US2918389A - Protective covering for metals - Google Patents

Description

. Dec. 22, 1959 J. J. KELLEY 2,918,389

PROTECTIVE COVERING FOR METALS Filed Feb. 2, 1956 3 Sheets-$heet 1 CLAY DUST MATERIAL ASPHALT BASE SHIELD PROT E C 7' WE WRAPPING MATER/AL ROLLED FOR APPLICATION uvmvron JOHN J. KELLEY Dec. 22, 1959 J. J. KELLEY j PROTECTIVE COVERING FOR METALS 3 Sheets-Sheet 2 Fil ed Feb. 2, 1956 x25. mm 2 II 0235mm OF .EE 1 mama wwfiw O M G 1|]! wzmmmmamn w 5353325358 mm? 5.5.: $026 ATTORNEY Dec. 22,1959

Filed Feb. 2, 1956 J, 'J. KELLEY PROTECTIVE COVERING FOR METALS COOLING CHAMBER MATERIAL PREPARED WRAPPING SSheets-Sheet 3 7 INVENTOR. ao/m/ J; KELLEY United States Patent PROTECTIVE COVERING FOR METALS JolmJ. Kelley, Golden, Colo. Application February 2, 1956, Serial No. 563,171

2 Claims, c1.117 ss This invention relates to a material or composition for useon metallic structures. that are exposed to severe corrosive conditions.

After study oftheprocesses of corrosion, it has been determined that it. would be advantageous to provide in a single. wrapping. material a mechanical shield, an electrical. insulator and a chemical protector. The mechanical shield must be of sufficient physicalstrength to resist abrasion, frictional wear and soil stresses when the protective material is to be. buried underground. Further, theshield must. be resistant to the ingress of moisture and, insofar as possible, the dissolving action of crude oil or. crude. oil products that might saturate the soil.

While the mechanical shield. should be designed to resist the. physical forces that act to deteriorate the protective material, it is advantageous. to provide a second barrier of] protection that: may be embodied in the same composition or material. The second, or insulator barrier, should'he designed to prevent corrosion due tothe co-action of electrolytic cells. in the surface of the metal and electrical. currents in the structure itself or stray electric currents in the. surrounding soil. when buried underground. Accordihgly, it is desirable to incorporate. in the unitary protective material an electrical insulator having a high dielectric strength, so that a thin sheet. or layer of the material may be used to avoid destroying the flexibility or pliability of the entire material. In addition to flexibility, which is provided to avoid cracking and peeling when the material is being applied around a pipe or other curvature of small diameter in cold'weather, the electrical insulator should be of a type that is unaffected by bacteria, acids and alkalis normally present in the soil.

A third barrier of protection should be provided to avoid the effects of chemical corrosion and to act as a primingmass. For such purpose, this innermostshield should be a material having the ability to penetrate through and around an existing body. of rust or mill scale to isolate all oxidation. products from the base metal and to provide a protective. film on the base metal, which, together with inhibitors, repellsany corrosive action of the. surrounding media. This innermost shield should further he possessed of properties which will prevent the rupture. of the shield by abrasions and scratches. Accordingly, this chemical barrier should be of a non-drying type that will flow to. cover any abrasions or tiny pock marks or depressions in the metallic surface.

It is the main object of this invention to provide a material or covering which may be placed as a unit about the exterior surface of metallic objects to successfully fulfill allof the above desirable features.

Another object of this invention is to. provide these desirable. features in a wrapping tape that may beconveniently handled and that is adapted to be wrapped about metallic objects to provide multiple layer. abrasion and corrosion resistant properties.

Other objects of the present invention will be apparent from, the following detailed. description and examples of the. desirable properties of this invention,, and from the drawihgs appended hereto, in which:

Fig. 1 is a perspective view in partial section showing the component elements of the completed wrappingmaterial made in accordance with this invention,

Fig. 2. is an illustrationshowing the completed wrap-- ping material inroll form,

Fig. 3 is a schematic illustration showingsteps in.the preparation of the exterior binder shield, and

Fig. 4 is a schematic illustration showing the application of the inner priming mass to the exterior binder shield material.

