FI70260B - METHOD FOR COATING A SKYDD SPECIFICALLY FOR A SCRAP GENER ANALYZING AV EN YTTRE STROEMKAELLA - Google Patents

Description

70260

Method for cathodic protection of ship hulls using an external power supply in particular - Method for the use of an external power supply for roof disks

The invention relates to a power supply anode and a reference electrode used in the cathodic protection of steel structures (e.g. ships, piers, tanks, etc.).

Cathodic protection prevents corrosion of the metal in an electrically conductive medium (e.g. seawater). A power supply connected between the structure to be protected and the anode supplies direct current from the anode through a medium (e.g. seawater) to the surface to be protected. The protective current lowers the corrosion potential of the surface to be protected to the so-called immunity zone and the corrosion of the metal is prevented. In the automatically controlled cathodic protection system 10, the potential of the surface to be protected is monitored by a so-called reference electrode 11a. The control unit monitors the potential difference between the surface to be protected and the reference electrode and determines the amount of current supplied by the power supply. Such externally powered cathodic protection equipment is currently installed in a considerable part of, for example, new construction equipment.

The main component of the power supply anode is a metal rail or plate through which power is supplied to the solution. The rail material is often platinum-plated titanium or niobium or lead-silver alloy, many other materials are also possible. The power supply rail or plate 20 must not be in direct conductive contact with the surface to be protected. Therefore, an insulating material must be used between them. The power supply board is attached to plastic or reinforced plastic, for example. Power supply An insulated cable is attached to the hood, through which power is supplied from the power supply.

25 The structure of the reference electrode is in principle similar to that of the anodes. The reference electrode uses an electrode whose potential difference with respect to the solution remains constant. Usually, in seawater, a metallic zinc or a silver-silver chloride electrode is used as such an electrode.

70260 2 This electrode must not be in direct conductive contact with the object to be protected. The electrode is insulated from the object, e.g. with plastic or reinforced plastic, and an insulated cable is attached to it, which leads to the control unit.

5 Currently, there are mainly two methods of mounting anodes and blood beauty electrodes: so-called surface mounting and so-called flush mounting.

In surface mounting, the anodes and reference electrodes embedded in plastic or similar insulation are attached to the surface of the structure to be protected (e.g. the hull of the ship) so that they are completely outside the surface profile. Fastening is done, for example, with bolts welded to the surface and gluing.

In flush mounting, housings for anodes and reference electrodes are first welded to the surface to be protected. Anodes and reference electrodes mounted on plastic or the like are now attached to these housings e.g.

15 with bolts and glue welded to the bottom of the housing. In this mounting method, the anodes and reference electrodes are entirely inside the surface profile. With this installation method, e.g. the significant advantage that the durability of the anodes, e.g. under ice conditions, is considerably improved.

There are problems with the anodes 20 and reference electrodes installed by the current method described above, either during installation itself or during use.

In surface mounting, the anodes and reference electrodes are relatively easy to attach. However, the anodes and reference electrodes thus mounted cannot withstand high mechanical stresses, such as e.g.

25 ice-consuming effect. Surface-mounted anodes are not suitable, for example, for cathodic protection of an icebreaker body.

7 0 2 6 0

The immersion installation achieves a uniform profile, so that, for example, ice cannot remove the anodes and reference electrodes. However, this form of installation is difficult to perform. A gap is left between the anode or reference electrode and the housing welded to the structure, which is filled with 5 plastic putty. Puttying is difficult to perform when the surfaces are vertical or curved downwards (e.g. hull). If the power supply plate is damaged, the anode must be replaced. The plastic putty used in the flush mounting has good strength and adhesion and the removal of the anode thus damaged is laborious.

10 Current methods of installing anodes and reference electrodes can therefore be considered unsatisfactory, especially when protecting structures that are subjected to high mechanical stress (eg icebreakers, off shore structures in ice conditions, etc.).

The method of the present invention overcomes the disadvantages set forth above. The invention is characterized by what is set forth in the characterizing part of claim 1.

The advantage of the invention is that it achieves a durable anode and reference electrode construction which, as an element structure, is easy to install by welding.

In the following, the invention will be described in detail with reference to the drawing of Annex 1. The structure (1) to be protected has a fire-cut opening first. A finished anode or blood beauty electrode element is attached to this opening with a welded joint (2). The anode element consists of the following parts: a current supply plate (3) (the reference electrode has an electrode, e.g. zinc, in place of the current supply rail); an insulated cable (4) leading to a direct current source (from the reference electrode a cable leading to a control unit), the power supply plate is insulated with an insulating material (5) from both the metal surface to be protected and the steel welded housing (6).

70260 4

What is essential in this anode and reference electrode construction is that the insulating material in which the power supply rail or electrode material is embedded is cast in a steel housing before the housing is welded to the object to be protected, i.e. it is a ready-to-weld element. As an insulating material, for example, two component non-solvent epoxy putties are used. This material has good adhesion to both steel and the power supply rail and comparator bone electrode material. The welding joint 2 is located so far from the insulating material (5) that the welding heat cannot adversely affect the insulating material. The minimum distance is 50 mm.

The anode and reference electrode housing are made of the same material as the object to be protected, thus avoiding a deterioration in the strength of the structure.

Claims (4)

5 '70260 A method for cathodic protection of ship hulls using an external power supply in particular, characterized in that prefabricated anode and / or reference electrode elements are attached to the structure to be protected, the hull part (6) being made of a material to be protected or suitable for welding with it. ) are ready to adhere to the insulating material (5). ί Method according to Claim 1, characterized in that an insulating material (5) containing the anode power supply plate or reference electrode (3) is cast in the housings (6) of the anode and / or reference electrodes to be fastened to the structure (1) to be protected; recessed. ! Method according to Claims 1 and 2, characterized in that the distance between the anode and reference electrode element and the fastening welding joint (2) of the structure to be protected is at least 50 mm from the insulating material (5). S A method according to claims 1, 2 and 3 n e characterized in that the binder of the insulating material (5) is a solvent-free epoxy. j | i i