Abstract: In order to prevent leakage at monolithic insulating joints of oil and gas pipelines, the possible leak locations, channels and leakage states were analyzed depending on the structural characteristics of these joints. Then, the corresponding leakage prevention measures were proposed. It is indicated that all internal parts shall be designed, verified and quality controlled strictly before leaving the factories so as to avoid leakage of insulation joints. With proper leak prevention methods that are developed for the designed operation conditions, the sealing performance of insulating joints can be guaranteed. These methods will play an instructive role for the design, manufacturing, finished products testing and installation of insulation joints.