A method has been developed to determine the location of welded joints of pipelines, using a proton magnetometer from the surface of the earth. In this case, there is no destruction of the protective layer of the pipeline. A theoretical model is presented and experimental data for a real pipeline are given. An algorithm for searching the location of a welded joint was developed. Experimental data obtained show that the magnetic field of real pipelines is of a complicated nature. The specific features of this field are mentioned.