US2934485A

US2934485A - Device and its use for protecting elements against galvanic dissolution

Info

Publication number: US2934485A
Application number: US658765A
Authority: US
Inventors: Rolland C Sabins
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-05-13
Filing date: 1957-05-13
Publication date: 1960-04-26
Anticipated expiration: 1977-04-26

Description

April 26, 1960 R. c. SABINS 2,934,485 DEVICE AND ITS uss FOR PROTECTING ELEMENTS AGAINST GALVANIC DISSOLUTION Filed May 13, 1957 FIG. 4 74 INVENTOR.

ROLLAMD C. SABINS BY 5 141:2??? d y/454, A

TTORNE YS United States Patent G if DEVICE AND ITS USE FOR PROTECTING ELE- MENTS AGAINST GALVANIC DISSOLUTION The present invention relates to a device and its use for protecting elements against galvanic dissolution. The present invention comprises a unit or assembly or what may be termed in legal parlance an article of manufacture. It includes primarily a bell or open end casing, which is attachable to the element to be protected against galvanic dissolution, an anode which is insulated from the bell, and a conductor connected with the anode and which is also connectable with the element to be protected. The bell per se may be formed of insulating material or other suitable insulating material may be interposed between the anode and bell.

More specifically, the unit includes an anode having a terminal which extends through a wall of the bell and the electrical conductor is connected to this extended end of the terminal.

The anodic or sacrificial metal, of course, is higher in the electro-chemical series than the metal to be protected and when the anode and the metal to be protected are subjected to the influence of the electrolyte, the metal to be protected functions as a cathode, that is, current is generated and impressed on the metal to be protected. For example, in a circuit including steel, such as the hull of a ship and sea water as an electrolyte, the steel has a potential of 630 millivolts in reference to a halfcell formed of silver silver-chloride, as is more fully set out in my co-pending applications Serial Number 586,969, filed May 24, 1956, now Pat. No. 2,903,405, and Serial Number 602,156, filed August 6, 1956, now Pat. No. 2,918,420. It is known that, to protect a steel such as a ships hull against corrosion, a potential must exist of approximately 890 millivolts with reference to the aforementioned half-cell, and accordingly the potential of the steel cathode (herein, as an example, the ships hull) must be raised 260 millivolts to prevent what is known as galvanic corrosion or galvanic dissolution of the steel.

My improved anode unit includes a resistance in the conductor which connects the anode with the cathode (the steel to be protected). This resistance is of such value as to limit the potential diiference between the anode and cathode to an average of approximately 260 millivolts. Thus the desired current is impressed on the cathode to insure prevention of galvanic dissolution of the cathode.

Preferably, to constitute a unit, this resistance is connected directly with the end of the anode terminal which end extends through a wall of the bell, and, this end as well as the resistance is imbedded in insulation, and preferably, to protect the insulation against breaking by abuse thereof, it is surrounded by a shield of metal.

In some embodiments or use of the invention wherein all of the metal, to be protected, is immediately adjacent the anode, as for example the condenser of a ships refrigerating system using the sailing water for cooling the condenser, the bell may be formed of steel and the end of the resistance opposite that end which is connected to the anode, is connected directly to the bell.

Patented Apr. 26, 1960 My invention further contemplates the ready replacement of the anodic or sacrificial material.

Further objects and advantages will be apparent from the following description, reference being bad to the accompanying drawings wherein preferred embodiments of the invention are illustrated.

In the drawings:

Fig. 1 is a perspective view of 'a ships hull showing one use of the present invention;

Fig. 2 is a longitudinal cross-sectional view of the protecting unit;

Fig. 3 is a side View of a condenser of a refrigerating system showing three of my protecting units attached thereto; and

Fig. 4 is a side view, partly in longitudinal section of the unit utilized in Fig. 3.

Referring more in detail to the drawings, the anode unit or assembly is indicated at 20; it includes preferably a cylindrical side wall or skirt 22 and an end wall or base 23, preferably joined as at 24. The

walls

22 and 23 cooperate to form a container or bell 25 having an open end 26. This bell 25 is lined with suitable

insulating material

28 and 29. The element to be' protected is indicated at 31. This may be, for example, formed of steel and be a hull of a barge 33.

