Dispositif de protection cathodique

摘要

An electrode assembly for use in a cathodic protection system for submerged metal structures, particularly ships' hulls, such as that described in Specification 957,468 as an impressed current anode or the electrode of a half cell comprises a head 12 provided with an exposed metallic surface 36 and a threaded stem 14, and an elongated nut 20 provided with internal threads at least at both ends and having an enlarged portion at one end with abutment surfaces on either side of the enlarged portion. The exposed metallic surface 36 is in the form of a bronze disc and is mounted on a base 38 of glass fibre reinforced polyester plastic. The edges of the disc are bent inwardly and secured by filling material 40 similar to that of the base 38. The nut 20 comprises a cylindrical portion terminating in a hexagonal enlarged portion and may be of bronze. In Fig. 1 the electrode assembly is employed as a sensing half cell and the threaded stem 14 passes through a hole in the steel hull 16 of a vessel and is secured by the nut 20. An insulating mat 18 separates the head 12 from the hull 16 and between the latter and the nut 20 are disposed a neoprene washer 22, a metal washer 24, and a lock washer 26. A lead-in wire 42 in the stem 14 is connected by a terminal 44 within the nut 20 to a wire 38. A tube 46 insulates the terminal 44 from the nut 20 and a sealing and retaining assembly 48 closes the end of the nut. The wire 38 is connected to a cathodic protection circuit including a meter 50, a lead 32 connected to the hull 16 and an anode 34 of construction similar to that described but with the bronze disc replaced by a platinum surfaced sheet metal element. In Fig. 2 (not shown) wherein the electrode assembly is secured to a wooden hull, the cylindrical portion of the elongated nut is accommodated in an opening in the hull and a neoprene washer, a metal washer, a spacer, and a lock washer are interposed between the hull and the enlarged portion of the nut.