US3717433A - Corrosion inhibition method - Google Patents

Abstract

A composition and method for inhibiting steam-corrosion, comprising adding to the water a stable, cationic, fatty amine emulsion which breaks down upon heating, thereby allowing the fatty amine to enter the vapor phase and coat the interior surfaces exposed to the steam. Optionally, an ethoxyiated straight chain aliphatic acid may be added where the boiler water contains inorganic salt impurities, or is at a high temperature in order to maintain stability of the emulsion.

Description

- [22] Filed:

United-States Patent 1 Scherf et a1.

1 Feb. 20, 1973 [54] CORROSION INHIBITION METHOD [75] Inventors: Gerhard W. Scherf, Ancaster, Ontario; Gary C. Pfaif, Dundas, Ontario, both of Canada [73] Assignee: Diamond Shamrock Corporation,

Cleveland, Ohio Feb. 15, 1972 [21] App]. No.: 226,560

Related US. Application Data [62] Division of Ser. No. 67,570, Aug. 27, 1970.

[52] US. Cl. ..21/2.7, 2l/2.5, 252/312, 252/391 [51] Int. Cl. .252 392, C23f 11/02, C231 11/16 [58] Field of Search ..2l/2.7, 2.5; 210/59; 106/14; 252/390, 391, 392, 394, 395, 180, 312, 356; 260/564 E 3,513,197 5/1970 Daum et a1 ..260/564 E Primary Examiner-Barry S. Richman Attorney-Roy Davis et al.

[57] ABSTRACT A composition and method for inhibiting steam-corrosion, comprising adding to the water a stable, cationic, fatty amine emulsion which breaks down upon heating, thereby allowing the fatty amine to enter the vapor phase and coat the interior surfaces exposed to the steam. Optionally, an ethoxyiated straight chain aliphatic acid may be added where the boiler water contains inorganic salt impurities, or is at a high temperature in order to maintain stability of the emulsion.

6 Claims, No Drawings CORROSION INHIBITION METHOD This is a division, of application Ser. No. 67,570 filed Aug. 27, 1970.

BACKGROUND OF THE INVENTION 1 Field of the invention This invention relates to the inhibition of corrosion in boiler systems.

2. Description of the Prior Art The use of fatty amines in boiler systems and the like is well known in the art. U.S. Pat. No. 2,400,543 discloses the use of aliphatic and aromatic amines which are water insoluble or only slightly water soluble to inhibit foam in boiler water. U.S. Pat. No. 2,460,259 discloses the use of primary aliphatic amines as corrosion inhibitors in boiler systems. U.S. Pat. No. 2,712,531 discloses the use of a blend of octadecylamine and octadecylamine acetate as a corrosion inhibitor. U.S. Pat. No. 2,882,171 discloses aliphatic amines with or without a non-ionic surface active dispersant used as a corrosion inhibitor. U.S. Pat. No. 2,947,703 discloses a method of inhibiting acid corrosion of ferrous metals by addition of higher alkyl substituted nitrogen bases,

including amines and thiourea or alkyl substitutedthioureas. U.S. Pat. No. 2,956,889 discloses an aqueous emulsion of an aliphatic amine with an ethylene oxide/high molecular weight aliphatic amine condensate used as a corrosion inhibitor. US. Pat. No. 3,088,796 discloses an emulsion of an aliphatic amine with an ethy lene amine salt or a polyoggyethylene amine compound used as a corrosion inhibitor. U.S. Pat. No. 3,239,470 discloses the combination of a primary aliphatic amine having 14-22 carbon atoms, an ethoxylated amine condensate, and a phenolic lignin sulfonate used as a corrosion inhibitor. U.S. Pat. No. 3,418,253 discloses an aqueous dispersion of a straight chain aliphatic hydrocarbon primary amine with an ethoxylated amide used as a corrosion inhibitor. U.S. Pat; No. 3,418,254 discloses an aqueous dispersion of a straight chain aliphatic hydrocarbon primary amine with an ethoxylated alcohol used as a corrosion inhibitor.

