Threaded Joint for Steel Pipes
AssigneesSumitomo Metal Industries, Ltd., Vallourec Mannesmann Oil & Gas France
InventorsKunio Goto, Ryuichi Imai
Life of this patent
Estimating the term…
Abstract
A threaded joint for steel pipes for use in an oil well which has improved galling resistance and which is protected from rusting comprises a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion. The contact surface of at least one of the pin and the box has a lower layer of a viscous liquid or semisolid lubricating coating comprising at least wax and a fatty acid alkaline earth metal salt and not containing a harmful heavy metal such as lead and an upper layer of a dry solid coating formed from an aqueous resin coating composition, an organic solvent type coating composition, or an ultraviolet curing coating composition.
Claims20
A threaded joint for steel 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 has a viscous liquid or semisolid lubricating coating and a dry solid coating formed atop the lubricating coating.
A threaded joint for steel 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 one of the pin and the box has a viscous liquid or semisolid lubricating coating and a dry solid coating formed atop the lubricating coating, and the contact surface of the other of the pin and the box has been subjected to preparatory surface treatment by a method selected from blasting, pickling, phosphate chemical conversion treatment, oxalate chemical conversion treatment, borate chemical conversion treatment, metal plating, and a combination of two or more of these treatments
(canceled)
A method for surface treatment of a threaded joint for steel pipes comprising a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion, the method comprising applying a coating composition comprising at least wax and a fatty acid alkaline earth metal salt and not containing a substantial amount of a harmful heavy metal to the contact surface of at least one of the pin and the box to form a viscous liquid or semisolid lubricating coating, and then applying an aqueous coating composition based on a water soluble or water dispersible polymeric compound to form a dry solid coating atop the lubricating coating.
A method for surface treatment of a threaded joint for steel pipes comprising a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion, the method comprising applying a coating composition comprising at least wax and a fatty acid alkaline earth metal salt and not containing a substantial amount of a harmful heavy metal to the contact surface of at least one of the pin and the box to form a viscous liquid or semisolid lubricating coating, and then applying a coating composition based on a polymeric compound dissolved in an organic solvent to form a dry solid coating atop the lubricating coating.
A method for surface treatment of a threaded joint for steel pipes comprising a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion, the method comprising applying a coating composition comprising at least wax and a fatty acid alkaline earth metal salt and not containing a substantial amount of a harmful heavy metal to the contact surface of at least one of the pin and the box to form a viscous liquid or semisolid lubricating coating, and then applying a coating composition based on an ultraviolet curing resin followed by irradiation with ultraviolet radiation to form a dry solid coating atop the lubricating coating.
Dependencies are inferred from the claim text.