Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
  • C10M169/04—Mixtures of base-materials and additives
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
  • F16L15/04—Screw-threaded joints; Forms of screw-threads for such joints with additional sealings
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
  • C10M2205/022—Ethene
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/14—Synthetic waxes, e.g. polythene waxes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/16—Paraffin waxes; Petrolatum, e.g. slack wax
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/17—Fisher Tropsch reaction products
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/18—Natural waxes, e.g. ceresin, ozocerite, bees wax, carnauba; Degras
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/02—Hydroxy compounds
  • C10M2207/023—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings
  • C10M2207/0235—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/02—Hydroxy compounds
  • C10M2207/023—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings
  • C10M2207/028—Overbased salts thereof
  • C10M2207/0285—Overbased salts thereof used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/10—Carboxylix acids; Neutral salts thereof
  • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
  • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
  • C10M2207/1253—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/10—Carboxylix acids; Neutral salts thereof
  • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
  • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
  • C10M2207/126—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids monocarboxylic
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/26—Overbased carboxylic acid salts
  • C10M2207/262—Overbased carboxylic acid salts derived from hydroxy substituted aromatic acids, e.g. salicylates
  • C10M2207/2623—Overbased carboxylic acid salts derived from hydroxy substituted aromatic acids, e.g. salicylates used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2219/00—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions
  • C10M2219/04—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions containing sulfur-to-oxygen bonds, i.e. sulfones, sulfoxides
  • C10M2219/046—Overbasedsulfonic acid salts
  • C10M2219/0463—Overbasedsulfonic acid salts used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/12—Inhibition of corrosion, e.g. anti-rust agents or anti-corrosives
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/64—Environmental friendly compositions
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
  • C10N2050/015—Dispersions of solid lubricants
  • C10N2050/02—Dispersions of solid lubricants dissolved or suspended in a carrier which subsequently evaporates to leave a lubricant coating
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
  • C10N2050/10—Semi-solids; greasy
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2080/00—Special pretreatment of the material to be lubricated, e.g. phosphatising or chromatising of a metal
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/02—Couplings; joints
  • E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
  • E21B17/042—Threaded

Definitions

• This invention relates to a lubricating coating composition suitable for lubricating coating treatment of tubular threaded joints which are used to connect oil country tubular goods (abbreviated as OCTG) to each other.
• OCTG oil country tubular goods
• a tubular threaded joint having a lubricating coating formed by treatment with a composition according to the present invention can be used to connect OCTG without application of a lubricating grease which contains a large amount of heavy metals and hence raises the a concern of causing environmental pollution, even if the joint is of the type having an unthreaded metal-to-metal contact portion which provides the joint with improved sealability but which makes the joint susceptible to galling.
• OCTG are tubing and casing which are used to excavate oil wells. They are normally assembled on site by connecting steel tubes having a length on the order of ten some meters to each other using tubular threaded joints. Conventionally, the depth of oil wells has been 2,000 - 3,000 meters, but in recent deep sea oil fields, it may reach 8,000 - 10,000 meters.
• a threaded joint for connecting OCTG is subjected not only to a load in the form of an axial tensile force caused by the weight of OCTG and joints connected thereto but also to a combined internal and external pressure and subterranean heat. Therefore, it must maintain an airtight connection without breakage even in such a severe environment.
• API the American Petroleum Institute
• API requires a tubular threaded joint for OCTG to have sufficient galling resistance to make it possible to carry out tightening (makeup) and loosening (breakout) ten times for a joint for tubing and three times for a joint for casing without the occurrence of galling (unrepairable severe seizure) while maintaining airtightness.
• a tubular threaded joint having good sealability when used to connect OCTG is of the pin-box structure capable of forming a metal-to-metal contact seal.
• a pin is formed on the outer surface of each end portion of a steel tube and includes a threaded portion with a male (external) thread and an unthreaded metal-to-metal contact portion, while a box is formed on the inner surface of a coupling, which is a separate connecting member, and includes a threaded portion with a female (internal) thread and an unthreaded metal-to-metal contact portion.
