US2619455A

US2619455A - Galvanic anode

Info

Publication number: US2619455A
Application number: US183024A
Authority: US
Inventors: Wesley W Harris; Brown Wiser
Original assignee: Aluminum Company of America
Current assignee: Howmet Aerospace Inc
Priority date: 1950-09-02
Filing date: 1950-09-02
Publication date: 1952-11-25
Anticipated expiration: 1969-11-25

Description

Nov. 25, 1952 w. w. HARRIS ET AL 2,619,455

GALVANIC ANODE Filed Sept. 2, 1950 Fig.1.

jg INVENTORS Wesley Ml. Harris,

Wz' er Brown ATTORNEY Patented Nov. 25, 1952 UNITED STATES PATENT OFFICE I 2,619,455 GALVANIC Knobs Wesley W. Harris, Cleveland, and Wiser Brown, South Euclid, Ohio, assignors' to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Application September 2, 1950, serial no. iaoai 13 Claims.

This invention relates to rod-like anodes of the type placed inside tanks, boilers and the like to protect them against corrosion. In particular, the invention is concerned with anodes having a wire core, the anodes being designed for separation into segments which remain connected solely through the core wire or its equivalent. 7

Although light metal rods three feet or more in length are used for cathodically protecting iron tanks, it is not always convenient or possible to install such rods in previously erected tanks or receptacles because of the small clearance between the tank and adjacent structure or equipment. To overcome this difiiculty it has been proposed that the anodes be made in sections and connected to each other by means of a wire, cable or other flexible metallic electrical conductor partially embedded in the anodes. The anode sections may be separately cast around short pieces of wire long enough to extend beyond the ends of the cast body and the sections then connected by forming linked eyes with the ends of the protruding wires or the connection maybe made in any other manner that will provide an articulated joint between the sections. Another method of connecting the sections is to cast them separately on a single long piece of wire. Still another method would be'to machine a solid rod having a wire core and expose short lengths of' the wire between the sections. In any case the series of connected sections can'be sharply bent at the joints, if necessary, when being inserted in a tank. On the other hand, satisfactory con-.

nected sections cannot be made from a solid rod having a wire core by simply breaking the rod at intervals without stretching, twisting or even breaking the wire when bending is attempted. A wire deformed in this manner would be apt to fail during subsequent service. I

To cast separate anode sections as mentioned above is, of course, an expensive operation lf the sections are to be separately cast on indi vidual wires, a large number of molds would be required for any sizable commercial operation. On the other hand, if a plurality of sections are to be placed on one wire, they may be cast successively or poured simultaneously with runners between adjacent sections. In the last na med instance, however, the runners would haveto be subsequently trimmed off. To machine sections" from a solid rod adds a step to the fabricating schedule with attendant increase in cost' of, the

final product. These disadvantages have ledus to devise a new type of anode which canserve as a rigid member or be separated into two or moreeonnected segments. The provision of such a galvanic anode is the principal object of our invention, V 7

One embodiment of our invention is illustrated in the accompanying drawings in which:

Fig. l is aside elevation of an anode; I

Fig. 2 is an enlarged cross section taken on line II of Fig. 1"; e r

Fig. 3 is an enlarged cross section taken on line II II of Fig. 1; I

, Fig. i is' a side elevation'of anode which has been separated into segments; and

Fig. 5 is aview, similar to Fig. 1, partially in section, wherein the notches do not expose the core member. '1 a v The novel article we have produced comprises an anodebody of rod-like proportions and flexible metallic core member such as a wire of another metal embeddied in the bodyand extending lengthwise thereof, and at least one transverse indentation or notch between the ends of the anode body which extends to a depth that permitsready breaking of the body and bending of the core member without substantial stretching ofysaid member and, preferably, is at least as deep as the embedded member thus leaving a substantial amount of metal in the cross section to form a rigid body. Usually a plurality of notches will be most advantageous. An anode of this character can be employed as any other rigid anode of similar length or it can be broken or otherwise separated into segments as determined by the notches. Its particular advantage, however, lies in the ease with which it can be converted into segmental form and the wire bent and straightened without damage. Inasmuch as the anode is initially an integral body we choose to refer to the parts thereof after the anode is broken as being segments.