Briefly stated, the present invention provides a. wrap ping material or coating that may be placed about metallicobjects to prevent corrosion due. to either. mechanical abrasion, electrolytic effects or chemicaldecompositiom. In order to attain the desired result, it. hasbeen found. advisable toprovide the desired product in a roll. wrap or bandage from which it maybe readily applied'to pipelines or other curvedsurfaces. H

To attain the desired properties, materials of different: consistency are applied to-opposite sides of a binder'material, such as a glass fibre mat, in such manner that'the exterior face of the assembled wrap will present a surface that is resistant to abrasion and that also acts as an electrolytic insulator. A priming mass made. up. primarily of a. petrolatum material is applied to the inner. face of the bandage for intimate contact with the metallic object to be preserved. in orderto decrease the moisture penetrability of the priming mass, certain additives'are mixed in the petrolatum, and rust inhibitors are likewise introduced to further prevent chemical or hydrolytic corrosion. In order that the bandage may be unwound for application, both the exterior surface and the-priming mass possess additional physical propertiesthat will allow the bandage to be unwound even after exposure to direct sun or cool temperatures.

A specific embodiment of the present inventionwould beprepared in accordance with the following provisions. In order to develop a priming mass having the desired properties, it has been found that petrolatum, 8111811101- phous mineral oil wax, is a most satisfactory base material; however, several desirable and necessary features of a satisfactory priming mass are lacking in petrolatum itself. it is necessary. for instance, to adjust the softening point of ordinary petrolatum, so that it willnot only withstand the intense heat of exposure to directsun in hot summer weather, but also so that it. will Withstand such heat and not penetrate and destroy or damageother parts of the roll bandage thereby'making application of the bandage diflicult. Further, petrolatum of itself is not possessed of inhibiting qualities to counteract the corrosive effects of an already wet metallic surface.

A petrolatum product obtainable onthe open market Whichconta'ns some of the chemical inhibitors and which has an improved softening point desirable for the present purposes and which also has improved self-healing qualities through the use of added ingredients is marketed by the Texas Company as their #1995 Rust Proof compound made and manufactured under a patent to Harry Roden, dated April 24, 1945, bearing Patent No. 2,374,565. In order to improve the corrosion-res stant features of this base material, additional inhibitors are added in the form of chromates of sodium and potassium to compensate for the excess moisture which it is believed may be encountered at the metallic surface. The two inhibitors chosen are purposely of different solubilities,,so that an initial contact between moisture and inhibitor will not leach out, dissolve or otherwise remove all of the inhbitor, but will leave some inhibitor in place in the priming mass for subsequent protection.

The most satisfactory quantities of additional inhibi-. tors are equal proportions of sodium and potassium and aggregating not less than 2 pounds per pounds of #1995 Rust Proof compound and not more than 3 pounds per 100 pounds of #1995 Rust Proof compound. The inhibitors should be finely pulverized and thoroughly dispersed throughout the compound for best results.

I It has been found that under certain conditions it is necessary to further elevate the softening point of the #1995 Rust Proof compound. Where the roll bandage is to be used during the summer season, it is preferable to add quantities of Dylt or Dygt polyethylene resin, which is commercially available from the Bakelite Corporation. This addition is accomplished by preparing a concentrate of the #1995 compound and a quantity of Dylt or Dygt, which is thoroughly mixed before subsequent addition to the bulk #1995 compound, which has been liquefied by application of heat. The add'tion of 5 parts by weight Dylt or Dygt to 100 parts by weight of #1995 compound results in a softening point elevation of the compound to 175 degrees-180 degrees Fahrenheit, which is adequate for this purpose.

In order to further improve the self-healing properties of the #1995 compound and to further insure against corrosive action at the protected metallic surface resulting from a prolonged or permanent encounter with water which has penetrated the exterior barrier due to damage or imperfections in the application of the strip, it has been found desirable to add a quantity of Georgia clay as a filler material to the #1995 compound. Preferably, the Georgia clay is added to the #1995 compound in a ratio of 25 to 40 parts by weight of Georgia clay to 100 parts by weight of #1995 compound.

