US3215613A

US3215613A - Anode assembly

Info

Publication number: US3215613A
Application number: US56263A
Authority: US
Inventors: John J Lainson
Original assignee: Western Plastics Corp
Current assignee: Western Plastics Corp
Priority date: 1960-09-15
Filing date: 1960-09-15
Publication date: 1965-11-02
Anticipated expiration: 1982-11-02

Description

Nov. 2, 1965 J. J. I AlNsoN 3,215,613

ANODE ASSEMBLY F'iled Sept. 15, 1960 3 Sheets-Sheet, 1

J. J. LAINSON Nov. 2, 1965 ANODE ASSEMBLY 5 Sheets-Sheet 2 Filed Sept. 15. 1960 F/ci daf/N J. AM/50N rrafeA/E/ Nov. 2, 1965 Filed Sept. 15. 1960 J. J. LAINSON ANODE ASSEMBLY 3 Sheets-Sheet 5 United States Patent O 3,215,613 ANODE ASSEMBLY John J. Lainson, Hastings, Nebr., assigner to Western Plastics Corporation, Hastings, Nebr., a corporation of Y Nebraska Filed Sept. 15, 1960, Ser. No. 56,263 3 Ciams. (Cl. 204-196) This invention relates to improved methods and apparatus for establishing and maintaining electrical circuit connections in corrosive and other harmful environments. The various structural features and method steps of this invention lare particularly adapted for use in cathodic protection systems for reducing corrosive deterioration in underground and underwater metallic structures.

Corrosion of natural gas pipelines, for example, results in substantial industrial losses each year. Accordingly, natural gas transmission systems are engineered before installation with a view toward improving operational reliability by minimizing the rate of corrosion due to moisture, soil chemicals and electrolytic current.

Corrosion of metals in soil or water is principally an electro-chemical process. The corrosion or metal loss is directly related to the direct current discharged from the metal surface at a metal/electrolyte junction. Potential differences exist or develop on the metal/ electrolyte junction surface of most structural metals when they are immersed in an electrolyte such as soil or water. These potential diiferences produce a battery action and current flow results.

Corrosion takes place where the metallic ions are discharged from the metallic surface at the metal/ electrolyte junction. This junction of ionic discharge is called an anodic area. In conjunction with this action, ions from the electrolyte are accepted or transformed at adjacent or remote metallic surfaces that are less electronegative. The latter junction is called a cathodic area.

The anodic areas of the steel pipe used in an underground natural gas transmission system are subject to severe corrosion which must be minimized if the system is to be operated reliably and economically. Accordingly, a considerable body of art has developed in which anode electrodes are buried adjacent the pipeline to be protected. The output voltage of a direct-current power supply is applied to the anodes and the pipeline with such a polarity that anodic areas are substantially eliminated from the pipeline surfaces. This arrangement reverses the electrolytic action which would otherwise take place. The anodes, therefore, are expended in preference to expending the steel pipeline. The foregoing approach to corrosion abatement is called cathodic protection.

vExperience in the pipeline transmission industry has shown that anodes buried in deep ground beds are to be preferred to anodes placed near the earths surface. In general, the use of deep anodes permits building lowresistance ground beds in favorable conducting strata underlying high resistivity surface soils that are unsuitable for cathodic protection.

Deep anode ground beds are usually more expensive to install than shallow beds. Additionally, once the anodes are installed they are relatively inaccessible. Repair work on the anodes and their associated conductors, which are usually interconnected in strings, is at best diicult and at worse, with some ground bed designs, impossible so that abandonment of the installation is necessary.

Although many ground bed and anode string arrangements appear in the prior art, substantially all require electrical conductors to connect the anodes in a multiple circuit connection relative one another. Unfortunately, conductor wire splices must be made to join the individual anode leads to a main trunk or riser conductor. Addition- 3,2l5,6l3 Patented Nov. 2, 1965 ally, the individual anode leads, which are usually copper wire, must be connected to the dissimilar metal of the anode. The conductor splices and the anode lead connections are subject to severe corrosion due to electrolytic action. Accordingly, these points of electrical connection must be effectively isolated from the electrolytic action resulting from their being embedded in moist soil and possibly under water.

