Gas pipeline crack electromagnetical ultrasonic oblique wave guide detecting method

The invention discloses an electromagnetic ultrasonic inclined guiding wave checking method of natural gas pipeline cracks, which is characterized in that electromagnetic ultrasonic energy exchanger units are composed of split-type broken line coils and permanent magnet blocks, and are arranged on an inner checking device in the pipeline along the inclined direction, and generated ultrasonic guiding waves have a certain checking sensitivity on cracks of each direction on the spreading route of the ultrasonic guiding waves. The inclined ultrasonic guiding wave and the supporting guiding wave after crack action of a single emitting electromagnetic ultrasonic energy exchanger unit are received by two annular receiving energy exchangers arranged on both sides of the emitting electromagnetic ultrasonic energy exchanger. A plurality of emitting energy exchanger units are arranged into an annular set, and orderly generate inclined guiding waves so as to cover the entire circumference of the pipeline wall according to time, and the positions and the sizes of the crack defects are fixed according to the received guiding wave signals and the arranging condition of the energy exchangers. The invention realizes the non-contact purpose of the cracks in the natural gas pipeline without liquid coupling check, and can be used for the crack defects of each direction.