Of course the bell 25 or container, including the cylindrical wall 22 and the base 23, may be formed of insulating material, but where such container is apt to be subjected to severe abuses, as in a ship, it is preferable to form the container walls of metal such as steel. In that event holes are cut into the side walls of the barge and the end of the cylinder 22 is joined at its periphery with the wall 31 of the hull in sealing relation therewith as by weld 34. Preferably the insulation 28 is flared outwardly as at 35. The unit 20 also includes the anodic or sacrificial metal in the form of a cylinder 36. An opening 37 extends axially through the central portion of the metal 36 and this opening receives a sleeve 38. The sleeve is fixed to the metal 36. The unit including the cylinder of metal 36 and sleeve 38 are fixed in position by a bolt 40 which extends through the sleeve 37 and beyond the base 23, the base 23 having an opening 42 for receiving the bolt. A bushing 44 extends within the opening 42 of the base 23 and surrounds the bolt 40. This bushing 44 is provided with a circular flare portion 45. A washer 47 is fixed, as by welding, to the bolt 40 and abuts the flare 45 of the bushing 44. The end of the bolt 40 which extends beyond the base 23 is threaded as at 49 for receiving a nut 50, a metallic washer 52 and an insulating washer 53 being interposed respectively be tween the nut 50 and the outer side of the base 23. When the nut 50 is drawn tight, the bolt will be locked in the base 23 by reason of the washer 47 being pulled tight against the flare 45 of the bushing 44. In other words, the base 23 is clamped between the washer 47 and bushing 44 and the insulating washer 53.

The opposite end of the bolt 40 extends outwardly beyond the sleeve 38 and the metal cylinder 36, and is threaded as is shown at 55 for receiving a nut 56, a washer 57 being interposed between the nut and the cylinder 36.

The cylinder 36, including the sleeve 38, is slid over the bolt until the right end thereof abuts the washer 47 and then the nut 56 is tightened to securely hold the cylinder 36 in position. Preferably the cylinder is provided with a cylindrically shaped insulating cup 59.

An electrical conductor 61 is connected to the metallic washer 52 and thus is connected to the anodic metal 36 through the bolt 40. This conductor includes a resistance element 63, the resistance element being connected di rectly to the washer 52. The right end of the bolt 40, the

washer 52, the washer 53, the nut 50, and the resistance tached to the element to be protected, for example the,

hull of the barge 33.

Preferably, the insulation 65 is an epoxy solution which hardens when subjected to air. After the parts are assembled as is shown, the unit is set upon its left side so that the end of sleeve 66 is open at the top. This epoxy material is then poured into the sleeve to imbed the parts as previously described. The insulating material 29 may bealso an epoxy material. It is poured in place while the unit is setting upon the right end of sleeve 66 and before the anodic material 36 is placed in position. When the container 25 is formed of metal, the base plate 23 is welded at 24 to the right end of the cylinder 22. Thus by reason of the welds and the insulating materials as described, the unit is hermetically sealed at those points where they are joined with other parts of the unit to thus prevent the leakage of water into the hull of the ship. I

Another aspect of the invention is shown in Fig. 4 wherein the end of the resistance 63 is secured to the sleeve 66 as at 70. This embodiment can be used where the immediate metal only is to be protected. An example of this is shown in Fig. 3 wherein the metal to be protected is a condenser 72 of a refrigerating systtm, for example of the type in which sea water is used as a coolant. Here the condenser includes a lower header 74 which leads to a pipe 75, an upper header 77 which receives gaseous refrigerant through a pipe 79, and ducts '81 which interconnect the headers 74 and 77. In this embodiment three units 20 are secured to the metallic framework 83 of the condenser 72 by bolts 84.

The resistance value of resistance element 63 is elected depending upon the area of the metal which is to be cathodically protected. In operation, for example, when the hull and the anode 36 are subject to the electrolyte (sea water), the resistance 63 is of such value so that the average potential of the hull is approximately 890 millivolts with reference to a half-cell formed of silver silver-chloride. The water line on the hull 33 is indicated by the line 86 when the barge is empty and at 87 when the barge is filled. It will be observed that the units 20 are disposed below the level line 36, and therefore the anode 36 is always submerged in water. Inasmuch as the sides of the barge 33 may be accidentally brought in contact with dock walls or the like, and inasmuch as the bottom of the hull is apt to scrape the bed of the sea, the units 20 are placed in a side wall 31 and are within the hull. In this manner they cannot be damaged. To renew the anodic or sacrificial material, it is necessary only to remove the nut 56 and the washer 57; then the sleeve 38 and what remains of the sacrificial material 36 can be removed and a new anode substituted. The washer 57 and the nut 56 are then placed in position to fix the anode within the bell 25. In such embodiment as that shown in Figs. 3 and 4, it of course would be necessary to remove the entire unit from, for example, the condenser 72, if the new anode cannot be inserted in position while the unit 20 is in position.