The fatty amines noted above are useful in inhibiting corrosion in boiler systems and the like due to their unique balance of hydrophilic/hydrophobic properties and relatively high molecular weight. Fatty amines possess very desirable film forming properties, which enable them to escape the aqueous phase and deposit as nearly insoluble protective films on all surfaces inside a boiler system or the like. The insolubility of fatty amines in water, however, makes the initial application throughout the system unusually difi'icult. In order to be fed uniformly into the boiler water, these film forming fatty amines must first be thoroughly emulsified in water. Existing U.S. Pat. Nos., such as 2,712,531; 2,882,171; 2,956,889; 3,088,796; 3,239,470; 3,418,253; and 3,418,254, each of which are described above, suggest that primarily non-ionic emulsifiers can be used with film-forming fatty amines to inhibit boiler system corrosion. Other emulsifiers which can be used with fatty amines, but which have not previously been used in boiler system corrosion inhibition applications are cationics, such as amine salts, quaternary ammonium compounds, and other nitrogenous bases such as isothiouronium salts. Thiouronium salts per se are well known. U.S. Pat. No. 2,051,947 discloses the use of S- alkyl and S-aryl isothiourea salts as emulsifying agents. U.S. Pat. No. 2,156,193 discloses that guanyl and biguanyl compounds including guanylisothiourea possess considerable wetting and dispersing action. U.S. Pat. No. 2.302,762 discloses a process of forming isothioureas and that they may be used as emulsifying agents. U.S. Pat No. 2,302,885 discloses hydrohalides of substituted isothioureas and their preparation. U.S. Pat. No. 2,323,075 discloses a method of preparing thiouronium salts. U.S. Pat. No. 2,332,401 discloses the use of S-alkyl (long chain) isothiourea hydrochloride as a plasticizer. U.S. Pat. No. 2,640,079 discloses alkylbenzylthiouronium salts for use as bactericides and fungicides. U.S. Pat. No. 2,717,826 discloses the use of S-benzylisothiourea as an additive to fuel oil to retard caterioration. U.S. Pat No. 2,840,610 discloses a phenol substituted amine/carbon disulfide reaction yielding an alkylamine thiouronium salt for use as a corrosion inhibitor. U.S. Pat. No. 2,947,703, discussed above, discloses a higher alkyl substituted organic nitrogen base/thiourea emulsion, used for acid corrosion inhibition of ferrous metals. U.S. Pat. No. 3,088,849 discloses a protective surface coating formed by interacting a fluorocarbon-substituted isothiouronium halide with an alkali. U.S. Pat. No. 3,093,666 discloses the use of high molecular weight isothiouronium compounds per se for inhibiting corrosion to metallic surfaces. U.S. Pat. No. 3,116,327 discloses gamma-dimethylaminopropyl isothiourea and its salts for use as a pharmaceutical. U.S. Pat. No. 3,123,636 discloses the use of n-thiouronium halides as surfactants. U.S. Pat. No. 3,155,645 discloses the use of an isothiouronium salt of a bromohydrin ether as a dyestuff. U.S. Pat. No."3,260,748 discloses S-(4-vinylbenzyl) isothiourea and its chloride salt for use as a fungicide and as an intermediate for making 4-(mercaptomethyl) styrene. U.S. Pat. No. 3,311,639 discloses a process for making hydrochloride salts of S- methylisothiourea compounds for use as pharmaceuticals and as chemical intermediates. U.S. Pat. No. 3,321,519 discloses a process for making substituted aminoalkyl isothiouronium salts for use as a pharmaceutical. U.S. Pat. No. 3,407,229 discloses phenolcarbamoylethyl isothioureas for use as a pharmaceutical. U.S. Pat. No. 3,407,230 discloses benzamidoalkylisothioureas for use as a pharmaceutical.

SUMMARY OF THE INVENTION As is apparent from the above description of the prior art, the use of fatty amines to form a corrosion inhibiting film on metallic surfaces, such as encountered in boiler systems, is well known. The use of an emulsifier to allow feeding of the otherwise insoluble fatty amines at a fixed rate into the boiler water is also well known. However, the only emulsifiers that have been used successfully prior to this invention have been nonionics such as ethoxylated amines. The disadvantages of previous emulsifiers such as ethoxylated amines is that upon breakdown of the emulsion, the emulsifier remains in the boiler water and accumulates without degrading, thus reducing the efficiency of the boiler system. In sharp contrast, the novel composition claimed in this invention uses an emulsifier which degrades, upon continued heating, into volatile fractions, which thus do not accumulate within the boiler water. We have discovered novel cationic fatty amine emulsions which are stable until subjected to heating, at which time they break down to allow the fatty amine to enter the vapor phase and thus be carried throughout the boiler system, coating all exposed metallic surfaces thereof with a corrosion inhibiting film.