• the tubular threaded joint is tightened by inserting the pin into the box and tightening the male and female threads until the unthreaded metal-to-metal contact portions of the pin and the box tightly contact each other to form a metal-to-metal contact seal.
• a lubricating grease called compound grease is usually applied to the surfaces of the threaded portions and the unthreaded metal-to-metal contact portions which are the engaging portions of the joint when it is tightened, in order to provide these portions with improved galling resistance and airtightness.
• the engaging portions of a tubular threaded joint may be pretreated so as to have an increased surface roughness by surface treatment such as phosphating in order to increase the retention of a compound grease.
• a compound grease contains a large amount of powder of heavy metals such as lead, zinc, and copper in order to provide the compound grease with sufficient lubricity and corrosion resistance. Therefore, the applied grease causes environmental pollution if it is washed off or squeezed out to its surroundings. In addition, the process of applying a compound grease worsens the work environment and decreases the efficiency of the operation of assembling OCTG. Accordingly, there has been a demand for a tubular threaded joint which fulfills its function sufficiently without application of a compound grease.
• Patent Document 1 JP 2002-173692 Al
• Patent Document 2 JP 2004-53013 Al
• Patent Document 3 JP 2004-507698 Al.
• HOCNF Harmonized Offshore Chemical Notification Format
• BOD Biodegradability
• a more specific object of the present invention is to provide a tubular threaded joint which can be used to connect OCTG without application of a lubricating grease such as a compound grease and without problems related to lubricity, which is prevented from rusting and exhibits improved galling resistance and airtightness, and which can be used even in countries or regions having strict environmental regulations.
• Another object of the present invention is to provide a lubricating coating composition for use in the manufacture of such a tubular threaded joint.
• the present inventors carried out investigations on various lubricating coating compositions suitable for a tubular threaded joint with respect to biodegradability, lubricity, and anticorrosive properties.
• BOD 28 The biodegradability assessed by either method is acceptable if the BOD value measured after 28 days (hereinafter referred to as BOD 28 ) is at least 20% or "BOD 28 > 20%".
• BOD 28 the BOD value measured after 28 days
• BOD 28 > 20% the minimum acceptable BOD value differs between countries or regions, but the criterion "BOD 28 > 20%” can meet the minimum acceptable level of BOD for substances which can be used on an offshore rig according to the regulations in Norway, which are said to be the strictest.
• a biodegradability test for use in designing the composition of a lubricating coating composition can be carried out separately on each of the candidate components in the composition.
• the final judgement of biodegradability should be made based on an overall assessment of a lubricating coating composition which combines the assessments of the individual components.
• a lubricant based on any of a basic sulfonate salt, a basic salicylate salt, a basic phenate salt, and a basic carboxylate salt is in the form of a grease-like semisolid at room temperature and exhibits fluidity under hydrostatic pressure.
• the present invention provides a lubricating coating composition
• a lubricating coating composition comprising at least one basic lubricant selected from a basic sulfonate salt, a basic salicylate salt, a basic phenate salt, and a basic carboxylate salt wherein the composition has a biodegradability value (BOD) of at least 20% when measured after 28 days in seawater.
• BOD biodegradability value
• a lubricating coating composition according to the present invention further comprises at least one additional lubricant selected from those having a higher (greater) biodegradability than that of the basic lubricant.
• the additional lubricant is preferably selected from a fatty acid metal salt and a wax, and more preferably it comprises at least one fatty acid metal salt and at least one wax.
• the fatty acid metal salt is preferably selected from alkaline earth metal salts of stearic acid or oleic acid.
• a preferred chemical composition of a lubricating coating composition according to the present invention may contain up to 30 mass% of a volatile organic dissolving medium (solvent), and the remainder comprises, when the total amount of the remainder composition is taken as 100 parts by mass, 55 - 75 parts by mass of a basic lubricant, 20 - 25 parts by mass of a fatty acid metal salt, and 10 - 20 parts by mass of a wax.
