Threaded joint for steel pipes
US6659509B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 11, 2003 |
| Grant date | Dec 9, 2003 |
| Priority date | — |
| Expiry date | Feb 11, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC10N2050/023
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
This invention relates to a threaded joint for steel pipes which comprises a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion and which guarantees galling resistance and gas tightness in a stable manner without application of a compound grease. A solid lubricating coating comprising a lubricating powder (e.g., molybdenum disulfide) and an organic or inorganic binder is formed on the contact surface of at least one of the pin and the box. The proportion of area of a cross section along the thickness of the solid lubricating coating which is occupied by secondary particles of the lubricating powder having an equivalent circular diameter of 15-60 &mgr;m is from 5-90%. Alternatively, the solid lubricating coating comprises, in addition to the lubricating powder, a fibrous filler (e.g., inorganic whiskers) in such an amount that the mass ratio of the fibrous filler to the binder is 0.01-0.5. As a result, galling resistance is improved, particularly at high temperatures.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.