OA17282A - Composition for use in forming solid coating film, and tubular threaded joint. - Google Patents
Composition for use in forming solid coating film, and tubular threaded joint. Download PDFInfo
- Publication number
- OA17282A OA17282A OA1201500077 OA17282A OA 17282 A OA17282 A OA 17282A OA 1201500077 OA1201500077 OA 1201500077 OA 17282 A OA17282 A OA 17282A
- Authority
- OA
- OAPI
- Prior art keywords
- solid coating
- coating
- composition
- threaded joint
- pin
- Prior art date
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- 239000011248 coating agent Substances 0.000 title claims abstract description 218
- 238000000576 coating method Methods 0.000 title claims abstract description 218
- 239000007787 solid Substances 0.000 title claims abstract description 177
- 239000000203 mixture Substances 0.000 title claims abstract description 79
- 229920005989 resin Polymers 0.000 claims abstract description 93
- 239000011347 resin Substances 0.000 claims abstract description 93
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 43
- 238000005755 formation reaction Methods 0.000 claims abstract description 43
- 239000000010 aprotic solvent Substances 0.000 claims abstract description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000012046 mixed solvent Substances 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims description 50
- 230000001050 lubricating Effects 0.000 claims description 45
- 239000004962 Polyamide-imide Substances 0.000 claims description 28
- 229920002312 polyamide-imide Polymers 0.000 claims description 28
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 11
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 10
- 239000003822 epoxy resin Substances 0.000 claims description 9
- 229920000647 polyepoxide Polymers 0.000 claims description 9
- YEJRWHAVMIAJKC-UHFFFAOYSA-N γ-lactone 4-hydroxy-butyric acid Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 claims description 7
- FXHOOIRPVKKKFG-UHFFFAOYSA-N DMA Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 4
- 238000007747 plating Methods 0.000 description 65
- 239000010410 layer Substances 0.000 description 58
- 239000003129 oil well Substances 0.000 description 26
- 229910000831 Steel Inorganic materials 0.000 description 24
- 239000004519 grease Substances 0.000 description 24
- 239000010959 steel Substances 0.000 description 24
- 230000003746 surface roughness Effects 0.000 description 24
- 150000001875 compounds Chemical class 0.000 description 22
- 239000010452 phosphate Substances 0.000 description 22
- NBIIXXVUZAFLBC-UHFFFAOYSA-K [O-]P([O-])([O-])=O Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 21
- 239000007788 liquid Substances 0.000 description 21
- 238000010438 heat treatment Methods 0.000 description 20
- 238000000227 grinding Methods 0.000 description 19
- 239000000126 substance Substances 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 17
- 239000011701 zinc Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 230000000694 effects Effects 0.000 description 13
- HCHKCACWOHOZIP-UHFFFAOYSA-N zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 13
- 229910052725 zinc Inorganic materials 0.000 description 13
- 210000002832 Shoulder Anatomy 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 12
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 12
- 238000007788 roughening Methods 0.000 description 12
- LRXTYHSAJDENHV-UHFFFAOYSA-H Zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 11
- 239000010949 copper Substances 0.000 description 11
- 230000001808 coupling Effects 0.000 description 11
- 238000010168 coupling process Methods 0.000 description 11
- 238000005859 coupling reaction Methods 0.000 description 11
- 239000010439 graphite Substances 0.000 description 11
- 229910002804 graphite Inorganic materials 0.000 description 11
- 239000003960 organic solvent Substances 0.000 description 11
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 11
- 239000000843 powder Substances 0.000 description 11
- 229910000165 zinc phosphate Inorganic materials 0.000 description 11
- 239000004810 polytetrafluoroethylene Substances 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 239000002356 single layer Substances 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000001012 protector Effects 0.000 description 8
- 239000002904 solvent Substances 0.000 description 8
- 238000005507 spraying Methods 0.000 description 8
- 239000003795 chemical substances by application Substances 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 238000009713 electroplating Methods 0.000 description 7
- 238000002156 mixing Methods 0.000 description 7
- 239000002365 multiple layer Substances 0.000 description 7
- CWQXQMHSOZUFJS-UHFFFAOYSA-N Molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 6
- 229910001297 Zn alloy Inorganic materials 0.000 description 6
- 238000007792 addition Methods 0.000 description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N n-methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 6
- 238000002845 discoloration Methods 0.000 description 5
- 229910001385 heavy metal Inorganic materials 0.000 description 5
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 5
- 238000005488 sandblasting Methods 0.000 description 5
- 229910020994 Sn-Zn Inorganic materials 0.000 description 4
- 229910009069 Sn—Zn Inorganic materials 0.000 description 4
- 239000004963 Torlon Substances 0.000 description 4
- 229920003997 Torlon® Polymers 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 230000000875 corresponding Effects 0.000 description 4
- 230000002708 enhancing Effects 0.000 description 4
- 150000003949 imides Chemical class 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 210000001503 Joints Anatomy 0.000 description 3
- 238000005422 blasting Methods 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- -1 polytetrafluoroethylene Polymers 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 229910052582 BN Inorganic materials 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N HCl Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N HF Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- PZNSFCLAULLKQX-UHFFFAOYSA-N N#B Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000001747 exhibiting Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- CTQNGGLPUBDAKN-UHFFFAOYSA-N o-xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 2
- MUBZPKHOEPUJKR-UHFFFAOYSA-L oxalate Chemical compound [O-]C(=O)C([O-])=O MUBZPKHOEPUJKR-UHFFFAOYSA-L 0.000 description 2
- 230000002093 peripheral Effects 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 239000003586 protic polar solvent Substances 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 239000011135 tin Substances 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000008096 xylene Substances 0.000 description 2
- WMWLMWRWZQELOS-UHFFFAOYSA-N Bismuth(III) oxide Chemical compound O=[Bi]O[Bi]=O WMWLMWRWZQELOS-UHFFFAOYSA-N 0.000 description 1
- 229910017755 Cu-Sn Inorganic materials 0.000 description 1
- 229910016347 CuSn Inorganic materials 0.000 description 1
- 229910017927 Cu—Sn Inorganic materials 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- GSDSWSVVBLHKDQ-UHFFFAOYSA-N Levofloxacin Chemical compound FC1=CC(C(C(C(O)=O)=C2)=O)=C3N2C(C)COC3=C1N1CCN(C)CC1 GSDSWSVVBLHKDQ-UHFFFAOYSA-N 0.000 description 1
- 210000004940 Nucleus Anatomy 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 210000003491 Skin Anatomy 0.000 description 1
- ITRNXVSDJBHYNJ-UHFFFAOYSA-N Tungsten(IV) sulfide Chemical compound S=[W]=S ITRNXVSDJBHYNJ-UHFFFAOYSA-N 0.000 description 1
- 238000005270 abrasive blasting Methods 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating Effects 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 230000003078 antioxidant Effects 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910000416 bismuth oxide Inorganic materials 0.000 description 1
- 230000000903 blocking Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000001680 brushing Effects 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- IQBJFLXHQFMQRP-UHFFFAOYSA-K calcium;zinc;phosphate Chemical compound [Ca+2].[Zn+2].[O-]P([O-])([O-])=O IQBJFLXHQFMQRP-UHFFFAOYSA-K 0.000 description 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 1
- 235000011089 carbon dioxide Nutrition 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000004059 degradation Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 125000003700 epoxy group Chemical group 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011133 lead Substances 0.000 description 1
- 238000011068 load Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- QLOAVXSYZAJECW-UHFFFAOYSA-N methane;molecular fluorine Chemical compound C.FF QLOAVXSYZAJECW-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910001453 nickel ion Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000011528 polyamide (building material) Substances 0.000 description 1
- 230000002940 repellent Effects 0.000 description 1
- 239000005871 repellent Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
Abstract
A composition for solid coating formation, includes a composition made by containing, in a mixed solvent including water and a dipolar aprotic solvent, a powdery organic resin which is partially soluble at least in the dipolar aprotic solvent. The powdery organic resin is present in the state of being dissolved or dispersed in the mixed solvent.
Description
[Type of Document] SPECIFICATION [Title ofthe Invention] COMPOSITION FOR SOLID COATING FORMATION
AND TUBULAR THREADED JOINT [Technical Field]
The présent invention relates to a composition for solid coating formation used to fasten a tubular threaded joint which connects steel pipes such as oil well pipes, and a tubular threaded joint having a solid coating formed by using the composition for solid coating formation.
Priority is claimed on Japanese Patent Application No. 2012-200118, filed on September 12,2012, and the content of which is incorporated herein by reference. [Background Art]
Oil well pipes such as tubing or casings are used for drilling an oil well to mine crude oil or gas oil. The oil well pipes are connected (fastened) to each other generally using a tubular threaded joint. The depth of an oil well according to the related art was 2000 m to 3000 m. The depth of a deep oil well such as an undersea oil well in recent years may reach 8000 m to 10,000 m.
