US3347699A

US3347699A - Corrosion protection

Info

Publication number: US3347699A
Application number: US336834A
Authority: US
Inventors: Donald O Hitzman
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1964-01-09
Filing date: 1964-01-09
Publication date: 1967-10-17
Anticipated expiration: 1984-10-17

Description

Oct 1967 11-0. HITZMAN CORROSION PROTECTION Filed Jan. 9, 1964 United States Patent Office 3,347,699 Patented Oct. 17, 1967 CORROSION PROTECTION Donald 0. Hitzman, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Jan. 9, 1964, Ser. No.-336,834 9 Claims. (Cl. 117-97) This invention relates to the prevention of corrosion. In one aspect this invention relates to the prevention of microbiological corrosion of an object in an inaccesible location. In another aspect this invention relates to a method of applying a protective coating to objects, especially those buried in the earth.

A major problem encountered with metallic objects, such as pipes, conduits, vessels and the like is damage caused by corrosion. Especially is corrosion a problem when the metallic objects are submerged in waters, buried in the earth, or surrounded by a moisture-containing environment. Corrosion of metals, either internally or ex- .ternally, is primarly an electrochemical process. However, mechanical factors such as flow of fluid along a metal surface can influence the electrochemical process responsible for corrosion. Also, microorganisms can exert effects which influence electromechanical processes and thus markedly accelerate the corrosion rate. Microorganism-promoted corrosion is extensive in metal pipes, conduits, buried pipe lines, storage tanks and reservoirs, barrels and the like containing or housing crude petroleum materials, gases, water and the like because such conditions provide an environment of moisture, suitable pH, sulfur, organic matter, and a source of energy which enhances microorganism growth.

It is known that protective coatings and wrapping can be applied to metal objects to retard the rate of corrosion. Generally employed as such coatings are bituminous materials. However, many bacteria such as aerobic bacteria can attack and destroy bituminous coatings. It has been proposed to add germicides to bituminous protective coatings for preventing corrosion of metallic objects buried in the earth as well as adding a germicide to the soil surrounding the object. This proposal is thoroughly described in U.S. Patent 2,979,377. Also, it has been proposed to employ cationic asphalt emulsions as protective coatings.

Although the field of protective coatings has been widely investigated, the application of coatings to objects still has disadvantages and inconveniences. Most emphasis has been directed to external coatings and wrappings. How ever, the internal protection of objects is now recognized as necessary to fully prevent rapid corrosion in various circumstances. Internal coating of metal objects presents various problems, especially when the objects, such as pipe lines, are already in place.

Accordingly, it is an object of this invention to internally protect objects from corrosion. It is another object of this invention to provide a method for protecting the internal surfaces of objects from microbiological corrosion. Still another object of this invention is to provide an improved method for applying a protective coating to the internal surfaces of metal objects. And still another object of this invention is to provide a method for applying an internal protective coating to objects and systems in place, such as pipe lines buried in the earth.

Other objects, aspects and advantages of this invention will become apparent to one skilled in the art upon further study of this disclosure and appended claims.

In accordance with my invention there is provided a method for preventing internal corrosion (particularly, microbiological) of objects, especially those buried in earth, which comprises placing a volume of a bituminous emulsion in the object and forcing it along the surface of said object to deposit a continuous coating thereto.

In one embodiment of my invention the formation of the protective coating is believed to be caused by the cations present in a cationic bituminous emulsion being oriented at a bitumen-water interface in such a manner that the hydrophobic portion thereof is dissolved in the bituminous material, with the positively charged polar groups facing away therefrom. The polar groups are strongly attracted to any negatively charged surface to which they firmly attach so that any surface water present is displaced. Since the emulsion rapidly breaks and the cations enclose the available surface, a permanent irreversible bond is made and stripping cannot take place because the cations are no longer available to act as an emulsifier.

Any bituminous emulsions containing cationic, anionic, or nonionic emulsifiers, or mixtures thereof are applicable to this invention.

