A method for the non-destructive inspection of a weld between a first metal pipe and a second metal pipe, wherein the method comprises the following steps: forming an austenitic weld between two pipe-sections (2a, 2b) during a method of laying a pipeline, providing a plurality of ultrasonic transducers, able to transmit and detect ultrasonic radiation, comprising two or more ultrasonic transducers arranged as a phased array, emitting from the phased array a first beam of ultrasonic radiation, focussed to be incident on a first region of the weld, emitting from one or more of the plurality of ultrasonic transducers a second beam of ultrasonic radiation incident on a second region of the weld, emitting from the phased array system a third beam of ultrasonic radiation, focussed to be incident on a third region of the weld, moving the plurality of ultrasonic transducers in a circumferential direction around the pipes, at least two of the first, second and third beams being emitted at the same time as another of the first, second and third beams, or being emitted in sequence sufficiently fast that the movement of the ultrasonic transducers around the circumference of the pipes is negligible, detecting with one or more of the plurality of ultrasonic transducers radiation from the first, second and third regions resulting from the incidence of the first, second and third beams, extracting information from the detected radiation, and using such information to provide an indication from which the likelihood of a defect in the weld may be discerned, wherein at least one of the first and third beams is a mode converted longitudinal wave generated by a reflection of a transverse wave on the inner wall of one of the pipes. forming an austenitic weld between two pipe-sections (2a, 2b) during a method of laying a pipeline, providing a plurality of ultrasonic transducers, able to transmit and detect ultrasonic radiation, comprising two or more ultrasonic transducers arranged as a phased array, emitting from the phased array a first beam of ultrasonic radiation, focussed to be incident on a first region of the weld, emitting from one or more of the plurality of ultrasonic transducers a second beam of ultrasonic radiation incident on a second region of the weld, emitting from the phased array system a third beam of ultrasonic radiation, focussed to be incident on a third region of the weld, moving the plurality of ultrasonic transducers in a circumferential direction around the pipes, at least two of the first, second and third beams being emitted at the same time as another of the first, second and third beams, or being emitted in sequence sufficiently fast that the movement of the ultrasonic transducers around the circumference of the pipes is negligible, detecting with one or more of the plurality of ultrasonic transducers radiation from the first, second and third regions resulting from the incidence of the first, second and third beams, extracting information from the detected radiation, and using such information to provide an indication from which the likelihood of a defect in the weld may be discerned, wherein at least one of the first and third beams is a mode converted longitudinal wave generated by a reflection of a transverse wave on the inner wall of one of the pipes.