• a volatile organic dissolving medium solvent
• the present invention also provides a tubular threaded joint constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions, characterized in that the surfaces of the engaging portions of at least one of the pin and the box are coated with the above- described lubricating coating composition to a thickness of at least 10 micrometers, thereby allowing the joint to be tightened without application of a compound grease.
• lubricant indicates a lubricity improving agent.
• a pin is a member of a tubular threaded joint which has a male (external) threaded portion, while a box is the other member of the joint having a female (internal) threaded portion.
• a tubular threaded joint having a lubricating coating formed from a lubricating coating composition according to the present invention has high biodegradability and still exhibits satisfactory galling resistance and anticorrosive properties on the same level as obtained with application of a compound grease. As a result, it can be used without application of a compound grease and without any concern for environmental pollution even in a country or region having strict environmental regulations.
• Figure 1 is a schematic diagram showing a steel pipe for OCTG and a coupling which are assembled together for shipment.
• Figure 2 is a schematic diagram showing a tubular threaded joint having a threaded portion and an unthreaded metal-to-metal contact portion.
• Figure 3 is a schematic diagram showing minute gaps in a threaded portion and an unthreaded metal-to-metal contact portion of a tubular threaded joint.
• any percent relating to a chemical composition is by mass unless otherwise indicated.
• a dissolving medium or solvent can be used in order to dissolve or disperse the basic lubricant and one or more optional lubricants as well as other additives, if used, thereby facilitating the formation of a lubricating coating having a uniform thickness and a uniform composition in an efficient manner. Therefore, if a satisfactory lubricating coating can be formed with the lubricant components alone, it is unnecessary to use a dissolving medium in a coating composition.
• an organic dissolving medium is used.
• dissolving medium are petroleum solvents such as those corresponding to industrial gasoline prescribed in JIS K2201 and including solvent and mineral spirit, aromatic petroleum naphtha, xylene, and Cellosolves.
• a dissolving medium having a flash point of 30° C or higher, an initial boiling temperature of 150° C or higher, and a final boiling point of 210° C or lower is suitable due to its ease of handling, rapid evaporation, and short drying time. From the standpoint of biodegradability, mineral spirit is preferable.
• the biodegradability of an organic dissolving medium is generally not so high. Therefore, if it is present in a lubricating coating composition in a large amount, the biodegradability of the entire composition is worsened.
• the amount of a dissolving medium is preferably selected, as long as the biodegradability of a lubricating coating composition satisfies the conditions for BOD defined by the present invention, such that the dissolving medium can improve the wettability of the surface to be coated and the spreadability of the coating composition and facilitate adsorption of the below-described lubricity improving agents (lubricants) by the surface, in addition to its intended function of dissolving or uniformly dispersing the lubricants.
• lubricity improving agents lubricants
• the amount of a dissolving medium in a lubricating coating composition is preferably in the range of from 0% to 30% and more preferably from 5% to 25%. If the amount is too small, the viscosity of the lubricating coating composition may be so high that it is difficult for the composition to form a uniform coating and exhibit the above-described adsorbing function. If it is too large, it is difficult for the composition to have a desired biodegradability. [Basic Lubricant]
• At least one basic lubricant selected from basic sulfonate salts, basic salicylate salts, basic phenate salts, and basic carboxylate salts is used as a principal component of lubricity improving agents (lubricants).
• lubricants lubricity improving agents
• the term "principal component" does not always mean that it is present in the largest amount, but indicates that the basic lubricant performs a main role to achieve the desired lubricating performance.
• All the above-described four classes of basic lubricants are a salt formed from an aromatic acid and an excess alkali. At room temperature, they are a grease-like semisolid substance comprising an oil and the excess alkali dispersed in the oil in the form of colloidal microparticles.
• a basic lubricant is present in a lubricating coating composition in an amount which is effective at improving the galling resistance and anticorrosive properties of the composition, provided that the composition as a whole has a biodegradability satisfying the above criterion.