The loss in transmission line investment due to a single splice failure can be tremendous particularly in the case of a deep anode bed. In many installations the anode string is buried at a depth of several hundred feet. A splice failure in these installations cannot be repaired, and therefore the an-ode bed must be abandoned with a resulting loss of several thousands of dollars. Additionally, in the event the cathodic protection system has been disabled for a considerable period of time, corrosion will substantialy reduce the life of the pipeline.

Heretofore, substantially all conductor splices and anode connections in cathodic protection systems have been protected by insulating tapes fabricated from various materials and adhesives. Many splices and anode connections thus protected ultimately corrode due to moisture leakage through the many overlap seams of the tap layers, and also due to imperfect seals between the conductor sheath and the tape.

Accordingly, a principal object of this invention is to improve the reliability of electrical connections subject to corrosive environments, such as are found in cathodic protection systems for underground metallic structures.

Another object is to provide an improved protective sealing sleeve for an electrical conductor splice which is to be buried underground and subjected to relatively high water pressures. Another object is to provide an improved protective sleeve design having basic elements which may be used in a group of similar protective sleeves, each adapted to receive different numbers of spliced conductors.

Another object is to provide a protective cap for sealing the anode lead connection to the anode of a cathodic protection system. l

Another object is to provide a protective sealing sleeve and a protective cap as outlined in the prior objects, both of which have many interchangeable elements.

Another object is to provide an improved method and apparatus for subjecting electrical connections to inert gases which will minimize corrosion tending to destroy the connections.

A first feature of this invention is directed to a protective sleeve for hermetically sealing an electrical cable splice which m-ay be buried several hundred feet. This protective sleeve is particularly adapted for use in enclosing the necessary splices which must be made lbetween the riser conductors and the anode leads of cathodic protection installations used in natural gas transmission pipelines. In a preferred embodiment, the protective sleeve comprises an insulating tube of plastic which encloses the cable `splice to be hermetically sealed. A pair of bushings plug each yend of the bore of the tube, and a sealing ring is sandwiched between the individual bushings of each pair so that the sealing ring is maintained in compression between the bushings and the exterior insulation cover Iof a spliced con-ductor. In view of the fact that the foregoing structure may be readily assembled in eld installation Iby a simple manual operation, the protective sleeve is readily adapted for the many and varied circuit arrangements which arise in anode installations.

A `second feature of this invention relates to a protective cap for hermetically sealing the anode lead at its point of connection to lan anode employed in a cathodic protection system. A preferred embodiment comprises a cap which is seated upon the terminal end of the anode to which the anode lead is connected Inasmuch as the connection joint to the anode lead involves dissimilar metals, for example, -copper to magnesium, this connection is readily subject to breaking due to corrosion. The anode lead is therefore sealed to the cap by use of the same lbushing arrangement previously employed in the protective sleeve for cable splices. Additionally, an anode bushing forcibly compresses a sealing ring against the anode surf-ace so as to contain the anode lead connection within a hermetically sealed cavity. In view of the fact that the protective sleeve and the protective anode cap of this invention contain identical bushing parts, field installation is greatly facilitated without the necessity of maintaining a large number of different parts.

While the foregoing protective sleeve and cap are admirably suited to accomplish their intended functions in the usual installation, a third feature of this invention further insures the reliability of a cathodic protective system. This feature employs interstices between the individual strands of the cables employed in the riser conductors and anode leads to transmit an inert gas to all splices and anode lead connections. The use of stranded cables, hermeti-cally sealed protective sleeves to enclose all splices, and hermetically `sealed anode caps to enclose all anode lead connections provides a gas passage for subjecting all of the electrical conductors and connections to an atmosphere of inert gas. The presence of this gas tends to substantially eliminate all moisture and other corrosive elements from making contact with circuit wires, splices, Iand connection joints. It is to be noted, however, that the protective sleeve and the protective cap of this invention may be advantageously employed without recourse to the inert gas feature. It is only injthose installations in which extreme Water conditions prevail and in which a long life is absolutely necessary, that the use of an inert gas as above described is recommended.

