the anti-corrosion finishing coat to effectively prevent the salt or water in the soil from coming into direct contact with the bottom of the tank, thus extending the service life of the tank. It should be inspected regularly throughout the life of the tank, especially in areas with a high degree of corrosion. At the same time, the inspection cycle of the tank is not required to be set too frequently, and at least one full systematic inspection every year is sufficient.
5. Coating package scheme for petrochemical storage tanks:
Based on years of actual production and construction experience, the following analysis and discussion are conducted on the anti-corrosion products of petrochemical storage equipment.
1. Causes of corrosion inside the storage tank:
Gas corrosion: There are places in the storage tank that are not in direct contact with petrochemical products, such as tank tops and tank walls that are not in contact with petrochemical products. These parts are attacked by acid gases such as sulfur dioxide and hydrogen sulfide, and sometimes they are affected by gases such as oxygen and carbon dioxide entering the tank during the filling process. If these gases are collected in the tank, a corresponding chemical reaction will occur, which will lead to a deeper corrosion of the tank top;
Liquid corrosion: The parts of the tank that are in direct contact with the petrochemical product are subject to corrosion by certain chemicals, especially at the bottom of the tank. The moisture and other impurities in the petrochemical product may settle due to gravity. The liquid not only has the effect of chemical corrosion, but also has the effect of electrochemical corrosion.
2. Anti-corrosion technology for corrosion inside the storage tank:
Reasonable use of anti-corrosion coatings: Coating protection can be used to protect the inside of the tank. This is the most economical and simplest and most convenient protection. When selecting anti-corrosion coatings, we must not only ensure that the coatings have good water resistance, chemical resistance and adhesion, but also have strong resistance to bending and impact, like epoxy coatings.
Adding a corrosion inhibitor: As the name implies, it is an additive that can effectively delay the corrosion. Applying it to the surface of the anti-corrosion coating can further protect the oil storage tank.
Increase the thickness of the steel: combined with practical experience, special treatment can be carried out on the parts of the storage tank which are easily corroded and have a deep corrosion degree, that is, the thickness of the steel in these parts can be appropriately increased, thereby effectively extending the service life of the storage tank. In addition, enterprises should check the corrosion of storage tanks regularly or irregularly, and effectively deal with the problems found in order to ensure the efficiency of the enterprise.
3. Causes of external corrosion of petrochemical tanks:
The external corrosion of the tank mainly comes from atmospheric corrosion. This is closely related to the environment in which the tank is located. For example, if the tank is placed closer to the coastal area, the deeper it is corroded, because the air humidity in these areas is greater than that of other inland areas, and it is easy to form a water film on the outer wall of the tank. When some substances in the air fuse with the water film, the polarization reaction is carried out under the action of oxygen. In addition, when the tank is in use, the surface of the bottom plate is most corroded because it is in direct contact with water or soil.
4. Introduction of common anti-corrosion technology for tank outer wall:
The most typical and most commonly used method is to apply different anti-corrosion coatings on the tank top, tank wall and tank bottom of the tank. The selection of the paint should be combined with the position of the tank to make the best use. And the choice of the coating should be combined with the location of the tank and match well with the environment to maximize the positive effects of anti-corrosion coatings. At the same time, in order to further extend the service life, the outer wall of the oil storage tank can be coated with a primer with excellent rust resistance (such as epoxy zinc-rich primer), a middle layer paint with good shielding performance (such as micaceous iron epoxy middle layer paint), and a finishing coat that can be coated repeatedly, with good gloss and color retention performance.
For the bottom of the tank, asphalt or epoxy coal tar paint can be used as the anti-corrosion finishing coat to effectively prevent the salt or water in the soil from coming into direct contact with the bottom of the tank, thus extending the service life of the tank. It should be inspected regularly throughout the life of the tank, especially in areas with a high degree of corrosion. At the same time, the inspection cycle of the tank is not required to be set too frequently, and at least one full systematic inspection every year is sufficient.
5. Coating package scheme for petrochemical storage tanks:
| Paint coating scheme for petrochemical storage tank | ||||||
| Part | Scheme | Coating types | Paint name | Recommended coating times | Film thickness (μm) |
|
| Storage tank | The internal | 1 | Primer | Oil resistant primer | 2 | 250 |
| Conductive finishing coat | Conductive polyurethane finishing coat | 2 | 200 | |||
| 2 | Primer | Inorganic zinc silicate primer | 1 | 60 | ||
| Seal coat | Epoxy seal coat | 1 | 30 | |||
| Middle layer paint | Acrylic polyurethane primer | 2 | 60 | |||
| Finishing coat | Acrylic polyurethane finishing coat | 2 | 80 | |||
| The external | 1 | Primer | Epoxy zinc rich primer | 1 | 70 | |
| Middle layer paint | Micaceous iron epoxy middle layer paint | 1 | 80 | |||
| Finishing coat | Chlorinated rubber finishing coat in all colors | 2 | 80 | |||
| 2 | Primer | Inorganic zinc silicate primer | 1 | 70 | ||
| Middle layer paint | Micaceous iron epoxy intermediate paint | 1 | 80 | |||
| Finishing coat | Chlorinated rubber finishing coat in all colors | 2 | 80 | |||
| 3 | Primer | Red lead rust-proof paint | 3 | 120 | ||
| Finishing coat | Alkyd enamel in all colors | 2 | 70 | |||
| 4 | Primer | Epoxy zinc rich primer | 1 | 80 | ||
| Middle layer paint | Micaceous iron epoxy intermediate paint | 1 | 80 | |||
| Finishing coat | Acrylic polyurethane finishing coat in all colors | 2 | 80 | |||
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