Claims
- 1. A threaded joint for steel pipes comprising a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion,characterized in that the contact surface of at least one of the pin and the box has a solid lubricating coating comprising a lubricating powder and a binder, wherein the proportion of area of a cross section along the thickness of the solid lubricating coating which is occupied by secondary particles of the lubricating powder having an equivalent circular diameter of 15-60 μm is from 5% to 90%.
- 2. A threaded joint for steel pipes comprising a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion,characterized in that the contact surface of at least one of the pin and the box has a solid lubricating coating comprising a lubricating powder, a fibrous filler, and a binder in which the mass ratio of the fibrous filler to the binder is in the range of from 0.01 to 0.5.
- 3. A threaded joint as set forth in claim 1, wherein the lubricating powder is powder of one or more substances selected from molybdenum disulfide, tungsten disulfide, organomolybdenum compounds, graphite, boron nitride, and polytetrafluoroethylene.
- 4. A threaded joint as set forth in claim 1, wherein the binder is an organic resin or an inorganic polymer.
- 5. A threaded joint as set forth in claim 2, wherein the ribrous fillers is in the form of fibers of one or more materials selected from potassium titanate, zinc oxide, aluminum borate, silicon carbide, and silicon nitride.
- 6. A threaded joint as set forth in claim 1, wherein the contact surface having the solid lubricating coating has a surface roughness of 5-40 μm Rmax.
- 7. A threaded joint as set forth in claim 1, wherein a porous coating layer is disposed as a primary coat between the solid lubricating coating and the contact surface.
- 8. A threaded joint as set forth in claim 7, wherein the porous coating layer is a phosphate chemical conversion coating or a coating of zinc or a zinc alloy.
- 9. A threaded joint as set forth in claim 1, wherein the secondary particles are aggregates of primary particles having a mean particle diameter of 0.5-15 μm.
- 10. A threaded joint as set forth in claim 2, wherein the lubricating powder is powder of one or more substances selected from molybdenum disulfide, tungsten disulfide, organomolybdenum compounds, graphite, boron nitride, and polytetrafluoroethylene.
- 11. A threaded joint as set forth in claim 2, wherein the binder is an organic resin or an inorganic polymer.
- 12. A threaded joint as set forth in claim 2, wherein the contact surface having the solid lubricating coating has a surface roughness of 5-40 μm Rmax.
- 13. A threaded joint as set forth in claim 2, wherein a porous coating layer is disposed as a primary coat between the solid lubricating coating and the contact surface.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2001-112883 |
Apr 2001 |
JP |
|
2001-155795 |
May 2001 |
JP |
|
Parent Case Info
This application is a continuation of International Patent Application No. PCT/JP02/03587, filed Apr. 11, 2002. This PCT application was not in English as published under PCT Article 21(2).
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Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/JP02/03587 |
Apr 2002 |
US |
Child |
10/361763 |
|
US |