• the amount of a basic lubricant is preferably in the range of 55 to 70 parts by mass when the total mass of the composition excluding the above-described dissolving medium (namely, the total amount of all the nonvolatile components which constitute a lubricating coating) is taken as 100 parts by mass.
• a basic sulfonate salt is most advantageous in terms of lubricity and anticorrosive properties.
• the sulfonic acid constituting the sulfonate salt may be either petroleum sulfonic acid obtained by sulfonating aromatic components of petroleum fractions or a synthetic sulfonic acid.
• Examples of the synthetic sulfonic acid include dedecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and the like.
• the salt of a sulfonic acid may be either an alkali metal salt or an alkaline earth metal salt.
• an alkaline earth metal salt and more preferably a calcium salt namely, a basic calcium sulfonate.
• a calcium salt namely, a basic calcium sulfonate.
• an alkaline earth metal salt and particularly a calcium salt is preferred.
• the basic lubricant is a basic calcium sulfonate
• the basic lubricant is a basic calcium sulfonate
• it is a basic salicylate salt, a basic phenate salt, or a basic carboxylate salt
• the amount of the basic lubricant can be adjusted taking into consideration the biodegradability and other properties of the composition.
• a basic calcium sulfonate which can be used in the present invention is a known substance and is commercially available under the trade name Sulfol 1040 from Matsumura Oil Research Corp. and under the tradename Lubrizol 5318 from Lubrizol Corp, for example.
• a basic calcium sulfonate may be prepared by dissolving a neutral sulfonate salt in a solvent, which can be suitably selected from aromatic hydrocarbons, alcohols, and mineral oil, and then adding to the resulting solution an amount of calcium hydroxide required to form a desired basic calcium sulfonate followed by mixing. Carbon dioxide gas is subsequently passed through the mixture in an excess amount so as to sufficiently carbonate the added calcium hydroxide, and the reaction mixture is filtered after addition of a filter aid such as activated clay.
• the desired basic calcium sulfonate is obtained by distilling the filtrate at a reduced pressure to remove the volatile solvent.
• a basic calcium sulfonate is a grease-like semisolid substance which contains calcium carbonate in the form of colloidal microparticles which are stably dispersed in an oil.
• the dispersed microparticles of calcium carbonate function as a solid lubricant and enable the basic sulfonate salt to exhibit significantly improved lubricity over common liquid lubricating oil particularly under severe tightening conditions having a large amount of thread interference.
• this lubricant works between frictional surfaces having minute irregularities (surface roughness), it can exhibit an even more improved galling-preventing effect due to the micro lubricating effect by hydrostatic fluid pressure of the oil combined with the solid lubrication action of the microparticles. This effect can be similarly achieved with other basic lubricants.
• the base number (as specified in JIS K2501) of the basic lubricant which is used increases, its lubricity (galling resistance) tends to increase, since the amount of calcium carbonate microparticles serving as a solid lubricant increases.
• the lubricant has a basicity higher than a certain level, it can exert its activity of neutralizing an acidic substance effectively, thereby making it possible to provide a lubricating coating with an increased anti-rust ability.
• the basic lubricant which is used in the present invention have a base number (according to JIS K2501) of at least 50 mg-KOH/g.
• the base number is a weighted average of their base numbers. However, if the lubricant has a base number exceeding 500 mg-KOH/g, its hydrophilic nature is increased, leading to a decrease in anticorrosive properties and easy occurrence of rusting.
• a preferred range for the base number of the basic lubricant is from 100 to 500 mg-KOH/g and a more preferred range is from 250 to 450 mg-KOH/g.
• a lubricating coating composition according to the present invention preferably contains one or more additional lubricants as lubricity improving agents. Those having better (higher) biodegradability than the basic lubricant are used as the additional lubricants. As a result, even in the case where a highly basic lubricant which does not have such good biodegradability is used as a principal lubricant, it is possible to obtain a lubricating coating composition satisfying the condition of biodegradability according to the present invention.
