Lubricating coating composition suitable for tubular threaded joints
A tubular threaded joint for connecting tubing or casing used to excavate oil wells have a lubricating coating formed from a lubricating coating composition comprising one or more basic lubricants selected from a basic sulfonate salt, a basic salicylate salt, a basic phenate salt, and a basic carboxylate salt and having biodegradability value (BOD) of at least 20% when measured after 28 days in seawater. The joint can be used without application of a compound grease containing heavy metals even in a country or region having severe environmental regulations.
1 . A lubricating coating composition comprising at least one basic lubricant selected from a basic sulfonate salt, a basic salicylate salt, a basic phenate salt, and a basic carboxylate salt, the composition having a biodegradability value (BOD) of at least 20% when measured after 28 days in seawater.
2 . A lubricating coating composition as set forth in claim 1 which further comprises at least one additional lubricant selected from those having a higher biodegradability than that of the basic lubricant.
3 . A lubricating coating composition as set forth in claim 2 wherein the additional lubricant is selected from a fatty acid metal salt and a wax.
4 . A lubricating coating composition as set forth in claim 3 wherein the additional lubricant comprises at least one fatty acid metal salt and at least one wax.
5 . A lubricating coating composition as set forth in claim 4 which contains 0-30 mass % of a volatile organic dissolving medium, the remainder comprising, when its total amount is taken as 100 parts by mass, 55-75 parts by mass of the basic lubricant, 20-25 parts by mass of the fatty acid metal salt, and 10-20 parts by mass of the wax.
6 . A lubricating coating composition as set forth in claim 3 wherein the fatty acid metal salt is selected from alkaline earth metal salts of stearic acid or oleic acid.
7 . A tubular threaded joint constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions, characterized in that the surfaces of the engaging portions of at least one of the pin and the box have a coating formed from a lubricating coating composition as set forth in claim 1 and having a thickness of at least 10 micrometers.
8 . A tubular threaded joint as set forth in claim 7 wherein the coating has a thickness of from 10 to 200 micrometers.
9 . A tubular threaded joint as set forth in claim 7 wherein the surfaces have a surface roughness of 5-40 micrometers Rmax.
10 . A tubular threaded joint as set forth in claim 9 wherein the surface roughness is formed by treating the surfaces by a method selected from sand or grit blasting, acid etching, phosphating, electroplating with iron or copper, and blast plating with zinc or a zinc alloy,
11 . A lubricating coating composition as set forth in claim 4 wherein the fatty acid metal salt is selected from alkaline earth metal salts of stearic acid or oleic acid.
12 . A lubricating coating composition as set forth in claim 5 wherein the fatty acid metal salt is selected from alkaline earth metal salts of stearic acid or oleic acid.
13 . A tubular threaded joint constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions, characterized in that the surfaces of the engaging portions of at least one of the pin and the box have a coating formed from a lubricating coating composition as set forth in claim 2 and having a thickness of at least 10 micrometers.
14 . A tubular threaded joint constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions, characterized in that the surfaces of the engaging portions of at least one of the pin and the box have a coating formed from a lubricating coating composition as set forth in claim 3 and having a thickness of at least 10 micrometers.
15 . A tubular threaded joint constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions, characterized in that the surfaces of the engaging portions of at least one of the pin and the box have a coating formed from a lubricating coating composition as set forth in claim 4 and having a thickness of at least 10 micrometers.
16 . A tubular threaded joint constituted by a pin and a box each having a threaded portion and an unthreaded metal-to-metal contact portion as engaging portions, characterized in that the surfaces of the engaging portions of at least one of the pin and the box have a coating formed from a lubricating coating composition as set forth in claim 5 and having a thickness of at least 10 micrometers.
17 . A tubular threaded joint as set forth in claim 8 wherein the surfaces have a surface roughness of 5-40 micrometers Rmax.