Abstract: Manganate-parkering of the oil pipe coupling aims to form a manganate phosphate film on the coupling surface.Owing to the film's feature of comparatively lasting absorption and retention of grease,the power-screwed pipe and coupling will have sufficient thread engagement strength and satisfactory sealing performance,whereas no gulling will occur between the threads of the pipe and the coupling.The CL-3601 manganate parkering agent is capable of producing a phosphate film which is quite different from the film as formed with any other parkering agent.Based on the results of lots of tests,the characteristics of the said phosphate film are analyzed,and accordingly measures for quality assurance of the film,and cautions for selecting parkering agent are proposed.