METHOD FOR GRADATION OF POTENTIALLY HAZARDOUS SECTIONS OF MAIN PIPELINES Russian patent published in 1998 - IPC

FIELD: examination and testing of main pipelines. SUBSTANCE: method consists in recording of maximum values of magnetic noise electromotive force along longitudinal axis in potentially hazardous sections, in sections of zero properties adjacent to potentially hazardous sections and in test specimen which is not subjected to load effect. Section with zero values of mechanical stresses along longitudinal axis is selected as section of zero properties. Difference between values of electromotive force in test section and values of electromotive force in potentially hazardous sections and in adjacent sections of zero properties is determined. Section which obtained differences turn to be maximum is considered most hazardous. Middle part of rectilinear underground section with extension of at least 30 outer diameters of main pipe may be selected as section of zero properties. EFFECT: higher efficiency. 2 cl, 2 tbl