On the tubular threaded joint for the oil well pipes, a load called an axial tensile force caused by the masses of the oil well pipes and the joint themselves under the use environment, a complex pressure such as internai and external surface pressures, and geothermal heat are exerted. Therefore, for the tubular threaded joint for the oil well pipes, maintaining gastightness is required without breakage under such severe environments.
A typical tubular threaded joint (called spécial threaded joint) used for tightening the oil well pipes has a pin-box structure. The pin-box structure is constituted by a member called a pin which is formed at both end portions of the oil
- 1 17282 well pipes, and a member called a box which is formed on the inner surfaces of both sides of a threaded joint component (coupling). The pin has male threads. The box has female threads. Seal portions are respectively formed at the outer peripheral portion near the end surface on the tip end side of the pin from the male threads and at the inner peripheral surface of the base portion of the female threads of the box. Shoulder portions (also called torque shoulders) are respectively formed at the end surface of the tip end of the pin and at the corresponding innermost portion of the box.
One end (pin) of the oil well pipe is inserted into the threaded joint component (box) and the male threads and the female threads are fastened until the shoulder portions of the pin and the box abut on each other and interfère with each other at an optimum torque. Accordingly, the seal portions of the pin and the box corne into close contact with each other and form a metal-to-metal seal, thereby ensuring gastightness of the threaded joint. The seal portions and the shoulder portions form unthreaded métal contact portions of the tubular threaded joint. The unthreaded métal contact portions and the threaded portions (the male threads and the female threads) become surfaces (called contact surfaces of the tubular threaded joint) that corne into contact with each other during fastening. An example of the spécial threaded joint is described in Patent Document 1 and Patent Document 2.
During an operation of lowering the oil well pipe to an oil well, due to various problems, the oil well pipe is temporarily pulled up from the oil well, and a threaded joint which is fastened once is loosened to release the fastening of the threaded joint. There is a case that the oil well pipe in which the fastening of the threaded joint is loosened is lowered after re-fastening the joint. API (The American Petroleum Institute) requires seizure résistance in such a sense that even when fastening (make-up) of a threaded joint and loosening (break-out) thereof are performed a plurality of times,
- 2 17282 seizure called galling does not occur and gastightness is maintained. For example, ten successfiil times are required for a tubing joint, and three successful times are required for a casing joint.
At the time of fastening, in order to achieve enhancement in seizure résistance and gastightness, a viscous liquid lubricant (grease lubricant), that is called a “compound grease”, containing a large amount of heavy métal powder is appiied to the contact surfaces of the threaded joint. Such a compound grease is specified in the Standard API BUL5A2.
For the purpose of enhancing the maintenance of the compound grease and improving lubricity, surface treatments for a single layer or two or more layers, such as a nitriding treatment, various plating processes including zinc-based plating and dispersion plating, and a phosphate chemical conversion treatment are performed on the contact surfaces of the threaded joint. However, there is a problem with the use of the compound grease in that there is concem about a harmful effect on the environment or human bodies as described below.
The compound grease contains a large amount of heavy métal powder such as zinc, lead, and copper. Particularly, there is a possibility that harmful heavy metals such as lead that is contained in the compound grease may hâve a harmful effect on the environment, marine organisms, and the like. Further, an operational environment is worsened by an operation of applying the compound grease, and there is a concem about a harmful effect on human bodies.
In recent years, upon the opportunity that OSPAR Convention (the Oslo and Paris Conventions, OSPAR) regarding the prévention of océan pollution of the northeast Atlantic Océan has taken effect since 1998, environment restrictions hâve strictly proceeded on a global scale. Accordingly, the use of the compound grease is also
- 3 17282 restricted in some régions. Therefore, in the operation of drilling a gas well or oil well, in order to avoid the harmful effect on the environment or human bodies, a threaded joint capable of exhibiting excellent seizure résistance without the use of the compound grease has been required.
As a threaded joint which can be used for fastening oil well pipes without the compound grease being applied, in Patent Document 3, a threaded joint for an oil well in which a resin coating containing lubricating powder is formed on the contact surfaces thereof is suggested. In addition, the applicant suggested a tubular threaded joint in which a solid coating is formed on each of a pin and a box in Patent Document 4.
[Prior Art Document] [Patent Document] [Patent Document 1]
Japanese Unexamined Patent Application, First
Publication No. H05-87275 [Patent Document 2]
Spécification ofUS Patent No. 5,137,310 [Patent Document 3]
PCT International Publication No. WÛ96/10710 [Patent Document 4]
PCT International Publication No. WÛ2009/072486 [Disclosure of the Invention] [Problem that the Invention is to solve]
In many cases, a period of time over one year from shipment is needed for transport to the field or storage of a tubular threaded joint until the tubular threaded joint is actually fastened in an oil well. In the meanwhile, the tubular threaded joint may be exposed to severe environments such as sea transport through the hot and humid equator, température changes of about 90°C from high températures (daytime) to below the freezing point (nighttime) in the Middle East area, and température changes of from 25 60°C (winter) to 40°C (summer) in the Arctic Circle.
- 4 17282
In a case where the tubular threaded joint according to the related art is exposed to an environment with an extremely severe hot and cold cycle, which is repeatedly exposed to an extremely low température to a high température of about 100°C, cracking may occur due to the détérioration of a solid coating or the solid coating may peel off due to the dégradation in the adhesiveness of the solid coating. Therefore, there is concem that a problem in which performance required by the solid coating cannot be exhibited may occur.
In the spécial threaded joint provided with the seal portions and the shoulder portions, the seal portions of the pin and the box form the metal-to-metal seal during fastening, thereby ensuring gastightness. However, when the solid coating partially peels off, not only seizure résistance but also gastightness is degraded.
Further, an operational environment in which the oil well pipes are fastened is also affected by a very wide range of températures of from a high température environment of 40°C or higher in the Middle East area and the like to a low température environment of about -40°C in the Arctic Circle and the like. Therefore, it is expected to exhibit suffi cient seizure résistance even when the température at the time of fastening is a severe température such as an extremely low température or an extremely high température. Even from this point, there is concem that the performance of the solid coating according to the related art may be insufficient.
An object of the présent invention is to provide a composition for solid coating formation of a tubular joint capable of forming a solid coating capable of maintaining and exhibiting seizure résistance, gastightness, and antirust properties without including harmful heavy metais such as lead which imposes a burden on the earth environment even in a hot and cold cycle of from an extremely low température to a high température during a period of time of over one year for transport or storage until actual
- 5 17282 fastening and even when the température at the time of fastening is an extremely high température or an extremely low température, and a tubular threaded joint having excellent hot and cold cycle performance by using the same.
Another object of the présent invention is to provide a composition for solid coating formation of a tubular joint capable of forming a solid coating by only using materials with a small environmental burden without the use of an organic solvent having a harmful effect on biotic environment, and a tubular threaded joint using the same.
[Means for Solving the Problems]
The présent invention employs the following means in order to accomplish the objects to solve the problems. That is, (1) A composition for solid coating formation according to an aspect of the présent invention, includes: a composition made by containing, in a mixed solvent including water and a dipolar aprotic solvent, a powdery organic resin which is partially soluble at least in the dipolar aprotic solvent, in which the powdery organic resin is présent in a state of being dissolved or dispersed in the mixed solvent.
(2) The composition for solid coating formation described in (1) may further include lubricating particies.
(3) In the composition for solid coating formation described in (1) or (2), the powdery organic resin may be one or more types selected from a polyamide-imide resin, an epoxy resin, and a fluororesin.
(4) In the composition for solid coating formation described in any one of (1) to (3), the dipolar aprotic solvent may be one or more types selected from Nmethylpyrrolidone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, and γbutyrolactone.
- 6 17282 (5) A tubular threaded joint according to another aspect of the présent invention includes: a pin and a box each of which is provided with a contact surface including a threaded portion and a unthreaded métal contact portion, in which the contact surface of at least one member of the pin and the box has a solid coating formed from the composition described in any one of (1) to (4).
(6) In the tubular threaded joint described in (5), the solid coating may hâve a first layer which does not contain lubricating particles and a second layer formed thereon, which contains lubricating particles.
(7) The tubular threaded joint described in (5) or (6), a thickness of the solid coating (a total thickness in a case of a coating having two or more layers) may be 5 pm to 100 pm.
In the présent invention, the “dipolar aprotic solvent” is an organic solvent made from polar molécules having an electric dipole moment in the molécules and means a solvent that does not substantially hâve a proton donatingproperty.
