Sumitomo Metal Industries, Inc.

Vallourec & Mannesmann Oil & Gas France

Nippon Steel Sumitomo Metal Corporation

Vallourec Oil and Gas France

Hiroaki Ikegami

Kunio Goto

Shigeo Nagasaku

Shigeo Onishi

Masaru Takahashi

Masanari Kimoto

Ryuichi Imai

Kunihiro Fukui

A threaded joint for steel pipes having excellent galling resistance, rust preventing properties, and airtightness without using a compound grease comprises a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion serving as contact surfaces. The contact surfaces of at least one of the pin and the box are coated with a multi-layered structure comprising, from the bottom, a first layer formed from a first metal or alloy, a second layer formed from a second metal or alloy which is softer than the first metal or alloy, and an uppermost layer of a solid lubricating coating comprising a lubricating powder in an organic or inorganic binder.

Threaded joint for steel pipes

A threaded joint for steel tubes has a contact surface () including a threaded portion and a non-threaded metal-to-metal contact portion. The contact surface of at least one of a pin and a box of the joint is coated with a first plating layer () made of a Cu&#x2014;Zn alloy or a Cu&#x2014;Zn-M1 alloy (wherein M1 is at least one element selected from Sn, Bi, and In). An undercoat () of one or both of a Ni plating layer () and a Cu plating layer () and an overcoat of a Sn-M2 alloy plating layer () (wherein M2 is one or more elements selected from Bi, In, Ni, Zn, and Cu) may be formed below and above the first layer, respectively. A solid lubricating coating () and a viscous liquid or semisolid lubricating coating () may also be formed atop the plating layer as a lubricating coating ().

Threaded joint for steel tubes

A threaded joint for steel pipes comprised of a pin () and a box () each having a threaded portion () and an unthreaded contact portion () exhibits adequate leakage resistance and galling resistance when used for makeup of oil country tubular goods with application of a green dope or even without any dope. The threaded joint has a first plating layer of Sn&#x2014;Bi&#x2014;Cu alloy plating formed on the contact surface of at least one of the pin () or the box (). The first plating layer may have a second plating layer selected from Sn plating, Cu plating, and Ni plating on its lower side and at least one layer of a lubricating coating, and particularly a solid lubricating coating on its upper side.

Growing community of inventors

Nishinomiya, Japan

Hiroaki Ikegami