The seal of the coating is the decisive factor in the success or failure of the mouth, especially the sealing property of the heat shrinkage belt and the heat shrink sleeve which is more widely used but the cathode shielding effect. The sealing area of ??the sealing is poor, the soil moisture will penetrate through the edge of the lap, resulting in failure of the mouth, and the cathodic protection current can not reach the surface of the tube, the tube corrosion. This is the heat shrinkage and heat shrinkable sleeve material sealing problem.

In the laboratory, the method is to hang the specimen in the solution, the specimen with the 6V DC power supply negative connection, at the same time will be immersed in the solution of an anode and the power supply positive connection to form a test circuit. The leakage current is present by periodically measuring the voltage drop produced by the calibrated resistor in the circuit. That is, not only to determine the insulation of the sealing material properties, but also to a certain extent, a comprehensive reflection of the raw material on the original coating and bare metal bonding capacity, and the original anti-corrosion layer sealing area of ??the integrity of the seal and the material Water absorption.

Heat shrinkage and heat shrinkage of the seal is only an indicator of their performance, the detailed indicators we will be introduced later for everyone slowly.