A particularly useful class of cationic emulsifying agents which can be so used are salts of organic nitrogen bases characteriaed by the presence of at least one basic nitrogen atom in their cation portion, and where the latter contains a long-chain aliphatic hydrocarbon radical of at least 12 and as many as 24 carbon atoms, preferably a straight chain fatty aliphatic group. A particularly useful subclass of such cationic emulsifying agents are the tetrasubstituted quaternary ammonium compounds, such as those of the general formula:

where R is a long alkyl chain of at least 12 and as many as 24 carbon atoms, and the R s are shorter alkyl radicals or benzyl radicals, the presence of which is sufiicient to impart oil solubility and emulsifying properties to the salt material, X is a hydroxyl or an anion such as nitrate, sulfate, secondary phosphate, acetate, benzoate, salicylate and preferably a halogen, such as chlorine or bromine, v is the valence of said hydroxyl or anion, and x is an integer equal to said valence. Another particularly useful subclass of cationic emulsifying agents are the salts of heterocyclic nitrogen bases, such as alkylpyridine, alkylquinoline, alkylisoquinoline and alkylimidazoline, a particularly useful group of'the latter being represented by the general formula:

j CHaGH NH:

where R is an aliphatic radical selected from the group consisting of alkyl and alkenyl radicals, preferably having 12 to 24 carbon atoms, R, is selected from the group consisting of hydrogen and alkyl radicals preferably having 1 to 4 carbon atoms, and X" is an anion such as nitrate, sulfate, secondary phosphate, acetate, benzoate, salicylate and preferably a halogen, such as chlorine and bromine, n is an integer equal to the valence of said anion, and x is an integer of 1 to 3. Primary, secondary and tertiary monoamines and diamines are also useful in this invention, particularly the fatty acid diamines of the general formula R NH(CH NH where R is as defined above in the formula and m is an integer in the range of 1 to 3.

Another particularly useful subclass of cationic emulsifying agents which can be used in combination with the nonionic emulsifying agents (especially where alkaline where R, and R are lower alkyl hydrocarbon radicals having, for example, 1 to 3 carbon atoms, such as methyl, ethyl, propyl (preferably methyl), R is alsovsuch an alkyl radical (preferably methyl) or an aryl, alkaryl or aralkyl hydrocarbon radical having, for example, 6 to 7 carbon atoms, such as phenyl, benzyl or tolyl, R is a lower alkylene hydrocarbon radical having, for example, 1 to 2 carbon atoms, such as methylene and ethylene, R is a long chain alkyl hydrocarbon radical having, for example, 8 to 25, preferably 8 to 20, carbon atoms, such as octyl, dodecyl, pentadecyl, eicosyl and pentacosyl, R and R7 are hydrogen atoms orlower alkyl radicals having, for example, 1 to v5 carbon atoms, A is a benzene, m is 0 or 1, X' is a hydroxyl or a salt-forming anion such as nitrate, sulfate, secondary phosphate, acetate, benzoate, salicylate and preferably a halogen, such as chlorine or bromine, v is the valence of said hydroxyl or anion,.and x is an integer equal to said valence. These cationic emulsifying. agents are quaternary ammonium compounds, and I prefer to use those which are chloride salts and where the sum of carbon atoms in R R and R does not exceed 12 and the sum of carbon atoms in R and R does not exceed 6.

Representative cationic emulsifying agents which can be used in this invention include n-hexadecyltrimethylammonium bromide, n-hexadecyldimethylethylammonium bromide, tallow trimethylammonium chloride (the term-tallow referring to the radical of a mixture of fatty acids derived from tallow), n-dodecyltrimethylammonium chloride, n-dodecyltriemthylammonium bromide, n-dodecyltrimethylammonium hydroxide, n-tetradecyltrimethylammonium chloride, n-hexadecyltripropylammonium iodide, n-octadecyltri-n-butylammonium nitrate, n-oetadecyltriethylammonium chloride, n-hexadecyltrimethylammonium chloride, n-eicosyltrimethylammonium chloride, n-tetracosyltrimethylammonium acetate, n-pentadecylethyldimethylammonium chloride, n-docosylpropyldimethylammonium chloride, n-tricosyl-n-decyldiethylammonium benzoate, n-tetradecyl-n-heptyldimethylammonium chloride, n-octadecyl-n-decyldirnethylammonium chloride, n-heptadecyldipropylmethylammoninm chloride, n-nonadecyl-di-n-octylmethylammonium chloride, n-hexadecylethyldimethylammonium chloride, n-dodccylbenzyldimethylammonium chloride, n-pentadecylbenzyldiethylammonium fluoride, n-octadecylpropyldimethylammonium salicylate, n-dodecyl-n-butylbenzylmethylammonium bromide, n-nonadecyldiethylmethylammonium sulphate, n-eicosyltrimethylammonium orthophosphate, 1- (Z-aminoethyl) -2- (4-tetradecenyl) -4,5-di-n-butyl -2- imidazOline, 1-(2-aminoethyl)-2-(1,1-diethyl-5,7-dodecadienyl)-4,5-