It is an object of this invention to provide a novel method for inhibiting corrosion in boiler systems by adding to the boiler water a stable, water-soluble emulsion of fatty amines with one or more cationic emulsifiers so that said emulsion is fed uniformly into the boiler water, heating the boiler water so that the said emulsion is broken down and the fatty amines enter the vapor phase, and having the fatty amines carried throughout the system while in the vapor phase, so as to deposit a fatty amine film on all exposed metallic surfaces of the boiler system.

Other objects of this invention will become apparent from the further disclosures herein. It is intended however, that the disclosures herein do not limit the invention but merely indicate preferred embodiments thereof, since various modifications within the scope of this invention will become apparent to those skilled in the art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Useful fatty amines include saturated n-alkyl amines containing 12 to 22 carbon atoms; unsaturated n-alkyl amines having a saturated backbone containing 12 to 22 carbon atoms with l or 2 unsaturated moieties on the backbone; branched alkyl amines containing 12 to 22 carbon atoms; mixtures of any or all of the above; and hydrogenated mixtures of any of the above unsaturated amines. Examples of useful fatty amines include, but are not limited to: dodecylamine, tridecylamine; tetradecylamine; pentadecylamine; hexadecylamine; heptadecylamine; octadecylamine; nonadecylamine; eicosylamine; heneicosylamine; docosylamine; hydroxyethylhexadecylamine; hydroxymethyldodecylamine; diethyl-hexadecylamine; dimethyl-tetradecylamine; triethyl-tridecylamine; tallow amines; hydrogenated tallow amines. The preferred fatty amines for utilization in this invention are octadecylamine and hydrogenated tallow amines. These fatty amines will be present in the composition of this invention in from about 8 to about parts by weight, and preferably from about 8 to about 12 parts by weight.

Useful cationic emulsifiers are the salts of nitrogenous non-quatemary bases containing at least one sulfur atom, and in particular isothiouronium salts having the general formula:

ronium chloride, eicosyl isothiouronium sulfate, hydroxymethyldodecyl isothiouronium acetate, triethyl-tridecyl isothiouronium bromide,

hydrogenated tallow isothiouronium chloride. The preferred cationic emulsifiers for utilization in this invention are dodecyl isothiouronium chloride and paraffin wax isothiouronium chloride. The cationic emulsifier will be present in the composition of this invention in from about 1 to 7 parts by weight, and preferably from 1 to about 4 parts by weight.

In order to maintain stability of the emulsion where the boiler water contains inorganic salts such as phosphates, and/or is at a high temperature, a straight chain aliphatic acid of C which has been ethoxylated with from 2 to 30 moles of ethylene oxide may be added to the emulsifier. The preferred stabilizer additive is octadecanoic acid ethoxylated with from about 5 to about 25 moles of ethylene oxide. The emulsion stabilizer will be present in the composition of this invention in from 0 to about 7 parts by weight and preferably from 0 to about 3 parts by weight. It should be noted that the preferred emulsion stabilizer is difficult to dissolve in water and therefore is not suitable for use as an emulsifier in the composition of this invention.

The foregoing components are combined with water to form a novel emulsion which is then diluted with water to form a steam-corrosion inhibiting composition containing from about 1 percent to about 25 percent by weight of solids.

The steam-corrosion inhibiting composition may be utilized in the following novel manner. Said composition is. added to the water in the boiler system by direct addition to the water storage tank, by feeding into water being added to the water storage tank, or by any other means, so that a ratio of from about 0.10 percent to about 2.0 percent by weight of said composition to the weight of the boiler water is maintained. The boiler water is then heated sufficiently to break down the emulsion into its component parts. Further heating of the boiler water will cause the fatty amine component to enter its vapor phase and become dispersed throughout the boiler system, whereupon it will become deposited as a film upon all exposed metallic interior surfaces of the system. Said film will then inhibit corrosion of the said surfaces caused by the steam passing across them. Although the film-coating process is independent of the steam generation, it is most frequently conducted simultaneously therewith.

The temperature at which the boiler system is functioning is not of importance as long as it is sufficient to break down the emulsion and vaporize the fatty amine. Thus, under pressures less than one atmosphere, the fatty amine will enter the vapor phase at a lower temperature and conversely, in a high pressure system, a higher temperature will be required to vaporize the fatty amine.