In the présent invention, “be partially soluble at least in the dipolar aprotic solvent” means “be dissolved in the dipolar aprotic solvent at a concentration of 5 mass% or higher at room température or during heating”.
[Advantage of the Invention]
According to the aspects, not only the solid coating itself, which is formed on the contact surfaces ofthe tubular threaded joint, but also the composition for solid coating formation for forming the solid coating contains only the components which hâve no or a low environmental burden. The solid coating does not contain harmful heavy metals which are contained in a compound grease according to the related art. Therefore, the manufacturing environment of the tubular threaded joint is properly maintained, and environmental (for example, océan) pollution during fastening is
- 7 17282 prevented.
Moreover, the solid coating has excellent hot and cold cycle performance, properly maintains the adhesiveness of the coating even in a hot and cold cycle of from an extremely low température (-60°C) to a high température (90°C). Furthermore, the solid coating exhibits seizure résistance even when a température during fastening is an extremely low température of -40°C. Therefore, the tubular threaded joint does not significantly deteriorate in seizure résistance and antirust performance even in such a hot and cold cycle, and continuously exhibits a lubricating function even when fastening and loosening are repeated, thereby ensuring gastightness after fastening. Furthermore, even when the tubular threaded joint is exposed to a high température close to 300°C in a high-temperature well, fastening can be released at the time of pulling an oil well pipe without seizure.
As described in Comparative Examples, which will be described later, even the compound grease, which has been generally regarded as a material having higher seizure résistance than a solid lubricating coating, is signifîcantly degraded in seizure résistance when the fastening température is a low température of -20°C. The solid coating formed by using the composition for solid coating formation according to the aspects of the présent invention exhibits higher performance than the compound grease under a hot and cold cycle environment and at a low température of -20°C or less even though heavy metals particles are not contained.
[Brief Description of the Drawing]
FIG 1 is a diagram schematically illustrating an assembled configuration of a steel pipe and a threaded joint component during shipment of the steel pipe.
FIG 2 is a diagram schematically illustrating fastening portions of a threaded joint.
- 8 17282
FIG 3 A is a diagram illustrating an example of a coating configuration of a tubular threaded joint according to an embodiment of the présent invention.
FIG 3B is a diagram illustrating another example of a coating configuration of a tubular threaded joint according to the embodiment of the présent invention.
[Best Mode for Carrying Out the Invention]
Hereinafter, an embodiment of the présent invention will be described in detail.
FIG 1 is a diagram schematically illustrating a state of a steel pipe for an oil well pipe and a threaded joint component during shipment.
Both ends of a steel pipe A are provided with pins 1 formed to hâve male threaded portions 3a. The male threaded portions 3a are formed on the outer surface of the pin 1. Both sides of a threaded joint component (coupling) B are provided with boxes 2 formed to hâve female threaded portions 3b. The female threaded portions 3b are formed on the inner surface of the box 2. The pin 1 is a threaded joint member having the male threaded portion 3a. The box 2 is a threaded joint member having the female threaded portion 3b. The tubular threaded joint is constituted by the pin 1 and the box 2.
The coupling B is fastened to one end of the steel pipe A in advance. Although not illustrated, to the pin 1 of the steel pipe A and the box 2 of the coupling B which are not fastened, protectors for protecting the threaded portions 3 a and 3b are respectively mounted before shipment, and the protectors are taken off before the use of the tubular threaded joint.
In the tubular threaded joint, as illustrated, the pins 1 are formed on the outer surfaces of both ends of the steel pipe A, and the boxes 2 are formed on the inner surfaces of the coupling B which is a separate member. However, although not illustrated, there is also an intégral type tubular threaded joint in which one end ofthe
- 9 17282 steel pipe A is a pin and the other end thereof is a box without the use of the coupling B. The présent invention can be applied to a tubular threaded joint in any of the above types.
FIG 2 is a diagram schematically illustrating the configuration of the tubular threaded joint (hereinafter, simply referred to as a “threaded joint”). The threaded joint is constituted by the pin 1 formed on the outer surface of the end portion of the steel pipe A and the box 2 formed on the inner surface of the coupling B. The pin 1 includes the male threaded portion 3 a, a seal portion 4a positioned on the tip end side of the steel pipe A from the male threaded portion 3a, and a shoulder portion 5a positioned on the end side from the seal portion 4a. According to this, the box 2 includes the female threaded portion 3b, and a seal portion 4b positioned on the base end side from the female threaded portion 3b, and a shoulder portion 5b formed on the base end side from the seal portion 4b.
In any of the pin 1 and the box 2, the seal portions 4a and 4b and the shoulder portions 5a and 5b constitute unthreaded métal contact portions. The unthreaded métal contact portions and the threaded portions 3 a and 3b are contact surfaces of the threaded joint. The contact surfaces require seizure résistance, gastightness, and corrosion résistance. For this, in the related art, a compound grease containing heavy métal powder is applied, or a viscous liquid, a semisolid, or a solid lubricating coating is formed on contact surfaces. However, as described above, the former has a harmiul effect on human bodies and the environment. The latter has problems in that gastightness is degraded during a hot and cold cycle of from an extremely low température to a high température or results in détérioration in lubricity and antirust properties are deteriorated.
According to this embodiment, the contact surface of at least one member of
- 10 17282 the pin 1 and the box 2 of the threaded joint has a spécifie solid coating, which will be described later in detail, thereby solving the above-described problems. The solid coating is preferably formed on the entire surface of the contact surface of the pin 1 and/or the box 2, but may also be formed on only a part of the contact surface, for example, the unthreaded métal contact portions (that is, the seal portions 4a and 4b and the shoulder portions 5a and 5b). In this case, a different coating may be formed on the residual part of the contact surface.
Further, in a case where the solid coating described above is formed on only the contact surface of one member of the pin 1 and the box 2, a different surface treatment may also be performed on the contact surface of the other member. For example, a solid anticorrosive coating or a liquid lubricating coating may also be formed on the contact surface of the other member.
[Solid Coating]
In this embodiment, on the contact surfaces at least including the unthreaded métal contact portions (the seal portions 4a and 4b and the shoulder portions 5a and 5b) of at least one member of the pin 1 and the box 2 of the threaded joint, a solid coating is formed by using a composition for solid coating formation which is a composition containing, in a mixed solvent of water and a dipolar aprotic solvent, a powdery organic resin that is partially soluble at least in the dipolar aprotic solvent, the powdery organic resin being présent in a state of being dissolved or dispersed in the mixed solvent.
The composition for solid coating formation may further contain lubricating particles. Accordingly, the lubricity of the solid coating is enhanced. Therefore, the seizure résistance of the threaded joint is enhanced.
As the powdery organic resin, a resin having heat résistance at a température of higher than 100°C is preferably used. As such a resin, a polyamide-imide resin, an
- 11 17282 epoxy resin, a fluororesin, and the Iike, which are commercially available in a powdery or dispersed liquid state, can be exemplified, and a mixture including two or more types thereof may also be used.
Among these, the polyamide-imide (PAI) resin is préférable as the powdery organic resin because it has particularly excellent in heat résistance, can maintain the coating strength and toughness at a température of 300°C without the significant dégradation therein, and also has excellent wear résistance and chemical résistance.
As the powdery polyamide-imide resin, Torlon (registered trademark) 4000T and 4000TF made by SOLVAY can be exemplified. The Torlon polyamide-imide resin is commercially available in a powdery form having a particle size of about 30 pm to 40 pm and is completely soluble in the dipolar aprotic solvent.
As another example of the powdery organic resin, there are an epoxy resin and a fluororesin which are reformed so that the surfaces thereof partiaily increase hydrophilicity. There may be cases where such a resin is commercially available in a water-dispersed liquid state. Even in this case, a treatment for changing a solvent to the above-mentioned mixed solvent is necessary.
In this embodiment, the powdery organic resin (hereinafter, simply referred to as an “organic resin”) is dispersed in the mixed solvent including water and the dipolar aprotic solvent and is mixed, thereby preparing a composition. Accordingly, the powdery organic resin is présent in the mixed solvent in a dispersed state or a dissolved state depending on the solubility thereof. Both water and the dipolar aprotic solvent are used as the solvent because even when the organic resin is dissolved or is not dissolved in the dipolar aprotic solvent, the surfaces of the particles of the organic resin are reformed to be hydrophilic and thus dispersibility in water is enhanced.
As the mixed solvent, instead of a dipolar protic solvent represented by alcohol
- 12 17282 or amine, a dipolar aprotic solvent such as dimethylformamide is preferably used.