dimethyl-Z-imidazoline, 1- (2-aminoethyl) -2-n-octadecyl-4-ethyl-2-imidazoline, I-(Z-aminoethyl)-2-n-eicosyl-2-imidazoline, 1-(2-aminoethyl)-2-(1,1-dimethyldecyl)-2-imidazoline, 1- (2-aminoethyl) -2-( IZ-heptadecenyl -2-imidazoline, 1-(2-aminoethyl)-2-(5,7-heptadecadienyl) -2-imidazoline, p-n-octylbenzyldimethylphenylammonium chloride, p-( 1,1,3,3-tetramethylbutyl)benzyltrimethylammonium chloride, 4-n-nonyl-3,5-dimethylbenzyldiethylbenzylammonium chloride,

4, 2-n-dodecyl-3-methyl-5-isopentylphenylethylmethyl-nbutyl-p-tolylammonium chloride, 4- (5,6-dimethyl pentadecyl-3 ,5 -diethylphenylethylmethylphenylammonium chloride, 3-methyl-4-n-eicosyl-5-ethylbenzyltriethylammonium chloride, 3,5-di-n-propyl-4-n-pentacosylphenylethyl-di-n-pentylm-tolylammoniurn chloride, p-n-octylphenoxyethoxyethyltrimethylammonium chloride, p-(3-methyldodecyl)benzyltriethylammonium chloride, p-(1,1,3,3-tetramethylbutylphenoxyethoxyethyldimethylbenzylammonium chloride; 3,S-dimethyl-4-n-octylphenoxyethoxyethyldiethylphenylammonium chloride, 2-(3,4,5-triethyl)tetradecyl-3,4-diisopropylphenoxyethoxyethylmethyln-butyl-o-tolylammonium chloride, p-( 1,1,3,3-tetramethylbutyl)-o-tolyloxyethyoxyethyltrimethylammonium chloride, 3-methyl-5-n-pentyl-4-n-eicosylphenoxyethyl-di-n-butylphenylammonium chloride, 2-methyl-6-n-amyl-4-n-pentacosylphenoxyethoxyethoxyethyl-di-n-amyl-p-tolylammonium chloride, and

' amomnium chloride; Hyamine 2389, methyldodecylbenzyltrimethylammoniurn chloride; Nalquate 6-8-12,

l-(2-oxyethyl)-2-n-alkyl-l (or 3 )-benZyl-2-imidazolinium chloride, Diam 1l-C (n-alkyl-l,3 propylenediamine); Aliquat 26, monotallowtrimethylammonium chloride; Alamine 26, primary tallow amine; Duomeen T, N-alkyltrimethylenediamine; and the like.

Representative anionic emulsifying agents which can be used in the invention include alkylaryl sulfonates, such as methylnaphthalene sodium. sulfonate (e.g., Petra-Ag),

; p-dodecylbenzene sodium sulfonate, nor iso-p-octylphenoxypoly(ethyleneoxy)ethanol sodium sulfonates, isopropylnaphthalenelsodium sulfonate (e.g., Aerosol OS), and tetrahydronaphthalene sodium sulfonate (e.g., Alkanol S), sulfates such as n-hexadecyl sodium sulfate, ammonium lauryl sulfate, and tridecyl sodium sulfate, phosphates, such as alkylpolyphosphates '(e.g., Estranol CP) and complex amido-phospho salts, and esters such as sodium diamyl sulfosuccinate (e.g., Aerosol AY) and disodium-N-octadecylsulfosuccinate (e.g., Aerosol 18), and the like.

Suitable nonionic emulsifying, agents applicable for this invention as shown by the general formula:

where R is selected from the group consisting of hydrogen, aryl, and alkaryl radicals; and x, y and z are integers, such that (1) when x is Zero, y is also zero, 2 is in the range of 20 to 60, inclusive, and said R is one of said and they each have a critical balance of a hydrophobic component (propyleneoxy) and a hydrophilic component (ethyleneoxy) which is necessary to prepare asphalt emulsions of this invention. Within the general formula given above for these nonionic emulsifying agents, there are the two preferred subclasses which can be represented by the following general formulas:

Where a and c are integers greater than zero and whose sum is in the range of 50 to 350, inclusive, b is an integer in the range of 40 to 60, inclusive, and R is selected from the group consisting of hydrogen and the hydrocarbon radical:

where R is as defined above.

