In order to protect the pipeline when the pipeline crossing the railway, roads, rivers and other obstacles generally additional casing pipe, casing also increase adverse local, when applied to the pipeline cathodic protection, pipeline cathodic protection sleeve has a shielding effect, make it difficult to reach the cathodic protection current pipe surface, therefore, domestic and foreign experts recommend to avoid the mounting sleeve. If you installed the casing, the pipe casing shall be individually protected, you can install the ribbon sacrificial anode, such as magnesium anodes, zinc anodes, such as in the casing, if the main channel has impressed current protection, it is best to use a magnesium anode potentials more negative . The main channel of the cannula should be used to strengthen the grade coating for protection, and pay attention to the length and depth of the coating to strengthen the protection of the main channel of the sleeve on both sides of the railway. If you do not increase the cross section of the casing in order to resist the soil pipe subjected to stress, vibration and stress or pressure pipe can be achieved by increasing the wall thickness of the pipe according to the actual situation.