In order that all of the structural features for attaining the objects of this invention may be understood, reference is herein made to the following drawings wherein:

FIGURE 1 is a simplified diagram of a deep anode installation incorporating the protective sleeve, protective cap, and inert gas features of this invention in a cathodic protection system for a natural gas transmission pipeline;

FIGURE 2 is a sectional view of the protective sleeve of this invention adapted for hermetically sealing a straight splice;

FIGURE 3 is a sectional view of a modification of the protective Vsleeve shown in FIGURE 2, which is adapted for hermetically sealing a multiple conductor splice;

FIGURE 4 is an end view of the lstructure shown in FIGURE 3;

FIGURE 5 is an enlarged sectional view showing the manner in which the bushings employed in the protective sleeves of FIGURES 2 and 3, and the protective cap of FIGURE 7, compress a sealing ring to establish a conductor seal;

FIGURE 6 is an enlarged sectional View showing the annular sealing ring groove of a lsealing ring bushing;

FIGURE 7 is a sectional View of a protective cap associated with an anode rod to hermetically seal the anode lead connection joint;

FIGURE 8 is a side view of a cable employing a plurality of wire strands;

FIGURE 9 is an end view showing the interstices between wire strands; and

yFIGURE 10 is a View of an inert gas coupling for connecting a source of pressurized gas to electrical riser conductors employing stranded cables.

Referring now to the cathodic protection system shown in FIGURE l, deep anode installation 10 is located in the right-of-way for gas transmission pipeline 11. Inasmuch as pipeline 11 is fabricated of steel and is also located underground, it is subject to electrolytic corrosion. The ground bed for installation 1t) is prepared by drilling a hole 12 by conventional means, such as a rotary rig. Hole 12 is held open with drilling mud until the two

anode strings

13 and 14 are lowered into hole 12.

Anode string 13 comprises individual anodes 13a 13b, 13C' 13d and 13e. Anode string 14 comprises individual anodes 14a, 14b, 14C, 14d and 14e. The -anodes are usually fabricated of such materials as magnesium, graphite or silicon. The anodes of each string are electrically connected in multiple. Main trunk or riser conductor 15, together with anode leads 16, connect anodes 13a through 13e in multiple; and main trunk or riser conductor 1'7, together with anode leads 18, connect anodes 14a through 14e in multiple. Both riser conductor 15, together with anode leads 16, connect anodes single pieces without splices. The conductors have an outer insulation cover which must have adequate mechanical properties to withstand the rigors of direct burial for the expected life of the installation. Stranded cable having a plurality of wire strands Z0 (FIGURES 8 andV 9) is also better able to meet the foregoing requirements than cables employing a single solid wire. Inasmuch as the strands 20 are subject to electrolytic corrosion, the cover must provide inherent moisture resistance of a high order so as to hermetically seal the wire strands 20 from the external enviroment. A preferred cover comprises an inner insulation layer 21 of polyethylene, and an outer sheath 19 of polyvinyl chloride.

A cable having a metallic sheath over the insulation, such as lead, protected by layers of jute, galvanized steel tapes, jute and asphaltic type material offers the maximum assurance that circuit difficulties will not develop through either mechanical damage, moisture, or chemical diffusion. It is, however, a costly construction and cannot be justied in cathodic protection systems for that reason.

Rubber-neoprene insulations or to a greater extent polyvinyl chloride resin have found use chiey because of the lower cost. Constructions of this sort have given reasonable service, however certain limitations to their use have lead to the developement of a cable having definite advantages for most applications.

A combination of polyethylene and polyvinyl chloride resin is now employed for this service. Polyethylene stands unchallenged as the best insulation in wet locations. The polyvinyl chloride sheath or protective jacket over the polyethylene affords a barrier to injury of the insulation due to mechanical damage and other factors encountered.