Since the dipolar protic solvent such as alcohol has too high an affinity to water, there may be cases where it is difficult to achieve the effect intended by the présent invention and there may be cases where the dissolving power of the organic resin is low.
As examples of the dipolar aprotic solvent, N-methylpyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), dimethylsulfoxide (DMSO), γ-butyrolactone (GBL), and the like may be used, and the dipolar aprotic solvent is not limited thereto. Among these, dimethylsulfoxide and γ-butyrolactone are préférable. Further, Torlon 4000T and 4000TF which are the polyamide-imide resin described above are soluble in the dipolar aprotic solvent. In a case where the amount of the dipolar aprotic solvent in the composition is a certain degree or higher and in a case where a température is high, the resin may be présent in a state of being dissolved in the composition. Otherwise, for example, in a case where the ratio of water is high or a température is low, the resin is présent in a dispersed state in the composition. Even in any of the forms being présent, a homogeneous solid coating can be formed.
In a case where the powdery organic resin is another resin such as an epoxy resin and a fluororesin, or is a mixture of such a resin and the polyamide-imide resin, there is a small possibility ofthe powdery organic resin being dissolved in the mixed solvent. However, the surfaces of the powdery resin particles are reformed to be hydrophilic as described above. In addition, depending on the case, the surfaces of the resin particles are partially dissolved.
In a case where the solid coating contains lubricating particles, as the lubricating particles that can be used, although not limited, for example, there are molybdenum disulfide, tungsten disulfide, graphite, graphite fluoride, an organomolybdenum compound (for example, molybdenum dialkylthiophosphate and
- 13 17282 molybdenum dialkylthiocarbamate), PTFE (polytetrafluoroethylene), BN (boron nitride), and the like. PTFE is a type of fluororesin, but is not soluble in the dipolar aprotic solvent. Therefore, PTFE may not be used as the organic resin of the coating formation components. One type or two or more types may be used as the lubricating particles. As the lubricating particles, graphite is préférable, and among the types thereof, earthy graphite and PTFE are particularly préférable.
Regarding the amounts of the components in the composition for solid coating formation, it is préférable that when the total amount of the components excluding the lubricating particles is 100 mass%, the amount of water be in a range of 10 mass% to 50 mass%, the amount of the dipolar aprotic solvent be in a range of 25 mass% to 55 mass%, and the amount of the organic resin be in a range of 5 mass% to 25 mass%. Regarding the ratios of the water and the dipolar aprotic solvent, it is préférable that water occupy 12 mass% to 60 mass% of the entire solvent. The ratios of the water and the dipolar aprotic solvent may be set so that the obtained composition has an appropriate viscosity for application and a solid coating having a desired thickness can be formed by a single application operation.
In a case of forming a solid coating containing the lubricating particles, it is préférable that the lubricating particles be contained in the solid coating at a ratio of 2 mass% to 20 mass%.
The composition for solid coating formation may contain other addition components that can be contained in the solid coating. As an example of the components, there is an antirust agent. The antirust agent reinforces an inorganic powder for adjusting the lubricity of the solid coating and the solid coating. Examples of the inorganic powder include titanium dioxide and bismuth oxide. Préférable examples of the antirust agent include calcium ion-exchanged silica. Furthermore, a
- 14 17282 commercially available reaction water repellent agent can also be contained in the solid coating. The inorganic powder, the antirust agent, and the other addition components may be contained in the solid coating at a total amount of up to 20 mass%.
The solid coating may contain, in addition to the above-mentioned components, a small amount of addition components of at least one type or two or more types selected from a surfactant, a colorant, an antioxidant, a defoaming agent, and the like at an amount of, for example, 5 mass% or less. Moreover, the solid coating may also contain an extreme pressure agent, a liquid oil agent, and the like at a very small amount of2 mass% or less.
The composition for solid coating formation can be prepared by adding the powdery organic resin that is soluble in the dipolar aprotic solvent as the coating formation component to the mixed solvent including the water and the water-miscible organic solvent, and stirring and mixing the résultant at an appropriate température to cause the organic resin to be dispersed or dissolved in the solvent. In a case where the solid coating contains the lubricating particles or the other addition components, thereafter, the addition components may be gradually added to form a uniform composition. It is préférable that the composition for solid coating formation be adjusted to an appropriate viscosity for stirring and application by setting the température to be in a range of 20°C to 60°C although it also dépends on the properties of the dipolar aprotic solvent.
The composition for solid coating formation is applied to the contact surfaces of the threaded joint to be coated by an appropriate method, and is heated as necessary to dry and cure the coating, thereby forming the solid coating on the contact surfaces. Application can be performed by, for example, spraying the composition while rotating the threaded joint at a predetermined speed. In addition, application methods such as
- 15 17282 brushing or immersion can also be employed. The heating température is set so that the solvent is completely volatilized and the resin is cured.
The solid coating which uses the composition for solid coating formation can be formed as a single layer or two or more layers. In a case of the single layer, in order to enhance lubricity, it is préférable that solid coating be a coating containing the lubricating particles. However, depending on the type of water-dispersed resin, a solid coating without lubricating particles being contained may also impart sufïicient seizure résistance to the threaded joint.
In a case of forming two or more layers of the solid coating, it is préférable that the first layer as the lower layer be a solid coating which is made of the organic resin and does not contain the lubricating particles in order to enhance coating adhesiveness and antirust properties. It is préférable that the second layer formed thereon be a solid coating which is made of the organic resin containing the lubricating particles in order to enhance lubricity (seizure résistance). Both the first layer and the second layer may contain the other addition components described above. Further, as the uppermost layer of the solid coating, a top coating layer (third layer) having antirust properties may also be provided.
In addition, in a case where the solid coating is formed in multiple layers, on a first layer that does not contain lubricating particles, a plurality of second layers containing lubricating particles may also be provided. In this case, it is préférable that the plurality of second layers be formed so that the ratio of the lubricating particles is increased from the lower layer to the upper layer. Accordingly, the solid coating having excellent coating adhesiveness and lubricity (seizure résistance) can be obtained.
In the case where the organic resin is the Torlon polyamide-imide resin, a préférable heating température after applying the composition for solid coating
- 16 17282 formation is as follows.
In the case where the solid coating is the single-layer coating, first, the composition for solid coating formation is appiied onto the contact surfaces of the threaded joint. Thereafter, the composition is heated and maintained at 80 to 100°C for 5 to 20 minutes for predrying. Next, the résultant is heated and maintained at 180 to 280°C for 10 to 30 minutes for main heating for curing. In a case of another organic resin, a heating température or a heating time may be appropriately depending on the type of the used organic resin, and any of predrying or main heating may be omitted.
In the case of forming the solid coating having two or more layers, predrying and main heating as described above may be performed on each layer for forming the coating. In addition, after the first layer is appiied and heated and maintained at 80 to 100°C for 5 to 20 minutes for predrying, main heating may be not performed thereon, and the second layer may be appiied and be subjected to main heating after the predrying. That is, main heating may be collectively performed on the first layer and the second layer.
In addition, the température or the holding time is a température measured at the contact surfaces of the threaded joint and is not the setting température or the holding time of a heating fumace.
It is préférable that the température of the contact surfaces of the threaded joint during application be atmosphère (about 20°C). In addition, in order to reduce an operation time, the contact surfaces to be appiied may be heated by setting the main heating température as the upper limit. In this case, it is préférable that the heating température be a température lower than the boiling points of the water and the dipolar aprotic solvent.
It is préférable that the thickness of the solid coating be 5 pm to 100 pm from
- 17 17282 the viewpoint of adhesiveness, seizure résistance, and antirust properties. In the case where the solid coating is two or more layers, the total thickness thereof is the thickness of the solid coating. When the thickness of the solid coating is less than 5 pm, the lubricity of the tubular threaded joint is insufficient, and seizure is likely to occur at the time of fastening and loosening. Further, although the solid coating has a certain degree of antirust properties, when the thickness thereof is too small, antirust properties become insufficient, resulting in dégradation in corrosion résistance of the contact surfaces. When the thickness of the solid coating is too large, it is difficult to sufficiently remove volatile materials such as moisture and the volatile materials are rapidly volatilized during the drying, heating, and curing treatments, and thus a coating with good smoothness in the surfaces thereof is not obtained. For this reason, the upper limit of the thickness of the solid coating is 100 pm. Considering the viewpoint of adhesiveness, a préférable upper limit of the thickness of the solid coating is 50 pm. [Base Treatment]
Regarding the threaded joint having the solid coating formed on the contact surfaces of the pin 1 and/or the box 2, when a base treatment for roughening the contact surfaces is performed thereon before forming the solid coating on the contact surfaces to increase the surface roughness to be higher than 3 pm to 5 pm which is the surface roughness after a cutting process, seizure résistance is enhanced in many cases. Therefore, it is préférable that the contact surfaces be roughened by the base treatment before forming the solid coating.