Representative examples of the nonionic emulsifying agents which can be used in preparing the novel asphalt emulsions of this invention include: phenoxynonadeca- (ethyleneoxy ethanol, phenoxyeicosa (ethyleneoxy ethanol, phenoxytricosa(ethyleneoxy)ethanol, phenoxypentacosa(ethyleneoxy)ethanol, phenoxyoctacosa(ethyleneoxy)- ethanol, phenoxytriaconta(ethyleneoxy)ethanol, phenoxyhentriaconta(ethyleneoxy)ethanol, phenoxydotriconta(ethyleneoxy)ethanl, phenoxytetraconta(ethyleneoxy)ethanol, phenoxypentaconta(ethyleneoxy)ethanol, phenoxynonapentaconta(ethyleneoxy)ethanol, 4-methylphenoxyeicosa- (ethyleneoxy)ethanol, 4-methylphenoxyheneicosa(ethyleneoxy)ethanol, 2,3,6 triethylphenoxydocosa(ethyleneoxy)- ethanol, 4-(1,1,3,3-tetramethylbutyDphenoxytetracosa(ethyleneoxy) ethanol, 4-(1, 3,5 -trimethylhexyl) phenoxyhexacosa (ethyleneoxy) ethanol, 4-nonylphenoxyheptacosa(ethylene0xy)ethanol, 2,3,4,5,6-penta-n-pentylphenoxytriaconta(ethyleneoxy)ethanol, 2-( 1,3,5-trimethylhexyl)-4-( 1,3- dimethylbutyl) phenoxyhentriaconta (ethyleneoxy) ethanol, 4 (3,5,5 trimethylheptyl)phenoxydotriaconta(ethyleneoxy)ethanol, 3 (3,5,7,7 tetramethyl 5 ethylnonyl) phenoxytetraconta(ethyleneoxy)ethanol, 4 (1,1,3,3,5,5, 7,7 octamethyldecyl)phenoxypentaconta(ethyleneoxy)- ethanol, 4 n pentacosylphenoxynonapentaconta(ethylene0xy)ethanol, 3,5 di- 11 decyl 4 n pentylphenoxynonapentaconta(ethyleneoxy)ethanol, beta hydroxyethoxytetraconta (propyleneoxy octatetraconta(ethy1eneoxy)- ethanol, beta-hydroxyethoxyoctatetraconta(ethyleneoxy)- tetracont-a (propyleneoxy) ethanol, beta-hyd-roxyethoxypentaconta(ethyleneoxy pentaconta (propyleneoxy) deca (ethyleneoxy)ethanol, beta-hydroxyethoxyocta(ethyleneoxy)- hexac0nta(propyleneoxy)nonaconta(ethyleneoxy)ethanol, beta hydroxyet-hoxyhecta(ethyleneoxy)pentatetraconta- (propyleneoxy)hecta(ethyleneoxy)ethanol, beta-hydroxyethoxydohecta(ethyleneoxy hexaconta (propyleneoxy) octatetracontahecta(ethyleneoxy)ethanol, phenoxyethyleneoxypentapentaconta propyleneoxy oct-atetraconta (ethyloxyethanol, 4 methylphenoxy 1 deca(ethyleneoxy)- nonatetraconta propyleneoxy) pentaconta ethyleneoxy)- ethanol, 4-( 1,3,5 -trimethylhexyl) phenoxyheptaconta(ethyleneoxy) pentaconta(propyleneoxy)triaconta(ethyleneoxyethanol, 4 n pentacosylphenoxydicta(ethyleneoxy)pentaconta(propyleneoxy)hecta(ethyleneoxy)ethanol, 2,4,5- trimethylphenoxypentacontahecta (ethyleneoxy) pentaconta( propyleneoxy) hexaconta (ethyleneoxy) ethanol, 2-( 1,3 5 trimethylhexyl) 4 (l,1,3,3 tetramethylbutyl)phenoxyhecta ethyleneoxy) hex atetraconta (propyleneoxy) dicta(ethyleneoxy)ethanol, 4-n-pentacosylphenoxyhecta(ethyleneoxy hexaconta propyleneoxy) nonatetracontadicta- (ethyleneoxy)ethanol, and the like, and mixtures thereof.