The anode leads 16 and 18 are also preferably of the same cable construction as

riser conductors

15 and 17. The anode leads 16 and 18 must necessarily be spliced to

riser conductors

15 and 17. Additionally, the anode leads must be connected to their associated anodes. The splicers and the anode connections are particularly subject to harmful environmental conditions inasmuch as there must be a break in the insulation cover in the connection areas. Accordingly, the cable splices are located within :and sealed by

protective sleeves

25 and 26. Like- Wise, the anode connections are located within and sealed by protective caps 27. The construction details for protective sleeves 25 and 26 (FIGURES 2 and 3), and protective caps 27 (FIGURE 7) are set fourth hereinafter.

In view of the fact that hole 12 for installation 10 is of the order of three hundred to tive hundred feet deep, the necessary electrical connections, including preparation of splices and installation of the protective sleeves and caps must be made at ground level as a field installation. The

anodes

13 and 14 are rigidly clamped to pipe section 28 by clamps 29. The clamped anodes thus are incapable of exerting excessive pulling on the

riser conductors

15 and 17 and the anode leads 16 as the anode strings 13 and 14 are lowered into hole 12. One or more additional pipe sections 30 are coupled to pipe section 28 by means of coupling such as 31, so that the interconnected anode strings may be carefully lowered into hole 12. Centering vane 32 appropriately guides pipe section 28 so that the anodes and the associated electrical system do not scrape the inside wall of hole 12. Hole 12 is ultimately back lled with mud. Various other steps, not essential to an understanding of the present invention may also be taken, in the preparation of the anode bed, in order to insure proper conduction between the anodes and the earth strata in which they are buried.

Riser conductors

15 and 17 are spliced together within inert gas coupling 35 (FIGURE l0). Cable 36 having a single solid wire core 37 is also connected to the joint formed by splicing

riser conductors

15 and 17. The terminal end of conductor 36 removed from inert gas coupling 35 is connected to the positive output terminal of a direct-current power supply 38. The negative output terminal of power supply 38 is connected directly to gas pipeline 11 through stranded cable conductor 40. The input terminals of power supply 38 are connected to alternating-

current line conductors

41 and 42. Corrosion of pipeline 11 is substantially eliminated by the foregoing cathodic protection circuit. The exposed surfaces of pipeline 11 are converted into cathodic areas. The surface of

anodes

13 and 14 define anodic areas which are subject to deterioration resulting from electrolytic action. The sacrice of anode metal, however, preserves the steel pipeline 11.

Protective sleeves

25 and 26, and protective caps 27 in many anode beds are buried several hundred feet deep and are subject to water pressures of several hundred pounds per square inch. This environment may lead to breakdown in the hermetic seals of

sleeves

25 and 26, and caps 27. Additionally, the hermetic seal of the insulation coverings of

cable conductors

15, 16, 17 and 18 may also be destroyed causing an open circuit due to corrosion of the conductor wires. It has been discovered that the life and the reliability of anode bed installations may be greatly improved by subjecting all underground wires, splices, and anode lead joints to an inert gas having a pressure at least equal to the environmental pressures to which the exposed ksurfaces of the insulation coverings, protective sleeves and protective caps are subjected. The interstices 45 (FIGURE 9) between wire strands 20 are capable of delivering an inert gas having the required pressure a distance of several thousand feet. Accordingly,

cables

15, 16, 17 and 18 serve a dual function of establishing the necessary circuit connections and to convey inert gas for safeguarding these circuit connections.

Although nitrogen is the most commonly used gas for protecting electrical circuits, a required supply of nitrogen cannot always be maintained .at a remote anode installation for natural gas pipelines. The novel c'athodic protection system of FIGURE l employs natural gas as the required gaseous medium. The inlet of compressor 46 is connected to pipeline 11 by metallic pipe 47. The outlet of compressor 46 is connected to inert gas coupling 35 by metallic pipes 48 and 49 through pressure regulator 50.

