US3616421A

US3616421A - Sacrifical anode construction

Info

Publication number: US3616421A
Application number: US807500A
Authority: US
Inventors: William D Mackintosh
Original assignee: Atlantic Richfield Co
Current assignee: Atlantic Richfield Co
Priority date: 1969-03-17
Filing date: 1969-03-17
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26

Abstract

A sacrificial anode construction in which the anode is supported in a loose-fitting porous container within the vessel to be protected. The container is constructed to substantially cease liquid flow around the anode when desired so that the anode can be replaced without the loss of an appreciable amount of liquid within the vessel.

Description

United States Patent William D. Mackintosh Tulsa, Okla.

Mar. 17, 1969 Oct. 26, 1971 Atlantic Richfield Company New York, NY.

Inventor Appl. N 0. Filed Patented Assignee SACRIFICAL ANODE CONSTRUCTION 11 Claims, 7 Drawing Figs.

References Cited UNITED STATES PATENTS 8/1888 Siebel 393,072 11/1988 Marquand 204/196 1,335,210 3/1920 Von Wurstemberger 204/196 2,244,322 6/1941 Zoller et a1. 204/197 2,666,026 1/1954 Gibbs 204/197 2,816,069 12/1957 Andrus 204/196 3,012,958 12/1961 Vixler 204/197 3,074,865 1/1963 Gaysowski... 204/196 3,138,549 6/1964 Adair 204/197 3,515,654 6/1970 Bordalen et a1 204/147 Primary ExaminerT. Tung Attorney-McLean, Morton and Boustead ABSTRACT: A sacrificial anode construction in which the anode is supported in a loose-fitting porous container within the vessel to be protected. The container is constructed to substantially cease liquid flow around the anode when desired so that the anode can be replaced without the loss of an appreciable amount of liquid within the vessel.

PAIENTEDnm 26 mm 3. 6 1 6,421

sum 1 OF 3 INVI-IN'IOR WILLIAM D. MACKINTOSH HYVWGM I,

PATENTEDUET 26 1971 SHEET 3 OF 3 INVl-ZN'IOR WILLIAM D. MACKINTOSH SACRIFICAL ANODE CONSTRUCTION SACRIFICIAL ANODE CONSTRUCTION This invention relates to a novel sacrificial anode construction useful in liquid-containing vessels below the liquid level line. In particular, this invention relates to a sacrificial anode construction in which the anode is contained within a loosefitting fluid permeable container wherein the liquid can permeate the container and contact the anode while in use but which allows replacement of the anode without an appreciable loss of liquid and without having to shutdown and drain the vessel.

The use of sacrificial anodes made of suitable metals, usually aluminum or magnesium or their alloys, in liquid-containing vessels is well known. By providing such an anode below the liquid level, corrosion of the container vessel is diminished and, instead, the anode is corroded. Many variations for the installation of sacrificial anodes are known. In some cases, bundles of anodes are held in strings and suspended in the liquid. In many vessels the sacrificial anode is made an integral part of the vessel wall during construction. Once this anode has been substantially corroded away, however, the vessel has to be drained and a new anode placed inside of the vessel. This procedure is not only inconvenient and expensive, with a substantial loss in production due to the downtime, but often the anodes are not changed until long after they are expended with consequent corrosion and ultimate loss of the vessel.

It is an object of this invention to provide a sacrificial anode construction particularly useful in liquid-containing vessels which provides for easy replacement of the anode while the vessel is full without an appreciable loss of fiuid from the vessel. It is another object of this invention to protect the anode in the vessel from erosion which greatly shortens the life of the anode. It is another object of this invention to provide an anode head which does not provide insulation for the anode through the tank shell, the insulation being provided on the anode. This simplified construction of the anode head makes it possible for the head to be reused on new anodes.

These and other objects are attained by enclosing the anode in a loose fitting container secured to the vessel wall. The permeability of the container can vary from slightly porous to very porous but in each case, the container provides a means to substantially cease liquid flow during changing of the anode. The containers are substantially permanently enclosed in the vessel wall and the anodes are insertable from the exterior of the vessel allowing easy replacement. The anodes can, if desired, be placed in a nylon bag to protect them from erosion.

The invention will be discussed in more detail with reference to the appended drawings in which:

FIG. I is an enlarged view of the mount for the sacrificial anode;

FIG. 2 is a cross-sectional view of one embodiment of this invention in which the container is a rigid porous member;

FIGS. 3 and 4 are cross-sectional views of a second embodiment of this invention in which the container includes a slidable sleeve;

FIGS. 5 and 6 are cross-sectional views of a third embodiment of this invention in which the container has an openable end; and

FIG. 7 shows a modification of the embodiment of FIGS. 3 and 4.