EXAMPLE 1 Preparation of an emulsifier within the scope of this invention A mixture of C -dodecyl chloride, (*This is a mixture of C1248 chain which is predominately C and sold as such.) 61.6 g., thiourea, 57 g., and ethyl alcohol, 200 g., was refluxed until a clear colorless solution was obtained. The reaction was then allowed to proceed closer to completion by refluxing for an additional 6 hours. Upon cooling, a heavy precipitate formed. The solid 38.6 g., assumed to consist primarily of unreacted thiourea, was filtered off, and the alcoholic filtrate, containing 79.7 g. of solids, preserved for evaluation purposes. The filtrate solids were determined to be dodecyl isothiouronium chloride. The product was identified by its strong infrared absorption at 1,645 cm, believed to originate from a moiety containing the amidino-radical, C(=NII)-NI-I,.

EXAMPLE II Emulsification of octadecylamine with dodecyl isothiouronium chloride octadecylamine, 18 g., was blended with the product of Example I, 2 g., (net, i.e., after evaporation of the alcoholic solvent) and subsequently ground in a por celain mortar until the two components were thoroughly mixed. Distilled water, 80 g., was then added dropwise and the grinding procedure continued until a uniform white emulsion was obtained. Care was taken to avoid the generation of foam during the later stages of the emulsification process. The emulsion was then divided into 2 parts and diluted to 16.6 and 7 percent solids," respectively, and the samples used for evaluation purposes. At 7 percent solids, the emulsion was very liquid, almost comparable to milk, and could be diluted infinitely with distilled water. No sign of phase separation occurred in 0.5 percent solutions of this emulsion in distilled water. The 16.6 percent emulsion had a cream-like appearance and showed the same characteristics as the 7% emulsion.

EXAMPLE III Emulsification of hydrogenated tallow amine with dodecyl isothiouronium chloride A mixture of fatty amine, (Armeen HTD, Armour Chem. Co.), 18 g., and the product of Example I, 3 g., was blended with water, 180 g., under continuous agitation. A small fraction of this quantity of water was added initially along with the fatty amine; the remainder was added slowly over a period of 1 hour. A viscous paste-like material formed under these conditions. An additional 3 g. of the emulsifier was then added, and the resulting product kept under slow agitation for 4 hours at 60-70C to yield a smoothly-flowing white emulsion.

EXAMPLE IV(a) Preparation of a modified version of dodecyl isothiouronium chloride Dodecyl chloride 2. This is a mixture of C chains which is predominantly C and sold as such. 218.5 g., thiourea, 152.2 g., and ethyl alcohol, 400 g., were allowed to interact at 80C under reflux conditions until the water-solubility test carried out with small samples of the reaction mixture according to the procedure described in Example IV(b) indicated that dodecyl chloride was converted nearly completely into soluble isothiouronium salts. The product was then isolated as described in Example I for C 2.1g dodecyl chloride. Example IV(b) Water-solubility test This test was developed as a control method for the production of dodecyl isothiouronium chloride from dodecyl chloride and thiourea, and is based on the water-insolubility of dodecyl chloride.

Equipment: Graduated test tube, centrifuge tube or cylinder (50 ml. size used on lab. scale reaction).

Procedure: 30 ml. of a 10% NaCl solution was placed in the graduated tube; 10 ml. of the alcoholic reaction mixture (after settling of the undissolved thiourea) are then mixed with the salt solution. (Because of the high content of unreacted thiourea which was dissolved in hot alcohol, but precipitates at room temperature, the sample may solidify in the sampling pipet. If this occurs, the sample can be recovered by warming the salt solution and drawing it up into the pipet several times, and by keeping the pipet in a hot water bath at l 00 C).

The product/salt mixture yields a cloudy white solution at room temperature; as product concentration increases however, a precipitate will form in larger quantities.

The graduated tube containing the product/salt mixture is then heated in a water bath until a clear solution is obtained. If any unreacted dodecyl chloride is present in the reaction mixture, it will reveal itself by forming a separate layer on the surface of the water/ salt solution. Measuring the volume of unreacted dodecyl chloride thus affords a semi-quantitative estimate of the progress of the reaction. In the final stage, no dodecyl chloride will separate out at 5060C. The mixture can then be centrifuged in order to facilitate the detection of any residual amounts of dodecyl chloride, which may have escaped the natural gravimetric separation. All samples are compared to a blank obtained by mere physical blending of the reagents mentioned above.

