Threaded joint for pipes
AssigneesNippon Steel & Sumitomo Metal Corporation, Vallourec Mannesmann Oil & Gas France
InventorsTakao Kuranishi, Kunio Goto, Keishi Matsumoto
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Abstract
A solid lubricating coating formed on a contact surface of a threaded joint for pipes has a matrix of a lubricating oil-containing polymer. The lubricating oil-containing polymer has either a uniform composition or a gradient composition in which the concentration of lubricating oil decreases towards the contact surface and in which there is substantially no lubricating oil in the vicinity of the contact surface.
Claims13
A threaded joint for 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 is coated with a solid lubricating coating having a matrix of a lubricating oil-containing polymer comprising a polyolefinic polymer selected from a polyolefin and a modified polyolefin and a lubricating oil which are dissolved in each other, the lubricating oil-containing polymer having a gradient composition in which the concentration of lubricating oil in the coating decreases towards the contact surface on which the coating is formed in the thickness direction of the coating.
Dependencies are inferred from the claim text.