Referring now to FIG. 1, sacrificial anode 10 is shown supported in nipple 14 which is mounted on tank shell 12, only a portion of which is shown, to provide an opening extending through shell 12. The anode is supported by threaded rod 16 running through the center of the anode. Rod 16 is secured to anode head by a mated, threaded rod 18, as shown, or, if desired,

rods

16 and 18 can be a single element. The

rods

16, 18 electrically connect anode 10 to the exterior of tank shell 12 and through wire 17 to the shell at a point remote from nipple 14. Rods l6, l8 are insulated from anode head 20 by plastic sleeve 22 and

plastic washers

24, 26.

Steel washers

28, 30 can be used to provide support at the connection if desired. Victaulic cap 32 connects anode head 20 to the nipple 14. Additional insulating material 34 is placed between anode l0 and nipple 14 to ensure that no contact occurs. Insulating material 34 can also be used to provide additional support for anode l0 and to assist in sealing nipple 14 so that the liquid within tank 12 does not leak out.

FIG. 2 illustrates one embodiment of this invention which is in the form of a cylindrical member 40 constructed of a suitable porous ceramic material. such as alumina, which allows passage of the liquid contained within tank I2 around anode 10 in a sufficient amount to protect the tank against corrosion but in an amount insufficient to allow substantial leakage during replacement of anode 10.

FIG. 3 shows another embodiment of the invention. In this form of the invention the anode is supported within a container formed by two

impervious sleeves

50 and 52, preferably made of a metal such as stainless steel coated to provide a liquid seal, e.g. PVC-coated, or neoprene-coated nylon, which contain a number of holes 54 and 54' in-the

sides

50 and 52, respectively. The ends of sleeves 50 and-52 within the vessel are solid and sleeve 52 is rigidly attached to the vessel wall 12 while sleeve 50 is slidable along its axis. Slidable sleeve 50 can be moved from the exterior of the vessel by rods 56 attached to the sleeve at 58 and running through seals 60 in the vessel wall 12. Anode 10 is attached to anode head 20 in the same manner as noted above, i.e., by a rod and sealed. Insulation 34 is provided to insulate the nipple and vessel wall from the anode. To protect anode 10 from erosion, so that it is not prematurely made ineffective, the anode can, when desired, be enclosed in a protective bag 35 made of a material such as nylon. In use,

sleeves

50 and 52 are arranged in tank 12 with the holes 54, 54' concentric as shown in FIG. 4. Thus, liquid can easily enter into contact with the mode. When the anode is to be removed, and changed as in the manner discussed above, sleeve 50 is moved along its axis a length equal to or slightly greater than the diameter of holes 54 by means of rods 56 such that holes 54 in the inner sleeve 52 are closed by the solid spaced between holes 54 in the outer sleeve 50 and vice versa as indicated generally in FIG. 3. This stops the flow of liquid into the container formed by the sleeves and limits the loss of fluid on changing of anode 10 to that amount which is trapped in the container. Cylinder 50 is moved back to its original operation position so that the holes are again concentric after a new anode I0 is in place. In the modification of FIG. 7 the inner and outer sleeves 50' and 52' are constructed with holes 54" and 54", respectively, in the sides 50 and 52' much as

sleeves

50 and 52. However, the holes 54" and 54" register to permit liquid to flow around anode 10 by a rotary movement of sleeves 50' and 52' rather than a reciprocating movement as in the embodiment of FIG. 3. This rotary movement is accomplished by turning the anode head 20 which is rigidly attached to anode 10 through rod I6 and pins 17, or other suitable means, and dished plate 15. Snap rings 19 hold plate 15 on rod 16 and removable pins 13 secure plate I5 to sleeve 52 to complete the connection. In this embodiment, rod 16 is sealed at anode head 20. The end of rod 16 at plate 15 is square to translate rotary movement of head 20 to plate 15 and pins 13 secure plate 15 to sleeve 52. To electrically insulate anode 10, plate 15 should be made of a suitable nonconductive material.

FIGS. 5 and 6 show another embodiment of this invention. In this embodiment, the container within which anode 10 is supported consists of an open-ended rigid, impervious sleeve 62.

Rods

64, 66 which extend from the exterior of the vessel through wall 12 into the liquid have attached at the inner end a cap 68 of solid, impervious material.

Rods

64, 66 pass through vessel wall 12 through seals 70. Anode 10 is again connected to anode head 20 by suitable means such as shown in FIG. I. In use, cap 68 is maintained at a position such that it is away from the open end of sleeve 62, as shown in FIG. 6. In such a position, the liquid in the vessel is free to contact the anode 10 by entry through the open end of sleeve 62. To change the anode, cap 68 is moved back to a position in contact with the sleeve 62 as shown in FIG. 5 to seal sleeve 62. This operation is accomplished by pulling

rods

64, 66, slidably sealed in the vessel wall 12. Anode is changed as before and the only loss of liquid is that liquid which is trapped inside the container or sleeve 62. As noted before, this trapped liquid is a relatively insignificant part of the total liquid in the vessel.

