Ultrasonic testing (UT) is a branch of nondestructive testing techniques that involve emitting high-frequency sound energy, or ultrasonic waves, into an asset for corrosion mapping, obtaining data/measurements or identifying cracks or defects. There are three basic components in UT:
Pulser/receiver: Device that emits the ultrasonic waves/pulses
Transducer: Driven by the pulser, the transducer generates high-frequency energy, which is sent into the asset in waves. When discontinuities or flaws are detected in the wave path, the energy is reflected and converted into an electric signal by the transducer.
Data display/visualization: After the transducer transforms the electric signal, the data is displayed on a screen for the controlling inspector to analyze.
UT offers numerous benefits over other types of nondestructive including, which include, but are not limited to, inspector safety speed, ease of use and accuracy. Robots like Gecko’s have made UT very productive. While it may seem using robotics for UT equates to automated ultrasonic testing (AUT), that notion is not technically accurate.
So, what’s the real difference between manual UT (MUT) and AUT?
In two words: scanner intelligence. While AUT involves the same components as conventional UT, or MUT (pulsing/receiving, a transducer and data visualization/display equipment, as discussed above) the scanners move the probe/s automatically. For MUT, the person carrying out the inspection is in control, whereas with AUT, the parameters—i.e., speed and data recordings—are controlled through the AUT equipment, thus eliminating the need for inspector control. AUT may involve the same motors and mechanized scanning as in MUT, but the UT data is recorded, allowing for live and post-inspection visual analysis, and automated data process or report writing. The process is highly repeatable with great accuracy.
For MUT commonly used at oil and gas facilities or power plants, readings of the asset are taken every so often. For manual ultrasonic gridding, for example, a grid is set up at a predefined distance, and one reading is taken per distance, or grid. Obtaining a high quantity of data can take quite a bit of time. With AUT, bulk data is gathered with increased quality of probability of detection. Continuous readings are achieved across the asset, rather than on specific, predefined points. Obtaining the extremely high-resolution data through AUT allows for a better understanding of certain types of damage mechanisms that may not be obvious with MUT. It includes generalized corrosion and wear, but can also profile other damage mechanisms. Using MUT to inspect piping, for example, creates potential risks for the ongoing operation of those piping circuits. If data samplings are only taken every so often along the course of the piping, there is a reasonable chance that a large damage mechanism will be missed, as piping runs can present greatly varying conditions.
To fully capitalize on the extensive, detailed data AUT inspections offer, it may take days or weeks to perform. It should be noted that, such as in cases of very large areas, AUT may be cost-prohibitive.
AUT encompasses several different techniques and technologies, which include, but not limited to, phased array ultrasonic testing (PAUT), rapid ultrasonic gridding (RUG), time-of-flight diffraction (TOFD), and pulse echo weld inspection.
Gecko’s fleet of PAUT and RUG robots enable detection of a full spectrum of damage mechanisms at any resolution, with the capability of distinguishing damage mechanisms like wall-thinning, coating loss, corrosion, pitting, weld cracking, hydrogen damage and more.
For more detailed information on PAUT, technology for AUT/PAUT inspections and how AUT/RUG work together, be sure to watch for our upcoming blogs.