Discussion and Suggestion on Pipeline Old Coating Displacement

Old coatings displacement is a necessary measures taken for elongating the service life of buried oil/ gas pipeline. The analysis and discussion have been made on the problems existed during the displacement by Qinhuangdao Oil Transportation Company. It is concluded that the standpoint which the service life of asphalt coating was 20-year is not correct on thoery, but the year should be an average service life and not treated as the same; the resistivity data of coating measured according to the current measurement method can not instruct the ageing extent of the coating; the old coating displacement is difficult to conduct because of inconvenient construction in the field. It is suggested that the displacement program should be worked out on the base of inspection; the displacement program of coatings should be firstly based on the results of leakage detection and bellhole inspection, secondly on analysis of the inspection of coating resistivity and daily inspection records; the displacement should be combined with coating repair; the quality supervision must be strenghened; the proper materials and new methods have to be selected to conduct the renovation and inspection of pipeline coatings.