It has thus been shown that this novel construction allows the easy replacement of sacrificial anodes from the exterior of the vessel and without appreciable loss of fluid.

lclaim:

l. A cathodic protection assembly comprising a vessel adapted to contain a liquid, a sacrificial anode construction extending through an opening in the wall thereof at a point other than the top of said vessel so that removal of the anode can cause substantial loss of liquid, a liquid-permeable container in said vessel, said container having an opening in communication with the exterior of said vessel, said container preventing a substantial loss of liquid through said opening when said anode is removed, at least one anode within said container, said anode being removable from outside said vessel, said container being such that it is not removable through said opening in said vessel wall, and means for liquid sealing said anode and container from the exterior of the said vessel.

2. The anode construction of claim I wherein said permeable container is a rigid, porous ceramic body loosely fitting about said anode.

3. The anode construction of claim 2 wherein said ceramic is alumina.

4. The anode construction of claim 2 wherein the porosity of the container is such that it prevents a substantial loss of liquid through said container when said anode .is replaced.

5. The anode construction of claim 1 wherein said permeable container is a solid body containing at least one normally open orifice and means operable from outside laid vessel for opening and closing said at least one orifice.

6. The anode construction of claim 5 wherein said container comprises a pair of concentric sleeves each having at least one orifice in its wall, the orifices in said pair of sleeves normally being in line with one another to allow the flow of liquid therethrough to contact said anode, at least one ot'said sleeves being movable relative to the other of said sleeves, and means for moving one of said sleeves so that the orifices are no longer in line so that liquid flow through the orifices to said anode is substantially stopped.

7. The anode construction of claim 6 wherein the outer sleeve is movable, and means for moving said outer sleeve comprising rods connected to said outer sleeve and extending through said vessel wall to the exterior of said vessel.

8. The anode construction of claim 6 wherein the inner sleeve is movable and means for moving said inner sleeve so that the orifices are no longer in line and liquid flow through said orifices is substantially stopped.

9. The anode construction of claim 8 wherein said means for moving said inner sleeve comprises rotatable means extending from the exterior of said vessel through said vessel wall, said rotatable means being connected to said inner sleeve so that rotation of said rotatable means rotates said inner sleeve.

10. The anode construction of claim 5 wherein said containcr comprises an open-ended rigid sleeve, and means for closing said open end.

11. The anode construction of claim 10 wherein said means for closing said open end is at least one rod extending from outside of and through said vessel wall, said at least one rod carrying a cap means in the interior of said vessel. said cap means being positioned adjacent said open end to close and open said open end upon movement of said red means.

# i l Q

Claims

2. The anode construction of claim l wherein said permeable container is a rigid, porous ceramic body loosely fitting about said anode.
3. The anode construction of claim 2 wherein said ceramic is alumina.
4. The anode construction of claim 2 wherein the porosity of the container is such that it prevents a substantial loss of liquid through said container when said anode is replaced.
5. The anode construction of claim 1 wherein said permeable container is a solid body containing at least one normally open orifice and means operable from outside said vessel for opening and closing said at least one orifice.
6. The anode construction of claim 5 wherein said container comprises a pair of concentric sleeves each having at least one orifice in its wall, the orifices in said pair of sleeves normally being in line with one another to allow the flow of liquid therethrough to contact said anode, at least one of said sleeves being movable relatiVe to the other of said sleeves, and means for moving one of said sleeves so that the orifices are no longer in line so that liquid flow through the orifices to said anode is substantially stopped.
7. The anode construction of claim 6 wherein the outer sleeve is movable, and means for moving said outer sleeve comprising rods connected to said outer sleeve and extending through said vessel wall to the exterior of said vessel.
8. The anode construction of claim 6 wherein the inner sleeve is movable and means for moving said inner sleeve so that the orifices are no longer in line and liquid flow through said orifices is substantially stopped.
9. The anode construction of claim 8 wherein said means for moving said inner sleeve comprises rotatable means extending from the exterior of said vessel through said vessel wall, said rotatable means being connected to said inner sleeve so that rotation of said rotatable means rotates said inner sleeve.
10. The anode construction of claim 5 wherein said container comprises an open-ended rigid sleeve, and means for closing said open end.
11. The anode construction of claim 10 wherein said means for closing said open end is at least one rod extending from outside of and through said vessel wall, said at least one rod carrying a cap means in the interior of said vessel, said cap means being positioned adjacent said open end to close and open said open end upon movement of said rod means.