US3603956A

US3603956A - Cathodic protection monitor

Info

Publication number: US3603956A
Application number: US837200A
Authority: US
Inventors: Darrel D Byerley; Robert B Fisher
Original assignee: TINKER AND RASOR
Current assignee: TINKER AND RASOR
Priority date: 1969-06-27
Filing date: 1969-06-27
Publication date: 1971-09-07
Anticipated expiration: 1988-09-07

Abstract

A device for attaching to piping systems or the like having a cathodic protection potential applied thereto and comprising a visual indicator operated by such potential for producing an alarm indication at an adjustable lower level of applied cathodic protection potential.

Description

United States Patent Inventors Darrel I). Byerley Baldwin Park;

Robert B. Fisher, El Monte, both of, Calif. 837,200

June 27, I969 Sept. 7, 1971 Tinker and Rasor San Gabriel, Calif.

Appl. No. Filed Patented Assignee CATHODIC PROTECTION MONITOR 6 Claims, 9 Drawing Figs.

US. Cl 340/249, 324/71 C Int. Cl G08b 21/00 Field of Search 204/147, 196; 340/249, 248; 324/65 C, 65 CR, 65 CP, 71 C, 115, 29.5, 30, 133; 307/95 [56] References Cited UNITED STATES PATENTS 1,807,903 6/1931 Finley 307/95 2,086,737 7/1937 Pearson.... 324/71 C 3,266,027 8/1966 Nichols 340/248 3,284,789 1 1/1966 Fisher 340/249 Primary Examiner-John W. Caldwell Assistant ExaminerDaniel Myer Attorney-Gregg & Hendricson ABSTRACT: A device for attaching to piping systems or the like having a cathodic protection potential applied thereto and comprising a visual indicator operated by such potential for producing an alarm indication at an adjustable lower level of applied cathodic protection potential.

CATHODIC PROTECTION MONITOR BACKGROUND OF INVENTION It has long been realized that metallic elements of dissimilar metals which may, for example, be buried in the ground are subject to disassociation. More particularly, chemical reactions between dissimilar metals take place in which a current flows therebetween so as to establish a flow of charged ions and electrons therebetween. Metals of different reactivity which are in contact with an electrically conductive path establish a potential difference, wherein one of such metals becomes an anode and the other the cathode, so that electrons fiow to the anode and ions flow from the anode to the cathode. In this circumstance, the anode loses metal, so as to become corroded. However, the other metal comprising the cathode, suffers no harmful effects.

Because of the general circumstances outlined in the preceding paragraph it has become common practice to establish a cathodic protection system, whereby metals otherwise subject to corrosion from electrolysis are maintained at a relatively negative potential so as to form the cathode of any electrolysis system, and thus suffer no corrosion or deterioration.

One of the problems in cathodic protection systems is the monitoring of the protection potential applied to such systems. While it may initially seem that the mere application of an appropriate DC potential to pipes, cables, or the like, of a system would prevent occurrence of the electrolysis problem, it has been found necessary to monitor the existence of this potential. While many piping systems may be protected by cathodic protection equipment, at least certain types of systems are critically protected. Thus, for example, gas piping or other piping systems wherein highly volatile or explosive materials are carried by the piping system must not only be protected against corrosion produced by electrolysis, but furthermore, must be periodically or even continuously checked to insure that no possible leak therein could ensue from electrolytic disassociation of metals. There have, in fact, been established by various governmental bodies requirements for monitoring cathodic protection to preclude failure of electrolysis protection systems of particular types of piping systems.

A straightforward approach to the determination of the maintenance of cathodic protection potential in any type of system is the periodic measurement of voltage and polarity thereof existing between the system and the earth. Despite the fact that such an approach is quite straightforward, it is inherently dangerous to the extent that checking is only periodic and, furthermore, requires the use of particular instrumentation and capabilities of those skilled in the art of employing and properly interpreting scientific instrumentation. A system or detector for overcoming this basic difficulty is set forth in US. Pat. No. 3,284,789, entitled Cathodic Protection System Detector and assigned to the same assignee as the present application. The detector of the above-noted patent provides a major advance in the field of cathodic protection monitoring. However, it has been determined that even this esiinple protector of the patent is beyond the comprehension or at least full understanding of those wholly unskilled in the art. The field of electricity or electronics may be wholly foreign to those assigned the responsibility of operating or maintaining various types of piping systems such as, for example, natural gas piping systems. The mere reading of a meter may, in fact, require interpretative abilities beyond the capabilities of personnel involved at a purely local level, wherein systems under cathodic protection are involved.