• Additional lubricants are preferably selected from fatty acid metal salts and waxes. More preferably, at least one fatty acid metal salt and at least one wax are used as additional lubricants. ⁇ Fatty acid metal salt>
• An alkaline earth metal salt of a fatty acid is preferably used as a fatty acid metal salt, since fatty acid salts with other metals have inferior biodegradability or are not preferred from an environmental standpoint.
• a fatty acid metal salt is active as a lubricant, although its activity is lower than that of the above-described basic lubricant such as a basic calcium sulfonate.
• the fatty acid portion of the salt is preferably one having 12 to 30 carbon atoms from the viewpoints of lubricity and anticorrosive properties.
• the fatty acid may be either a mixed fatty acid derived from natural fat or fatty oil such as beef tallow, lard, wool fat, palm oil, rape-seed oil, and coconut oil, or a single fatty acid such as lauric acid, tridecanoic acid, myristic acid, palmitic acid, lanopalmitic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, arachic acid, behenic acid, erucic acid, lignoceric acid, and lanoceric acid.
• Particularly preferable fatty acid metal salts in terms of biodegradability are alkaline earth metal salts of stearic acid or oleic acid, and a calcium salt of such an acid is particularly suitable.
• the fatty acid metal salt may be either a neutral salt or a basic salt.
• a fatty acid metal salt in a lubricating coating composition there is no limit on the amount of a fatty acid metal salt in a lubricating coating composition, and it may be 0%. However, such a salt is usually added in at least a certain amount in order to provide the composition with the desired biodegradability.
• a preferred amount of the fatty acid metal salt is in the range of from 20 to 25 parts by mass when the total mass of the composition excluding the dissolving medium is taken as 100 parts by mass. If this amount is too large, the amount of the basic lubricant which is a principal lubricant becomes relatively small, leading to a decrease in lubricity. ⁇ Wax>
• a wax may be added in order to enhance the biodegradability of a lubricating coating composition, although its lubricity is lower than that of the above-described basic lubricant.
• waxes which can be used include animal waxes such as beeswax and whale tallow; vegetable waxes such as Japan wax, carnauba wax, candelilla wax, and rice wax; mineral waxes such as paraffin wax, microcrystalline wax, petrolatum, montan wax, ozokerite, and ceresin; and synthetic waxes such as oxide wax, polyethylene wax, Fischer-Tropsch wax, amide wax, and hardened castor oil (castor wax).
• petrolatum which is a kind of mineral wax, is preferred from the standpoint of biodegradability.
• a wax in a lubricating coating composition there is no limit on the amount of a wax in a lubricating coating composition, and it may be 0%. However, at least certain amount of wax is usually added in order to provide the composition with the desired biodegradability.
• a preferred amount of the wax is in the range from 10 to 20 parts by mass when the total mass of the composition excluding the dissolving medium is taken as 100 parts by mass. If this amount is too large, the amount of the basic lubricant which is a principal lubricant becomes relatively small, leading to a decrease in lubricity.
• a tubular threaded joint is constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions.
• a lubricating coating composition according to the present invention can be applied to the surface of the engaging portions of at least one of the pin and the box.
• a tubular threaded joint is shipped in the state shown in Figure 1.
• a steel pipe A for oil country tubular goods (OCTG) has a pin with a male threaded portion 3 formed on the outer surface at both ends thereof, and a coupling B has a box with a female threaded portion 4 formed on the inner surface at both sides thereof.
• the coupling B is connected to one end of the steel pipe A.
• an unthreaded metal-to-metal contact portion is omitted.
• a tubular threaded joint is not limited to the type illustrated in Figure 1.
• a different type of tubular threaded joint called an integral type can also be used.
• This type which has a pin with a male thread on the outer surface at one end of a steel pipe for OCTG and a box with a female thread on the inner surface at the other end of the pipe, does not need to use a coupling for tightening.
• the present invention will be described with respect to an example of a tubular threaded joint having the form shown in Figure 1.
• Figure 2 schematically shows a cross section of the connecting portion of a tubular threaded joint.
