Abstract: The copper-based nano-composite antifriction coating also named as AFRICO-ZG is applied upon the hitemperature phosphated coupling of the J55 tubing.Afterwards the make-up and break-off test,the hydrostatic test,and the tensile failure test are conducted to the said object for more than twenty times.The test results show that after twenty makeup/break off tests,both the J values and the torques are all within the specified normal ranges,and no thread galling is found;and that both the leakage-resistance and the overall tensile strength of the thread connection are better than the requirement as specified under relevant standard.Therefore it is concluded that the AFRICO-ZG coating is capable of enhancing the galling resistance of the thread connection,and thus extending the service span of the tubing proper.