Example V Emulsification of octadecylamine with a modified version of dodecyl isothiouronium chloride octadecylamine, 9 g., was blended with the product of Example IV(a), l g. (net, i.e., after evaporation of the alcoholic solvent), and subsequently ground in a porcelain mortar until the two components were thoroughly mixed. Distilled water, g., was then added dropwise and the grinding procedure continued until a uniform white-creamy emulsion was obtained. Care was taken to avoid the generation of foam during the later stages of the emulsification process. No sign of phase separation occurred in 0.5 percent solution of this emulsion in distilled water.

EXAMPLE VI Preparation of an emulsifier within the scope of this invention A mixture of chlorinated paraffin wax containing 40-42 percent chlorine by weight, 89 g., thiourea, 34 g., and acetic acid, 200 g., was refluxed for 8 hours at 122C. Ether was then added to the reaction mixture at room temperature in order to extract the acetic acid and unreacted thiourea. Filtration of the ether/product mixture yielded a light-brown semi-solid material (78 percent yield) which was found to be completely soluble in water at low concentrations.

EXAMPLE VII Emulsification of octadecylamine with paraffin wax isothiouronium octadecylamine, 10 g., was blended with the product of Example V1, 2.5 g., and subsequently ground in a porcelain mortar until the two components were thoroughly mixed. Distilled water, 90 g., was then added dropwise and the grinding procedure continued until a uniform creamy-white emulsion was ob- M mortar and pestle EDTA Ethylenediamine tetra-acetic acid SP tribasic sodium phosphate TEA triethanolamine tained. Great care was taken to avoid the generation of TPP triphenyl phosphate foam during the later stages of the emulsification HX 1,2-hexanediamine process. No sign of phase separation occurred in 0.5 SA=salicylic acid percent solution of this emulsion in distilled water. OA oxalic acid In the following examples emulsions of the fatty Pl-lA phthalic acid amine and emulsifier were prepared. These examples 10 T 3 Elhoduomeen (Amollfflmodifiecl are summarized in the following two tables where there polyacrylamide) is recorded for each example the amine, the emulsifier, H Homogenizer the stabilizer where used, the method of mixing and the CP35 Cyanamer P-35 (polyethoxylated aliphatic stability of the resulting emulsion. l5 diamine) The stability tests were carried out by placing h at and agitate between 1 to 10 parts of weight of the emulsion into ap- LTM-N lauryl trimethylene ammonium chlorIde proximately 100 grams of the test medium which was CPA Noniomc polyacrylamide catiomzed with N- distilled water, tap water, cold and hot (80C) salt solumethylol dimethylamme tion andobserving the effects of this dilution upon the ST ethoxylated Stearic acid of 39 percent by emulsion. Then the consistency of the final mixture was Weight ethylene oxide observed. Where stability upon dilution with distilled IMD lmldazoline which Is the reaction product of water was not obtained, it was concluded that the initial quim lar amounts Of hydroxyethyl emulsification of the amine was incomplete. ethylenediamine and oleIc acid.

As the use of these compositions on occasion LAO lauryl alcohol ethoxylated with 12 moles of requires stability under more severe conditions, such as ethylene oxide. in the presence of salts, selected compositions of the HTAA=HYdfgenated allow amine acetate emulsified amines were also tested for their stability HTA=HydY8enated tanow amme towards inorganic salts and towards hot salt solutions. a t S ution an aqueous Solution of:

In the tables, the following symbols or abbreviations .75 percent by weight of mono and dI-sodium are used: phosphate T t water 0.25 percent by weight of sodium hydroxide D distilled water 0.50 percent by weight of sodium sulfite ODAM =octadecylamine 0.50 percent by weight of ethyelene diamine tetra- B mechanical blender 3 acetic acid TABLE I I l Emulsi- Method Stability to Example Water Water, Amine Amine, Emulsifier ficr, Stabilizer Stabilizer, of No. used gms. used [HHS- used gms. used gins. mixing Distilled water Tap water VIII T 90 ODAM 9 Same asin EBLVI... l B Emulsifies Emulsifies. L D 90 ODAM 0 Same as in Ex. I 1 M Uniform Uniform dispersion. dispersion. X ,.t. D 83 ODA 1 EDTA 1 M Emulsifies Nodispersion. XL D 83 ODAM 1 P l M No dispersio D0. XIL. I) 33 ODAM l TEA l M D0. XIII. l) 83 Ol)AI\l 1 TPP 1 M Do. XI\' 4 1) no ODAM 1 NaOH 0.5 M

dispersion. xvu I) ma ()DAM 1 UK 0.5 M Little 0 dispersion. dispersion. XVI I) H11 5 ()UAM 1 SA 0.5 M Uniform Emulsifios.

