| 摘要 |
PURPOSE: To secure sufficient gas tightness and liquid tightness, and prevent off-specification of a shoulder torque value. CONSTITUTION: In a surface treatment method to a special coupling part of a steel pipe which is excellent in seizure resistance, abrasion resistance, gas tightness, and handling easiness in connection, a blasting process is applied to a surface of a special screw of the steel pipe with zirconia-silica ceramic beads of a spherical form of a grain size of 10-500μm, so smooth irregularities of an average roughness of Ra0.1-10μm are formed on the screw surface. Handling easiness in connection of the pipes at an oil well and a gas well can thus be largely improved.
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