Many of the nonionic emulsifying agents which can be used in this invention are commercially available, such as Triton X-205, Triton X-305 and Triton X-405, each of which is a mixture of octylphenoxypoly(ethyleneoxy)- ethanols with 20, 30 and 40 ethyleneoxy groups in the poly(ethyleneoxy) chain, respectively, and Pluronic P-104, Pluronic P-105 and Pluronic F-l08, which are materials having the general formula where the sum of a and c is about 50, 74 or 296, respectively, and where b is about 56.

Asphalts which can be employed in the preparation of the asphalt emulsions of this invention include. any of those bituminous materials used heretofore and known in the prior art, such as natural asphalt or those derived from petroleum refining, for example, by steam refining and/ or air blowing, etc. Paving asphalts characterized by penetrations (ASTM D5) from 0 to about 300 or even higher, and preferably from about 40-300, and having softening points (ASTM D3626) in the range of to 250 F., preferably to F., represent suitable asphalts which can be used. .Such. bituminous materials include coal tar pitch, petroleum asphalts, and the like.

The recipes for bituminous emulsions are well known in the art. Such cationicemulsions containing the essential ingredients as well as various additives are described in Us. Patents 3,026,266 and 3,032,507. A typical cationic asphalt emulsion can be prepared containing by weight 60 parts asphalt, 40 parts water, 0.2 part fatty diamine, 0.5 part acetic acid, and 0.1 part calcium chloride. Since most cationic emulsifiers have bactericidal properties, the coating of this invention protects the covered surfaces from bactericidal as well as other types of corrosion. Other bactericides may also be added to the emulsion, if desired. Suitable bactericides are described in US. Patent 2,979,377. Also, conventional corrosion inhibitors can be added to the emulsion. I

In a preferred embodiment of my invention, a pig is inserted into the pipe line, a volume of a typical cationic emulsion (as described above) sufficient to coat the interior of a metal pipe line buried in earth is inserted therein behind the pig, and water is injected into thepipe line behind the emulsion to drive and force the emulsion through the pipe line. As the emulsion flows across the internal surface of the pipe line, a continuous layer of same is deposited thereon, thus providing a protective coating. If a thicker coating is desired, the above operation may be repeated to build up layers of the emulsion coating.

This method of applying protective coatings of bituminous emulsions to objects in place overcomes the disadvantages of coating the parts and then assembling. In coating the inside of pipe lines in accordance with the invention, the joints of the pipe line are protected by the material as well as being sealed thereby.

In accordance with the attached drawing, loading chamher 2 communicates at one end with a pipe line 4 and at the other with a driving fluid source 6, such as water. Chamber 2 is defined by valves 8 and 10 and at each end thereof. A pig 12 is positioned in chamber 2 and emulsion is introduced to chamber 2 behind pig 12 through conduit 14 having control valve 16 therein; Conduit 18 with valve 20 therein communicates with chamber 2 for introducing material, such as soda ash, to control the pH of the driving water in response to pH sensing element 26 and flow recorder controller 28 operatively manipulating valve 20.

Conduits

22 and 21 with valves 24 and 24', respectively, therein communicate with the forward end of chamber 2 for venting same during positioning of pig 12 and emulsion introduction. The pH sensing element can be made retractable to insure against coating by the emulsion. A

metal thereby leaving a coating thereon. At the driving fluid (water)-emulsion interface, the pH of the water can be controlled in response to a pH measurement and.

introduction of soda ash thereto to break the emulsion at this interface so that droplets of asphalt contact the coating and attach to increase the thickness thereof.

Although particular emphasis has been placed on cationic-bituminous emulsions, which are preferred, the anionic and nonionic emulsions are applicable to the method of this invention. However, when employing anionic and nonionic emulsions, other steps will be re quired to apply the coating, such as evaporation of the solvent (water). Such additional requirements are well known in asphalt technology.

Although this invention has particular advantage in coating internal surfaces of buried pipe lines used for transporting crude petroleum streams and water for waterflooding or irrigation, it is equally applicable to other surfaces and objects such as individual lengths of pipe, storage tanks, barrels, and the like. Concrete and/or cement conduits and other objects may be coated in accordance with this invention.

The emulsion can be driven along the surface of the object to be coated by direct contact with liquid or gaseous fluids which are insoluble in the emulsion and vice versa',

provided the fluid does not interfere with the stability of the emulsion. Suitable driving fluids include air, nitrogen, water, and the like.

It is not necessary that the surface to be coated is dry; however, if the surface is dirty, it is desirable that a solution of detergent or other cleaning agent be forcedthrough the object prior to the emulsion coating.

