Method for finishing a tubular threaded member with a dry protection coating
View Patent ↗A tubular threaded element including a dry protective coating. The coating includes a solid matrix adhering to the substrate in which there are dispersed particles of at least one solid lubricant belonging to one and the same class. The solid matrix is lubricating and has a rheological behavior of plastic or viscoplastic type. The coating protects the threadings of the threaded elements, used for example in hydrocarbon wells, from corrosion and galling.
1. A process for finishing a tubular threaded element, comprising:
applying only a single coating that is an antigalling coating in a form of a layer at least to a surface of a threading to produce a solid coating, and
subjecting the surface to be coated to a surface treatment for improving adhesion of the coating,
wherein constituents of the coating comprise a solid matrix and, in the matrix, a dispersion of particles of at least one solid lubricant, and
wherein the solid matrix is lubricating and presents a rheological behaviour of plastic or viscoplastic type.
2. A process according to claim 1 , wherein the constituents of the coating are raised to a temperature higher than a melting temperature of the matrix and then the coating is applied by spraying of the constituents comprising the matrix in a molten state.
3. A process according to claim 1 , wherein the coating is applied by projection through a flame of a powder formed by the constituents of the coating.
4. A process according to claim 1 , wherein the coating is applied by spraying an aqueous emulsion in which the constituents of the coating are dispersed.
5. A process according to claim 1 , wherein the threaded element is raised to a temperature higher than or equal to 80° C.
6. A process according to claim 1 , wherein the threaded element is at ambient temperature.
7. A process according to claim 1 , wherein the surface treatment is selected from mechanical treatments, chemical treatments, and non-reactive deposits.
8. A process according to claim 1 , wherein the surface to be coated is a metallic surface and the surface treatment is a treatment for chemical conversion of the surface.
9. A process according to claim 8 , wherein the chemical conversion treatment is a phosphatation process.
10. A process according to claim 1 , wherein the surface treatment is followed by a treatment for impregnation of roughness or porosities to the surface to be coated with nanomaterials with an anti-corrosion action.
11. A process according to claim 10 , wherein the nanomaterials are particles of zinc oxide.
12. A process according to claim 10 , wherein the nanomaterials are of a median particle size of the order of 200 nm.
13. A process according to claim 10 , wherein the nanomaterials are applied in a form of a dispersion.
14. A process according to claim 1 , wherein the dispersion of particles of at least one solid lubricant comprises particles of lubricant including:
solid bodies having lubricating properties due to a crystalline structure of the solid bodies;
solid bodies having lubricating properties due to a crystalline structure of the solid bodies and due to a reactive chemical element of a composition of the solid bodies;
solid bodies having lubricating properties due to a chemical reactivity of the solid bodies; or
solid bodies having lubricating properties due to a plastic or viscoplastic behaviour under frictional stress.
15. A process according to claim 1 , wherein no separate corrosion protective coating is formed atop of the coating.
16. A process according to claim 1 , wherein the solid matrix comprises at least one thermoplastic polymer, and is solidified by cooling.
17. A process according to claim 1 , wherein the applying includes covering the surface of the threading homogeneously with the constituents of the coating.