While the forms of embodiment herein shown and described constitute preferred forms, it is to be understood that other forms may be adopted falling within the scope of the claims that follow.

I claim:

1. In combination, with a metallic element to be protected against galvanic dissolution; an anode of sacrificial material having a passage extending therethrough; means forming a bell connected with said element, said bell having a base and connected skirt, a metallic conductor mem ber attached to the base and extending into the skirt, said anode being removably and fixedly carried within the bell by said member with the member extending into the passage of the anode and metallically connected with the anode; means insulating the anode and bell directly from one another; and a conductor connected to the member and to the element.

2. A combination as defined in claim 1, characterized in that a portion of the member extends through the base and the conductor is connected with the extended portion of the member; and further characterized in that a sleeve surrounds the extended portion and is filled with a solid insulating material embedding the extended portion.

,3. A combination as defined in claim 1, characterized in that a portion of the member extends through the base and the conductor is connected with the extended portion of the member; and further characterized in that the conductor includes a resistance connected with the extended portions of the member, a sleeve surrounds the extended portion and is filled with a solid insulating material embedding the resistance and the extended portion.

4. In an anode mounting assembly for cathodically protecting a metal structure, a substantially cylindrical metal member having one open end, a substantially cylindrical sacrificial anode recessed within said member, metallic means releasably securing said anode to said member, insulating means serving to insulate the metallic means from the metal member, further insulating means disposed within the member and serving to insulate the member from the anode, a resistance element connected to the metallic means, and a conductor having one end connected to the resistance element, the other end of the conductor being adapted to be connected to the metallic structure.

5. In an anode mounting assembly for cathodically protecting a metal hull immersed in water, a metal mounting member having an open end, the opening in the metal mounting member being adapted to be cooperatively aligned with an opening in the hull, and adapted to be secured to the hull below the water level line so that water can pass through the opening in the hull into the mounting member, a sacrificial anode recessed within the mounting member, a metallic rod mounted in the mounting member and serving to support and retain the anode within the mounting member, insulating means serving to insulate the metallic rod from the mounting member, further means mounted within the mounting member for insulating the anode from the mounting member and conductor means having one end connected to the metallic rod, the other end of the conductor being adapted to be connected with the metal hull.

6. In the combination of an anode mounting assembly with a metal hull immersed in water, the metal hull having an opening therein below the water line, the metal mounting member having an opening end, the opening in the metal mounting member being cooperatively aligned with the opening in the hull and secured to the hull so that the water can pass through the opening in the hull into the mounting member,'a sacrificial anode recessed within the mounting member, a metallic rod mounted in the mounting member and serving to support and retain the anode in the mounting member, insulating means serving to insulate the metallic rod from the mounting member, means mounted within the member for insulating the anode from the mounting member, and conductor means having one end connected to the metallic rod and having the other end connected'with the huli.

7. In an anode mounting assembly for cathodically protecting a metal structure, a substantially cylindrical metal member having one open end, a substantially cylindrical sacrificial anode recessed within said member, metallic members releasably securing said anode to said member, insulating means disposed within the member and serving to insulate the member from the anode, the

, resistance element connected to the metallic means, said resistance element being embedded in a plastic-like body protecting a metal hull immersed in water, a metal mountingmember having an open end, the opening in the metal mounting member being adapted to be cooperative- Jy aligned with an opening in the hull, and adapted to be secured to the hull below the water line so that water can pass through the opening in the hull into the mounting member, a sacrificial anode recessed within the mounting member, a metallic rod mounted to the mounting member and serving to support and retain the anode in the mounting member, means mounted within the mounting member for insulating the anode from the mounting member, conductor means connected to the metallic rod, said conductor means including a fixed resistance, and a plastic-like body enclosing and supporting the resistance, said plastic like body being mounted on the mounting member.

9. In the combination of an anode mounting assembly with a metal hull immersed in water, the metal hull having an opening therein below the water line, a metal mounting member having an open end, the opening in the metal mounting member being cooperatively aligned with the opening in the hull and secured to the hull so 6 that the water can pass through the opening in the hull into the mounting member, a sacrificial anode recessed within the mounting member, a metallic rod mounted in the mounting member and serving to support and retain the anode within the mounting member, means mounted within the member for insulating the anode from the mounting member, conductor means connected to the metallic rod, said conductor means including a fixed resistance together with a plastic-like body enclosing and supporting the resistance, said plastic-like body being mounted on the mounting member.

References Cited in the file of this patent UNITED STATES PATENTS