The transverse notch or indentation should be wide enough to allow the segments to be turned at-fa right angle to each other if the notch forms the inside of the angle without compressing the ends of the segments or stretching the core member. Preferably, the notch should have .a base section that exposes a short length of the core member, however, this may not be necessary under all conditions and it may be advantageous not to expose the core member. Where this condition exists the notch should have a sufficient depth to permit easy breakage of the anode body through the portion having a diminished cross section and the metal between the notch and the core member should be relatively thin so that it willbreak away from the core or at least not half way through the anode and to employ a fiat base section the length of which is not less V than half the maximum cross sectional 'dimension of the anode and slopethe walls or sides at The not more than 45 to the axis of the rod. side walls of the notch need not be flat nor is it essential that they taper inwardly as previously mentioned, only that they be suificiently separated at their base to permit turning the segments as far as a right angle to each other Without the walls of the notch pressing against each other. The notch may have a curved surface, if desired, of either uniform or non-uniform radius. Where the surface is curved, that portion of the notch which exposes the core member or, is closest thereto, is to be considered its base.

An anode which possesses the foregoing features is illustrated in the accompanying drawings where the rod-like anode body I is of circular cross section. Concentrically embedded in the anode and extending beyond the ends thereof is wire 2. The notches at regular intervals have tapered sides 3 and fiat sections 4, the length of the fiat section being equal to the radius of the rod. To facilitate breakage of the anode at the center of the notches it may be desirable to provide small transverse grooves 5 on the opposite side of the rods. In the broken anode shown in Fig. 4, the wire 2 is seen as the connection between the segments. In Fig. 5 the wire 2 is not exposed at the base 4 of the notch, however, the notch is of a depth which permits breakage of the anode and a bending of the Wire without substantial stretching thereof.

The anodes may be of any convenient length and cross section except that the length should considerably exceed the transverse dimension. A ratio of length to maximum cross sectional dimension exceeding to 1 is an example of such a proportion. In cross section the anodes may be round or polygonal, the shape being a matter of choice and ease in manufacture. Because. their length considerably exceeds the transverse dimension, the anodes are here referred to as being rod-like.

Anodes made of the light metals provide the mostefficient cathodic protection based upon the ampere-hours produced per unit weight of metal consumed and they are therefore preferred. However, heavier metals such as Zinc can be employed in the same manner and anodes of the kind described above can be made of this metal. The term light metal as used herein refers to aluminum and magnesium, and the alloys in which they predominate. Those alloys in which aluminum or magnesium constitute at least 70% of the total weight are most desirable. Among the alloying elements which improve the performance of magnesium for cathodic protection are aluminum, zinc, and manganese in amounts of 1 to 30%, l to 25% and 0.1 to 2%, respectively. In the case of aluminum base alloys the addition of 1 to zinc is advantageous.

The anodes may be in either cast or wrought form but the most convenient method of producing them is by casting. In this way wires of the desired length can be easily embedded in the desired place and the notches made at the desired locations. Also, anodes of any length can be made without cutting a longer body. Wrought rods can be fabricated which have an embedded wire core. For example, an extruded rod can be produced that has a Wire core. Such a product may be rolled or forged and notches made at regular intervals in known manner as by die .rolling or by machining.

' 'The embedded wires or similar members serve both to mechanically connect the separated seg- ..ments and as electrical conductors from the antility to permit bending. A good metal to metal contact should exist between the member and the anode metal to insure as low resistance as possible to flow of the electric current. Generally the metal core member should have a melting point above that of the anode metal to avoid melting during the casting operation but this may be unnecessary where the anode is extruded around the member. The wire should in most cases be of a metal that is cathodically protected by the anode metal. Such metals as copper, iron, steel, stainless steel and Monel metal are suitable for the purpose but steel is usually preferred because of its cheapness. Although wires are generally most useful, larger embedded connectors such as rods may be employed providing they can be easily bent. Stranded cables or other flexible metal connectors may also be used. The size and shape of the wires form no part of the instant invention. It is preferable that the wire be concentrically positioned in the anode but this is not essential providing it is exposed over a short distance and the anode can be broken or separated without undue strain upon the wire. The wires, rods, stranded cables, or their equivalents are herein referred to as flexible metallic core members. In some cases it may be desirable to employ two or more core members providing they are in the same plane and therefore can be bent alike in the same bending operation.

