JP2008057641A - Special screw fitting for oil well pipe, and its manufacturing method - Google Patents
Special screw fitting for oil well pipe, and its manufacturing method Download PDFInfo
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Abstract
Description
本発明は、油井管用特殊ねじ継手およびその製造方法に関し、特に、切削加工ないしショットブラスト等表面処理のばらつきに起因するシール性のばらつきを小さくしかつシール性をさらに向上させた油井管用特殊ねじ継手およびその製造方法に関する。 The present invention relates to a special threaded joint for oil well pipes and a method for manufacturing the same, and in particular, a special threaded joint for oil well pipes that reduces variation in sealing performance due to variations in surface treatment such as cutting or shot blasting and further improves sealing performance. And a manufacturing method thereof.
近年、開発の容易な油井、ガス井が減少するとともに、より高深度でかつ高温高圧の井戸が増加している。また、掘削技術の進歩に伴い、傾斜井戸、水平井戸など、より複雑な形状の井戸が増加している。これに伴い、油井管のねじ継手に対する要求、例えば、引張、圧縮、内外圧、曲げなどの複合荷重下における気密性などの要求もますます高度化している。(非特許文献1)
油井管用特殊ねじ継手は、図1に示すように、ねじ結合される雄側のピン1と雌側のボックス(またはカップリング)2とからなり、これらの双方が互いに対応する箇所に、ねじ締結部3と、ねじ締結部3の片側に連なる、メタル‐メタル接触によるシール部4、あるいはさらにこれに連なるショルダー部5を有するねじ継手である。ねじ締結部3にはテーパねじが設けられている。なお、ピン側のねじ締結部のテーパねじをピンねじ、ボックス側のそれをボックスねじと呼ぶ。
In recent years, oil wells and gas wells that are easy to develop have decreased, and wells at higher depths and higher temperatures and pressures have increased. In addition, with the progress of drilling technology, wells with more complicated shapes such as inclined wells and horizontal wells are increasing. Along with this, requirements for threaded joints of oil well pipes, such as airtightness under complex loads such as tension, compression, internal / external pressure, and bending, are becoming increasingly sophisticated. (Non-Patent Document 1)
As shown in FIG. 1, a special threaded joint for oil well pipes is composed of a
シール部は、一般に先端R0.8mm程度のポイントカットツールと呼ばれる菱形の工具で送り0.1mm/回転程度で切削加工され、加工後の表面粗さがRa≦1.6μmに仕上げられる。また、9%以上のCrを含有する合金鋼油井管については、継手締結時にゴーリングと呼ばれるかじりが発生しやすく、この防止のため、通常、ピン側表面にはガラス、アルミナ、セラミック、ステンレス等からなるショット粒を用いたブラスト処理が施され、また、ボックス側表面には銅めっき等のめっき処理が施される。なお、ブラスト後のピン表面粗さはRa1.0〜3.0μm程度まで上昇する。
上述の仕上げ切削加工ないし表面処理後の表面は、微小な凹みが一種の油溜りとなり、その潤滑作用によりゴーリングを防止すると考えられているが、一方、ガスシール試験においては、それらが連続してシール部に存在した場合、ガスのリークパスとなり、シール性低下の要因となる。
一方、締付け‐締戻し作業に伴うゴーリング防止の目的で、ボックス側表面に厚さ5〜20μm程度のCuめっき,Cu‐Snめっき等のめっきが施される。このゴーリング防止用めっきは、締付け時に削られあるいは剥がれることにより地肌を露呈させるようなものでない、硬質めっきであることが肝要である。もっとも、このゴーリング防止用めっきでは、ゴーリングに伴うリークパス発生を抑止する効果はあるものの、ピン側の表面性状に起因するリークパスを抑止する効果はないので、さらなるシール性向上効果は望めない。
The surface after the above-mentioned finishing cutting or surface treatment is considered to be a kind of oil sump that is a kind of oil sump and prevents goling by its lubricating action. If it exists in the seal portion, it becomes a gas leak path, which causes a decrease in sealing performance.
On the other hand, plating such as Cu plating or Cu—Sn plating having a thickness of about 5 to 20 μm is performed on the surface on the box side for the purpose of preventing goling associated with the tightening / returning operation. It is important that the anti-goling plating is a hard plating that does not expose the background by being scraped or peeled off during tightening. However, although this gol prevention plating has an effect of suppressing the occurrence of a leak path due to goling, it does not have an effect of suppressing the leak path due to the surface property on the pin side, and therefore a further improvement in sealing performance cannot be expected.
