Protective liner with wear detection

An apparatus for transporting materials including an electrically conductive substrate and a protective liner being in contact with the transported materials. The protective liner includes an electrically non-conductive first layer coupled to the substrate, and an electrically conductive second layer coupled to the first layer. The first layer electrically insulates the second layer from the substrate. A monitoring device is connected to the substrate and the second layer, and configured to detect an electrical connection between the substrate and the second layer indicative of wear of the protective liner. The apparatus can be in a form of a pipe, hose, elbow, valve or tank, and may be used to transport abrasive materials.