In the petrochemical industry, special working environments such as high temperature and corrosive media can make corrosion more serious. The consequences of corrosion are also more serious, such as the leakage of toxic and harmful substances and flammable and explosive substances, so the corrosion protection of chemical equipment is very important. The basis for the matching selection of anti-corrosion coatings for storage tanks is ISO 12944. According to various factors of environmental conditions and requirement of the service life, the matching varieties and film thickness of storage tank coatings are determined. According to the specific medium in the storage tank, it is necessary to discuss with the paint supplier and determine the suitable storage tank coatings variety and anti-corrosion solution for the inner wall of the storage tank.
The corrosion of the outer wall of the storage tank is mainly atmospheric electrochemical corrosion in the chemical atmosphere. At present, the most commonly used heavy-duty anticorrosive paint system is an epoxy zinc-rich primer or inorganic zinc silicate primer/epoxy mica iron oxide intermediate paint / acrylic polyurethane topcoat / novolac coating. According to the different corrosive environment of the storage tank, the dry film thickness is 200-300μm. The dry film thickness of epoxy zinc-rich primer is usually not less than 50μm. If the inorganic zinc silicate primer is used as the anti-rust primer, a sealant paint must be applied to it. Polysiloxane paint has outstanding weather resistance and can be applied in high-thickness films. Using polysiloxane paint as topcoat, only two coats of paint are required for construction, saving the construction man-hours and material costs of the intermediate coat.
The corrosive environment within the storage tank is mainly the medium stored in the storage tank. The oil itself, whether it is crude oil, semi-finished oil or refined oil, is not corrosive, but the corrosive impurities such as inorganic salts, acids, sulfides, oxygen, and water in the oil will corrode the inner wall of the tank. The fuel storage tank paint for the inner wall of the oil tank are first required to have good corrosion resistance, good solvent resistance, and not pollute the medium in the storage tank. In order to store oil safely, it is also necessary to use anti-static oil tank paint. The service life of the coating system on the inner wall of the storage tank is closely related to the steel condition of the inner wall of the storage tank and the selected coating material. According to the coating thickness, the storage tank coatings types of the inner wall can be divided into three categories: thin coating, heavy anti-corrosion coating, and glass flake/fiber-reinforced lining.
Thin coatings mainly include pure epoxy coatings and phenolic epoxy. The dry film thickness of each coating is controlled at 100-150μm, and the total film thickness is 300μm.
Heavy-duty anti-corrosion coating layer mainly refers to low-solvent and solvent-free epoxy coatings, including solvent-free glass flake coatings, with a design dry film thickness of 500-1000μm.
Glass flake paint or glass fiber reinforced lining, with a dry film thickness of 1000-1500μm, mainly including epoxy glass flake paint, vinyl ester glass flake paint, polyester glass flake paint, and solvent-free epoxy glass fiber reinforced lining and etc.