• 1 is a pin
• 2 is a box
• 3 is a male (external) thread portion
• 4 is a female (internal) thread portion
• 5 is an unthreaded metal- to-metal contact portion of each of the pin and box.
• the male and female threaded portions 3 and 4 and the unthreaded metal-to-metal contact portions 5 of the pin and box serve as engaging portions of the tubular threaded joint and form frictional interfaces during tightening of the joint.
• a lubricating coating composition is applied to the engaging portions of at least one of the pin and box (i.e., to the threaded portion 3 or 4 and the unthreaded metal-to- metal contact portion 5) so as to form a grease-like semisolid lubricating coating.
• the pin and the box are shaped so as to interfit with each other, but when they are observed in detail, as shown in Figure 3, there are minute gaps 6 particularly between mating male and female threads. In the absence of these gaps between mating threads, tightening of a tubular threaded joint becomes practically impossible. In addition, a larger minute gap 6 usually exists between the unthreaded metal-to-metal contact portions and the thread portions of the pin and box as depicted. A lubricating composition such as a compound grease is retained in these gaps and can seep out to their surroundings under the pressure exerted during tightening and thereby prevent galling, so these minute gaps contribute to lubrication.
• a lubricating composition such as a compound grease is retained in these gaps and can seep out to their surroundings under the pressure exerted during tightening and thereby prevent galling, so these minute gaps contribute to lubrication.
• a lubricating coating formed from a lubricating coating composition according to the present invention is semisolid like a compound grease and thus can seep out, thereby providing improved lubricity and airtightness to the joint. Also like a compound grease, a lubricating coating composition according to the present invention has improved anticorrosive properties. As a result, after a tubular threaded joint has been shipped in the state shown in Figure 1, the engaging portions of the joint to which the lubricating coating composition is applied are protected from rusting. [Thickness of lubricating coating]
• a primary purpose of the formation of a lubricating coating in a tubular threaded joint is prevention of galling even under severe lubrication conditions which may be accompanied by plastic deformation as encountered when the pressure applied to the joint is locally excessive due to misalignment or inclination of the joint caused by some problems in assembling the joint for tightening or due to incorporation of foreign matter.
• it is essential to introduce lubricants (lubricity improving agents) into the frictional interfaces and maintain the lubricants therein.
• a lubricating coating composition must be applied in an amount sufficient to fill the minute gaps 6 such as those between mating threads in the engaging portions of a tubular threaded joint. If the applied amount is too small, it becomes impossible to expect the lubricants to seep into frictional interfaces or seep into a gap from other gaps under the action of the hydrostatic pressure generated by tightening.
• the thickness of a lubricating coating is preferably at least 10 micrometers. Since the engaging portions of a box and a pin contact each other when a tubular threaded joint is tightened, in the interest of achieving lubricity, it is sufficient to form a lubricating coating on the engaging portions of only one of the pin and box.
• a lubricating coating with a thickness of at least 10 micrometers is preferably formed on the engaging portions of both members.
• both the pin and box have a lubricating coating.
• a lubricating coating formed from a lubricating coating composition according to the present invention does not need to be made extremely thick since it contains a basic lubricant such as a basic calcium sulfonate which has a significantly high lubricity. Too thick a coating not only wastes materials, but works against the goal of preventing environmental pollution, which is an important object of the present invention.
• the upper limit of the coating thickness is not limited, it is preferably approximately 200 micrometers.
• a more preferable thickness of the lubricating coating is in the range of 30 to 150 micrometers.
• the thickness of the lubricating coating is preferably larger than the value of the surface roughness (Rmax).
• the thickness of a lubricating coating formed on a rough surface is defined in the present invention as the mean value of the smallest thickness and the largest thickness.
• the dissolving medium which is generally volatile, vaporizes from the applied coating and leaves a semisolid lubricating coating.
• Application of the lubricating coating composition can be carried out by any suitable coating method such as brush coating, dip coating, or spray coating.
