A method of detecting a locally generated corrosion of a metal element when exposing said metal element to a corrosive environment, comprising: providing said metal element constituting a first element defining opposite first and second surfaces (14, 15), said first surface defining an exposed outer surface to be exposed to said corrosive environment, said first element comprising a first pair of terminals (9, 10), providing a first pair of electrical connectors, and contacting each connector of said first pair of electrical connectors with a respective terminal of said first pair of terminals (9, 10) for allowing an injection of an electric current into said first element, providing a sponge, said sponge constituting in dry state an electrical insulator and constituting an electrical conductor when wetted in said corrosive environment, and applying said sponge to said second surface of said first element, providing a second element of an electrically conductive material, and arranging said second element opposite to said second surface of said first element, and sandwiching said sponge between said first element and said second element, providing an electrical insulator, said electrical insulator together with said first element encapsulates said second element and said sponge for preventing said second element and said sponge from being directly exposed to said corrosive environment, characterised in injecting a specific electric current into said first element via said first pair of electrical connectors, and measuring a voltage between the terminals of said first pair of terminals (9, 10), and monitoring a gradual increase in said voltage due to a corrosion of said first element, and detecting a decrease in said voltage caused by a pinhole being generated in said first element, causing said sponge to be wetted and allowing said second element to provide a shunt relative to said first element thereby reducing a resistance between the terminals of said first pair of terminals (9, 10). providing said metal element constituting a first element defining opposite first and second surfaces (14, 15), said first surface defining an exposed outer surface to be exposed to said corrosive environment, said first element comprising a first pair of terminals (9, 10), providing a first pair of electrical connectors, and contacting each connector of said first pair of electrical connectors with a respective terminal of said first pair of terminals (9, 10) for allowing an injection of an electric current into said first element, providing a sponge, said sponge constituting in dry state an electrical insulator and constituting an electrical conductor when wetted in said corrosive environment, and applying said sponge to said second surface of said first element, providing a second element of an electrically conductive material, and arranging said second element opposite to said second surface of said first element, and sandwiching said sponge between said first element and said second element, providing an electrical insulator, said electrical insulator together with said first element encapsulates said second element and said sponge for preventing said second element and said sponge from being directly exposed to said corrosive environment, characterised in injecting a specific electric current into said first element via said first pair of electrical connectors, and measuring a voltage between the terminals of said first pair of terminals (9, 10), and monitoring a gradual increase in said voltage due to a corrosion of said first element, and detecting a decrease in said voltage caused by a pinhole being generated in said first element, causing said sponge to be wetted and allowing said second element to provide a shunt relative to said first element thereby reducing a resistance between the terminals of said first pair of terminals (9, 10).