Positioning method suitable for welding seam in pipeline

The invention discloses a positioning method and system suitable for a welding seam in a pipeline, and belongs to the technical field of pipeline welding seam detection. Firstly, a positioning coordinate system of the welding seam in the pipeline is established, and a direction characterization mode of the welding seam in the pipeline is determined; determining the width of a welding seam in the pipeline; a welding seam image in the pipeline is obtained manually, and a welding seam image histogram is established after segmentation; secondly, remotely collecting an image in the pipeline, segmenting the image, establishing a histogram of the image in the pipeline, and comparing the histogram with the established weld seam image histogram; if the similarity of the statistical data is smaller than a set value, the collected image in the pipeline is not a weld seam image; and if the similarity of the statistical data is not less than a set value, verifying the acquired in-pipeline image by using a minimum frame se