Guided Wave Ultrasonic Testing of Encased Pipeline and Spacer Selection The performance of guided wave ultrasonic testing (GWUT) or long-range ultrasonic testing (LRUT) is generally well understood in aboveground and underground inspection applications [1]. At this time, the expected inspection range for uncoated and coated pipe are also well understood for GWUT testing of above and underground piping systems [2]. A niche GWUT testing market are pipelines that travel under