' This application is a continuation-in-part of co-pending application Serial No. 23,546, filed April 27, 1948, now abandoned.

- Having thus described our invention, we claim:

1. An anode of rod-like proportions comprising a rigid anode body and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode body having at least one transverse notch between its ends exposing a portion of said core member.

2. An anode of rod-like proportions comprising a rigid anode body and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member and is of a length not less than half the maximum cross sectional dimension of the anode body.

3. An anode of rod-like proportions comprising a rigid anode body and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member and is substantially flat and parallel to the axis of the anode, said base havin a length not less than half the maximum cross sectional dimension of said anode body.

4. An anode of rod-like proportions comprising a rigid anode body of circular cross section and a flexible metallic core member cathodic to the anode body concentrically embedded lengthwise in said body, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member and is of a length not less than half the maximum diameter of the anode body.

5. An anode of rod-like proportions comprising a rigid anode body of circular cross section and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode having at least one transverse notch between its ends the base of which exposes a portion of said core member, is substantially fiat and parallel to the axis of said anode body, and of a length not less than half the maximum diameter of said anode body, the side walls of said notch being fiat and sloping inwardly toward the base, said sloping side walls being at an angle of not more than 45 to the axis of the anode body.

6. An anode of rod-like proportions comprising a rigid anode body having a ratio of length to maximum cross sectional dimension exceeding to 1 and a flexible metallic core member cathodic to the anode body concentrically embedded lengthwise in said body, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member and is of a length not less than half the maximum cross sectional dimension of said anode body.

'7. An anode of rod-like proportions comprising a rigid anode body and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode body having at least one transverse notch between its ends, the base of which exposes a portion of said core member, and a transverse groove on the side of said body opposite said notch.

8. An anode of rod-like proportions comprising a rigid light metal anode body and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member.

9. An anode of rod-like proportions comprising a rigid anode body of magnesium base alloy havin a circula cross section, a flexible metallic core member cathodic to said magnesium base alloy concentrically embedded lengthwise in said 6 body, said anode body having at least one transverse notch between its ends, the base of which exposes a portion of said core member and is of a length not less than half the maximum diameter of said anode body.

10. An anode of rod-like proportions comprising a rigid light metal anode and a flexible steel wire core member embedded lengthwise in said body, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member.

11. An anode of rod-like proportions comprising a rigid cast magnesium alloy anode body of circular cross section and a flexible steel wire core member concentrically embedded lengthwise in said body and extendin beyond the ends thereof, said anode body having at least one transverse notch between its ends the base of which exposes a portion of said core member and is of a length not less than half the maximum diameter of said anode body.

12. An anode of rod-like proportions comprising a rigid anode body and a flexible metallic core member cathodic to the anode body embedded lengthwise in said body, said anode body having at least one transverse notch between its ends of a substantial depth, the base of said notch being in close proximity to the core member, the thickness of the metal between said notch base and the core member being such that the metal is broken away from said core member when the anode is broken and the core member is bent in the direction of the notch.

13. An anode of rod-like proportions comprising a rigid anode body of magnesium base alloy and a flexible steel wire core member embedded lengthwise in said body, said anode body having at least one transverse notch between its ends of a substantial depth, the base of said notch being in close proximity to the steel wire core member, the thickness of the metal between said notch base and the steel wire being such that the metal is broken away from said wire when the anode is broken and the wire is bent in the direction of the notch.

WESLEY W. HARRIS. WISER BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 752,844 Kinnear Feb. 23, 1904 2,204,823 Rhodes June 18, 1940

Claims

1. AN ANODE OF ROD-LIKE PROPORTIONS COMPRISING A RIGID ANODE BODY AND A FLEXIBLE METALLIC CORE MEMBER CATHODIC TO THE ANODE BODY EMBEDDED LENGTHWISE IN SAID BODY, SAID ANODE BODY HAVING AT LEAST OEN TRANSVERSE NOTCH BETWEEN ITS ENDS EXPOSING A PORTION OF SAID CORE MEMBER.