US2816069A - Self-sealing anode structure - Google Patents

Description

o. E1. ANDRUS 2,816,069

SELF-SEALING ANODE STRUCTURE Filed July s, 195s Dec. l0, 1957 Y INVEN TOR.

ORRIN E. NDEUS ATTORNEYS.

United States Patent SELF-SEALING AN ODE STRUCTURE Orrin E. Andrus, Milwaukee, Wis., assigner to Op. Smith Corporation, Milwaukee, Wis., a corporation or New York Applikation July 3, i953, Serial No. 365,797

1 Claim. (Cl. 204-196) This invention relates to an anode device with an electrical lead construction which is self sealing against loss of uid therethrough.

An object of the invention is to provide a protective anode supporting device with the anode connected to a source of current and electrically insulated from the tank to be protected.

Another object of this invention is to provide an anode lead construction for carrying a current to an anode for cathodically protecting a metallic structure with said lead construction having self-sealing means to prevent loss of liquid from the structure should the lead corrode.

Another object of the invention is to provide an anode supporting device which has a resilient material disposed between the support and the anode to reduce the transfer of mechanical shock from the tank to the anode in handling and installation.

Another object of the invention is to provide an anode support which includes a sealing material between the anode and the support to prevent the liquid from contacting the lead wire.

A further object of the invention is to provide a low cost anode unit.

In general, the invention comprises an anode supported within a metallic tank which contains a corrosive liquid. The anode is electrically insulated from the tank. A conductor extends from the anode to a suitable generator in order to carry a current to the anode. The conductor is sealed to the anode in such a manner that the corrosive liquid does not contact the conductor. A exible sealing member, under compression, is employed to prevent leakage of iiuid from the tank should the above mentioned sealing material fail or should the conductor corrode. If the conductor corrodes within the flexible sealing member, the hole through the latter remains sealed by reason of expansion of the previously compressed member and thereby prevents leakage of iiuid from the tank.

In the drawing:

Figure l is a view of one embodiment of the invention, partly in section and partly in elevation;

Fig. 2 is a view similar to Figure l with the anode and part of the lead wire corroded away;

Fig. 3 is a view in cross-section of another embodiment of the invention;

Fig. 4 illustrates a further embodiment of the invention, partly in section and partly in elevation;

Fig. 5 is a cross-sectional view of another embodiment of the invention.

Referring particularly to Figure l, the support plug i is externally threaded and secured to a tank of which only a portion of a wall 2 thereof is shown. The wall 2 has a correspondingly threaded aperture to receive plug l.

Although the plug is shown secured to the wall 2 by correspondingly threaded portions, the plug may be otherwise secured to the wall, for instance, as by welding or brazing.

The structure, of which only wall 2 is shown, is any "ice metallic structure which is in contact with a corrosive liquid and which is adaptable to cathodic protection for corrosion prevention. The anode unit is of particular importance in the field of domestic hot water heaters and more specifically glass-lined domestic hot water heaters.

The opening extending through plug l is made with lesser diameters at the ends of the plug to provide support for the self-sealing mechanism as is subsequently described.

The lip 3 which extends inwardly within the tank from supporting ledge 4 of plug 1 is preferably swaged or crimped about the anode 5 to support the anode within the tank. The anode 5 preferably has a conical enlargement which serves to support it within swaged lip 3. A lining 6 of a rubber-like composition or similar sealing and insulating material separates the anode 5 from the plug 1, maintaining a liquid-tight seal therebetween. Preferably the lining 6 extends between anode 5 and a conning washer 7. The transfer of mechanical shock from the tank to the anode may be lessened by the use of a lining composition having adequate resilience. To minimize the current ow between the anode and plug through the liquid, the lining 6 preferably extends back over the end of lip .3, as illustrated.

A preferably bare conductor is connected to the insert rod 9 of anode 5 as by weld lil or other suitable means so as to form an electrical connection therebetween. The conductor 8 extends outwardly through the opening in plug 1 to the positive side of a suitable source of direct current, not shown. A conductor ll connects the walls of the structure to the negative side of the source of electrical current.

The confining washer 7 preferably made of laminated Bakelite or other physically strong insulating material rests on the supporting ledge 4 of the plug l. The washer 7 has an opening equal to the size of the bare conductor 8 through which the latter passes.

Confined under compression within the enlarged opening in plug l and abutting washer 7 is a pliable electrically insulating and sealing member 12 made of foam rubber or other compressible material. The compressed pliable sealing member 12 forms a liquid-tight seal which will close and seal the plug against leakage therethrough should the conductor 7 sufficiently corrode.

