NL9001145A - LUBRICANT. - Google Patents

Description

Lubricant

The invention relates to lubricants which can advantageously be used for a wide range of applications, especially for applications involving extreme pressures and workloads.

Lubricants are materials that can be placed between opposite solid surfaces, e.g. the surfaces of machine parts, to prevent these surfaces from touching and to facilitate relative movement between them, if necessary. As a result, these lubricants should usually have hydrodynamic properties, that is, the ability to build up an internal pressure sufficient to absorb the load on the opposite surfaces, as well as friction reducing and wear reducing properties.

Many lubricants are in the form of lubricating oils and greases and can be used for a wide variety of applications. Lubricating oils can be based on petroleum derivatives, on animal or vegetable oils or on synthetic materials such as polyalkylene glycols, dibetic esters, phosphate esters, silicones, silicate esters and the like. Lubricating greases are combinations of such oils with thickeners such as, for example, metal soaps, modified clays, fine silica and the like, and / or fillers such as, for example, asbestos, graphite, metal carbonates, hydroxides, oxides, phosphates, sulfides and the like. In addition, lubricating oils and greases may also contain special additives, e.g. to increase oxidation and corrosion resistance and to improve such properties as adhesion, film strength and water washout resistance.

Other lubricants have particulate solids as an essential ingredient and can be used in cases where the opposing surfaces are exposed to extreme pressures and work loads during use. Such particulate solid lubricants can be inorganic compounds with laminar crystal grids such as crystalline graphite, molybdenum disulfide and the like, other soft inorganic compounds such as lead oxide, lime, talc, bentonite and the like, soft organic compounds such as soaps, waxes and fats, soft polymers such as poly (tetrafluoroethylene) or poly (chlorofluoroethylene) and the like, or crushable metals such as aluminum, copper, lead and the like, or fragile metals such as zinc. All these solid lubricants have in common that they are plastic, elastic, crushable or fragile and that they are generally soft in the sense that their mechanical properties have a rather low yield point, or at least a yield point that is less than the forces due to pressure or workload exerted on them during use. The particulate solid lubricants can be used as such or as dispersions in oils, greases or even water-based carrier media.

The present invention now provides lubricants consisting of dispersions of solid particles in a carrier medium. Contrary to what the prior art teaches, however, the solid particles in the lubricants according to the invention consist of substantially round and smooth particles of a hard, abrasion and break-resistant, thermally stable and chemically inert material. Surprisingly, agents containing such particles will have excellent lubrication properties under high pressure and workload conditions, as well as under other lubrication conditions, precisely because the yield limits of the mechanical properties of the particles are high enough to withstand the forces applied thereto during use.

It is therefore an object of the invention to provide lubricants capable of withstanding high forces from pressures and work loads during use. Another object is to provide lubricants that can be used in a variety of applications, including bearings and threaded joints, regardless of the occurrence of high pressures and workloads therein.

The invention will now be explained in more detail.

The solid particles in the lubricant according to the invention must be made of a hard, abrasion and break-resistant, thermally stable and chemically inert material in order to withstand extreme pressures and workloads during use. Many ceramic materials will meet these conditions, although some other materials may also be suitable. Furthermore, the particles will have to be substantially round and smooth to reduce friction and wear during use or to otherwise participate or contribute to the lubrication function. Their average particle size should be small, i.e. less than about 100 microns in diameter for practical purposes and preferably between about 1 and about 60 microns, although particles outside this range can still be used for some agents. Furthermore, the deviation from the average particle size in a given amount of material should preferably be as small as possible in order to form a uniform layer of separating and supporting material between the opposite parts, regardless of whether the particles are small or large take up part (less than or more than approx. 25%) of the volume of a lubricant.

