Copper-clad steel is made of steel core wire and tightly covered copper layer to form a metal core, and the outermost is a PE anti-corrosion layer. The copper core wire is generally composed of the innermost layer of the copper core wire, the insulating foreskin of the intermediate layer and the outermost protective skin. The copper-clad aluminum is composed of an aluminum core wire and a copper layer that is tightly coated to form a metal core, and the outermost layer is a PE anti-corrosion layer.

Because the outermost anti-corrosion layer of the steel gas pipeline is a plastic layer or coating with insulation and anti-corrosion properties, it is similar to the outermost layer of copper-clad steel, copper core wire, copper-clad aluminum and other plastic layers with insulation and anti-corrosion properties. Therefore, we will be equivalent to detect the average insulation quality of the anti-corrosion layer of the tracer wire by using the PCM pipeline current attenuation rate method [1]. The detection principle is to apply a current signal of a certain frequency to the tracer wire, which will gradually decay when the current is transmitted from the tracer to the distance. The attenuation size is related to the insulation resistivity of the plastic layer of the tracer wire. The higher the average insulation resistivity of the plastic layer of the tracer wire, the slower the current attenuation, and vice versa, the faster the attenuation.