A second confining washer 13 similar to washer of a physically strong insulating material such as laminated Bakelite is disposed between the pliable sealing member l2 and centrally extending ange 14 of plug 1. An opening in the washer i3 allows the conductor 7 to pass to the exterior of the plug 1. The iiange i4 of plug .i holds the Washer 13 in position against the forces of the compressed pliable member l2. By inwardly crimping an initially extending lip to a final position, the flange l-fi may be formed as illustrated.

Coniining washers 7 and 13 serve not only to confine the sealing member l2 but they also serve to insulate the conductor 8 from the plug 1 and therefore from the structure wall 2. The conductor 3 may be insulated in any other suitable manner such as by a rubber coating or constructing the washers of a non-insulating material with an insulating insert.

Anode 5 is illustrated as provided with an insert rod 9 of iron, stainless steel or other suitable conducting material. rfhe anode 5 is formed of zinc, carbon or other appropriate material l5 which is die cast, extruded or otherwise formed around insert rod 9. The insert rod 9 may be knurled, notched or metallically bonded to prevent movement between the rod and the anode and also to provide better electrical contact therebetween. The anode construction described is the preferred form for purposes of illustration and it is to be understood that it may be otherwise formed within the scope of the invention; for example, an anode without an insert rod may be employed. The conductor 8 is preferably covered with a sleeve type insulation le which may be a part of the washer 13, as illustrated, to insure against an electrical short of the conductor against the plug.

Fig. 2 is a view of the embodiment illustrated in Figure l with the anode and part of the conductor removed by corrosion. The compressed pliable member lf2 is confined within the plug l by the washer 7 resting on the supporting ledge 4. The compressed pliable sealing member i2 expands or iiows and closes the opening which would otherwise be left by the corrosion of the conductor 8 and seals the unit against leakage therethrough.

The embodiment of the invention illustrated in Fig. 3 and described as applicable to a tank employs a compressed gasdilled doughnut-shaped member 17 as the self-sealing means in lieu of the compressed pliable sealing member l2 of Figure l.

An aperture i8 in the tank wall accommodates a grommet i9 of a suitable insulating and sealing material. A supporting screw 20 extends through the grommet and is threaded into the anode 21.

Supporting screw 2@ is provided with a head 22 which compresses the grommet when the screw is threaded into anode 2l. The resulting structure thereby insulates, supports and seals the anode from the tank wall 22 so that liquid cannot normally cause corrosion of the lead wire 24.

An annular member 25 on the exterior surface of wall 23 surrounds the screw 2u and opening 1S in the tank and is tightly secured to wall 23 in any desired manner; such as, by a circumferential weld 26. Threaded cap 27 is screwed on to annular extension 25.

The gas-lilled doughnut shaped member i7 is held under compression within the chamber defined by the annular member 2S and cap 27. Air, nitrogen, or other suitable compressible fluid may be employed within the doughnut-shaped member 17.

An insulating and retaining washer 28 of laminated Bakelite or other suitably strong insulating material is disposed between the doughnut-shaped member i7 and the tank wall 23. Washer 23 is provided with a small opening through which the lead wire 24 passes.

An insulating and retaining washer 29 is also disposed between the cap 27 and the doughnut-shaped member i7. The washer 2,9 preferably has an annular extension 3i) which protrudes out of an opening in cap 27. The lead wire 24 passes through the annular extension 30 to a suitable source of electrical current, not shown.

When the cap 27 is screwed onto the annular member 25', the doughnut-shaped member i7 is placed under compression between washers 23 and 29 and annular memer 25 so that member i7 is in readiness to seal the tank against fluid leakage should the lead wire 24 corrode.

In the embodiment of the invention illustrated in Fig. 4, the force applied te the pliable member is obtained from the stress in tubular member 3l. Metallic tubular member 3l is brazed or otherwise secured to the wall of the aperture 32 in the plug 33 and extends outwardly therefrom. Aperture 32 is preferably enlarged as at 34 in order that only the lower portion of the tubular member 3l is secured to the plug 33. The conductor 35 which is welded or otherwise secured to the anode 36 extends through the tube 3l to a suitable source of current, not shown. The end of the tube 3l at the innermost end of aperture 323 has an inwardly extending annular ledge 37. A confining washer is supported on the ledge 37 and extends to the innermost end of the tube to insulate the conductor from the tube A pliable insulating and sealing plastic 39 is coniined within the tube 31 by coniining washer 3S and a conning washer 40 in the outer end of tube Sil. The. confining washer 40 is preferably held therein by crimping the end of the tube inwardly as at 4l. The confining washer 40 is preferably constructed with an annular extension through which the conductor 35 extends.