Good results have been obtained with particles produced by Zeelan Industries Ine. in St. Paul, Minnesota, U.S.A., are manufactured and sold under the Zeeospheres brand. These Zeeospheres are thick-walled hollow spheres of a ceramic silica-alumina material with a hardness of 7 on the Mohs scale, a softening point of approx. 1200 ° C and a specific gravity (ASTM D-153) between 2.4 and 2.0 g / cm3. Their compressive strength is reported to be greater than 60000 psi (i.e. greater than 4200 kg / cm2) but may in fact be significantly higher. The Zeeospheres are available in various types, which differ in average particle size; specific weight; and specific surface. According to the manufacturer's published data, some of these types can be specified as follows:

TABLE

Zeeospheres, type 200 400 600 800 850 X-60

Average particle size, microns 4.9 6.9 9.9 27.1 55.9 2.9 Specific gravity (g / cm3) (ASTM D-153) 2.3 2.2 2.1 2.0 2.0 2.3 specific area (m2 / cm3) 1.52 1.24 1.03 0.62 0.18 2.31

While experiments with type 200 Zeeospheres have given good results, other types can be used with the same or even greater benefit depending on the lubricant in which they are used and the application for which the lubricant is used.

The solid particles, as defined above, can be used in amounts of at least 0.1% by weight of the total lubricant. The upper limit will be determined by practical considerations, including the intended use of the lubricant, and by the nature of the carrier medium.

The solid particles are incorporated in a carrier medium which can be any petroleum based medium, organics based, silicone based or even water based. Preferred media are those which have lubricating properties of their own, such as, for example, the known lubricating oils and greases. The lubricating oils to be used as the carrier medium can be of any conventional type and can thus be based, for example, on petroleum derivatives, animal or vegetable oils, or on synthetic materials, such as polyalkylene glycols, esters of dibasic organic acids, phosphate esters, silicones, silicate esters and such. The lubricating greases to be used as the carrier medium will usually consist of a combination of such oils with thickeners, such as, for example, metal soaps (salts of alkali metals or alkaline earth metals with monobasic or polybasic aliphatic acids, such as sodium, lithium, barium stearates, hydroxystearates, - oxalates, sebacinates and the like), modified clays, fine silicas and the like, and / or fillers or additives such as, for example, asbestos, graphite, metal carbonates, oxides, hydroxides, phosphates, sulfates, sulfides and the like. Such thickeners, fillers and additives are commonly used, where applicable, in gel or fine particulate form, and care must be taken that the fillers and additives are non-abrasive and will not agglomerate on their own or in combination with other substances. loss of their small particle shape.

In the case where a lubricating oil or grease is used as the carrier medium, the said solid particles can preferably be used in an amount of about 50-60% by weight, based on the total lubricant. This means that the agent may preferably contain about 50-60% by weight of particles of a hard, abrasion and break-resistant, thermally stable and chemically inert material and about 40-50% by weight of a lubricating oil or grease.

In some instances, yet another particulate lubricating material such as molybdenum disulfide, other metal sulfides, graphite, fatty esters, fluorine-containing olefin polymers, metal oxides, hydroxides, carbonates, phosphates, sulfates, chlorides, bromides, -iodides or combinations thereof, metal stearates, oxalates, sebacinates, metal salts of monobasic or polybasic aromatic acids, malleable metals such as aluminum, copper and lead or any other material which is compatible with the carrier medium and is insoluble therein, additionally be included in the lubricant. These additional materials, when in fine particulate form, have no abrasive action and will not agglomerate on their own or in combination with water and other materials, losing their fine particulate form or, where relevant, their functionality.

If such additional lubricating materials are used, they should preferably be present in an amount of not less than about 0.1% by weight of the total lubricant. An amount of about 1-5 wt.% Will suffice for many purposes and is therefore preferred. In that case, the total lubricant may be about 45-59% by weight of particles of a hard, abrasion and break-resistant, thermally stable and chemically inert material, about 1-5% by weight of particles of another lubricating material, and about 40- 50% by weight of carrier medium.

Furthermore, conventional additives such as corrosion inhibitors and anti-oxidants, adhesives and wetting agents can be included in the lubricant, usually as a component of the carrier medium, provided they do not significantly affect the functioning of the major components.

