Ultrasonic testing uses high frequency sound energy to conduct examinations and make measurements. The uses of UT include flaw detection and evaluation, dimensional measurements and material characterisation.
High frequency sound waves are very directional, and they will travel through a medium (like a piece of steel or plastic) until they encounter a boundary with another medium (like air), at which point they reflect back to their source. By analysing these reflections, it is possible to measure the thickness of a test piece or find evidence of cracks or other hidden internal flaws.
UT is sensitive to both surface and subsurface discontinuities. Its depth of penetration for flaw detection or measurement is superior to other non-destructive testing methods. Ultrasonic testing is completely non-destructive. The test piece does not have to be cut, sectioned, or exposed to damaging chemicals. Access to only one side is required, unlike measurement with mechanical thickness tools like callipers and micrometers. There are no potential health hazards associated with ultrasonic testing, unlike radiography. When a test has been properly set up, results are highly repeatable and reliable.
Guided Wave Ultrasonic Testing
Guided Wave Ultrasonic Testing detects corrosion and other defects over long distances in piping, quickly and safely. A tool is clamped around the pipe and transmits guided waves in both directions along the pipe. Reflected signals from defects and pipe features such as welds are received by the transducer ring and sent to the main unit.
Unlike conventional ultrasonic, there are an infinite number of guided wave modes that exist for a pipe geometry, and they can be generally grouped into three families, namely the torsional, longitudinal and flexural modes.
The acoustic properties of these wave modes are a function of the pipe geometry, the material and the frequency. Predicting these properties of the wave modes often relies on heavy mathematical modelling which are typically presented in graphical plots called Dispersion curves.
Automated & Long Range Ultrasonic Testing
LRUT
Long Range Ultrasonic Testing is used for screening metallic piping systems. LRUT reduces the costs of gaining access and avoiding extensive removal of insulation (where present). The whole pipe wall is tested, achieving a 100% examination (including areas such as at clamps, and sleeved or buried pipes).
The LRUT system generates ultrasonic guided waves longitudinally down the length of pipe. The distance covered by the ultrasonic wavs is dependent on several factors related to pipe coating, branch connections, fittings and above ground or buried locations. The system can inspect both directions from each inspection location and therefore can maximise production.
AUT
Automated Ultrasonic Testing accurately monitors discontinuities over successive intervals, calculate growth rates of discontinuities and plan repair or replacement activities. AUT uses several types of ultrasonic testing transducers, depending on the examination type and the desired inspection to be performed.
The transducers are mounted to a magnetic robotic crawler, which has the ability to cover large areas of the vessel or piping surface. The collected data is displayed in real-time colour using various views.
Manual UT
Utilising 0 degree as well as angled probes to evaluate welds and areas of concern such as localised corrosion. Experienced UT technicians can accurately size defects normally first discovered by rapid scanning techniques such as MFL, vacuum box testing, MPI etc.