Guided Wave Ultrasonic Testing (GWUT)

Guided wave examination (GWUT), also referred to as Guided Wave Testing (GWUT), has become a standard NDT method for inspecting pipework. The method allows for volumetric examination of piping systems whether the line is insulated, buried, as cased road or railway crossings, high line, river or bridge crossings, or configured as offshore pipeline risers without having to access the entire piping system. Usually, guided wave ultrasonic testing is well-suited for inspecting long sections of pipework. GWUT is a screening tool which detects cross sectional changes in the wall thickness of the system being examined. Data is typically analyzed on site to determine if complimentary inspections are required.

GWUT will detect the following:

  • internal & external corrosion

  • internal & external cracking

  • corrosion under supports/clamps

  • corrosion under insulation

  • erosion in elbows

  • soil air interface corrosion

  • girth welds, attachments & clamps


Performing a Guided Wave Examination

A removable transducer ring is wrapped around the circumference of the pipe that can be located at a distance from the target inspection area. Force is then applied to the transducer to acquire a solid coupling. Signals are generated and then received by advanced computer hardware. The resulting data can be interpreted by a trained inspector.

UltraWave LRT System

Nortech Advanced NDT uses the UltraWave LRT system which uses uses low-frequency ultrasonic waves to scan pipe from 2” to 60” in diameter with ranges up to 300’ on either side of the GWUT collar. We are able to locate areas of concern without having to access the entire system. Ultrawave LRT is ideal to screen pipes and pipelines that are in current service, as well as inspect difficult to access pipes from a single inspection point.

Examination can be performed on in-service systems with full volumetric examination of the pipe. Ultrawave LRT is capable of detecting variance in wall thickness and providing critical information regarding the circumferential extent through focusing. The UltraWave LRT system is able to give a precise location for further inspection based on initial signal response as well advanced synthetic focusing algorithms & active focusing. Minimal time & space is required to set up the system.

Various factors impact the distance in which inspection can be carried out. These include pipe configuration, soil conditions, environment, fluid inside of the line as well as the coating used.