dispersion. XYll l) XELI'I ()l)/\I\l 1 0A 0.5 M (l0 D0. :\'III 1) ms ()DAM I lllA 0.5 M No No dispersion. dispersion .\l.\ 1) U0 ()DAM 10 Same asin Ex. IV... 2.5 M Uniform Uniform dispersion. dispersion.

TABLE II Stability to IillllliSi lvlitllfiti Example Water W:I|.I-I- Alllilli AIIIiIII- litl', Stabilizer Stabilizer, ||()t.\'1l|i.$llill NII. llSt'Il unis IIsI-Il tllllh'i l'IIIIIIIsiIivI- llSltl KIIIS. IIs'l'Il KIIIS. mixing Salt solution tion (940" 4 .l

XX I) .ll) UliAM .l (IIA. M Nnrlispvrsiun NUtilSlNl'Slllll, XXI l) 37. 7X ()DAM lll SzIIIIt' HS in Ex. lVzt .\"l() 1. li ll l'lInlllsilii-s. XXII l) 87.78 ()I)AM It), (i() CV35 1 ll XXII] l) 87.78 ()HAM ll) ,IIII J H'IU 2 M XX I) .ll) ()DAM .l STU, V, l ,7 M XXV. I) 37. TX ()DAM 10 Same as in Ex. lVn. 3 715 Slt) 1 M XXYL l) 8&5 {GUAM I1 IH'IO v 1.5 ll'l l-HlIA 5 1 tion occurred. tion occurred. XX\ 11., I) Hi! TA 10 No dispersion." No dispersion. XXVIIL, I) fill lllA l0 ""410 Do. XXIX.. l) 87. TN ODAINI ll) Samcnsin Ex. IVZL. 2. Emulsilics Little (.l1ll]isinn. .10 ODAM .l E-Tl3 1 M Nodispursion Nodisplersiou. 8E) lITA l0 ll'IAA l. M Ill) Du It is apparent from the results shown in the tables above that complete emulsification of the octadecylamine as judged by the above-mentioned solution test was only achieved when at least one of the emulsifiers cited in the relevant claims of this application were applied. Stability of the emulsion towards salt solution could be achieved by means of selected stabilizers such as ethoxylated stearic acid. It should be noted also that that the pressure solely of the compounds classed as stabilizers in this application was not sufficient to bring about emulsification of the fatty amine.

What we claim is:

l. A method of steam-corrosion inhibition in boiler systems consisting essentially of:

A. adding from about 0.10 percent to about 2.0 percent by weight of a steam-corrosion inhibiting composition which comprises an aqueous emulsion containing from about 1 percent to about 25 percent by weight of solids consisting of:

1. from about 8 to about 20 parts by weight of a fatty amine selected from the group consisting of a. one or more saturated n-alkylamines containing from about 12 to about 22 carbon atoms, b. tallow amine, c. hydrogenated tallow amine, d. branched alkyl amines containing from about 12 to about 22 carbon atoms, and e. a mixture of any of the above said amines;

2. from about 1 to about 7 parts by weight of a cationic emulsifier having the general formula RSC=NH-HR where R is an alkyl hydrocarbon having from about 10 to about 22 carbon atoms and R is one of a group consisting of an acetate, a bromide, a chloride, and a sulfate; and

3. from 0 to about 7 parts by weight of an emulsion stabilizer consisting of an ethoxylated straight chain aliphatic acid containing from about 14 to about 20 carbon atoms in the chain;

B. heating the boiler water containing said composition thereby breaking down the said composition into its comporent parts;

C. further heating said boiler water so that the fatty amine component of said composition enters its vapor phase;

D. dispersing said fatty amine while in its vapor phase throughout said boiler system; and

E. depositing said fatty amine as a steam-corrosion inhibiting film upon exposed metallic interior surfaces of said boiler system.