The pliable plastic 39 is under a compressive force from the mechanically stressed tube 31. Therefore, should the conductor 3S corrode, the stress in the tube 31 will force the pliable sealing plastic 39 to close the void left by the corroded conductor. The metallic tube 31 is stressed preferably by applying an appreciable force to the pliable plastic 39 and the confining washer 40 prior to crimping the end of the tube inwardly as at 41. Other means of stressing the metallic tube may be employed; for example, swaging.

As in the previously described embodiments, the anode 36 is supported by plug 33 by clamping the lip 42 thereabout. An insulating and sealing lining 43 of a suitable composition is disposed between the plug 33 and the anode 36.

The lining 43, as previously noted with respect to lining 6 of Figure l, may have resilient characteristics to lessen the transfer of mechanical shocks from the structure to the anode. As previously noted, the lining 43 may extend back over the lip 42.

The plug 33 is secured to an aperture in the structure wall by correspondingly threaded portions as previously described with respect to Figure l.

The embodiment of the invention illustrated in Fig. 5 employs a spring-loaded sealing unit to insure against fluid leakage from the structure, such as a tank.

The anode 44 is supported by plug 45 so that it is in contact with a corrosive liquid. The anode 44 and plug 45 of Fig. 5 are the same as anode 36 and plug 33 of Fig. 4.

A tube 46 is welded, brazed or otherwise secured to the aperture in plug 45 and extends therefrom to an aperture in a receptacle 47 to which it is likewise secured.

The conductor 48 extends from the anode 44 through the tube 46 and receptacle 47 to a suitable source of electrical current, not shown. Rubber or other suitable insulating material 49 ills the tube 46 about the conductor 48.

A pliable insulating and sealing material Sti is conlined under a compressive force within the receptacle 47 by means of the compression spring 5l. The cap 52 is preferably threaded on to receptacle 47 so that the spring 51 may be compressed sutiiciently to exert a compressive force on the material 50.

The insulating and conlining washer 53 between the material 5t) and spring 51 prohibits the ow of material 50 out of the receptacle. Washer S3 preferably is provided with an annular extension 54 which passes through an aperture in the cap 52. The conductor 4S passes through the annular extension 54 and is thereby insulated from the receptacle 47.

An insulating and confining washer 55 between the base of the receptacle 47 and the pliable insulating and sealing material 5@ has an opening which allows the conductor 4S to pass therethrough. The small opening in washer 55 prohibits the iiow of material out of the receptacle into the tube 46.

If the anode 44 is removed by corrosion or the sealing means between the anode 44 and plug 45 fails, the liquid within the tank can leak out of the tank only to the receptacle 47 and the tank is effectively sealed against loss of liquid.

In the construction of the invention, the conductor carrying the current to the anode should be as small as compatible for the current it must carry in order to facilitate the sealing should it be removed by corrosion.

The opening through the confining washers should be a minimum to allow passage of the lead wire in order to minimize the extrusion of the sealing member therethrough.

The sealing member and the confining washers for retaining the sealing member under compression have been described as constructed of insulating materials in order to insulate thellead wire from `the tank wall. The lead wire may be otherwise insulated from the tank wall such as by a rubber coating on the lead wire.

The invention as disclosed above provides an anode with a current impressed thereon which may be applied to any metallic structure which contacts a corrosive liquid without danger of leakage should the anode or conductor be removed as a result of corrosion. The sealing member is retained under a compressive force within a chamber which securely seals the opening through which the conductor passes.

Various embodiments of the invention may be employed within the scope of the following claim.

I claim:

A self-sealing anode structure for a cathodic protection `device wherein the wall of a tank or the like is pro tected from corrosion by a corrosive liquid in Contact therewith, comprising: an anode, electrical insulating means `carried by the tank wall and supporting said anode within the tank and submerged in the corrosive liquid therein, an electrical conductor extending yfrom said anode through an opening 4in the wall of the tank to the positive side of a source of direct current potential having its negative -terminal connected to the tank Wall to provide cathodic protection for the tank, tubular means carried by the tank wall and providing a chamber surrounding said conductor externally of said insulating means and having its inner end initially sealed by said insulating means from the passage of `corrosive liquid into the chamber from the tank, said conductor being subject to progressive corrosion following consumption of the anode thereby tending to leave a passage through said insulation and chamber to the outside of said tank for leakage of the corrosive liquid from the tank, and compressed sealing means surrounding said conductor, and confined in said chamber, expansible upon corrosion of ysaid conductor, to seal the chamber against the passage of liquid therethrough, whereby further corrosion of the conduc-t-or is prevented and the seal is maintained against leakage of corrosive liquid lfrom the tank.

References Cited in the `1le of this patent UNITED STATES PATENTS 1,731,597 Spear Oct. 15, 1929 2,568,594 Robinson Sept. 18, 1951 FOREIGN PATENTS 24,967 Great Britain 1899

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