• the viscosity of a lubricating coating composition When the viscosity of a lubricating coating composition is too low for it to be applied at room temperature as in the case where the amount of a dissolving medium is small or even zero, it can be applied after heating to a temperature sufficient to lower the viscosity to such a degree that the composition can be applied easily.
• the intensity of these functions depends on the magnitude of the surface roughness regardless of the method of forming the surface roughness.
• a range of surface roughness suitable for improvement in galling resistance is 5 - 40 micrometers expressed as Rmax. If the surface roughness exceeds 40 micrometers Rmax, sufficient sealing cannot be obtained in the peripheries of indentations, and the desired hydrostatic pressure is not generated so that sufficient lubrication is not obtained.
• a more preferable range of Rmax is from 10 to 30 micrometers.
• Blasting with sand or grid as abrasive grains The surface roughness which is obtained can be controlled by the size of the abrasive grains.
• Etching with an acid The surface is roughened by immersion in a strongly acidic solution such as sulfuric acid, hydrochloric acid, nitric acid, or hydrofluoric acid.
• Phosphating A chemical conversion coating with a phosphate such as manganese phosphate, zinc phosphate, iron-manganese phosphate, or zinc-calcium phosphate is formed. As the phosphate crystals deposited on the surface by phosphating grow, the roughness of the crystal surface increases.
• a phosphate such as manganese phosphate, zinc phosphate, iron-manganese phosphate, or zinc-calcium phosphate is formed. As the phosphate crystals deposited on the surface by phosphating grow, the roughness of the crystal surface increases.
• Electroplating Copper plating or iron plating is suitable. Electroplating occurs preferentially in protruded portions on the surface, leading to a slight increase in surface roughness.
• Dry-process impact plating This is a plating method such as zinc blasting or zinc-iron alloy blasting in which particles having an iron core coated with a metallic material for plating (such as a zinc or a zinc alloy) are blasted onto a surface to be plated using centrifugal force or air pressure.
• Methods (3) through (5) result in the formation of an undercoat layer having an increased surface roughness, which prevents direct metal- to-metal contact in the engaging portions after a lubricant coating has been lost, so these methods are preferred in that galling resistance and anticorrosive properties are simultaneously improved.
• a coating of manganese phosphate is preferable since it is made of bristling acicular crystals and hence can easily achieve a large surface roughness, which is good at retaining a large amount of lubricants.
• the thickness of the undercoat layer is preferably greater than the surface roughness of the undercoat layer, since the layer has good retention of lubricants and good adhesion.
• the thickness of the undercoat layer is preferably in the range of 5 - 40 micrometers.
• lubricating coating compositions were prepared and their biodegradability was determined using the following two methods (a) and (b), which are commonly employed for evaluation of biodegradability of a substance in seawater in environmental impact assessment:
• the value of the overall biodegradability was calculated as a weighted average of the values of biodegradability of the individual components by considering their contents in the composition.
• tubular threaded joints used for testing were of the type having a threaded portion and an unthreaded metal-to-metal contact portion on each of the pin and box and capable of forming a metal-to-metal seal.
• the engaging surfaces of a pin which include the surface of its threaded portion and unthreaded metal-to-metal contact portion, will be referred to as the "pin surface”
• the engaging surfaces of a box which includes the surface of its threaded portion and unthreaded metal-to-metal contact portion will be referred to as the "box surface”.
• the tubular threaded joints underwent the following surface treatment for surface roughening.
• the pin surface of a tubular threaded joint of the carbon steel was treated by zinc phosphating, and the box surface thereof was treated by manganese phosphating.
• the box surface of a tubular threaded joint of the 13Cr steel was coated with copper plating, and the pin surface thereof remained as machined without surface treatment.
• the 13Cr steel is a kind of high alloy steel and is more susceptible to galling than the carbon steel.
• a lubricating coating composition to be tested was applied by brush coating only to the box surface of a tubular threaded joint which had been surface treated as described above so as to form a lubricating coating having a thickness of 30 micrometers.