It is readily apparent that I have now provided an improved method for protecting corrodible internal surfaces in place from various types of corrosion. My invention provides the application of a triple barrier to internal surfaces which guards against all types of corrosion in that the bituminous material prevents oxygen corrosion and abrasion, the bactericide cationic emulsifier prevents microbial growth on the bitumen surface and penetration thereof, and a corrosion inhibitor prevents other types of corrosion.

Variations and modifications of the invention which will not depart from the spirit and scope thereof will be apparent to those skilled in the art in view of this disclosure.

That which is claimed is:

1. A method for providing a corrosion-protective coating on the internal surfaces of a hollow object, having a negative ionic charge thereon, While in place comprising:

(a) injecting a bituminous emulsion containing a cationic emulsifying agent in said object, the quantity of said emulsion being sufficient to provide a continuous coating on the internal surfaces of said object; and

(b) moving said emulsion inside said object so that said emulsion intimately contacts the entire internal surface of said object and deposits a continuous coating thereon.

2. The method of claim 1 wherein said object is a metal,

fluid-transmission pipe.

3. The method of claim 1 wherein said emulsion further contains a bactericide.

4. The method of claim 1 wherein said hollow object is a metal object.

5. A method for providing a corrosion-protective coating on the internal surfaces of a hollow object, having a negative ionic charge thereon, while in place comprising;

(a) inserting a pig inside said object;

(b) injecting a cationic asphalt emulsion into said object behind said pig, the quantity of said emulsion being suflicient to provide a continuous coating on the internal surfaces of said object; and (c) injecting a fluid into said object behind said emulsion to drive said pig and emulsion therethrough so that said emulsion contacts the entire internal surface of said object and deposits a continuous coating thereon. 6. The method of claim 5 wherein-said fluid is selected from the group consisting of air, nitrogen and water.

7. The method of claim 6 wherein said fluid is water further comprising:

(a) adding a neutralizing solution to said water to maintain the pH thereof at a desired level; (b) continuously sampling and determining the pH of said water; (0) producing a signal representative of said pH; and (d) controlling the rate of addition of said neutralizing solution to said water responsive to said signal so as to inaintain the pH of said water at a predetermined evel. 8. The method of claim 5 wherein said emulsion is an asphalt emulsion containing a member selected from the groups defined as fatty diamine salts and quaternary ammonium compounds- 9.-The methodfor providing a corrosion-protective coating to the inside walls of a metal, fluid-transmission pipe, having a negative ionic charge thereon, buried in the earth, while in place comprising:

(a) inserting a pig into said pipe; (b) injecting an asphalt-tetramethyl ammonium chloride emulsion into said pipe behind said pig, the

quantity of said emulsion being'sufficient to provide a continuous coating to the inside wall of said pipe; and (c) injecting air into said pipe behind said emulsion to drive said pig and emulsion the-rethrough so thatsaid emulsion contacts the entire inside wall of said pipe nad deposits a continuous coating thereon.

References Cited UNITED STATES PATENTS 2,314,329 3/1943 Ericson 117-4168 2,533,301 12/ 1950 Watkins '117-97 2,685,523 8/1954 Cross et al. 106-14 2,712,506 7/1955 Farris 117-168 2,744,880 5/1956 Brown 117-97 2,793,138 5/1957 Wilkinson 107-135 3,070,524 12/1962 Alexander et al. 106-14 3,108,012 10/ 1963 Curtis 117-97. 3,257,231 6/1966 McEachran et al. 117-168 ALFRED L. LEAVITI, Primary Examiner.

A. H. ROSENSTEIN, Assistant Examiner.

Claims

1. A METHOD FOR PROVIDING A CORROSION-PROTECTIVE COATING ON THE INTERNAL SURFACES OF A HOLLOW OBJECT, HAVING A NEGATIVE IONIC CHARGE THEREON, WHILE IN PLACE COMPRISING: (A) INJECTING A BITUMINOUS EMULSION CONTAINING A CATIONIC EMULSIFYING AGENT IN SAID OBJECT, THE QUANTITY OF SAID EMULSION BEING SUFFICIENT TO PROVIDE A CONTINUOUS COATING ON THE INTERNAL SURFACES OF SAID OBJECT; AND (B) MOVING SAID EMULSION INSIDE SAID OBJECT SO THAT SAID EMULSION INTIMATELY CONTACTS THE ENTIRE INTERNAL SURFACE OF SAID OBJECT AND DEPOSITS A CONTINUOUS COATING THEREON.