Through the investigation and study of lightning protection measures for more than 200 50,000-150,000 m3 external floating roof storage tanks. The results of the investigation are as follows: 

(1) There are two types of external floating roof oil tank sealing, namely mechanical seal and soft seal (bladder seal);

(2) The conductive sheet of the floating plate of the outer floating roof oil tank is mostly "coated";

(3) The secondary sealing of the outer floating roof oil tank is not tight;

(4) The concentration of combustible gas in the secondary sealed cavity of the outer floating roof oil tank can reach the explosive limit concentration;

(5) The metal components in the primary sealed cavity of the outer floating roof oil tank are not equipotentially connected;

(6) The secondary sealing metal sealing baffle of the outer floating roof oil tank has no equipotential connection;

The connection form of the two grounding wires on the floating plate of the outer floating roof oil tank is incorrect:

(8) The floating plate escalator of the outer floating roof oil tank has no equipotential connection with the floating plate and the tank wall;

(9) The resistance value between some conductive sheets and the floating plate does not meet the requirements, and some resistance values ​​tend to "o0";

(10)The resistance values ​​of most conductive sheets and the tank wall do not meet the requirements, and most of the resistance values ​​tend to " o";

(11) There is no high and medium frequency lightning current shunt facility for the floating plate of the outer floating roof oil tank;

(12) There is no medium and low frequency lightning current shunt facility for the floating plate of the outer floating roof oil tank;

(13) The breathing valve on the floating plate is not bridged;

(14) The forced breathing valve on the floating plate is not bridged;

(15) High-tower lightning rods and overhead lights are set up around the oil tank.