The present invention is particularly directed to the simplification of cathodic protection monitoring or electrolysis protection monitoring, such that regardless of the skill of the one viewing the monitoring device or system there can be no question as to whether or not cathodic protection is actually being provided to the system.

SUMMARY OF lNVENTlQN There is provided by the present invention an cxtrcmcly simplified version of a cathodic protection system in which any person responsible for checking the system will be immediately apprised of the failure of cathodic protection thereof. In actuality, the present invention is a simplification of the invention covered by the above-noted patent. This simplification has been made primarily for the purpose of electrolysis protection monitoring, so that wholly untrained personnel will be immediately apprised of cathodic protection failure without the necessity of such personnel reading or interpreting any type of meters or the like. Furthermore, the present invention is particularly directed to the minimization of maintenance problems in the monitoring of electrolysis prevention systems.

While the various fields of engineering are undoubtedly interrelated in many respects, it is a commonly acknowledged fact that those employed in particular fields of engineering may be wholly untrained, insofar as the basic field of engineering is concerned, and thus the equipment provided for their utilization must be designed for unambiguous interpretation. While it may be considered, for example, that mechanical engineers designing and installing a natural gas system will be sufficiently cognizant of the principles of electrical engineering that they can properly interpret electrical meters, or devices, it should not be postulated that those ultimately charged with the responsibility of maintaining such a natural gas system will be equally qualified. Thus, we are here posed with the problem of an electrical or electronic phenomenon of basic importance in the field of mechanics or structural engineering.

By the simplification of electrolysis protection monitoring, the present invention provides for a truly practical advance in the art, whereby substantially untrained personnel in the field of electricity will have no hesitation or uncertainty in the interpretation of test results provided to them, so far as action that should be taken thereon.

The present invention comprises a very simplified and straightforward indicating device producing an unequivocable go or no go indication of cathodic protection of any type of metallic system possibly subject to electrolysis. More specifically, the invention provides a small metal housing adapted to be physically mounted upon a pipe, cable, or the like, of a metallic system and having a wire extending therefrom for electrical connection to another portion of the system which is electrically insulated from the portion engaged by the housing. There is provided at the housing a flag indicator which exhibits at a face thereof either a white or a colored indication in response to the voltage applied to the indicator, so that one viewing the, housing will immediately be apprised of the presence or absence of requisite cathodic protection. There is furthermore provided by the present invention simplified means for establishing the appropriate range of voltage covered by the flag indicator thereof. This is herein provided by a terminal board located immediately beneath a removable cover of the above-noted housing and having a jumper connector thereon extending from a first terminal of a tapped resistor into connection with any desired other terminal thereof, in order to cut out the desired amount of resistance in series with the flag indicator of the invention. All of the operative elements of the present invention disposed within the housing thereof are potted by the provision of a plastic solidified in place therein and retaining and supporting the above-noted terminal board in position immediately beneath the removable cover plate of the housing.

Further to the present invention, it is noted that in addition to the above-noted patent of the common assignee hereof, there have been developed certain advances in the general field of underground piping protection, such as that set forth in US. Pat. No. 1,807,903 which, however, is particularly directed to the discharging of potential from an insulated pipe. Such patent is only identified herein to positively identify the basic differences between the concepts thereof and thoseof the present invention. The present invention is directed to monitoring of the maintenance of a cathodic protection potential, while the basic idea and concepts of the abovenoted patent are the discharge of electrical charges that may be established between an insulated pipe and an electrical conductor. It is believed important to emphasize that the present invention is particularly directed to a simplification of cathodic protection monitoring which is applicable to electrically conducting systems in which cathodic protection is applied, and which require a monitoring of the existence of such potential. The mechanical and electrical details of the present invention have been simplified to a material extent, so as to provide for installation of the present invention by untrained personnel and the reading of the indication produced by this invention by untrained personnel. This, then, removes the necessity of personal monitoring or reading of meters by those versed in the field of electricity, and truly extends the field of cathodic protection systems to all possible applications regardless of the types of people involved in the installation, maintenance and interpretation thereof.