While it is recognized that Georgia clay is a type of bentonitic clay, and accordingly other types of bentonitic clay might presumably be substituted for the Georgia clay without departing from the scope of this invention, it must be recognized that the Georgia clay has certain inherent characteristics which make it a much more sat'sfactory filler material than other types of bentonitic clays. The proportions set forth herein are derived with full knowledge of the exact range of swelling due to the presence of bentonitic materials in the Georgia clay, and such proportions would necessarily have to be modified where other types of bentonitic clays are to be utilized.

- In addition to the use of the Georgia clay to improve the self-healing qualities of the priming mass, it has been found desirable to add additional quant ties of Georgia clay to the #1995 compound to reduce bleeding of the priming mass under conditions of extreme heating in hot summer sun. Although addition of 25 parts by weight of Georgia clay to the compound is adequate for the purpose of moisture occlusion, it is desirable to increase the proportion to 40 parts by weight of Georgia clay if the protective tape being made is to be used in summer heat. With the inclusion of the additional quantity of Georgia clay, bleeding and cross-interpenetration of the priming mass and exterior shield will be minimized. Through experimentation, it has been found that a priming mass made in accordance with these specificatfion?1 will fully satisfy the requirements and objects set on While the desired mechanical shield and electrical insulator have previously been described as separate bar- Tiers, it has been found possible to select substances which will satisfy the requirements for both the electrical insulator and the mechanical shield and to combine them into a single major component of the strip of material. Asphalt, because of its high dielectric strength and strong physlcal properties, is particularly suited to this purpose. because of the lack of tensile strength, however, it is Important that a reinforcing medium be provided with the asphalt. A most satisfactory reinforcing medium which W111 serve as a binder for the bandage roll or tape is Owens-Cornings Type 20 Coromat, a glass fibre mat which has incorporated in it strong longitudinal reinforcing fibres. In order to obtain the best shield possible, the natural properties of different types of asphalt have been studied, and as a result of such study, it has been found that catalytically-blown Wyoming asphalt, commercially available as C-19O from the Huskey Refinery at Cody, Wyoming, and the same type of asphalt from the Lion Oil Company Refinery at Eldorado, Arkansas, are well suited for this purpose, and either may be used. The unusual qualities of these asphalts when used in membrane form, as to ductility, penetration, softenng point, toughness or resistance to wear, are outstanding.

Because of the possibility of interpenetration of the asphalt shield in the petrolatum priming mass, which would make the roll bandage hard to apply, it is advantageous to harden the asphalt shield and further ra'se its softening point. This may best be accomplished by the addition of a high melt hydrocarbon, preferably derived from the same crude as the asphalt. One successful method has been to add #310 "Mineral Rubber hydrocarbon pellets from the Huskey Refinery to their C-l asphalt in a ratio of 1 part #310 to 10 parts Cl90 thereby raising the softening point to 220 degrees Fahrenheit. This increase in softening point temperature is accompanied by some loss of penetration and ductility. While the foregoing proportion is satisfactory for winter use, it has been found that the ratio should be increased to 2 parts #310 to 10 parts C-l90 for summer use.

To compensate for the aforementioned loss of duetility and penetration, and further to improve such quali' ties as impact resistance, elasticity, toughness and aging, it is advantageous to add to the asphalt a commercially available material made by Rubarite, inc. The material used, which is a free-flowing, unvulcanized, synthetic rubber product sold under the trade name Rubarite," is added to the asphalt in the amount of 12 parts by weight of Rubarite to 200 parts by weight of the asphalt.

As a further additive to the asphalt shield, it has been found desirable to include approximately 10 to 15 parts by weight of Georgia clay to parts by weight of the asphalt to further prevent the penetration of moisture.

As a possible substitute for the glass fibre mat and asphalt exterior shield, it has been found that coal tar saturated asbestos pipe line felt, which is readily available in either 8-pound or 15-pound per 100 sq. ft. grades, may be used without further modification or change. This type material is especially useful in applications where the possibility of contact with crude oil or petroleum products is prevalent. Likewise, the material is relatively impervious to chemical solutions encountered in soil.

