Threaded joint for steel pipe with excellent seizure and corrosion resistances

A technology for threaded fasteners and steel pipes, applied in the direction of pipes/pipe joints/fittings, damage protection, pipeline anticorrosion/rust protection, etc., which can solve problems such as wear, air tightness, reduction, and unstable joint fixation
CN1488051AInactive Publication Date: 2004-04-07NIPPON STEEL CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
NIPPON STEEL CORP
Publication Date
2004-04-07
Estimated Expiration
Not applicable · inactive patent

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Abstract

A threaded joint for steel pipe, comprising a pin and a box allowed to be fitted to each other, wherein a porous zinc or zinc alloy layer as a lower layer by a projection plating method and a solid lubrication film (film containing lubricating powder in organic or inorganic binder) or a liquid lubricating film not containing heavy metal powder (example: liquid film formed mainly of high base organic metallic salt such as high base sulphonate) as an upper layer are provided on the thread part and the metal contact part without thread of at least either of the pin and box, whereby the threaded joint can provide excellent seizure resistance, corrosion resistance, and airtightness even after exposed to high temperature, and is allowed to be tightened and loosened repeatedly in a hot oil well without using compound grease containing heavy metal powder.
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Description

technical background

[0001] The present invention relates to a threaded joint for steel pipes, especially oil well pipes, which has improved wear resistance, rust resistance and air tightness, and can be used without the use of liquid greases containing heavy metal powders, such as complex greases in the case of. Background technique

[0002] Oil well tubulars used in oil well drilling, such as pipes and casings, are generally connected to each other by threaded joints. In the past, the depth of oil wells was generally 2,000 to 3,000 meters, but recently, the depth of oil wells in offshore oil wells and other deep wells can reach 8,000 to 10,000 meters. Threaded joints of oil well pipes are subjected to various forces in the service environment, including loads such as axial tension generated by the weight of oil well pipes and threaded joints, the combination of internal and external pressures, and Increased geothermal. Therefore, threaded joints must be able to remain a...

Claims

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