そこで、本発明は、仕上げ工程の切削加工ないしショットブラスト等表面処理のばらつきに起因するシール性のばらつきを小さくしかつシール性をさらに向上させた油井管用特殊ねじ継手およびその製造方法を提供することを目的とする。 Accordingly, the present invention provides a special threaded joint for oil well pipes and a method for manufacturing the same, in which the variation in sealing performance due to variations in surface treatment such as cutting or shot blasting in the finishing process is reduced and the sealing performance is further improved. With the goal.
発明者は、前記目的を達成するために鋭意検討し、前記ゴーリング防止用めっきの上にSnめっき等の軟質めっき(締付け時に容易に削られる軟らかいめっき)を施すとよいことを見出した。また、これに加えて、油井管用特殊ねじ継手の製造工程の最終段階で、ピンねじとボックスねじを締結するにあたり、この締結作業を2回以上実施するとさらによいことを見出した。すなわち、本発明は、以下のとおりである。 The inventor has intensively studied in order to achieve the above object, and has found that it is preferable to apply a soft plating such as Sn plating (a soft plating that is easily scraped during tightening) on the plating for preventing goling. In addition, in the final stage of the manufacturing process of the special threaded joint for oil country tubular goods, it has been found that it is better to perform this fastening operation twice or more when fastening the pin screw and the box screw. That is, the present invention is as follows.
1. ピンとボックスとのねじ締結部とメタル‐メタル接触によるシール部とを有する油井管用特殊ねじ継手であって、少なくとも前記シール部において、ピン側の締結前の表面粗さがRa1.0〜3.0μmであり、かつ、ボックス側の素地上に厚さ5〜20μmのゴーリング防止用めっき層およびさらにその上に厚さ1μm以上の軟質めっき層を有することを特徴とする油井管用特殊ねじ継手。 1. A special threaded joint for oil well pipes having a screw fastening part between a pin and a box and a seal part by metal-metal contact, and at least the seal part has a surface roughness Ra of 1.0 to 3.0 μm before fastening on the pin side A special threaded joint for oil well pipes having a 5-20 μm thick anti-goling plating layer on the substrate side of the box side and a soft plating layer having a thickness of 1 μm or more thereon.
2. 前記ねじ締結部が1回以上の締付け‐締戻し後の最終締付けにより締結されたことを特徴とする前項1に記載の油井管用特殊ねじ継手。
3. ピンとボックスとのねじ締結部とメタル‐メタル接触によるシール部とを有する油井管用特殊ねじ継手の製造方法において、ピンねじとボックスねじを螺合する前に、ピン側の少なくともシール部をブラスト処理してその表面粗さをRa1.0〜3.0μmとし、ボックス側の少なくともシール部に厚さ5〜20μmのゴーリング防止用めっきを施し、その上に厚さ1μm以上の軟質めっきを施すことを特徴とする油井管用特殊ねじ継手の製造方法。
2. 2. The special threaded joint for oil country tubular goods according to
3. In a manufacturing method of a special threaded joint for oil well pipes having a screw fastening portion between a pin and a box and a seal portion by metal-metal contact, at least the seal portion on the pin side is blasted before screwing the pin screw and the box screw. The surface roughness is Ra 1.0 to 3.0 μm, and at least the seal part on the box side is plated with a 5 to 20 μm thick anti-goling plate, and the top is subjected to a soft plating with a thickness of 1 μm or more. A manufacturing method for special threaded joints for oil well pipes.
4. 前記ねじ締結部を形成するにあたり、ピンねじとボックスねじを螺合して1回以上の締付け‐締戻しを行った後に最終締付けを行うことを特徴とする前項3に記載の油井管用特殊ねじ継手の製造方法。
4). The special threaded joint for oil country tubular goods according to the preceding
本発明によれば、安定して優れたシール性を発揮する油井管用特殊ねじ継手が得られる。 According to the present invention, it is possible to obtain a special threaded joint for oil country tubular goods that stably exhibits excellent sealing properties.
本発明では、ピン側の少なくともシール部をブラスト処理してその表面粗さをRa1.0〜3.0μmとし、ボックス側の少なくともシール部に厚さ5〜20μmのゴーリング防止用めっきを施し、その上に厚さ1μm以上の軟質めっきを施してから、ピンねじとボックスねじを締付ける。なお、ピン側でシール部以外の部分(ねじ締結部など)にも前記ブラスト処理を施すのは構わない。また、ボックス側でシール部以外の部位(ねじ締結部など)にも前記ゴーリング防止用めっきおよび軟質めっきを施すのは構わない。 In the present invention, at least the seal part on the pin side is blasted to have a surface roughness Ra of 1.0 to 3.0 μm, and at least the seal part on the box side is plated with a thickness of 5 to 20 μm for preventing goling, Apply soft plating with a thickness of 1 μm or more on top, and then tighten the pin screw and box screw. It should be noted that the blasting process may be performed on a portion other than the seal portion (screw fastening portion or the like) on the pin side. In addition, the gol prevention plating and the soft plating may be applied to portions other than the seal portion (such as a screw fastening portion) on the box side.
