EP0453486B1

EP0453486B1 - Holder device for marine anodes

Info

Publication number: EP0453486B1
Application number: EP90902166A
Authority: EP
Inventors: Joergen Leon Hoegberg; Bent Grumstrup Soerensen
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-01-11
Filing date: 1990-01-09
Publication date: 1995-04-19
Anticipated expiration: 2010-01-09
Also published as: DK12989D0; AU4958290A; DE69018814D1; WO1990008204A1; DE69018814T2; EP0453486A1; DK0453486T3

Abstract

A holder device for a marine anode (2) which is mounted to ship's cladding plates to prevent or reduce their corrosion, by connection to the ship's side (10) of protruding end parts (8) of anode carrier irons (6) preferably embedded in the anode (2), consists of a steel body (12) which is adapted to be welded onto the exterior of the ship's side (10), and which is shaped with a hollow (14) which is open to receive one of the said end parts (8) of the anode carrier iron (6), and in connection with the said hollow (14), the holder device includes clamping means (16) which are arranged to retain the said end part (8) and to establish an efficient conductive connection between the said end part of the anode carrier iron (6) and the ship's side (10). In this way it becomes possible to attain a substantial facilitation and reduction of cost in changing marine anodes, as the change can be made in a relatively short time by a diver without the ship needing to visit a yard or to be docked.

Description

The present invention relates to a holder device for a marine anode which is mounted to ships' cladding plates to prevent or reduce their corrosion, by connection to the ship's side of protruding end parts of anode carrier irons embedded in the anode, said holder device comprises a steel body, which is adapted to be welded onto the exterior of the ship's side, and provided with a cavity adapted to receive one of said end parts of the anode carrier iron, said steel body, in connection with said cavity, comprises clamping means which are arranged to retain said end part and to establish an efficient conductive connection between said end part of the anode carrier iron and the ship's side.
With a view to preventing or reducing the galvanic corrosion of ships' cladding plates of metal, for example steel, it is known to mount specially shaped zinc anodes directly onto the ship's cladding plates with the purpose of protecting the steel plates and of concentrating the corrosive action on the anodes. Known zinc anodes are provided with embedded anode carrier irons comprising formbent iron slabs whose opposing end parts protrude from the zinc anode and which usually are flushed with a side face thereof. Opposing parts of the anode carrier iron are intended to be welded directly onto the ship's cladding plates; or the anode carrier iron is possibly connected to the cladding plates by means of bolts which are welded onto the ship's side.
On larger ships a very large number of zinc anodes is used, for example 100 - 400 units. It goes without saying that the ship's zinc anodes must be changed at regular intervals. It is a very extensive and costly matter to change these anodes, and with larger ships the change of the anodes requires docking, that is the ship must visit a yard. It must be mentioned that besides being corroded away as a result of galvanic corrosion, the anodes are also worn off which occurs in particular when sailing in ice-filled waters. The layer of zinc oxide which is formed rather quickly on the surface of the anode and which shows that the anode works, is worn off again relatively quickly. Under normal conditions the anodes must be changed about once a year. It is not uncommon, however, that ships which sail in ice-filled waters must have changed the anodes a number of times a year.
GB-A-1 553 813 discloses a system comprising a particular lock chamber system by means of which the electrical cable leading to the anodes is sealed from the sea-water and by means of which it becomes possible to replace the anti-corrosion anodes whilst the ship is still afloat without the need of placing the ship in dry dock. However, this known system still involves time consuming operations both outside the ship by a diver and inside the ship for the replacement of the anodes and the reestablisment of the electrical connections to the anodes.
US-A-3 232 857 discloses a cathodic protection anode structure comprising particular shaped mounting brackets of steel and permanently welded to the hull in positions of longitudinal alignment thereon, and particularly shaped intervening anode metal bars comprising internal supporting core rods engaging with the mounting brackets. However, by this known systen the main purpose is to provide a compact, rugged and efficient anode structure which lends itself to smooth contouring so as to present minimum drag, and minimum likelihood of being scraped or torn loose. The system requires docking of the ship.
US-A-4 191 625 describes a mode of fixation of the anode by means of a holder, welded to the hull through a hole of which a T screw is passed, clamping the anode lugs with the aid of washer and a bolt. This known anode assembly system involves no advantages in the mounting situation - for a diver it would be difficult to replace the anode when the ship was still afloat.
The purpose of the invention is to provide a holder device for marine anodes by means of which the work with changing the marine anodes can be substantially facilitated and made less costly.
The holder device according to the invention is distinctive in that said cavity is provided in said steel body at one side which is intended to be placed against the ship's side, as said cavity communicates with a top side edge and an end edge of the steel body, facing the anode, and in that the cavity is formed with a funneled shape, as the cavity opposite to said end edge is formed with a side face which slopes downward from said top side edge towards a mainly horizontal limiting edge, and as the cavity opposite the side of the steel body intended to be placed against the ship's side slopes downward and inward at least on a partial stretch from said top side edge and down towards the limiting edge, said partial stretch defining an upper longitudinal sloping face. The mounting itself of holder devices according to the invention possibly will require a docking of the ship; but then succeeding changes can be made by a diver, possibly in a number of rounds, for example if a ferry in regular service is concerned. A very substantial advantage in the anode holder device according to the invention is that one can avoid always having to remove the old anode carrier irons by flame cutting, that is, one avoids creating cutting scars in the cladding plates of the ship. For the very reason of avoiding such cutting scars in the ship's side one has up to now often chosen to let the old anode carrier irons remain in place on the ship's side, which is inappropriate as it is desirable that below the water line, the ship's side should be as smooth as possible.
And with a view towards protecting the anode and diverting forces exerted for example by ice in the water, the holder device according to the invention can advantageously be shaped such that opposite the end edge which faces the anode, the steel body is shaped with a side face sloping inward toward the side of the steel body which is intended to be placed against the ship's side.
In the following the invention will be more closely explained with reference to the drawing, wherein:

Fig. 1: is a perspective view for illustrating a known way of mounting (welding) an anode directly on the ship's side,
Fig. 2: is a corresponding perspective view of an embodiment of anode holder devices according to the invention, for example for mounting the anode shown in Fig. 1 on a ship's side, and
Fig. 3: is a perspective view of an anode holder device according to the invention, cf. Fig. 2.

Fig. 1 shows a marine anode 2 as is known, consisting of an anode body 4 of zinc or of an alloy mainly of zinc wherein an anode carrier iron 6 consisting of a form-bent iron slab is mounted by embedding it in such a way that protruding end parts 8 of the anode carrier iron 6 are flush with the back side of the marine anode 2, such that the latter can be mounted closely to a ship's side 10 by welding the end parts 8 onto it. The marine anode 2 as shown is intended for mounting on a straight side part of a vessel; but also curved marine anodes are known for mounting on curved surfaces of ships. Instead of welding it directly onto the ship's side 10, the marine anode 2 shown in Fig. 1 can - as shown in Fig. 2 be mounted in anode holders 12 which are welded onto the ship's side 10 beforehand at correct mutual distances. The anode holders 12 are formed from steel and arranged to be welded onto the ship's side 10 with a sturdy circumferential weld - except for a corner area of the holder 12 where a cavity 14 is provided for receiving one of the end parts 8 of the anode carrier iron 6. The cavities 14 of the respective anode holders 12 are open upwardly along the ship's side 10, that is that it is quite easy to place the marine anode 2 in the holders 12 before the end parts 8 are efficiently clamped to the ship's side 10 and the anode holders 12, respectively, by means of sturdy pointed screws 16, which can be tightened, via a threaded bore 17 from the front side of the holder 12, against an end part 8 of an anode carrier iron 6 placed in said cavity 14, such that an effective connection is established between the ship's side 10 and the marine anode 2.
As shown in Fig. 3 the cavity 14 is double funnel-shaped as an end face 18 opposite the marine anode 2 slopes down from an upper side edge 20 from which a longitudinal surface part 22 slopes down as well, the surface part 22 passing into a face 24 which is parallel with a base surface 26 of the anode holder, that is also parallel with the ship's side 10.
The anode holder 12 can be opened and closed by means of a sturdy hexagonal spanner as the sturdy pointed screw 16 is preferably an UNBRACO™ pointed screw with a cutting edge. Finally it should be mentioned that the anode holder according to the invention is adapted for known marine anodes. In the future it is expected, however, that marine anodes for different purposes may advantageously be adapted to anode holders according to the invention.

Claims

A holder device for a marine anode adapted to be mounted on ships' cladding plates to prevent or reduce their corrosion, by connection to the ship's side (10) of protruding end parts (8) of anode carrier irons (6) embedded in the anode (2), said holder device comprises a steel body (12) which is adapted to be welded onto the exterior of the ship's side (10) and provided with a cavity (14) adapted to receive one of said end parts (8) of the anode carrier iron (6), said steel body (12), in connection with said cavity (14), comprises clamping means (16) which are arranged to retain said end part (8) and to establish an efficient conductive connection between said end part (8) of the anode carrier iron (6) and the ship's side (10), characterized in that said cavity (14) is provided in said steel body (12) at one side which is intended to be placed against the ship's side (10), as said cavity (14) communicates with a top side edge (20) and an end edge (19) of the steel body (12), facing the anode (2), and in that the cavity (14) is formed with a funneled shape, as the cavity (14) opposite to said end edge (19) is formed with a side face (18) which slopes downward from said top side edge (20) towards a mainly horizontal limiting edge (21), and as the cavity (14) opposite the side of the steel body (12) intended to be placed against the ship's side (10) slopes downward and inward at least on a partial stretch from said top side edge (20) and down towards the limiting edge (21), said partial stretch defining an upper longitudinal sloping face (22).