Industry Knowledge

Design of sacrificial anode protection for crude oil storage tank
Sep 12, 2017

      Taijin is a state-governed electrode manufacturer for 17 years, and the earliest and biggest electrode manufacturer in China,Our company studied the technology of cathodic protection for crude oil tank,At the same time, our company can also provide you with magnesium anode, aluminum anode and zinc anode technical support, so that you can better understand the application of sacrificial anode in the field of cathodic protection

       As the scale of production continues to expand, refining capacity will increase accordingly, and crude oil tanks will increase and increase accordingly.At present, due to the gradual increase of domestic crude oil, the acid value increases and sulfur content increases, which causes the corrosion of water accumulation at the bottom of the crude oil tank. The corrosion characteristics of the bottom of the crude oil tank are pitting and pitting corrosion, and the corrosion rate is over lmm/a.The design life of the original oil tank is generally 20 years, but in fact, the bottom plate of the crude oil tank is often perforated for several years, and the bottom plate needs to be replaced. Therefore, effective corrosion prevention measures must be taken for the original oil tank.The sacrificial anode protection of 1# crude oil tank is discussed as an example.

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        1、corrosion reasons

         Crude oil is mainly composed of various hydrocarbons and asphalt, and does not corrode the steel. Therefore, the side walls of the crude oil tank are basically non corrosive.But the most dangerous part is the bottom of the crude oil tank. Because the tank bottom sedimentary water containing inorganic salt, chloride, sulfide, organic acids and other microorganisms, it will form acidic electrolyte solution, oil tank bottom plate itself and weld defects, corrosion battery greatly small, which contributed to the external and internal corrosion.In addition, dirt deposited on the bottom will cause fouling and pitting.Because the original tank is equipped with steam heater heating, the bottom temperature is higher, due to natural convection, the top oxygen downward movement, the bottom water upward movement, also accelerated corrosion.

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        2、corrosion protection design of crude oil tank

        According to the experience of domestic brother enterprises, sacrificial anode protection is adopted for the 1# crude oil tank, and the specific anticorrosion design is as follows.

        (1) specifications of crude oil tank

         Size: 20000m3

          Specification: Phi 40632mm * 15895mm

        (2)corrosion protection area and protection area

         The bottom of the crude oil tank is at the bottom and the first lap steel plate is 1m. That is to say, the surface area of the water tank at the bottom of the tank is the area covered by sacrificial anode.

S= PI R2+2 PI R.h

Sacrificial anode protection area of S-- crude oil tank, m2;

R-- tank radius, m;

H-- oil tank, take LM off the floor height;

S=3.14 x (40.632/2) 2+2 x 3.14 * 40.632/2 * l

=1421.28m2

In the design of sacrificial anode protection for crude oil tank, how should the sacrificial anode material be chosen?

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