これにより、ボックス側シール部の最表層の軟質めっき層が、締付け時にピン側シール部の微小な凹み面を埋めることになり、均一で滑らかなシール表面が形成され、結果としてシール性が向上する。
軟質めっきの材料は、締付け工程での締付け力により容易に削られる程度の軟らかさをもつ材料でなければならず、かかる材料として、Sn,Al,Pb,Bi,Auなどの金属あるいはこれらの合金が挙げられる。軟質めっき層の厚さは、1μmに満たないとシール性向上効果に乏しいため、1μm以上とする。なお、軟質めっき層の厚さは、厚すぎると干渉量管理の点で不利なので、20μm以下とするのが好ましい。
As a result, the outermost soft plating layer of the box-side seal portion fills in the minute concave surface of the pin-side seal portion during tightening, and a uniform and smooth seal surface is formed, resulting in improved sealing performance. .
The soft plating material must be soft enough to be easily scraped by the clamping force in the clamping process, such as a metal such as Sn, Al, Pb, Bi, Au, or an alloy thereof. Is mentioned. If the thickness of the soft plating layer is less than 1 μm, the effect of improving the sealing property is poor, so that it is 1 μm or more. The thickness of the soft plating layer is preferably 20 μm or less because it is disadvantageous in terms of interference amount management if it is too thick.
ゴーリング防止用めっきの材料は、締付け工程での締付け力により削られないあるいは剥がれない程度の硬さもつ材料でなければならず、そのような材料として、Cu等の金属や、Cu‐Sn等の合金が挙げられる。ゴーリング防止用めっき層の厚さは、薄すぎるあるいは厚すぎるとゴーリング防止効果が不十分となるので、5〜20μmとする。
ピン側シール部の表面粗さは、小さすぎるとゴーリング防止効果に乏しく、大きすぎるとリークパスの封鎖が困難となるので、Ra1.0〜3.0μmとする。
The material for the anti-goling plating must be a material that is not hardened or peeled off by the tightening force in the tightening process. Examples of such a material include metals such as Cu and Cu-Sn. An alloy is mentioned. If the thickness of the plating layer for preventing goling is too thin or too thick, the effect of preventing goling becomes insufficient.
If the surface roughness of the pin-side seal portion is too small, the effect of preventing goling is poor, and if it is too large, it becomes difficult to block the leak path, so Ra is set to Ra 1.0 to 3.0 μm.
また、本発明では、最終締付けの前に、予備の締付け‐締戻しを少なくとも1回実施するのが好ましい。これにより、切削加工、ブラスト等で発生したピン側、ボックス側両面不均一に一種の馴染みが得られ、より安定した、かつ、より優れたシール性が得られる。この馴染みの現象は、大きく分けて2つの理由によって起こる。1つは、局所的な過度の表面粗さがなくなること、もう1つは、表面の微細な凹み部が潤滑剤その他で埋まることである。なお、潤滑剤としては、通常、Cu,Pb等を適量含有するグリース系コンパウンドが用いられる。 Also, in the present invention, it is preferable to perform preliminary tightening-rewinding at least once before final tightening. Thereby, a kind of familiarity is obtained in a non-uniform manner on both the pin side and the box side generated by cutting, blasting, etc., and a more stable and superior sealing property is obtained. This familiar phenomenon occurs mainly for two reasons. One is the elimination of excessive local surface roughness, and the other is that fine dents on the surface are filled with a lubricant or the like. As the lubricant, a grease compound containing an appropriate amount of Cu, Pb or the like is usually used.
なお、予備の締付け‐締戻しの回数は、好ましくは5回以下である。5回を超えると、かじりが生じやすくなって好ましくない。 Note that the number of preliminary tightening and retightening is preferably 5 or less. If it exceeds 5 times, galling is likely to occur, which is not preferable.