Inert gas coupling 35 comprises a cylindrical tube section 51 having internally threaded ends to which end caps 52 and 53 are coupled by means of their mating threads. End cap 52 is formed with two access openings (not shown) which are plugged by'mated bushing pairs 55 and 56. Bushing pairs 55 and 56

seal riser conductors

15 and 17, respectively. End cap 53 is also formed with two access openings. Bushing pair 57 plugs one of these access openings and pipe 49 is coupled to the other. Bushing pair 57 seals positive conductor 36. The detailed structure of bushing pairs 55, 56 and 57 is shown in FIGURES :and 6 to be described hereinafter.

Inert gas coupling 35 denes a hermetically sealed cavity 60 having a gas inlet at the opening of pipe 49.

Gas is released from the coupling only through the interstices 45 (FIGURE 9) appearing between the wire strands of

riser conductors

15 and 17. In view of the fact that conductor 36 has only a single conductor hermetically sealed to its outer covering, gas is not transmitted through bushing pair 57.

Tube section 51 and

end caps

52 and 53 are preferably fabricated of a plastic having a high burst pressure, such as Teon. In the event coupling 35 is to be subjected to the relatively high gas pressures required for deep anode installations,

parts

51, 52 and 53 should be constructed of a metal, such as stainless steel.

Bushing pairs 55, 56 and 57 are preferably fabricated from a plastic, such as Kralastic, although these parts can be fabricated from stainless steel if pressure requirements so dictate. Each fbushing pair comprises an end plug bushing 60 (FIGURE 5) and a sealing ring bushing 61. The llower shank portion of end plug bushing 60 is formed with a standard pipe thread 62 which is coupled to an internal mating thread lining the bores of the laccess openings (not shown) formed in

end caps

52 and 53. The upper portion of end plug bushing 60 is formed with an internally threaded counterbore which receives the lower threaded shank portion 63 of seal-ing ring bushing 61. An annular sealing ring groove 64 (FIGURE 6) is defined lby projecting lip 65. This groove houses sealing ring 66, which may be a neoprene Oring.

Bushings

61 and 60 are formed with aligned conductor feedthrough lholes through which the sealed conductors pass.

Sealing ring bushing 61 has a wrench head 67 of square cross-section (FIGURE 4). The application of a wrench turning force to this head compresses sealing ring 66 between its adjacent bushing surfaces causing the sealing ring to project into the conductor passageway formed by the bushing feed-through holes, thereby to lit closely around and to establish a hermetic seal with the insulation covering of the bushing contained conductor.

The protect-ive sleeve 26 shown in FIGURE 2 is adapted to hermetically seal the straight splice joining riser conductor 15 to anode lead 16 for anode 13e, and also the straight splice joining riser conductor 17 to anode lead 18 for anode 14e. Protective sleeve 26 comprises a cylindrical tube 70 having internally threaded ends. A threaded end cap 71 closes the upper opening of the bore for tube 70, andra threaded end cap 72 closes the lower opening of the bore for tube 70. Each of the end caps is formed with a threaded access opening for receiving a bushing pair 60-61 as shown in FIGURE 5. A sealing ring, corresponding sealing ring 66 of FIGURE 5, forms a seal with each associated conductor, thereby hermetically sealing the contained splice. The flanges of end caps 71 and 72 are formed with holes 75 for receiving the round pins of a spanner wrench used to tighten the caps The protective sleeve 25 shown in FIGURES 3 and 4 is a modication of the sleeve shown in FIGURE 2 which is adapted to hermetically seal a multiconductor splice, such as the T-joint splice connecting riser conductor 15 to anode leads 16 for anodes 13a through 13d and the T-joint splice connecting riser conductor 17 to anode leads 18 for anodes 14a through 14d.