DESCRIPTION OF FIGURES The present invention is illustrated as to particular preferred embodiments thereof in the accompanying drawings wherein:

FIG. 1 is a side elevational view of a preferred embodiment of the present invention with a portion of the housing broken away to illustrate an internal connection;

FIG. 2 is an end elevational view of the embodiment of FIG.

FIG. 3 is a bottom plan view of the invention as illustrated in FIGS. 1 and 2;

FIG. 4. is a sectional view, taken in the plane 44 of FIG. 2;

FIG. 5 is a top plan view of the embodiment of the invention illustrated in FIG. 1 with the cover removed, as indicated by the plane 5-5 of FIG. 2;

FIG. 6 is a circuit diagram of an embodiment of the present invention;

FIG. 7 is a schematic illustration of a monitor in accordance with the present invention mounted upon a piping system for use in monitoring cathodic protection potential;

FIG. 8 is a circuit diagram of an embodiment of the present invention employing a semaphore indicator; and

FIG. 9 is an illustration of an alternative indicator face that may be employed in the monitor of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to FIGS. 1 to 4 of the drawings, there will be seen to be provided a metal housing 11 having a removable cover 12 which may be secured to the housing by means of bolts 13 extending through the cover and threaded into the top of the housing. The housing 11 is formed with an internal chamber 16 and the front of the housing is formed with a hollow cylindrical extension therefrom, within which is fitted a flag indicator 17. This indicator may comprise a conventional voltage indicating unit having, for example, a pair of openings 18 in the front face thereof with a flag, or the like, moved into registry with these openings by the application of a minimal potential to the indicator. Removal of such voltage or lowering of same below this minimum causes the flag to move out of registry with the openings so as to expose a colored background, preferably red. The indicator face thus comprises some type of opaque mask with at least one opening therethrough and adapted to provide a different color indication at such opening for different voltages applied to the indicator.

The housing 11 is also formed with mounting means for ready attachment of the housing to a metallic pipe, cable, or the like. Such mounting means may comprise a pair of lugs or

feet

21 and 22 extending laterally from opposite sides of the housing at the bottom thereof and having openings therethrough for the extension of bolts to engage a clamp.

These mounting

feet

21 and 22 may be formed integrally with the housing in extension below same as well as laterally thereof, and a stepped indentation is provided between the feet underneath the housing, as shown at 23 in FIG. 1. Thus, the underside of the housing at the laterally projecting feet forms one-half of a pipe clamp for ready attachment of the housing directly to a pipe. Naturally, alternative connections may be made in the instance wherein the pipe has such a large diameter that the clamping portion of the housing is not adequate to properly fit thereon.

The indicator 17 extends into the housing chamber 16 and is there provided with at least two

terminals

26 and 27. The indicator is adapted to have a cathodic protection potential applied across these terminals. To this end, a conductor 28 is shown to be electrically connected to the housing itself, which thus forms one electrical connection to a piping system to be monitored for the presence of cathodic protection potential.

With regard to the other electrical connection of the monitor, reference is made to FIGS. 5 and 6, where there will be seen to be illustrated resistance means 31 connected in series with the indicator 17 from the terminal 26 thereof to a conductor 32. This resistance means may, for example, comprise a plurality of small resistors connected in series and having connecting taps extending from the junction of each pair of resisters. The circuit also includes a jumper conductor 33 connected to the conductor 32 at the outer end of the resistance means from the indicator and having connection means 34 thereon for connection to any one of the taps of the resistance means. This jumper conductor 33 thus provides for controllably establishing the amount of resistance in series with the indicator between the connecting

conductors

32 and 28.

Considering the physical embodiment of the wiring system, reference is made to FIGS. 4 and 5, wherein it will be seen that there is provided herein an insulating terminal board 41 fitted into the housing chamber 16 at the top thereof and having a plurality of terminals extending upwardly therefrom. These terminals, numbered 42 to 49, comprise the taps of the resistance means 31, and thus these same numbers are employed in FIG. 6. The terminals 42 to 49 may be physically formed as threaded elements extending upwardly from the terminal board 41, with the jumper connector 33 permanently attached at one end to the terminal 42. The other end of the jumper connector 33 may be formed as an apertured metal connector adapted to fit upon any one of the terminals so that a small nut may be threaded onto the terminal above the connector to firmly engage the jumper conductor end with the terminal. The resistance means 31 may be comprised as a plurality of small resistors having the ends thereof soldered to separate tabs depending from the terminals of the terminal board beneath the latter. The conductor 32 extending from the end terminal 42 extends in insulated relationship through the bottom of the housing, as shown in FIG. 1. This conductor 32 may, for example, be jointed at a connector to a larger conductor within the housing, as illustrated, but electrically this conductor extends from the housing for electrical connection to a clamp 51 or electrical connector employed in the manner described below.