(実施例1)
13%Cr鋼からなる外径5.5”、肉厚0.415”の110ksiグレード油井管用特殊ねじ継手において、実質シール干渉量を通常公差の最小値の70%とした限界調査サンプルについて、ガスシール試験を行なった。この試験に供した発明例および比較例のサンプルの概略仕様を表1に示す。なお、発明例、比較例とも締付けは1回のみ(最大トルク24877N・m)とした。その結果、比較例では、図3に示す95%VME(フォンミーゼス[Von Mises]の相当応力)曲線上の点LP2(ISOのロードポイント‘2’)でリークが発生したのに対し、発明例では、リーク発生はなく合格した。
(Example 1)
About a limit investigation sample of a special threaded joint for 110 ksi grade oil well pipes made of 13% Cr steel with an outer diameter of 5.5 "and a wall thickness of 0.415" where the actual seal interference amount is 70% of the minimum tolerance. A seal test was performed. Table 1 shows the general specifications of the samples of the inventive examples and comparative examples subjected to this test. The invention example and the comparative example were tightened only once (maximum torque 24877 N · m). As a result, in the comparative example, a leak occurred at the point LP2 (ISO load point '2') on the 95% VME (Von Mises equivalent stress) curve shown in FIG. Then, there was no leak and passed.
(実施例2)
表1のNo.1と同じ仕様のサンプル10本のうち、5本について、ピンねじとボックスねじとの螺合に3回の締付け(最大トルク24877N・m)‐締戻しを行った後最終締付けを行い(グループAとする)、残りの5本は、実施例1と同様に1回だけの締付けを行った(グループBとする)。これらについて、実施例1と同様にガスシール試験を行なった。その結果、グループBでは、5本中、前記点LP2(ISOのロードポイント‘2’)でリークが発生したものが2本あった(3本はリーク発生なしの合格)が、グループAでは、5本の全数リーク発生はなく合格した。
(Example 2)
No. in Table 1 5 out of 10 samples with the same specifications as 1 are tightened 3 times (maximum torque 24877 N · m) in the screwing of the pin screw and the box screw, and finally tightened (Group A) And the remaining 5 pieces were tightened only once as in Example 1 (referred to as group B). About these, the gas-seal test was done like Example 1. FIG. As a result, in group B, there were 2 leaks at the point LP2 (ISO load point '2') among 5 (3 passed without leak occurrence), but in group A, There was no leak of all 5 pieces and it passed.
1 ピン
2 ボックス(カップリング)
3 ねじ締結部
4 シール部
5 ショルダー部
10 ゴーリング防止用めっき層
11 軟質めっき層
1
3
Claims (4)
4. The special screw for oil well pipe according to claim 3, wherein, in forming the screw fastening portion, the pin screw and the box screw are screwed together to perform at least one tightening-tightening and then final tightening is performed. A method for manufacturing a joint.
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2009131253A1 (en) * | 2008-04-24 | 2009-10-29 | 木村洋一 | Method for high speed plastic machining of metal component |
CN107152247A (en) * | 2017-06-28 | 2017-09-12 | 贵州航天凯山石油仪器有限公司 | A kind of method and structure of the anti-thread gluing of screw thread |
WO2018016422A1 (en) * | 2016-07-22 | 2018-01-25 | サンデン・オートモーティブコンポーネント株式会社 | Housing seal structure and fluid machine having same |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2001065753A (en) * | 1999-08-27 | 2001-03-16 | Sumitomo Metal Ind Ltd | Screw joint for oil well pipe |
JP2002221288A (en) * | 2001-01-25 | 2002-08-09 | Sumitomo Metal Ind Ltd | Threaded joint for steel pipe excellent in seizure resistance and rust preventability |
JP2002327875A (en) * | 2001-05-01 | 2002-11-15 | Sumitomo Metal Ind Ltd | Screw joint for steel pipe with excellent seizure resistance, rustproofness and airtightness |
JP2003074763A (en) * | 2001-08-31 | 2003-03-12 | Kawasaki Steel Corp | Joint for oil well steel pipe |
-
2006
- 2006-08-31 JP JP2006234774A patent/JP4613899B2/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2001065753A (en) * | 1999-08-27 | 2001-03-16 | Sumitomo Metal Ind Ltd | Screw joint for oil well pipe |
JP2002221288A (en) * | 2001-01-25 | 2002-08-09 | Sumitomo Metal Ind Ltd | Threaded joint for steel pipe excellent in seizure resistance and rust preventability |
JP2002327875A (en) * | 2001-05-01 | 2002-11-15 | Sumitomo Metal Ind Ltd | Screw joint for steel pipe with excellent seizure resistance, rustproofness and airtightness |
JP2003074763A (en) * | 2001-08-31 | 2003-03-12 | Kawasaki Steel Corp | Joint for oil well steel pipe |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009131253A1 (en) * | 2008-04-24 | 2009-10-29 | 木村洋一 | Method for high speed plastic machining of metal component |
WO2018016422A1 (en) * | 2016-07-22 | 2018-01-25 | サンデン・オートモーティブコンポーネント株式会社 | Housing seal structure and fluid machine having same |
CN107152247A (en) * | 2017-06-28 | 2017-09-12 | 贵州航天凯山石油仪器有限公司 | A kind of method and structure of the anti-thread gluing of screw thread |
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