Threaded joint for steel tubes
US8276946B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Sep 1, 2009 |
| Grant date | Oct 2, 2012 |
| Priority date | — |
| Expiry date | Sep 1, 2029 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D5/36
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A threaded joint for steel tubes has a contact surface (30) 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 (34) made of a Cu—Zn alloy or a Cu—Zn-M1 alloy (wherein M1 is at least one element selected from Sn, Bi, and In). An undercoat (32) of one or both of a Ni plating layer (32a) and a Cu plating layer (32b) and an overcoat of a Sn-M2 alloy plating layer (36) (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 (38a) and a viscous liquid or semisolid lubricating coating (38b) may also be formed atop the plating layer as a lubricating coating (38).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.