| abstract |
A LUBRICATING COATING (31) WHICH IS FREE FROM HARMFUL HEAVY METALS IS FORMED ON A PREMIUM THREADED JOINT FOR PIPES CONSTITUTED BY A PIN (1) AND A BOX (2) EACH HAVING A CONTACT SURFACE COMPRISING A THREADED PORTION (3A, 3B) AND AN UNTHREADED METAL CONTACT PORTION (A SEALING SURFACE AND SHOULDER) IN ORDER TO PROVIDE THE JOINT WITH GALLING RESISTANCE, GAS-TIGHTNESS, AND ANTICORROSIVE PROPERTIES SUCH THAT THE UNTHREADED METAL CONTACT PORTION IS PREVENTED FROM YIELDING EVEN WHEN THE JOINT IS MADE UP WITH A HIGH TORQUE. THE LUBRICATING COATING (31) COMPRISES ONE OR BOTH OF A ROSIN AND CALCIUM FLUORIDE; METAL SOAP; WAX; AND A BASIC METAL SALT OF AN AROMATIC ORGANIC ACID, AND PREFERABLY IT FURTHER INCLUDES A LUBRICATING POWDER, MAGNESIUM CARBONATE, AND/OR A CARBOHYDRATE, PARTICULARLY A CYCLODEXTRIN. |