Detailed magnetic surveys have been made to see if the form of magnetic anomalies produced by buried metal pipelines can be used to predict the position of joints between individual sections of pipe. This information can help minimize the amount of excavation required when pipelines have to be examined. Magnetic measurements have been made over pipelines where the position of joints is known, others where their position is unknown, and over a range of types and sizes of pipe with either spigot and socket or welded joints. It is shown that in open country the magnetic anomalies over pipelines consist of a sequence of magnetic highs and lows. This pattern is related to the individual sections of pipe from which the pipelines are constructed, and can be used to determine the position of joints between pipe sections. This method of joint location has been unsuccessful in urban areas due to the presence of other disturbing magnetic anomalies, and the sections of pipe not being uniformly magnetized.

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