LRUT (Long range ultrasonic testing) was a term coined in the early 1990s to describe guided wave testing of pipes. However, the term “long-range” in LRUT is unclear because the inspection range can vary depending on pipe conditions and the sensor configuration. In addition, the physics around guided wave inspection is very different than ultrasonic bulk wave inspection.

Guided Wave UT implies that the interaction of guided waves with defects is similar to that of high frequency bulk ultrasonic waves; however we find that this is often not the case.

GWT (Guided Wave Testing) is our preferred name for the general inspection method. The name reinforces that the configuration of the system and interpretation of the guided wave results is very different from conventional ultrasonic testing. The ‘guided’ nature of the wave has a very large influence on how it interacts with any pipe features. GWT is described in several international standards including:

• BS 9690-1:2011, Non-destructive testing. Guided wave testing. General guidance and principles
• BS 9690-2:2011, Non-destructive testing. Guided wave testing. Basic requirements for guided wave testing of pipes, pipelines and structural tubulars
• ASTM E2775 – 16, Standard Practice for Guided Wave Testing of Above Ground Steel Pipework Using Piezoelectric Effect Transduction

GUL Screening is used to refer to Guided Ultrasonics Ltd’s implementation of the Guided Wave Testing method. This incorporates all of the information GUL has learned and packaged into the system to make sure that the inspector can get the most out of guided wave testing and maximize the benefit to the client. The name itself emphasises “Screening” or detection component of this NDT method.