In order to attain the desired separation between the exterior shield material and the interior priming mass, it has been found desirable to manufacture the protective wrapping material in a batch-type step process illustrated in Figs. 3 and 4. When asphalt is to be used, the ingredients of C- asphalt and #310 hydrocarbon are placed together in an open-top, heated vessel and are heated to a temperature of 325 degrees Fahrenheit. The Rubarite and Georgia clay are added, and the mixture is agitated vigorously for at least 15 minutes. Thereafter, moderate agitation is continued to prevent settling out of any ingredients. The tank is equipped with a horizontal depressing rod under which the fibre glass mat is passed to insure complete saturation with the asphaltic compound. The saturated glass is then passed between two horizontal, heated tubes which serve as screeds to squeeze entrapped air out of the asphaltic compound and adjust the thickness of the reinforced asphaltic sheet to 0.031 inch, while also giving the asphaltic compound the maximum density. The sheet is then passed through a cooling chamber where it is air-cooled to about 90 degrees to 100 degrees Fahrenheit. Next, it enters a dusting chamber where it passes through an atmosphere of dust-laden air. The dust used is Georgia clay, which clings to the asphaltic sheet and especially settles in surface pores that might, later be weak spots in the sheeting,

thus concentrating the swelling agent where it will be most needed, as well as reducing the sticky quality of the sheet. This feature is advantageous in reducing unwinding problems.

Meanwhile, a batch of priming mass is prepared by first preparing a concentrate of #1995 Rust Proof compound and the required amount of Dylt or Dygt. Later this concentrate is introduced into the bulk of #1995 compound, which has previously been liquified by the application of heat. In similar manner, the other ingredients, inclusive of additional inhibitor and Georgia clay, are added to the liquified mass and stirred therein to assure a complete and homogeneous mixture of all the ingredients. When thoroughly mixed, the priming mass is introduced into an open-top heated tank where it is heated to 185 degrees Fahrenheit and subjected to further agitation to prevent settling out of ingredients. This tank is equipped with a licking drum which is a large diameter, cylindrical drum placed in horizontal position and revolved slowly in the liquid batch of priming mass, with the upper section of the drum above the surface of the liquid mass. One satisfactory arrangement is to use a 14-inch diameter drum 37 inches long, revolving at nine revolutions per minute. The direction of rotation should be opposite to the direction of movement of the sheet.

At this point, the aforementioned pipe line felt may be substituted for the asphaltic sheet derived in the first step of this process. The sheet of desired material is then passed over the top of the drum in such manner as to cause the priming mass to be licked on the underneath side of the sheet. The thickness of coating applied here should be not less than 4 inch and not more than %,2 inch thick. Adjustment of the thickness can be made by changing the temperature of the liquid mass, the tem perature of the asphaltic or pipe line felt sheet, the speed of revolution of the drum and the speed of travel of sheet substance.

The resulting strip of material is then passed through another cooling chamber where it is reduced to atmospheric temperature or lower by air cooling. The cooled strip may then be passed through a slitting device to cut it to appropriate width before rolling, or it may be rolled in the full width of material processed to be out later with a band saw. Another, and most desirable, method is to start the process with fibre mat or felt which has already been cut to the appropriate width.

As an example of the proportionate quantities of materials utilized in making the desired protective material, a recap of proportions is presented herewith:

100 pounds catalytically-blown asphalt-Huskey C-190. to 20 pounds #3l0-Huskey Co. hydrocarbon pellets.

These ingredients are added together and heated to 325 F. in an open vat. Subsequently, add:

12 pounds Rubarite-unvulcanized Rubarite, Inc. 10 to 15 pounds Georgia clay.

synthetic rubber by Agitate the combined mixture vigorously for at least 15 minutes before passing the Type glass fibre Coromat through the liquid mass of materials.

After the mechanical shield-insulator, as above, has cooled, it should be dusted with Georgia clay before being passed through a batch of priming mass prepared in the following proportions:

possible todetermineyit is be} lieved that the ingredients of #1995 Rust Proof compound made by The Texas Company come within the Insofar as it has been scope of the claims in the Roden Patent No. 2,374,565,

which would indicate that the composition itself is made up of materials in the following percentages:

It will be apparent from the foregoing description that the present invention is adaptable to various modifications and changes without departure from the scope of the invention as defined in the hereunto appended claims.