Particularly, in the case where the solid coating is the single-layer coating containing the lubricating particles, there is a tendency to reduce coating adhesiveness compared to a coating without lubricating particles being contained. Therefore, it is préférable that the contact surfaces be roughened in advance. As a matter of course,
- 18 17282 even in the case where the solid coating is the laminated coating described above, when the contact surfaces are roughened by the base treatment, enhancement in seizure résistance is obtained in many cases.
As the subsurface treatment, for example, there is a blasting treatment of projecting a blast material such as a shot material having a spherical shape and a grid material having an angular shape. In addition, as the subsurface treatment, for example, there is pickling which damages the skin due to immersion in a strong acid liquid such as sulfuric acid, hydrochloric acid, nitric acid, and hydrofluoric acid. In addition, as the subsurface treatment, for example, there are a chemical conversion treatment such as a phosphatizing treatment, an oxalate treatment, or a borate treatment (the roughness of crystal surfaces increases as the generated crystals grow), electro plating of metals such as Cu, Fe, Sn, or Zn or an alloy thereof (since convex portions are preferentially plated, surfaces are slightly roughened), and impact plating in which a porous plated coating can be formed. In addition, as a type of electro plating, composite plating in which a plated coating is formed by dispersing solid fine particies in a métal is possible as a method of imparting roughness to surfaces because the solid fine particies protrude from the plated coating.
Even when the subsurface treatment for the contact surfaces is any of the methods, it is préférable that the surface roughness Rmax after roughening by the subsurface treatment be 5 pm to 40 pm. When Rmax is less than 5 pm, adhesiveness to the solid coating and maintenance of the coating may become insufïicient. On the other hand, when Rmax exceeds 40 pm, frictional force is increased, and thus the coating may not bear shear strength and compressive force at a high surface pressure and may be easily broken or peel off. As the subsurface treatment for roughening, two or more treatments may be used in combination, and the treatment method may use
- 19 17282 well-known methods.
From the viewpoint of the adhesiveness of the solid coating, the subsurface treatment capable of forming a porous coating, that is, the chemical conversion treatment and the impact plating are préférable. In this case, in order for Rmax of the porous coating to be 5 gm or greater, it is préférable that the thickness thereof be 5 gm or greater. Although the upper limit of the thickness is not particularly specified, typically, a thickness of 50 gm or less, and preferably, a thickness of 40 gm or less is sufficient. When the solid coating is formed on the porous coating formed by the subsurface treatment, the adhesiveness thereof to the solid coating is increased due to the so-called “anchor effect”. As a resuit, even when fastening and loosening are repeated, peeling of the solid coating is less likely to occur. Accordingly, metal-tometal contact is effectively prevented, and thus seizure résistance, gastightness, and corrosion résistance are further enhanced.
..Particularly préférable subsurface treatments for forming a porous coating are a phosphate chemical conversion treatment (a treatment using manganèse phosphate, zinc phosphate, ferromanganese phosphate, or zinc calcium phosphate) and formation (porous métal plating) of a coating of zinc or an alioy of zinc and iron by impact plating. Among these, from the viewpoint of adhesiveness, a manganèse phosphate coating is more préférable. On the other hand, from the viewpoint of corrosion résistance, a coating of zinc or an alioy of zinc and iron by which sacrificial corrosion résistance can be expected due to zinc is more préférable.
The phosphate chemical conversion treatment can be performed by immersion or spraying according to an ordinary method. As a chemical conversion treatment liquid, an acidic phosphate treatment liquid for general zinc plating can be used. For example, a zinc phosphate-based chemical conversion treatment using 1 to 150 g/L of
- 20 17282 phosphate ions, 3 to 70 g/L of zinc ions, 1 to 100 g/L of nitric acid ions, 0 to 30 g/L of nickel ions can be employed. In addition, a manganèse phosphate-based chemical conversion treatment which is commonly used for a threaded joint can also be used. The température of the liquid may be atmosphère (room température) to 100°C, and the treatment time may be up to 15 minutes depending on a desired thickness. In order to accelerate the formation of the coating, before the phosphate treatment, an aqueous solution for surface adjustment, which contains a colloïdal titanium may be supplied for surfaces to be treated. After the phosphate treatment, drying is preferably performed after water washing or hot-water washing.
The impact plating can be performed by mechanical plating in which particles and an object to be plated impact with each other in a rotating barrel or projection plating in which particles and an object to be plated impact with each other using a blasting device. In the threaded joint, plating may be performed only on the contact surfaces. Therefore, it is préférable to employ projection plating which enables local plating.
For example, a projection material made of particles obtained by coating the surfaces of iron-based nuclei with zinc or a zinc alloy is projected onto the contact surfaces to be coated. The content of zinc or the zinc alloy in the particles is preferably in a range of 20 mass% to 60 mass%. The particle diameters of the particles are preferably in a range of 0.2 mm to 1.5 mm. Through projection, only zinc or the zinc alloy which is the coating layer of the particle adhères to the contact surfaces which are the base body, and a porous coating made of zinc or the zinc alloy is formed on the contact surfaces. The projection plating enables a porous métal plated coating with good adhesiveness to be formed on the surface of steel regardless of the material of the steel.
- 21 17282
The thickness of zinc or the zinc alloy formed by the impact plating is preferably 5 pm to 40 pm in terms of both corrosion résistance and adhesiveness.
When the thickness is less than 5 pm, sufficient corrosion résistance cannot be ensured.
When the thickness exceeds 40 pm, adhesiveness to the solid coating may be degraded.
Two or more types of the above-described subsurface treatments may be combined to be performed.
As another subsurface treatment, aithough there is a slight roughening effect, spécifie single-layer or multiple-layer electro plating is performed, adhesiveness between the solid coating and the subsurface is increased, and the seizure résistance of
As the subsurface treatment for the solid coating, for example, electro plating using metais such as Cu, Sn, and Ni or an alloy thereof may be employed. Plating may be single-layer plating or multiple-layer plating for two or more layers. As spécifie examples of this type of electro plating, there are Cu plating, Sn plating, Ni plating, CuSn alloy plating further described in Japanese Unexamined Patent Application, First Publication No. 2003-74763, Cu-Sn-Zn alloy plating, two-layer plating including Cu plating and Sn plating, and three-layer plating including Ni plating, Cu plating, and Sn plating. Particularly, in a tubular threaded joint manufactured from a steel type in which the Cr content exceeds 5%, seizure is very likely to occur. Therefore, it is préférable that single-layer plating of a Cu-Sn alloy or a Cu-Sn-Zn alloy, or multiplelayer métal plating using a combination of two or more types of plating selected from the alloy plating, Cu plating, Sn plating, and Ni plating be performed as the subsurface treatment. As the multiple-layer métal plating, for example, there are two-layer plating including Cu plating and Sn plating, two-layer plating including Ni plating and Sn plating, two-layer plating including Ni plating and Cu-Sn-Zn alloy plating, and three- 22 17282 layer plating including Ni plating, Cu plating, and Sn plating.
Such plating may be performed according to a method described in Japanese Unexamined Patent Application, First Publication No. 2003-74763. In the case of the multiple-layer plating, a plated coating (typically Ni plating) at the lowest layer is preferably a plated layer called strike plating, which has an extremely small thickness of 1 pm or less. It is préférable that the thickness of the plating (the total thickness in the case of the multiple-layer plating) be in a range of 5 pm to 15 pm.
As still another subsurface treatment, a solid anticorrosive coating treatment is also possible. The above-described solid coating is a viscous liquid or a semisolid as described above, and the surface thereof has slight stickiness. Particularly, the solid coating of the viscous liquid has high stickiness. As a resuit, particularly at the time of allowing the oil well pipe to stand upright, rust that remains on the inner surface or abrasive grains for abrasive blasting injected to remove the rust fall, and they may adhéré to the solid coating and be buried into the solid coating. The foreign matter buried into the coating is not completely removed by air blovving or the like and causes dégradation in lubricity. In order to solve this problem, a thin dried solid coating may also be formed on the upper layer of the solid coating. The dried solid coating may be a general resin coating (for example, an epoxy resin, a polyamide resin, a polyamideimide resin, or a vinyl resin), and the coating can be formed from any of a water-based composition and an organic solvent-based composition. Further, a small amount of wax may be contained in the coating.