Protective sleeve 25 comprises a cylindrical tube 80 having internally threaded ends. A threaded end cap 81 closes the upper opening of the bore of tube 80, and a threaded end cap 82 closes the lower opening of the bore of tube 80. Each of the end caps is formed with two threaded access openings for receiving a bushing pair 60-61 as shown in FIGURE 5, with the exception of the right access opening of end cap 81. In view of the fact that protective sleeve 25 is to house a T-joint splice, one of the upper access openings is appropriately sealed by a threaded plug 85. A sealing ring, corresponding with sealing ring 66 of FIGURE 5, forms a seal with each conductor associated with a bushing pair 60-61.

The tubes and end caps of protective sleeves 70 and 86 may be fabricated of a plastic, such as Teflon. Although metal parts may be employed, if the conductive characteristics of metal can be tolerated.

In the preparation of a plurality of sequentially disposed T-joint splices, the main trunk conductor, such as riser conductors and 17 should preferably not be cut. Protective sleeve 25 meets this requirement, and at the same time can be installed in a simple field operation as follows.

The outer insulation covering of

riser conductor

15 or 17 is removed in two or three inch sections 88 (FIGURE 3) at every cable point 'a splice is to be made. The necessary bushing pairs 60-61 (loosely coupled relative one another so as not to force sealing ring 66 against the insulation covering and removed from their associated end caps) and the tubes 80 with tightly coupled end caps S1 and 82 'are strung on the conductor in the proper sequence required for appropriate final assembly.

A bushing pair 60-61 (loosely coupled relative one another so as not to force sealing ring 66 against the insulation covering) is strung on each anode lead 16-18, and the stripped anode lead end 86 (FIGURE 3) is passed into access opening 87 and is snaked out of access opening 89. With section 88 outside of the bore of tube 80 and below access opening 89, end 86 is spliced to section 88 as shown, and then the splice 90 is forced back within tube 80.

The bushing pairs 60-61 are then appropriately moved on their associated conductors and coupled to the

ends

81 or 82, as the case maybe. Each sealing ring bushing 61 is then tightly coupled to its associated end plug bushing so yto compress each sealing ring 66.

The protective cap 27 shown in FIGURE 7 is adapted to hermetically seal the anode lead connection 91 to anode rod 13-14. This connection joint is particularly subject to corrosion-because fof the dissimilar metals involved.

Cap 27 comprises a cup-shaped body 92 formed with an annular side Wall 93 tocollar the connected end of the anode rod 13414. The upper end of the anode rod contacts the bottom wall 94 of the cup-shaped body 92. TheV annular side wall 93 is formed with a projecting lip 95 that is internally threaded. A threaded -anode lrod bushing 96 tightly collars the anode nod 13-14 and is coupled to the projecting lip 95. housed within an annular retaining groove formed in upper lip 98 of anode rod bushing 96. Sealing ring 97 is severely compressed by tightly coupling anode rod bushing 96 relative cup-shaped body 92 by inserting spanner wrench pins in holes 75, thereby establishing a hermetic seal at its contacting area with the anode rod. Anode lead 16-18 is sealed relative cup-shaped body 94 vby bushing pair 60-61 previously described. All parts of protection cap 27 are preferably formed from plastics, such as Kralastic and Teflon.

It should be understood that the above described arrangements are merely illustrative of the principles of this invention, and that modification can be made without departing from the scope of this invention.

What is claimed is:

1. An anode assembly comprising to a rod-type anode electrode, a cup-shaped body of solid insulating material formed with an annular side wall contacting and collaring one end of the rod electrode and a bottom wall contacting and covering the collared anode end, an anode rod bushing coupled to the annular body wall and tightly collaring the anode rod, said anode rod bushing having the same internal diameter as said side wall of said body, a rod sealing ring disposed between the body and the inner end of said rod bushing and fitted around the electrode rod to establish a hermetic seal in response to compression of the ring, and a bushing pair of electrical insulation material hermetically fitted to an access opening in the bottom wall with each bushing of the pair formed with aligned conductor feed-through holes, and a conductor sealing ring disposed between the bushings A sealing ring 97 is of'the pair with the inner peripheral surface of the ring projecting into the passageway formed by the conductor feed-through holes thereby to t closely around and to seal the conductor passing therethrough in response to compression of the ring by the bushing pair.