What is claimed is:

1. A protective covering material adapted for shipment and handlin in roll bandage unit form comprising an exterior mechanical shield and electrical insulator and an interior priming mass integrally formed and applied to prevent corrosion of metallic objects, said mechanical shield and insulator comprising a glass fibre binder material and a compound for impregnating said binder, said compound comprising a base of catalytically-blown asphalt, a high melting point hydrocarbon hardener derived from the same asphalt as said base added in the ratio of 10 to 20 pounds of said hardener for every pounds of said asphalt base for raising the softening point of said asphalt, and 10 to 15 pounds of Georgia clay for each 100 pounds of said base asphalt to prevent moisture penetration of said compound and exterior shield, said interior priming mass being deposited on said exterior shield for intimate contact with the metallic objects to be protected, said priming mass comprising a homogeneous mixture of materials compounded within the limits of the following proportions:

Petrolatum primer 100 pounds.

Sodium chromate inhibitor---" 1 to 1 /2 pounds per 100 pounds of primer.

Potassium chromate inhibitor--- 1 to 1 /2 pounds per 100 pounds of primer.

Georgia clay 25 to 40 pounds per 100 pounds of primer.

said priming mass being deposited on one side of said impregnated binder for contact with objects to be protected.

2. A protective covering material adapted for shipment and handlding in roll bandage unit form comprising an exterior mechanical shield and electrical insulator and an interior priming mass integrally formed and applied to prevent corrosion of metallic objects, said mechanical shield and insulator comprising a glass fibre binder material and a compound for impregnating said binder, said compound comprising a base of catalytically-blown asphalt, a high melting point hydrocarbon hardener derived from the same asphalt as said base added in the ratio of 10 to 20 pounds of said hardener for every 100 pounds of said asphalt base for raising the softening point of said asphalt, 10 to 15 pounds of Georgia clay for each 100 pounds of said base asphalt to prevent moisture penetration of said compound and exterior shield and 6 pounds of an unvulcanized synthetic rubber compound for each 100 pounds of asphalt base to improve the ductility of said binder, said interior priming mass being deposited on said exterior shield for intimate contact with the metallic objects to be protected, said priming mass comprising a homogeneous mixture of materials compounded within't he limits of the following proportions:

Petrolaturn primer 100 pounds.

Sodiurnchromate inhibitor 1 to 1 /2 pounds per 100 5 pounds of primer. Potassium chromate inhibitor 1 to 1 /2 pounds per 100 pounds of primer.

said priming mass being deposited on one side of said impregnated binder for contact with objects to be protected,

and additional Georgia clay dusted on said combined convering material to facilitate separation of saidroll bandage unit. v v a References Cited in the file of this patent UNITED STATES PATENTS Roden Apr. 24, 1945 2,374,565 2,433,847 Jennings et al Jan. ,6, 1948 2,523,759 Grant Sept. 26, 1950 OTHER REFERENCES Asphalts and Allied Substances (Abraham), pub-l lished by D. Van NostrandCo Inc. (New York), 1945, (page 533 relied on). (Copy in Div. 25.)

Claims (1)

1. A PROTECTIVE COVERING MATERIAL ADAPTED FOR SHIPMENT AND HANDLING IN ROLL BANDAGE UNIT FORM COMPRISING AN EXTERIOR MECHANICAL SHIELD AND ELECTRICAL INSULATOR AND AN INTERIOR PRIMING MASS INTEGRALLY FORMED AND APPLIED TO PREVENT CORRISION OF METALLIC OBJECTS, SAID MECHANICAL SHIELD AND INSULATOR COMPRISING A GLASS FIBRE BINDER MATERIAL AND A COMPOUND FOR IMPREGNATING SAID BINDER, SAID COMPOUND COMPRISING A BASE OF CATALYTICALLY-BLOWN ASPHALT, A HIGH MELTING POINT HYDROCARBON HARDENER DERIVED FROM THE SAME ASPHALT AS SAID BASE ADDED IN THE RATIO OF 10 TO 20 POUNDS OF SAID HARDENER FOR EVERY 100 POUNDS OF SAID ASPHALT BASE FOR RAISING THE SOFTENING POINT OF SAID ASPHALT,

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