FIG 3A is a diagram schematically illustrating a coating structure in a case where a subsurface treatment layer (for example, a phosphate chemical conversion treatment coating or a porous métal plated coating formed by impact plating) 32 for roughening is first formed on the contact surface of a base body 30 that forms the pin 1
- 23 17282 and/or the box 2 of the tubular threaded joint and a solid coating 31b, which contains the lubricating particles, is formed thereon. As described above, roughening may also be achieved by roughening the contact surface itself through, for example, sandblasting instead of forming the base treatment layer 32. Further, the solid coating may also not contain the lubricating particles.
FIG 3B is a diagram schematically illustrating a coating structure in a case where a solid coating 31a, which does not contain the lubricating particles, is formed as a first layer on the contact surface of a base body 30 of the pin 1 and/or the box 2 of the tubular threaded joint and a solid coating 31b, which contains the lubricating particles, is formed thereon as a second layer. It is préférable that, on the contact surface of the base body 30, the subsurface treatment coating for roughening be formed as illustrated in FIG 3A, or the two layers of solid coatings be formed after roughening the contact surface itself.
[Surface Treatment of Counterpart Member]
In a case where the solid coating is formed on the contact surfaces of only one member (for example, the box 2) of the pin 1 and the box 2 of the tubular threaded joint, the contact surfaces of the other member (for example, the pin 1) that is not coated with the solid coating may be untreated. However, preferably, the above-described subsurface treatment for roughening may be performed thereon to roughen the contact surfaces. That is, the roughening can be performed by employing a blasting treatment, pickling, a chemical conversion treatment using phosphate, oxalate, borate, or the like, electro plating, composite plating in which a plated coating containing solid fine particles is formed, and a combination of two or more types thereof. At the time of fastening a counterpart member which is coated with the solid coating, the contact surfaces of the other member which does not hâve the solid coating exhibits good
- 24 17282 maintenance due to the anchor effect by the roughening. Accordingly, the seizure résistance ofthe tubular threaded joint is increased.
In addition, in order to impart antirust properties, a well-known waterproof coating such as a ultraviolet curable resin or a thermosetting resin may also be performed after the subsurface treatment, if desired. By blocking the contact with the atmosphère by the antirust coating, even when contact with water occurs due to the dew point during storage, génération of rust on the contact surfaces is prevented.
Since the surface treatment of the contact surfaces of the counterpart member is not particularly limited, the other surface treatments can also be performed. For example, various solid coatings (for example, a solid lubricating coating) which are different from the solid coating of this embodiment can be formed on the contact surface of the counterpart member.
[Examples]
The effect of the présent invention is exemplified by the following Examples and Comparative Examples. Further, hereinafter, the contact surface including the threaded portion and the unthreaded métal contact portion of the pin is referred to as a “pin surface” and the contact surface including the threaded portion and the unthreaded métal contact portion of the box is referred to as a “box surface”. Surface roughness is Rmax. “%” is “mass%” unless otherwise designated.
On the pin surface and the box surface of a coupling type premium threaded joint VAM TOP (outside diameter: 17.78 cm (7 inches), thickness: 1.036 cm (0.408 inches), including the threaded portion, the seal portion, and the shoulder portion) made of any of a Cr-Mo steel A, a 13% Cr steel B, a 25% Cr steel C shown in Table 1, the subsurface treatment shown in Table 3 was performed, and by using a composition for solid coating formation having the chemical composition shown in Table 2, a solid
- 25 17282 coating was formed under the solid coating formation conditions shown in Table 3.
Regarding the average thickness of the obtained solid coating, the thickness of the solid coating at the unthreaded métal contact portion was measured by a commercially available thickness meter. .
The composition for solid coating formation was prepared by preparing a mixed solvent by mixing a dipolar aprotic solvent and pure water at a predetermined ratio, adding a powdery organic resin to the mixed solvent, and stirring the résultant at a température of 60 to 80°C using a stirrer to cause the resin powder to be dissolved or dispersed in the solvent. In a case where the composition contains the lubricating particles, lubricating particles are added and further stirred to cause the particles to be uniformly dispersed for the préparation. Further, in a case of a resin which is obtained in a dispersed liquid state, the solvent is prepared to be the mixed solvent according to the embodiment of the présent invention, and lubricating particles are further added and stirred depending on the case, thereby forming the composition for solid coating formation.
[Table 1]
| Symbol | C | Si | Mn | P | S | Cu | Ni | Cr | Mo |
| A | 0.25 | 0.25 | 0.8 | 0.02 | 0.01 | 0.04 | 0.05 | 0.95 | 0.18 |
| B | 0.19 | 0.25 | 0.8 | 0.02 | 0.01 | 0.04 | 0.1 | 13 | 0.04 |
| C | 0.02 | 0.3 | 0.5 | 0.02 | 0.01 | 0.5 | 7 | 25 | 3.2 |
(Note) The content of each element is mass%, and the balance being Fe and impurities.
[Table 2]
| No. | Constitution of composition for solid coating formation (mass%) | |||
| Waterdispersibler esin | Water | Aqueous organic solvent | Lubricating solid particles | |
| Example 1 | Polyamideimide resin (15) | Pure water (balance) | NMP (50) | |
| Example 2 | Polyamideimide resin (12) | Pure water (balance) | DMSO (45) | PTFE particles (5) |
| Example 3 | Epoxy | Pure | GBL | Amorphous |
- 26 17282
| resin (12) | water (balance) | (40) | graphite (10) | ||
| Example 4 | First layer | Mixture of polyamideimide resin and fluororesin (12) | Pure water (balance) | DMSO (47) | |
| Second layer | Mixture of polyamideimide resin and fluororesin (12) | Pure water (balance) | DMSO (47) | Amorphous graphite* (17) | |
| Comparative Example 2 | Polyamideimide resin (10) | Organic solvent (other than xylene) (balance) | Molybdenum disulfide (30) |
* The amount of amorphous graphite is an added amount with respect to 100 parts by mass of the total amount of resin, water, and organic solvent.
[Table 3]
| No. | Pin | Box | Steel composition | ||||
| Subsurface treatment | First layer of solid coating | Second layer of solid coating | Subsurface treatment | First layer of solid coating | Second layer of solid coating | ||
| Example 1 | 1. Grinding finish (R=3) 2. Zinc phosphate (R=8)(t=12) | Polyamideimide resin (t=25) | 1. Grinding finish (R-3) 2. Manganèse phosphate (R=10) (t=15) | Polyamideimide resin (t=25) | A | ||
| Example 2 | Sandblasting (R=10) | Polyamideimide resin with PTFE powder dispersed (t=20) | 1. Grinding finish (R=3) 2. Ni strike plating+Cu piating (t=10) (R=5) | Polyamideimide resin with PTFE powder dispersed (t=20) | / | B | |
| Example 3 | Sandblasting (R=10) | Epoxy resin with amorphous graphite dispersed (t=30) | 1. Grinding finish (R=3) 2. Ni strike plating+CuSn-Zn alloy piating (t=7)(R=5) | Epoxy resin with amorphous graphite dispersed (t=30) | C | ||
| Example 4 | Grinding finish (R=3) | Mixture of polyamide- | Mixture of polyamide- | Grinding finish | Mixture of polyamide- | Mixture of polyamide- | A |
- 27 17282
| imide resin and fluororesin (t=15) | imide resin with amorphous grpahite dispersed and fluororesin (t=20) | (R=3) | imide resin and fluororesin (t=15) | imide resin with amorphous grpahite dispersed and fluororesin (t=20) | |||
| Comparative Example 1 | 1. Grinding finish (R=3) 2. Zinc phosphate (R=8) (t=12) | Compound grease specified in the Standard API BUL 5A2 | 1. Grinding finish (R=3) 2. Manganèse phosphate (R=10) (t=15) | Compound grease specified in the Standard API BUL 5A2 | A | ||
| Comparative Example 2 | 1. Grinding finish (R=3) 2. Zinc phosphate (R=8) (t=12) | Polyamideimide resin with molybdenum disulfïde dispersed (t=25) | 1. Grinding finish (R=3) 2. Manganèse phosphate (R=10) (t=15) | Polyamideimide resin with molybdenum disulfïde dispersed (t=25) | / | A |
R: Surface roughness (pm), t: Thickness (pm)
For the évaluation, in a state where protectors for protecting a pin threaded portion and a threaded portion of a box inner surface of a coupling of an oil well pipe were mounted before fastening, a weather résistance test in which ail climates were 5 simulated in the order from a frigid weather to a high température under the test climate conditions (humidity is relative humidity) as described in Table 4 was performed. Thereafter, the coupling was taken off, the pin surface and the box surface were visually observed, the extemal form of the solid coating (presence or absence of peeling, discoloration, and the like) was examined, and the hardness of the solid coating before 10 and after the weather résistance test was measured by a pencil hardness tester.