2. A cathodic protection anode assembly comprising a rod-type anode buried in an anode ground bed, a cupshaped body of insulation material formed with an annular side wall contacting and collaring one end of the anode rod and a bottom wall contacting and covering the collared anode end, an anode rod bushing coupled to the annular body wall and tightly collaring the anode rod,

said anode rod bushing having the same internal diameterV as said side wall of said body, a rod sealing ring disposed between the body and the inner end of said rod bushing and fitted around the anode rod to establish a hermetic seal in response to compression of the ring, and a bushing pair of electrical insulation material hermetically fitted to an access opening in the bottom wall with each bushing of the pair formed with aligned anode lead feed- 4 through holes, and an anode lead sealing ring disposed soy between the bushings `of the pair with the inner peripheral surface of the ring projecting into the passageway formed by the anode lead feed-through holes thereby to lit closely around and to seal an anode lead passing therethrough in response to compression of the ring by the bushing pair.

3. A cathodic protection anode assembly comprising a rod-type anode buried in an anode ground bed, a cupshaped body of insulation material formed with an annular side wall contacting and collaring one end of the anode rod and a bottom Wall contacting and covering the collared anode end, an anode rod bushing coupled to the annular body wall and tightly collaring the anode rod, said anode rod bushing having the same internal diameter as -said side wall of said body, a rod sealing ring disposed between the body and the rod bushing and fitted around.

the anode rod to establish a hermetic seal in response to compression of the ring, and a bushing pair of electrical insulation material including an'end plug bushing and a sealing ring bushing seated within a .counterbore formed in the end plug bushing hermetically fitted to an access opening in the bottom wall with each bushing of the pair formed with aligned anode feed-through holes, and an anode lead sealing ring disposed between the bushings of the pair with the inner peripheral surface of the ring projecting into the passageway formed by the anode lead feed-through holes thereby to t closely around and to seal an anode lead passing therethrough in re-` spouse to compression of the ring by the bushing pair.

2,127,315 8/38 Thayer 204-196 2,304,210 l2/42 Scott et al 174-102 2,466,997 4/49 Morris 174-93 2,616,780 11/52 Atkinson et al. 21-2.5 2,621,228 12/52 Tompers 174-93 2,803,602 8/57 De Cowsky et al 204-196 2,926,066 2/60 Lew 21-2.5 2,926,128 '2/60 Flower 204-196 2,937,228 5/60 Robinson 174-93 2,949,417 -8/60 Preiser et al 204-196 2,958,722 11/60 Rubin et al. 174-93 2,972,004 2/61 Merrell et al. 174-93 3,013,101 12/61 Domenach 174-19 3,020,121 2/62 Bull 21-2.5 3,022,243 2/62 Anderson 204-196 3,043,765 7/62 Bryan et al. 204-196 3,058,086 10/62 Zwanzig 204-196 JOHN H. MACK, Primary Examiner.

JOHN R. SPECK, JOSEPH REBOLD, MURRAY TILLMAN, Examiners.

Claims

1. AN ANODE ASSEMBLY COMPRISING TO A ROD-TYPE ANODE ELECTRODE, A CUP-SHAPED BODY OF SOLID INSULATING MATERIAL FORMED WITH AN ANNULAR SIDE WALL CONTACTING AND COLLARING ONE END OF THE ROD ELECTRODE AND A BOTTOM WALL CONTACTING AND COVERING THE COLLARED ANODE END, AN ANODE ROD BUSHING COUPLED TO THE ANNULAR BODY WALL AND TIGHTLY COLLARING THE ANODE ROD, SAID ANODE ROD BUSHING HAVING THE SAME INTERNAL DIAMETER AS SAID SIDE WALL OF SAID BODY, A ROD SEALING RING DISPOSED BETWEEN THE BODY AND THE INNER END OF SAID ROD BUSHING AND FITTED AROUND THE ELECTRODE ROD TO ESTABLISH A HERMETIC SEAL IN RESPONSE TO