Further, with regard to the present invention, it is preferable to provide a ripple filter in electrical connection across the indicator 17 and this is shown in FIG. 6 to be accomplished by the connection of a capacitor 19 across the indicator. Such capacitor 19 is illustrated as to physical embodiment in FIG. 4, wherein it will be seen to have the ends thereof electrically connected to the

indicator terminals

26 and 27, and to be disposed within the housing beneath the terminal board. In order to provide a firm support for the terminal board 41 and also to protect the elements and connections within the housing, the entire chamber beneath the terminal board is filled with a potting material, i.e., an electrically insulating plastic which hardens in place. This is illustrated in FIG. 4 by conventional crosshatching. Upon hardening of this material, each of the elements, conductors, and the like, within the housing are fixed in position so that the possibilityof displacement of same or breaking of connections during usage of the monitor are substantially precluded.

Considering now an application of the present invention, reference is made to FIG. 7. There is shown in FIG. 7 a piping system 61 which may have a portion thereof extending into the ground, as illustrated at 62. The piping system is formed of electrically conducting material and in order to prevent electrolysis is supplied with a cathodic protection potential schematically illustrated in FIG. 7 as a battery 63. It will be seen that potential applied to the system is such as to maintain the portion thereof in contact with the earth at a negative potential, so as to prevent any portion of the system from becoming an anode in an electrolytic system. Such a cathodic protection system is conventional and is, in fact, required for many types of installations. In such systems there is normally employed an insulated coupling shown in FIG. 7 at 64, to prevent the application of the protection potential to portions of the system that may be subject to human contact. It is assumed in cathodic protection systems that some return path to ground is provided as, for example, through burners of a natural gas range, or the like, and thus the monitor of the present invention is connected across the insulating coupling 64 of the system. The cathodic protection potential will appear across this insulating coupling, and the monitor of the present invention is provided for the purpose of continuously indicating the presence of requisite cathodic protection potential. As shown in FIG. 7, the housing 11 may be physically mounted upon a pipe 66 of the system on the ground side of the insulating coupling 64 in the system. This is shown to be accomplished by provision of another side of a pipe clamp 67, fitting on the opposite side of a pipe from the housing 11 and attached thereto by bolts 68 extending through the housing feet and engaging the lower clamp half 67. This, then, provides for physical mounting of the housing and also for electrical connection of the housing to the pipe 66, particularly at the stepped indentation 23 at the bottom of the housing.

The insulated electrical conductor 32 extending from the housing is electrically connected to a portion of the piping system on the opposite side of the insulating coupling 64 from the housing. This may be accomplished by a clamp 51 bolted or otherwise affixed to a pipe 69 of the system, such as shown in FIG. 7.

Considering now the operation of the present invention, it is first noted that the monitor is physically mounted upon the piping system in the manner described above. With the cathodic protection potential applied to the system the cover of the housing 11 is then removed and the jumper connector 33 attached to the lowest numbered terminal which will produce a voltage indication on the indicator 17. This will then place the greatest amount of resistance in series with the indicator that is possible to employ with the particular cathodic protection potential applied, and yet produce a showing by the indicator of the existenceof cathodic protection potential. With the jumper connector 33 firmly connected to the appropriate terminal 43 to 49, the cover is then returned to the housing and secured thereon. In this condition, with the indicator 17 of FIG. 2, there will normally be shown a white background through the openings 18 in the face of the indicator. At any time that the cathodic protection potential decreases to the point where the indicator 17 is no longer actuated sufficiently to maintain a white flag, or the like, behind the openings 18 in the face of the indicator, such flag or flags will move away from the openings 18 to reveal a colored background, such as red. Thus, the present invention provides for continuous monitoring of the existence of appropriate cathodic protection potential to metallic systems and reading and understanding of the monitor can be accomplished by anyone, no matter how unskilled. At any time the indicator shows a red color through the openings in the face thereof, investigation should be made to determine the cause of difficulty which has produced the reduction in cathodic protection potential on the system. Although it may be necessary in the investigation and correction of difficulties to employ trained personnel, it is certainly not necessary with the present invention to require any type of specialized training to read the monitor hereof. Even though one checking the system may be wholly uninformed about the problems of cathodic protection, they will be immediately apprised of some type of difficulty in the system by noting the red color appearing in the face of the indicator. There is thus established by the present invention a go-no go indication, wherein no meter readings are required and no external indicating or detecting equipment is employed. The monitor of the present invention is adapted for substantially permanent attachment to piping or cable systems requiring cathodic protection.