2. A method according to claim 1 in which said fatty amine is octadecylamine.

3. A method according to claim 1 in which said fatty amine is hydrogenated tallow amine.

4. A method according to claim 1 in which said cationic emulsifier is dodecyl isothiouronium chloride.

5. A method according to claim 1 in which said cationic emulsifier is paraffin wax isothiouronium chloride.

6. A method according to claim 1 in which said emulsion stabilizer is octadecanoic acid ethoxylated with from about to about 25 moles of ethylene oxide.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,717, 63

DATED February 20, I973 lN\/ ENTOR(S) Gerhard w. Scherf and Gary c. Pfaff it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Under Abstract, l ine 6, ethoxyiated" should be --ethoxylated--.

l ine 32, "amine" should be --amino--. Column 2 l ine l7, "caterioration" should be --deterioration- Column l ine after "to" insert the word "about"; Column i, 1 ine 59 "chain" should be -chains--. Column 5,

l ine S0, should be Column 5, l ine 50, before "This" insert Column 5 l ine 5l after "such." insert Column 8, l ine l5 "the" should be --HT-- Table l Example XIX, under heading "Emuls i fier used", Same as in Ex. IV" should be --Same as in Ex. Vl Column 9, l ine 9, delete "that" (second occurrence) Column 9, l ine 9, "pressure" should be --presence-- Column l0, l ine l l "comporent" should be --component--; Column l0 l ine 32 the superscript "5" should be -5--.

Signed and Sealed this Eleventh Day 0i January 1977 Column l,

'[SBAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (vmmissinner oj'Patentx and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,7l7, r33

DATED February 20, l973 INV ENTOR(S) Gerhard W. Scherf and Gary C Pf ff It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Under Abstract, l ine 6, "ethoxyiated" should be --ethoxylated-- l ine 32 "amine" should be -amino--. Column 2 l ine l7, "caterioration should be -deterioration- Column l, l ine l after "to" insert the word "about"; Column l ine 59 "chain" should be -=-chains- Column 5, 0 line 50, should be Column 5, line 50, before "This" insert Column 5 l ine 5i after such." insert Column 8, l ine l5 "the" should be --HT--. Table l, Example XIX, under heading "Emulsifier used", "Same as in Ex. lV" should be --Same as in Ex. VI Column 9,

l ine 9, delete "that" (second occurrence) Column 9 l ine 9 'pressure" should be --presence--. Column l0, l ine l l "comporent" should be 9 --component--; Column l0, line 32, the superscript "5" should be --5--.

Signed and Scaled this Eleventh Day Of January 1977 Column l,

[SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arte-sting Office Commissioner ofPalents and Trademarks Q

Claims (8)

1. A method of steam-corrosion inhibition in boiler systems consisting essentially of: A. adding from about 0.10 percent to about 2.0 percent by weight of a steam-corrosion inhibiting composition which comprises an aqueous emulsion containing from about 1 percent to about 25 percent by weight of solids consisting of:

1. from about 8 to about 20 parts by weight of a fatty amine selected from the group consisting of a. one or more saturated n-alkylamines containing from about 12 to about 22 carbon atoms, b. tallow amine, c. hydrogenated tallow amine, d. branched alkyl amines containing from about 12 to about 22 carbon atoms, and e. a mixture of any of the above said amines;

2. from about 1 to about 7 parts by weight of a cationic emulsifier having the general formula where R is an alkyl hydrocarbon having from about 10 to about 22 carbon atoms and R1 is one of a group consisting of an acetate, a bromide, a chloride, and a sulfate; and

2. A method according to claim 1 in which said fatty amine is octadecylamine.

3. from 0 to about 7 parts by weight of an emulsion stabilizer consisting of an ethoxylated straight chain aliphatic acid containing from about 14 to about 20 carbon atoms in the chain; B. heating the boiler water containing said composition thereby breaking down the said composition into its comporent parts; C. further heating said boiler water so that the fatty amine component of said composition enters its vapor phase; D. dispersing said fatty amine while in its vapor phase throughout said boiler system; and E. depositing said fatty amine as a steam-corrosion inhibiting film upon exposed metallic interior surfaces of said boiler system.

3. A method according to claim 1 in which said fatty amine is hydrogenated tallow amine.

4. A method according to claim 1 in which said cationic emulsifier is dodecyl isothiouronium chloride.

5. A method according to claim 1 in which said cationic emulsifier is paraffin wax isothiouronium chloride.