Thereafter, a repeated fastening and loosening test, which will be described later, was immediately performed, and occurrence of seizure was examined. In addition, in Table 4, under the océan environment exposure condition, a saturated NaCI solution for a sait
- 28 17282 spray test according to the JIS standard was sprayed for the test under the conditions of +40°C and a humidity of 98%.
In the repeated fastening and loosening test, the threaded joint was fastened at a fastening speed of 10 rpm and a fastening torque of 20 kN-m, and the seizure statuses of 5 the pin surface and the box surface were examined after loosening. The first to fourth fastening and loosening operations were performed in a warm environment (about 20°C). The fîfth and the rest fastening and loosening operations were performed at 20°C by cooling the periphery of the fastened part with dry ice. In a case where seizure marks generated by fastening were small and re-fastening was possible after repair, fastening and loosening were continued after the repair. The results of the weather résistance test and the repeated fastening and loosening test performed thereafter are collectively shown in Table 5.
[Table 4]
| Order | Climate conditions | Température (°C) | Humidity (%) | Test time |
| 1 | Thermal détérioration | +40 | Not designated | 6 days |
| 2 | Exposure to low température | -60 | Not designated | 3 days |
| 3 | Température change | +20 | 98 | Total of 36 cycles of 4 hours per each température |
| -20 | Not designated | |||
| 4 | Hot and humid | +40 | 98 | 5 days |
| 5 | Exposure to océan environment (sait spray) | +40 | 98 | 2 days |
| 6 | Exposure to high-temperature steam | -40 | Not designated | 1 hour |
| +100 | 98 | 1 minute |
[Table 5]
| No. | Seizure occurrence status (numéral value: the number of fastening operations) | Weather résistance test resuit | Note | ||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||||
| Examples | 1 | O | O | O | O | O | O | O | O | Δ | Δ | No change |
- 29 17282
| 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | No change | ||
| 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | No change | ||
| 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | No change | ||
| Comparative Examples | 1 | 0 | 0 | 0 | 0 | 0 | Δ | Δ | X | No change | Heavy metals such as lead are contained and there is a harmful effect on human bodies and the environment, and stickiness is significant. | ||
| 2 | 0 | 0 | Δ | Δ | X | Significant coating peeling | A harmful organic solvent is used. |
(Note)l) O: No occurrence of seizure, Δ: Slight occurrence (seizure marks are réparable and re-tightening is possible), x: Significant occurrence (irréparable) (Example 1)
On the pin surface and the box surface of the premium threaded joint made of the Cr-Mo steel having the composition A shown in Table 1, surface treatments were performed to achieve the subsurface treatment and the solid coating configuration shown in Example 1 of Table 3.
The box surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was immersed in a manganèse phosphate chemical conversion treatment liquid at 80°C to 95°C for 10 minutes, thereby forming a manganèse phosphate coating (a surface roughness of 10 pm) having a thickness of 15 pm.
The pin surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was immersed in a zinc phosphate chemical conversion treatment liquid at 75 to 85°C for 10 minutes, thereby forming a zinc phosphate coating (a surface roughness of 8 pm) having a thickness of 12 pm.
Next, onto the pin surface and the box surface subjected to the subsurface
- 30 17282 treatment, a composition for solid coating formation made by mixing a polyamideimide resin (Torlon™ 4000TF made by SOLVAY) as an organic resin that is soluble in a dipolar aprotic solvent, pure water, and NMP (N-methylpyrrolidone) as the dipolar aprotic solvent to hâve the composition of Example 1 of Table 2 was applied through spraying. Thereafter, résultant was subjected to predrying (at 80°C for 10 minutes) and main heating (at 230°C for 30 minutes), thereby forming a solid coating having an average thickness of 25 pm.
After mounting the protectors made of resin to the pin and the box having the solid coatings formed thereon, the weather résistance test shown in Table 4 was performed. As shown in Table 5, détérioration such as peeling, discoloration, and hardness dégradation of the solid coatings of the pin surface and the box surface was not confirmed after the test. Subsequently, the repeated fastening and loosening test was performed. After the ninth loosening, slight seizure had occurred in the threaded portion of the pin surface. However, the threaded portion was repaired and continuously subjected to the test as it was, and tenth fastening and loosening could be performed.
(Example 2)
On the pin surface and the box surface of the premium threaded joint made of the 13% Cr steel having the composition B shown in Table 1, surface treatments were performed to achieve the subsurface treatment and the solid coating configuration shown in Example 2 of Table 3.
The box surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) shown in Table 3 and thereafter was subjected to, first, Ni strike plating, and next, Cu plating through electro plating, thereby forming a plated coating (a surface roughness of 5 pm) having a total thickness of 10 pm. The pin surface was
- 31 17282 subjected to sandblasting in which sand is blasted 80 times to hâve a surface roughness of 10 pm.
Next, onto the pin surface and the box surface subjected to the subsurface treatment, a composition for solid coating formation made by mixing a polyamideimide resin (the same as that of Example 1) as an organic resin that is soluble in a dipolar aprotic solvent, pure water, DMSO (dimethylsulfoxide) as the dipolar aprotic solvent, and PTFE particles as lubricating particles at the ratio shown in Example 2 of Table 2 was applied through spraying. Thereafter, the résultant was subjected to predrying (at 85°C for 10 minutes) and main heating (at 280°C for 30 minutes), thereby forming a solid coating having an average thickness of 20 pm.
After mounting the protectors made of resin to the pin and the box having the solid coatings formed thereon, the weather résistance test shown in Table 4 was performed. As shown in Table 5, détérioration such as peeling, discoloration, and hardness degradation.of the solid coatings of the pin surface and the box surface was not confirmed after the test. Subsequently, the repeated fastening and loosening test was performed, and fastening and loosening could be performed 10 times without the occurrence of seizure.
(Example 3)
On the pin surface and the box surface of the premium threaded joint made of the 25% Cr steel having the composition C shown in Table 1, surface treatments were performed to achieve the subsurface treatment and the solid coating configuration shown in Example 3 of Table 3.
The box surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was subjected to, first, Ni strike piating, and next, Cu-Sn-Zn alloy piating through electro piating, thereby forming a plated coating (a
- 32 17282 surface roughness of 5 pm) having a total thickness of about 7 pm. The pin surface was subjected to sandblasting in which 80th sand is blasted to hâve a surface roughness of 10 pm.
Next, onto the pin surface and the box surface subjected to the subsurface treatment, a composition for solid coating formation made by mixing a commercially available water-dispersible epoxy resin (MODEPICS301 (registered trademark) made by Arakawa Chemical Industries, Ltd., obtained in a water-dispersed liquid state) as an organic resin that is partially soluble at least in a dipolar aprotic solvent, GBL (γbutyrolactone) as the dipolar aprotic solvent, and amorphous graphite as lubricating particles at the ratio shown in Example 3 of Table 2 was appiied through spraying. Thereafter, the résultant was subjected to predrying (at 80°C for 10 minutes) and main heating (at 230°C for 30 minutes), thereby forming a solid coating having an average thickness of 20 pm.
After mounting the protectorsmade of resin to the pin and the box having the solid coatings formed thereon, the weather résistance test shown in Table 4 was performed. As shown in Table 5, détérioration such as peeling, discoloration, and hardness dégradation of the solid coatings of the pin surface and the box surface was not confirmed after the test. Subsequently, the fastening and loosening test was performed, and fastening and loosening could be performed 10 times without the occurrence of seizure.
(Example 4)
On the pin surface and the box surface of the premium threaded joint made of the Cr-Mo steel having the composition A shown in Table 1, surface treatments were performed to achieve the subsurface treatment and the solid coating configuration shown in Example 4 of Table 3.
- 33 17282
The pin surface and the box surface were subjected to a mechanical grinding finish (a surface roughness of 3 pm). Onto the pin surface and the box surface, first, as a first layer, a composition for solid coating formation made by mixing a mixture (the mass ratio of polyamide-imide resin/fluororesin = 70/30 in terms of solid content) of a polyamide-imide resin (the same as that of Example 1) as an organic resin that is soluble in a dipolar aprotic solvent and a commercially available water-dispersible fluororesin (POLYFLON (registered trademark) PTFE D-210C made by DAIKIN INDUSTRIES, ltd., obtained in a water-dispersed liquid state), and as the balance, pure water and DMSO as the dipolar aprotic solvent at the ratio shown in the first layer of Example 4 of Table 4 was applied through spraying. Thereafter, the résultant was subjected to predrying (at 80°C for 10 minutes). Next, as a second layer, a composition for solid coating formation made by further adding and dispersing 17 parts by mass of amorphous graphite in 100 parts by mass ofthe composition for solid coating formation for the first layer was applied through spraying. Thereafter, the résultant was subjected to predrying (at 80°C for 10 minutes) and main heating (at 230°C for 30 minutes). Accordingly, a solid coating in which the first layer and the second layer hâve a total average thickness of 35 pm was formed. As shown in Table 3, the thickness of the first layer that did not contain lubricating particles was about 15 pm, and the thickness of the second layer that contained the lubricating particles (amorphous graphite) was about 20 pm.