It is to be appreciated that numerous variations in the present invention are possible, and thus, for example, as illustrated in FIG. 8, a semaphore-type indicator 71 may be employed in place of the flag indicator described above. The circuitry in this circumstance would remain the same. Similarly, it is possible for the indicator to be alternatively comprised even to the extent of having a meter face. It is, however, provided in accordance with the present invention, that a go-no go" indication shall be provided by the invention. Thus, in FIG. 9 there is illustrated the face 81 of an indicator 82 connected as described above, and having a needle or arm 83 movable thereacross, in accordance with many types of meters. In order to preclude the necessity of meter reading, the present invention provides a mask 84 across a portion of the meter face, so that the needle 83 only becomes visible when it moves beyond the mask. The left of the face in FIG. 8 may be considered the mask aperture, and the needle 83 may be brightly colored so that its presence at the left of the face would be immediately apparent to one viewing the indicator.

Again, it is noted that simplification of cathodic protection monitoring is a major aim in the present invention. Variations of the invention from the specifically described and illustrated details are, of course, possible. Reference is made to the appended claims for a precise definition of the invention.

We claim:

1. An electrolysis protection monitor for use with a metallic system having a cathodic protection potential applied thereto comprising:

a housing having a removable cover,

a flag voltage indicator mounted in a wall of said housing with a face open to the exterior of the housing and terminals within the housing,

electrical resistance means having a plurality of taps thereon connected at a first end to a first indicator terminal,

means mounting said resistance means in said housing with the taps thereof adjacent said cover,

a jumper conductor connected to a second end of said resistance means and having connection means for selective connection to resistance taps to establish the effective value of resistance thereof, and

conductors extending from a second indicator terminal and from the second end of said resistance means for electrical contact with a piping system on opposite sides of an electrically insulating portion thereof.

2. The monitor of claim 1 further defined by a terminal board disposed within said housing adjacent said cover with terminals thereof facing the cover, means mounting said resistance means on the opposite side of said board from said terminals with said taps comprised by said terminals and said jumper conductor being connected to one end terminal of said board and the connection means being adapted for removable engagement with said terminals on said board.

3. The monitor of claim 1 further defined by said flag voltage indicator including a face having a mask with at least one opening therethrough and voltage-responsive movable means mounted to move into registry with said mask opening with reduction of voltage applied to the indicator.

4. The monitor of claim 1 further defined by said housing being formed of metal with extensions for attachment of the housing to a pipe or the like, and said conductors extending in place all elements within the housing.

6. The monitor of claim 1 further defined by said indicator having a meter face with an arm movable thereacross indicating voltage applied to the indicator and an opaque mask extending over a portion of said meter face whereby said indicator arm is only visible for a predetermined low voltage applied to the indicator.

Claims

1. An electrolysis protection monitor for use with a metallic system having a cathodic protection potential applied thereto comprising: a housing having a removable cover, a flag voltage indicator mounted in a wall of said housing with a face open to the exterior of the housing and terminals within the housing, electrical resistance means having a plurality of taps thereon connected at a first end to a first indicator terminal, means mounting said resistance means in said housing with the taps thereof adjacent said cover, a jumper conductor connected to a second end of said resistance means and having connection means for selective connection to resistance taps to establish the effective value of resistance thereof, and conductors extending from a second indicator terminal and from the second end of said resistance means for electrical contact with a piping system on opposite sides of an electrically insulating portion thereof.

4. The monitor of claim 1 further defined by said housing being formed of metal with extensions for attachment of the housing to a pipe or the like, and said conductors extending first from the second indicator terminal into electrical contact with the housing and second from the second end of said resistance means through the housing wall in insulated relation thereto for electrical connection to a pipe of the system at a distance from the housing.

5. The monitor of claim 2 further defined by the interior of said housing beneath said terminal board being filled with a plastic solidified in place for holding the terminal board in place adjacent said housing cover and surrounding and fixing in place all elements within the housing.