Threaded joint for an oil well pipe

• Main Authors: Yamamoto, Hideo, Nakasuji, Kazuyuki
• Format: Patent
• Language: English
• Published: 20.01.2004

This invention relates to a threaded joint for an oil well type having excellent galling resistance. More particularly, it relates to a threaded joint for an oil well pipe used in the excavation of crude oil and which can undergo repeated tightening and loosening without using a liquid lubricant and without galling, which maintains air tightness, and which can be used repeatedly. A threaded joint for an oil well pipe is provided which prevents the occurrence of galling at the time of repeated tightening and loosening and which provides a high degree of air tightness and has excellent galling resistance and air tightness without using a liquid lubricant such as a compound grease.1. A lubricating film of an inorganic polymeric compound which has an M (metal element)-O (oxygen) backbone and has a solid lubricant dispersed therein is formed on a threaded portion or an unthreaded metal contact portion.2. A phosphate film and the lubricating film of the inorganic polymeric compound is formed on the threaded portion or the unthreaded metal contact portion.3. A Cu plating layer and the lubricating film of the inorganic polymeric compound or a lubricating film of a resin in which a solid lubricant is dispersed is formed on the threaded portion or the unthreaded metal contact portion.4. A lubricating film of the inorganic polymeric compound or a lubricating film of the polymer and a rust preventing film containing an alkali metal salt of a carboxylic acid or an alkali earth metal salt of a carboxylic acid are formed on the threaded portion or the unthreaded metal contact portion.