The lubricants of the present invention can be used for a wide variety of applications, especially those where high pressures and workloads as well as high temperatures are involved. However, the range of possible applications is not limited to high workloads or high temperatures, and use at moderate or even low workloads and moderate or low temperatures can be equally beneficial. Furthermore, the lubricants can be used without regard for relative movement between the parts to which they are applied; this means that the lubricants of the present invention will function as well in high relative speed cases as in low relative speed cases between the lubricated parts, where only a separating function is required. As a result, the lubricants can be used to lubricate all types of machinery, including armies, and construction and mining equipment.

In the oil and gas production industry, special types of lubricants are used to provide threaded pipe fittings between the male and female parts. This is done to prevent such parts from becoming stuck or welded together and also, in many cases, to provide a liquid / gas tight seal therebetween during use. Such lubricants, (often referred to as "thread compounds"), ensure that the threaded couplings can be assembled and loosened many times during the construction of oil and gas wells, despite the high workloads imposed upon them. In addition, after assembling the threaded couplings, the lubricants should be able to provide a liquid / gas tight seal between the threaded parts, even if an oil or gas or drilling fluid or other liquid or gaseous material is subjected to high pressure through the coupled pipe or pipeline flows. It has been found that the lubricants of the present invention can meet all of these requirements.

Furthermore, in the oil and gas production industry, special types of lubricants are commonly used to lubricate threaded couplings in the drill rod of a rotary drill, couplings between ear tubes (rotary shoulder couplings or tool couplings), couplings between the lower component of a hearing tube and drill collar, couplings between a drill collar and a drill bit, and couplings between any other tool or device screwed in place above or below these parts. Such lubricants (eg, so-called "tool joint compounds" and "drill collar compounds") should ensure that the tubing and other devices are screwed together with a minimal tendency for continued tightening during drilling so that during this operation ensured the transfer of energy (torque) from pipe section to pipe section down the drill rod and further to the other equipment. It has been found that the lubricants of the present invention can meet such requirements and that they can be used for all of these different applications, including couplings between pipe rods and underground motors.

A presently preferred lubricant composition for use in armies is the following: Ingredients: weight ratio:

Zeeospheres, type 200 55

Lithium grease (NLGI No. 2) 42

Molybdenum disulfide 3 100

In this lubricant, the lithium grease is a dispersion of 7.5% lithium 12-hydroxystearate in petroleum oil.

Preferred lubricant compositions for use in threaded fittings are:

Ingredients: weight percentage:

Zeeospheres, type 200 57.0

Crystalline graphite 3.0

Carrier medium 40> 0 100.0

Ingredients; weight percentage:

Zeeospheres, type 200 57.0

Molybdenum disulfide 3, o

Carrier medium 40, q 100.0

In these lubricants, the carrier medium will usually be a lubricating grease (e.g. a dispersion of metal soap in oil), which contains a tacky substance, a humectant, an anti-corrosion agent and an anti-oxidant agent.

A preferred lubricant composition for use in casing fittings and all drilling applications is the following:

Ingredients: weight percentage:

Zeeospheres, type 200 57.0

Molybdenum disulfide 3, o

Carrier medium 40.0 100.0

In this lubricant, the carrier medium will have the same meaning as above.

Other compositions, especially to meet various needs, can be easily devised by a skilled person.

Furthermore, the lubricants according to the invention can also be used for applications where the term "lubricant" is not usually used, but where a certain lubricating function is nevertheless always present. Such applications are, for example, the use of these agents

M

as coolants in metalworking operations (such as, for example, cutting, pressing, drawing, honing, grinding and polishing) and the use of such agents as drilling fluids or drilling mud in drilling operations. In the latter case, the solid particles are preferably used in an amount of 5-10 parts by weight of the total agent. In other words, the drilling fluid or drilling fluid will contain about 5-10 parts by weight of particles of a hard, abrasion and break-resistant, thermally stable and chemically inert material and about 90-95 parts by weight of a conventional water-based medium for a drilling fluid, which medium further may include high specific weight fillers, thickeners, wetting agents and the like.