• the tubular threaded joint having a lubricating coating formed from the composition on the box surface was subjected to a repeated tightening and loosening test with a tightening torque of 20,000 N-m for up to ten cycles, and the lubricity of the lubricating coating composition was evaluated by the number of tightening cycles before galling occurred in the test.
• each lubricating coating composition was evaluated by a salt spray test (SST) specified in JIS Z2371 using a test sheet with dimensions of 50 mm x 100 mm and 2 mm in thickness made of the carbon steel or the 13Cr steel having the compositions shown in Table 1.
• a lubricating coating to be tested was formed to a thickness of 30 micrometers from each composition on the test sheet as machined without surface treatment.
• the coated test sheet was subjected to the salt spray test for 1000 hours, and the presence or absence of rust was determined visually.
• compositions of the lubricating coating compositions which were tested and the test results are shown in Table 2.
• a lubricating coating composition which contained 25% of mineral spirit as a dissolving medium, 50% (66.7 parts) of basic calcium sulfonate having a base number of 400 mg-KOH/g as a basic lubricant, and 17% (22.7 parts) of calcium stearate and 8% (10.6 parts) of petrolatum wax both as additional lubricants.
• the parts in parentheses are the amounts of the respective components in parts by mass based on 100 parts by mass of the total amount of the components in the composition excluding the dissolving medium.
• This lubricating coating composition contained a dissolving medium and thus had a low viscosity and a high spreadability, so it was easy to apply and could be applied by brush coating to the box surface of a test threaded joint to be used in a repeated tightening and loosening test and the surface of a test sheet for a salt spray test while remaining at room temperature.
• the biodegradability (BOD 28 ) of the entire lubricating coating composition in seawater was 26%, which was higher than the minimum acceptable value of 20% but was lower than that of the composition of Example 2 containing no dissolving medium.
• a lubricating coating composition was prepared which did not contain a dissolving medium but contained 65% of the same basic calcium sulfonate as used in Example 1 as a basic lubricant, and 23% of calcium stearate and 12% of petrolatum wax both as additional lubricants. Since this lubricating coating composition did not contain a dissolving medium and thus had a high viscosity at room temperature, it was previously heated to 60° C to lower its viscosity and then applied by brush coating to the box surface of a test threaded joint to be used in a repeated tightening and loosening test and the surface of a test sheet for a salt spray test.
• a lubricating coating composition was prepared which contained 15% of mineral spirit as a dissolving medium, 72% (84.7 parts)of the same basic calcium sulfonate as used in Example 1, and 8% (9.4 parts) of petrolatum wax and 5% (5.9 parts) of a polyethylene resin powder (which is described in JP 2002-173692 Al as a preferable lubricating additive due to its effect on improving galling resistance) both as additional lubricants.
• the parts in parentheses are the amounts of the respective components in part by mass based on 100 parts by mass of the total amount of the components in the composition excluding the dissolving medium.
• This lubricating coating composition contained a dissolving medium and thus had a low viscosity and a high spreadability, so it was easy to apply and could be applied by brush coating to the surfaces of a test threaded joint to be used in a repeated tightening and loosening test and a test sheet for a salt spray test while remaining at room temperature.
• the dissolving medium which does not have good biodegradability, a high content of the basic lubricant, and the presence of a polyethylene resin powder
• the biodegradability (BOD 28 ) of the entire lubricating coating composition in seawater was 12%, which was below the minimum acceptable value of 20%.
• the desired galling resistance and anticorrosive properties could be achieved since the composition which was used contained a large amount of a basic calcium sulfonate having good lubricity and anticorrosive properties along with polyethylene powder having good lubricity.
• the composition could not satisfy the desired biodegradability and therefore cannot be used in a country or region having strict environmental regulations.
• the galling resistance and anticorrosive properties of a lubricating coating composition according to the present invention which has good biodegradability are as good as those of a compound grease which contains a large amount of harmful heavy metals such as lead and hence cannot be used in a region having strict environmental regulations.

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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Lubricants (AREA)
• Non-Disconnectible Joints And Screw-Threaded Joints (AREA)

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• 2006
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