After mounting the protectors made of resin to the pin and the box having the solid coatings formed thereon, the weather résistance test shown in Table 4 was performed. As shown in Table 5, détérioration such as peeling, discoloration, and hardness dégradation of the solid coatings of the pin surface and the box surface was not confirmed after the test. Subsequently, the repeated fastening and loosening test was
- 34 17282 performed. Fastening and loosening could be performed 10 times without the occurrence of seizure.
(Comparative Example 1)
On the premium threaded joint made of the Cr-Mo steel of the composition A shown in Table 1, the subsurface treatment of Comparative Example 1 of Table 2 was performed, and a grease (a compound grease in a viscous liquid form specified in the Standard API BUL 5A2) that contained heavy metals such as lead was applied thereto.
The box surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was immersed in a manganèse phosphate chemical conversion treatment liquid at 80 to 95°C for 10 minutes, thereby forming a manganèse phosphate coating (a surface roughness of 10 pm) having a thickness of 15 pm. Next, the compound grease was applied onto the surface subjected to the subsurface treatment, thereby forming a lubricating coating (a total amount of the compound grease applied onto the pin and the box was 50 g, and the application area thereof is approximately 1400 cm2 in total)
The pin surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was immersed in a zinc phosphate chemical conversion treatment liquid at 75 to 85°C for 10 minutes, thereby forming a zinc phosphate coating (a surface roughness of 8 pm) having a thickness of 12 pm. The compound grease as such was applied onto the surface thereof.
After mounting the protectors made of resin to the pin and the box, the weather résistance test shown in Table 4 was performed. As shown in Table 5, no significant changes in the lubricating coating grease on the pin surface and the box surface were confirmed after the test. In the fastening and loosening test performed subsequently, during the first to fourth fastening and loosening operations performed in a warm
- 35 17282 environment (about 20°C), seizure had not occurred. However, in the fifth and the rest fastening and loosening operations at about -20°C, seizure had occurred in the threaded portion of the pin from the sixth fastening and loosening operation, and seizure in the eighth fastening and loosening operation was at such a level that could not be repaired. Therefore, the test was stopped.
From the results, it was determined that even though the compound grease containing heavy métal powder, which had been used from the past, was considered to hâve excellent seizure résistance, satisfactory performance could not be exhibited during fastening in a low température environment after an exposure to a hot and cold cycle of from an extremely low température to a high température.
(Comparative Example 2)
On the pin surface and the box surface of the premium threaded joint made of the Cr-Mo steel having the composition A shown in Table 1, surface treatments were performed to achieve the subsurface treatment and the solid coating configuration shown in Comparative Example 2 of Table 3.
The box surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was immersed in a manganèse phosphate chemical conversion treatment liquid at 80 to 95°C for 10 minutes, thereby forming a manganèse phosphate coating (a surface roughness of 10 pm) having a thickness of 15 pm.
The pin surface was subjected to a mechanical grinding finish (a surface roughness of 3 pm) and thereafter was immersed in a zinc phosphate chemical conversion treatment liquid at 75 to 85°C for 10 minutes, thereby forming a zinc phosphate coating (a surface roughness of 8 pm) having a thickness of 12 pm.
Next, onto the pin surface and the box surface subjected to the subsurface treatment as such, a composition for solid coating formation (corresponding to the
- 36 17282 composition described in Patent Document 1) made by mixing a polyamide-imide resin (VYLOMAX (registered trademark) HR-BNX made by TOYOBO CO., LTD.) that is soluble in a non-dipolar (non-polar) organic solvent, a mixed solvent including xylene and NMP at a mass ratio of 33 and 67 as an organic solvent, and molybdenum disulfide as lubricating particies at the ratio shown in Comparative Example 2 of Table 2 was applied through spraying. Thereafter, the résultant was subjected to predrying (at 80°C for 10 minutes) and main heating (at 230°C for 30 minutes), thereby forming a solid coating having an average thickness of 25 pm.
After mounting the protectors made of resin to the pin and the box having the solid coatings formed thereon, the weather résistance test shown in Table 4 was performed. As shown in Table 5, partial peeling and blisters were observed from the solid coatings of the pin surface and the box surface after the test. In the repeated fastening and loosening test performed subsequently, during the first to fourth fastening and loosening operations performed in a warm environment (about 20°C), seizure had started to occur in the threaded portion of the pin from the third fastening and loosening operation. Thereafter, the threaded portion was repaired to continue the test. However, in the fifth fastening and loosening operation which was the fastening and loosening test performed at about -20°C, and seizure was at such a level that could not be repaired. Therefore, the test was stopped.
From the results, even in the tubular threaded joints having the solid coatings made of the simiiar polyamide-imide resins as such, it was apparently seen that the solid coating formed from the composition dissolved in the organic solvent of Comparative Example 2 and the solid coatings formed from the compositions dispersed in water in Examples 1 to 4 were different in the performance in the hot and cold cycle of from an extremely low température to a high température and in the seizure résistance
- 37 17282 performance in the fastening and loosening test at a low température.
The antirust properties of the tubular threaded joints of Examples 1 to 4 and Comparative Examples 1 and 2 were examined by performing the same subsurface treatments as those of the pin surfaces and the box surfaces of Table 3 on additionally prepared coupon specimens (70 mmxl50 mmxl.O mm thick) and forming the same solid coatings. The specimens were provided for a sait spray test (based on JIS Z2371 (corresponding to ISO 9227), a température of 35°C, 1000 hours) and a humidity test (based on JIS K5600-7-2 (corresponding to ISO 6270), a température of 50°C, a humidity of 98%, 200 hours) to examine presence or absence of rust being generated. As a resuit, it was confirmed that there was no rust being generated in ail the Examples 1 to4.
While the présent invention has been described according to the embodiments which are considered to be préférable at this point in time, the présent invention is not limited to the embodiments disclosed above. Modifications can be added in a range that does not départ from the technical idea of the présent invention that can be read from the appended claims and the entire spécification, and it should be understood that threaded joints according to such modifications are included in the technical scope of the présent invention.
[Description of Reference Numerals and Signs]
A: STEEL PIPE
B: COUPLING
1: PIN
2: BOX
3a: MALE THREADED PORTION
3b: FEMALE THREADED PORTION
- 38 17282
4a, 4b: UNTHREADED METAL CONTACT PORTION
5a, 5b: SHOULDER PORTION
30: STEEL SURFACE a: SOLID COATING (FIRST LAYER IN TWO-LAYER
CONFIGURATION)
31b: SOLID COATING (IN SINGLE-LAYER CONFIGURATION OR
SECOND LAYER IN TWO-LAYER CONFIGURATION)
32: SUBSURFACE TREATMENT LAYER
Claims (6)
- [Claim 1]A composition for solid coating formation, comprising a composition made by containing, in a mixed solvent including water and a dipolar aprotic solvent, a powdery organic resin which is partially soluble at least in the dipolar aprotic solvent, wherein the powdery organic resin is présent in a state of being dissolved or dispersed in the mixed solvent.
- [Claim 2]The composition for solid coating formation according to Claim 1, further comprising lubricating particles.
- [Claim 3]The composition for solid coating formation according to Claim 1 or 2, wherein the powdery organic resin is one or more types selected from a polyamide-imide resin, an epoxy resin, and a fluororesin.
- [Claim 4]The composition for solid coating formation according to any one of Claims 1 to 3, wherein the dipolar aprotic solvent is one or more types selected from Nmethylpyrrolidone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, and γbutyrolactone.
- [Claim 5]A tubular threaded joint comprising a pin and a box each of which is provided with a contact surface including a threaded portion and a unthreaded métal contact portion,- 40 17282 wherein the contact surface of at least one member of the pin and the box has a solid coating formed from the composition for solid coating formation according to any one of Claims 1 to 4.
- [Claim 6]5 The tubular threaded joint according to Claim 5, wherein the solid coating has: a first layer which does not contain lubricating particles; and a second layer formed thereon, which contains lubricating particles. [Claim 7]The tubular threaded joint according to Claim 5 or 6,10 wherein a thickness ofthe solid coating is 5 pm to 100 pm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012-200118 | 2012-09-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA17282A true OA17282A (en) | 2016-04-29 |
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