First, let's look at the characteristics of FRP storage tanks:

1. Corrosion resistance: it can resist the erosion of acid, alkali, salt, seawater, untreated sewage and many chemical media, and will not react with the media and affect the properties of the media;

2. Antifouling and moth resistance: the surface is clean and smooth, and will not be contaminated and mothed by bacteria and other microorganisms in sewage, so as to increase the roughness rate, and it will be clean for long-term use;

3. Thermal insulation and frost resistance: FRP storage tank can be used for a long time in the range of - 40 ℃ - 120 ℃, with good toughness and extremely high strength;

4. Strong designability: FRP storage tank has strong designability. Fiber wound FRP can change the resin system or reinforcement to improve the physical and chemical properties of FRP tank. The bearing capacity of the tank can be adjusted through the winding angle and wall thickness structure design to meet the needs of different media and working conditions, which can not be compared with isotropic metal materials;

5. Long service life, safe and reliable: its design service life is 20;

6. Good comprehensive benefits: considering the construction investment, installation and maintenance cost, service life, energy saving and other factors, the comprehensive benefits of FRP tanks are considerable. Compared with traditional steel tanks, some tanks need to be repaired by replacing the ring plate and tank bottom in the maintenance process of oilfield metal tanks every year, while for those tanks that are seriously corroded and can not be repaired and reused, the whole tank renewal method is adopted, The repair cost is high, which requires shutdown, tank cleaning and hot work. The construction cost and safety measures are high, and the service time after repair is relatively short. FRP storage tank can be used for long-term operation without annual maintenance, and the comprehensive benefit is more than 20% higher than that of traditional steel storage tank.

At present, the anti-corrosion measures taken for metal storage tanks in China mainly include:

1. Chemical anti-corrosion (using corrosion inhibitor, bactericide, Deoxidizer and cathodic protection);

2. Epoxy resin anticorrosive coating;

3. Anti corrosion of flake resin coating.

The main advantages of the above anti-corrosion technology are low material price, which is suitable for general corrosion conditions. For the application in high corrosion environment of oil field, it has the following problems:

1) The thickness of the anti-corrosion coating is generally only 0.3mm, and the construction operation quality is not easy to control, which is easy to cause uneven coating and form more porous coatings, which is difficult to prevent the passage of corrosive media such as oxygen, water, hydrogen ions, hydrogen sulfide and Cl - and corrode the metal;

2) Due to the different properties of different materials (such as expansion coefficient), when the ambient temperature changes, stress will be generated at the interface and phase separation will be generated into holes, forming a corrosive medium penetration channel, resulting in tank wall corrosion;

3) Large environmental pollution: during the production process, the construction personnel use the brush or roller to apply the paint, which is easy to cause the spilling or dripping of the paint and pollute the environment. At the same time, a large number of paint odors in the construction are not conducive to the physical and mental health of the construction personnel.

4) Short anti-corrosion service life: the anti-corrosion of epoxy coating can only be maintained for about 3 years, and there will be pitting corrosion, and even perforation of metal tank wall. The tank needs to be stopped for inspection and repair every year, affecting the normal production and operation of the oilfield.