The invention is further illustrated by the following non-limiting examples.

EXAMPLE I

Lubrication of armies:

Lubricants that resp. 10 wt.%, 20 wt.%, 30 wt.%, 40 wt.%, 50 wt.%, 55 wt.%, 57 wt.% And 60 wt.% Zeeospheres type 200 in the above lithium lubricating grease (NLGI No. 2) were tested on Timken tapered roller bearings in a Sun Oil Company tester. The armies were rotated at high speed at temperatures deliberately aimed at decomposition of the petroleum lube grease.

Each test ended when the armies got stuck due to thermal decomposition of the grease. The time to seizure was measured and showed a gradual increase in the range of lubricants, starting with a Zeeospheres content of 10% and ending with a Zeeospheres content of 55%. The time for lubricants with 57% and 60% of Zeeospheres was equal to that of the lubricant with 55% of Zeeospheres. Inspection of the armies afterwards taught in all cases that no wear had occurred in the tests using lubricants containing 40% and more of Zeeospheres.

Another test was done with a lubricant containing 35 wt% Zeeospheres type X-60 and 65 wt% lithium grease (NLGI No. 2). The result was almost the same as that of the test with a 55% lubricant of Zeeospheres type 200.

A further run was made with a lubricant containing 30 wt% Zeeospheres type 200, 3 wt% molybdenum disulfide and 67 wt% lithium lubricating grease (NLGI No. 2). The result was almost the same as that of the test with a lubricant of 50 wt% Zeeospheres type 200 and 50 wt% lithium lubricating grease (without molybdenum disulfide).

Additional tests with similar lubricants as the latter, but in which the molybdenum disulfide was replaced by an equal amount of zinc oxide, respectively. zinc orthophosphate, calcium borate or graphite showed similar results.

EXAMPLE II

Lubrication and sealing of threaded fittings.

A lubricant containing 57.0 wt% Zeeospheres type 200, 3.0 wt% molybdenum disulfide and 40.0 wt% carrier medium (a lithium grease with adhesive substance and wetting agent, equivalent to the specifications of a grease according to NLGI no. 1) was used to lubricate and seal the threaded fittings of two test samples, each consisting of two tubes ("pin by pin pup joints") connected by an Atlas Bradford TC type fitting.

The coupling piece was made of steel type N-80 with an outside diameter of 2 7/8 inch and with metal to metal seals. The from. threaded couplings were assembled and loosened many times, plotting the torque and loosening torque used on each occasion against the time and number of revolutions plotted. the graphs showed that the tightening torques for successive screwing operations were nearly identical, indicating that the lubricant used was effective and that the threads, shoulders, and seals were not damaged by the assembly and loosening process. This was confirmed by visual inspection.

One assembled test sample was tested for sealing properties by filling it with nitrogen gas under high pressure and then immersing the object in a water bath. After a test period of 15.5 hours at an internal pressure of 12000 psi (840 kg / cm2), the coupling was found to be free of leaks. Thus, the lubricant used did not adversely affect the sealing of the coupling with metal to metal seals.

EXAMPLE III

In another test, a similar lubricant as in Example II was used to lubricate and seal the threaded fittings of a test sample, consisting of two 2 7/8 inch outer diameter tubes and N-80 steel, which are terminated by a coupling piece were connected together. The threads of the threaded fittings were non-sealing and showed leakage between the male and female parts after assembly. The couplings were assembled and detached ten times. No damage to the threads could be observed during inspection. Sealing properties were found by immersing the test sample in a water bath at an internal nitrogen gas pressure of 10,000 psi (700 kg / cm2) for 30 minutes.

EXAMPLE IV

Lubrication and sealing of rotating shoulder couplings.

