| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw joint for oil-well pipe having a screw interference amount which has no fear of generating a stress corrosion at its joint part without acting of stress exceeding yield strength of a base material on an outer surface of a box part. SOLUTION: This screw joint for oil-well pipe comprises a pin part having a tapered male screw in which a shoulder part without screw is formed at its tip, a box part having a tapered female screw formed with a receiving part against which the shoulder part without screw abuts at its deep inner part. A screw interference amount T (mm) of this screw joint for oil-well pipe meets an expression T<[σy- 2D12Pi/(D32-D12)}]×2D2(D32-D12)}/E(D22-D12)}, wherein D1 represents an inner diameter (mm) of the pin part, D2 represents a screw effective diameter (mm) of a basic diameter position, D3 represents an outer diameter (mm) of the box part, Pi represents a load internal pressure (kg/mm2),σy represents yield strength (kgf/mm2) of a base material, E represented Young's modulus (kg/mm) of the base material.
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