BE570372A - - Google Patents

Description

       

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   The present invention relates to lubricants for pipe threads, and in particular to lubricating compounds suitable for sealing or sealing the joints of threaded pipes at risk of those used for drilling oil wells, where the joints must remain. waterproof under high pressure. The pressure on the pipe joints is considerable where there is a deep borehole.



   Threaded joints are not pressure tight under high pressure unless the threads are coated with a suitable sealing compound. Generally speaking, the sealing compounds used take the form of lubricating grease compounds containing powdered metallic zinc, but even these compounds are not entirely satisfactory because they allow leakage through the seals under extreme pressures.

   The, Amercan Petro- leum Institute gives the requirements for a lubricant for high pressure pipe threads and indicates that a suitable lubricant of this kind should have the following characteristics:
1- suitable lubricating qualities to prevent scratching of threaded connections during fitting;
2- no tendency to disintegrate, no radical change in volume at temperatures up to 300 F;
3- no tendency to become excessively fluid at temperatures as high as 300 F;
4- sufficient sealing properties to prevent leakage at temperatures as high as 300 F;
5- absence of any disadvantageous instability and of any hardening or drying agent which will evaporate or oxidize, thus changing the properties of the net compound;

   
6- resistance to water absorption;
7. inert load sufficient to prevent leakage at pressures as high as 10,000 pounds per square inch;
8- easy brush application to pipe joints in cold weather.



   Recently, Esso Research and Engineering Company has provided a new class of lubricating compounds which include mineral lubricating oil or synthetic lubricating oil and a complex of an organic metal salt and a metallic soap. . The soap is a metallic soap of a carboxylic acid containing 12 to 30 carbon atoms per molecule, and the salt is a metallic salt of an aliphatic carboxylic acid of lower molecular weight than the C12 to C3O carboxylic acid. This salt is preferably a salt of a C1 to C6 aliphatic carboxylic acid and the complex preferably contains more than 7 moles of the salt of the lower carboxylic acid for each mole of the C12 to C carboxylic acid soap. 30.

   The preparation of complexes of this general type and their use in lubricating oil compositions are developed in detail in British Patent 775,027. Lubricant-salt-soap complex-containing compounds of this general type have excellent lubricating qualities. They have a good consistency and a remarkable load bearing capacity. They have no tendency to decay or undergo a drastic change in volume at temperatures up to 300 F.



  They don't get excessively fluid at temperatures as high as 300 F, and they are resistant to water absorption. However, they cannot be used as such as lubricants for pipe threads to be used under extremely high pressures. It has now been found that a pipe thread lubricant having all of the desirable properties given by the American Petroleum Institute can be obtained if graphite and certain metals. powders are combined with lubricating oil compounds containing

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   soap / salt complexes of C8 to C30 carboxylic acids and salts of C1 to C6 aliphatic carboxylic acids.



   The present invention thus relates to a lubricating oil composition comprising:
1- a lubricating oil, this oil is preferably a mineral lubricating oil but. a synthetic lubricating oil, such as a polymer oil or a ballast type oil, can be used; or, an oil of vegetable or animal origin can be used;
2- a metal salt of a C1 to C6 aliphatic carboxylic acid;
3- a metallic soap of a C8 to C30 carboxylic acid;
4- graphite;
5- pulverized metal.



   The lubricating oil preferably represents the major proportion of the total composition but it can be present in any amount between 40 and 70% by weight of the total composition. Especially preferred are amounts of lubricating oil between 50 and 60% by weight.



   The salt / soap complex is preferably up to 5 to 30% by weight of the total lubricating oil composition, and the amount of graphite used is preferably between 5 and 25% by weight. of the total composition. Especially preferred are amounts of graphite between 10 and 20%.



   The pulverized metal used is preferably zinc or lead dust or a mixture of the two. The total amount of metal sprayed can range from 2 to 30% by weight of the total fat composition, with amounts from 7 to 20% being especially preferred. Carboxylic acids having 8 to 30 carbon atoms per molecule can be derived from synthetic materials or from saturated or unsaturated natural products. The fatty acids normally used in the manufacture of conventional fats, especially the more saturated acids, are preferred.

   Examples of such acids are stearic, hydroxy stearic, such as 12-hydroxy stearic, di-hydroxy stearic, poly-hydroxy stearic and other saturated hydroxy fatty acids, arachidic acid, fish oil acids and of hydrogenated tallow. However, unsaturated acids, such as oleic, ricinoleic and the like, can also be used. The acids preferably contain from 18 to 22 carbon atoms per molecule. Acids derived from coconut oil are especially preferred.



   Suitable lower molecular weight acids are saturated and unsaturated aliphatic monocarboxylic and polycarboxylic acids having 1 to 6 carbon atoms, such as formic, acetic, propionic, a-crylic, adipic and the like, including their hydroxy derivatives. , such as lactic acid, etc. Acetic acid is preferred.



   The alkaline earth metals, especially calcium, barium and magnesium, are most valuable in the preparation of the salts and soaps used in the present invention. These metals allow the production of greases with outstanding load bearing characteristics and satisfactory structural stability at elevated temperatures and under mechanical stress without the use of common stabilizers and extreme pressure.



   Other metals useful for the preparation of the salts and soaps of the complexes used in the present invention are the heavy metals of groups I, II and IV of the Periodic System of the Elements and nickel, cobalt, chromium, manganese, etc. and especially copper, zinc and lead, which can be used either alone or together with alkaline earth metals in

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 the preparation of the complexes. Lead increases their ability to support loads.



   The metallic elements of the complexes may be any of the metals mentioned above or the complex may contain two different metals.



