| 摘要 |
PROBLEM TO BE SOLVED: To stably secure seizure resistance and airtightness without applying compound grease in a threaded joint for steel pipes formed by a pin and a box respectively having contact surfaces containing a threaded part and a threadless metal contact part. SOLUTION: A solid lubricating film made of solid lubricant (e.g. molybdenum disulfide) and organic or inorganic binder is formed on at least one contact surface of the pin and the box and in a cross section in the depth direction of the solid lubricating film, a ratio of area occupied by secondary particles with equal area corresponding size of solid lubricant of 15-60μm is set to the range of 5-90%. Such a film can be formed by applying coating liquid containing, for example, solid lubricant with average particle size of 1-10μm, binder and solvent after mixing and then placing still for cohering of the solid lubricant.
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