A lubricant of the same type as in Example II was used to lubricate and seal the test sample threaded fittings, consisting of two 5.5 inch drill pipe pieces, interconnected by a rotary coupling with shoulders and API threads. The couplings have been assembled many times to a recommended torque and loosened without damaging threads, shoulders or other parts.

In another experiment, the same couplings were assembled many times with an excess of 25% of the recommended torque. No damage was again observed.

EXAMPLE V

Use in drilling reels.

A conventional drilling mud consisting of 88 wt% water and 12 wt% combination of Wyoming bentonite with thickener and wetting agent plus alkali, which is usually sufficient for drilling oil and gas wells in southern Texas and Louisiana to depths of approximately 1500 meter, was modified by adding Zeeospheres type 200.

In a first run, five parts of Zeeospheres were added to 100 parts of drilling mud, after which the resulting agent was used in a drilling test in coal-containing rock. A small increase in drilling depth was observed.

In a second experiment, ten parts of Zeeospheres were added to 100 parts of drilling mud. It turned out that the increase in drilling depth was significant.

In both cases, the torque on the drill pipe was kept almost at the same level, and the rotation speed was found to increase. Furthermore, the Zeeospheres appeared to be well suspended in the liquid.

EXAMPLE VI

A similar lubricant as described in Example II was used as a lubrication for a frictional bearing capable of carrying about 40 tons of workload in some construction auxiliary equipment. The lubricant worked well. No wear in the slip bearing was observed during dismantling.

EXAMPLE VII

A lubricant with 57 wt% Zeeospheres type 200, 5 wt% zinc phosphate and 38% aluminum complex grease (equivalent to a NLGI No. 2 grease) was used as a hinge for an oven door. The agent worked satisfactorily, so that normal operation of the doors was possible even after a long period of time.

Claims (12)

Lubricant, comprising: - at least 0.1% by weight of substantially round and smooth particles of a hard, wear-resistant and fracture-resistant, thermally stable and chemically inert material, which particles have an average particle size of less than about 100 microns and preferably between about 1. and have a diameter of about 60 microns, and a maximum of 99.9% by weight of carrier medium. Lubricant according to claim 1, characterized in that the particles consist of a ceramic silica-alumina material. Lubricant according to claim 1, characterized in that the particles are thick-walled hollow spheres. Lubricant according to claims 1-3, characterized in that the particles have an average particle size (diameter) of approximately 4.9 microns, a specific gravity of approximately 2.3 grams / cm3 and a specific surface area of approximately 1 52 m2 / cm3. Lubricant according to claims 1 to 4, characterized in that the carrier medium is a petroleum based medium, based on an organic substance, on a silicone basis or on a water basis. Lubricant according to claim 5, characterized in that the carrier medium is a lubricating oil or grease. Lubricant according to claims 1-6, containing about 50-60% by weight of particles of a hard, abrasion and break-resistant, thermally stable and chemically inert material and about 40-50% by weight of lubricating oil or grease. The lubricant of claim 1, further comprising particles of another lubricating material such as molybdenum disulfide, graphite, talc, mica, fatty esters and the like, in an amount of not less than about 0.1% by weight of the total agent . Lubricant according to claim 8, comprising about 45-59% by weight particles of a hard, abrasion and break-resistant, thermally stable and chemically inert material, about 1-5% by weight particles of another lubricating material, and ca. 40-50 wt% carrier medium. Use of the lubricant according to any of claims 1-9 for lubricating armies, lubricating and sealing threaded and rotary shoulder couplings, and lubricating construction and mining equipment. Use of the lubricant according to claim 1 as a lubricating or cooling fluid in metalworking operations or as a drilling fluid or drilling fluid. Lubricant according to claim 1, suitable for use as a drilling fluid or drilling mud, comprising about 5-10 parts by weight or more of particles of a hard, wear-resistant and break-resistant, thermally stable and chemically inert material and about 90-95 parts by weight or less of a water-based carrier medium for a drilling fluid or drilling fluid.