   The complexes of the invention can be prepared by coneutralizing a mixture of the high and low molecular weight acids with suitable bases, especially the hydroxide and / or carbonates of the desired metals.



  This coneutralization phase is most suitably carried out in situ in the liquid solvent to which the complex is to be applied in real use. For example, the acid mixture can be neutralized in some or all of the lubricating oil forming the dispersant of a grease to be thickened by the complex. Likewise, the coneutralization can be carried out in a fuel oil or other dispersing fluids or solvents, the characteristics of which must be modified by the complex. The coneutralization is especially advantageous in cases where the salts have the same metallic component.

   Usually, the coneutralized material is heated to elevated temperatures of about 450 to 550 F or more, before use to dehydrate the product and to promote complex formation. When this heating phase is carried out in a liquid dispersant, the latter should have a boiling point higher than the heating temperature or the heat treatment should be carried out under pressure.



   Instead of using the high molecular weight fatty acids themselves, their esters can be employed. For example, glycerides or other hydrolyzable derivatives, such as nitriles, which can be used as starting materials. Animal or vegetable oils and fats constitute materials of this type. Likewise, the low molecular weight carboxylic acids can be employed in the form of suitable esters, such as those of glycerin ethanol, or other hydrolyzable derivatives of the carboxylic acid, such as nitrates. Common conditions which aid in the saponification of these esters can be employed, followed by dehydration and alcohol removal.

   Esters of this type can be used, as described, in the case of neutralization, as well as in the case of separate formation of the two salts described below.



   The complexes of the present invention can also be prepared by previously and separately forming the high molecular weight soap / acid and / or the low molecular weight carboxylic acid salt, and by intimately mixing the soap and the salt. followed by heating, if necessary: This process is of interest especially when different metals are used as bases for the two components of salts.



   The lubricating oils used for the pipe thread lubricants of the present invention should preferably have a viscosity in the range of 60 to 2500 Universal Saybolt Seconds at 100 F and 35 to 150 S.S.U. at 210 F, a defrosting point of about +20 to -30 F, and a flash point of about 3500 to 650 F. Mineral lubricating oils can be used, as well as synthetic oils. synthetic hydrocarbon, hydrocarbon polymer, ester, complex ester, formal, mercaptal, polyalkylene oxide, silicone or the like, including particular oils, such as di-2-ethylhexyl sebacate, di azelate. -C8-Oxo.



   EXAMPLE
An example of a lubricating oil composition according to the present invention was prepared with the following composition: by weight
7 'glacial acetic acid - 3.5 fatty acids from cqprah (mainly C8 to C14 fatty acids)

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5.8 hydrated lime
0.7 phenyl alpha-naphthylamine
53 mineral lubricating oil (distillate of mineral oil of the naphthenic type, having a viscosity of 55 S.S.U.

   at 210 F)
15 graphite
12 zinc dust (90-92 mesh)
3 lead powder (100 meshes minimum)
The lubricating oil composition was made by first preparing the salt / soap complex by loading the copra fatty acids, hydrated lime and mineral oil into a fire-heated cauldron equipped with a heating medium. stirring, and the mixture was heated to about 130 F. Glacial acetic acid was then added and heating was then continued until the temperature reached 500 F. At this point, heating was stopped and the fat was allowed to cool to 200 F with continual agitation. Then the fat was homogenized at a high shear rate on the Gaulin apparatus.



  Phenyl alpha-naphthylamine was added during the cooling cycle when the temperature reached about 250 F. Zinc dust, graphite and lead powder were added to the finished fat after homogenization. The grease had a post work penetration at 77 F of 265 mm / 10 and - an A.S.T.M. of 250 F.



   Tests on this fat composition were conducted on a probing apparatus with excellent results despite pressures on the order of 1470 pounds per square inch. No loss of lubricant occurred and there was no seizure of the threads when unscrewing the threaded joints.



   In summary, the present invention provides a lubricating oil composition comprising a lubricating oil, a small proportion of a complex of a metal soap of a C8 to C30 carboxylic acid and a metal salt of a. C1 to C6 aliphatic carboxylic acid a small proportion of graphite and a small proportion of one or more powdered metals.



   Preferred compositions contain 5 to 30% by weight of the soap / salt complex, 5 to 25% by weight of graphite and 2 to 30% by weight of the powdered metal.



   It should be understood that the lubricating oil composition of the present invention may contain other components, such as oxidation inhibitors, colorants, metallic deactivators, corrosion preventers or deodorants.



   CLAIMS.



   1. A lubricating oil composition, comprising a lubricating oil, a small proportion of a complex of a metal soap of a C8 to C carboxylic acid and a metal salt of an aliphatic carboxylic acid. C1 to C6 a small proportion of graphite and a small proportion of one or more powdered metals.


    

Claims (1)

2. A lubricating oil composition according to claim 1, wherein the lubricating oil constitutes between 40% and 70% by weight of the total composition. 3. A lubricating oil composition according to claims 1 or 2, wherein the graphite represents between 5 and 25% by weight of the total composition. 4. A lubricating oil composition according to any one of claims 1 to 3, wherein the pulverulent metals represent between 2 and 30% by weight of the total composition. 5. A lubricating oil composition according to any one of the preceding claims, in which there is also a small amount of phenyl alpha-naphthylamine. <Desc / Clms Page number 5> 6. A lubricating oil composition according to any preceding claim, wherein the soap and salt are alkaline earth metal salts and soap. 7. A lubricating oil composition according to any one of the preceding claims, in which the C8 to C30 carboxylic acid consists of a mixture of acids obtained from coconut oil. 8. A lubricating oil composition according to any preceding claim, wherein the salt is a salt of acetic acid. 9. A lubricating oil composition as described above.