Effects of Thermal Gradients in High-Temperature Ultrasonic Non-Destructive Tests

Abstract

Ultrasonic inspection techniques and non-destructive tests are widely applied in evaluating products and equipment in the oil, petrochemical, steel, naval, and energy industries. These methods are well established and efficient for inspection procedures at room temperature. However, errors can be observed in the positioning and sizing of the flaws when such techniques are used during inspection procedures under high working temperatures. In such situations, the temperature gradients generate acoustic anisotropy and consequently distortion of the ultrasonic beams. Failure to consider such distortions in ultrasonic signals can result, in extreme situations, in mistaken decision making by inspectors and professionals responsible for guaranteeing product quality or the integrity of the evaluated equipment. In this scenario, this work presents a mathematical tool capable of mitigating positioning errors through the correction of focal laws. For the development of the tool, ray tracing concepts are used, as well as a model of heat propagation in solids and an experimentally defined linear approximation of dependence between sound speed and temperature. Using the focal law correction tool, the relative firing delays of the active elements are calculated considering the temperature gradients along the sonic path, and the results demonstrate a reduction of more than 68% in the error of flaw positioning.

Collaborative Robotic Wire + Arc Additive Manufacture and Sensor-Enabled In-Process Ultrasonic Non-Destructive Evaluation

“…This means the signal strength propagating into the specimen was fluctuating with the varying profile of WAAM. Further losses of SNR, especially for Tube 2, could be associated with a lack of compensation for the thermal gradient that affects an ultrasound wave velocity during propagation, as also pointed out in [12,37]. This means the image signal amplitude is negatively affected due to the loss of focusing precision during TFM image forming.…”

Experimental Investigation on the Corrosion Detectability of A36 Low Carbon Steel by the Method of Phased Array Corrosion Mapping

“…After considering the aforement issues and conducting several trials, a preferable testing combination was ultimatel covered. The testing uses a high-temperature-resistant wedge [48] and focuses on limitin tact time during detection, while the phased array probe uses a general-purpose probe [49]. The water-soluble couplant is also replaced with high temperature-res oil [50].…”

“…A schematic diagram of the phased array corrosion mapping experimental se shown in Figure 4 below, where the heat treatment equipment is used to heat the men to a specific temperature required for the experiment, and the PAUT equipmen lects the data and further transmits them to a computer for interpretation. The testing uses a high-temperature-resistant wedge [48] and focuses on limiting contact time during detection, while the phased array probe uses a general-purpose 5L64 probe [49]. The water-soluble couplant is also replaced with high temperature-resistant oil [50].…”

Non-Destructive Inspection of High Temperature Piping Combining Ultrasound and Eddy Current Testing

“…The maximal operation temperature is also limited by the properties of the material used for the transducer’s assembly. Another aspect to consider is the temperature increase effect during increases in wave attenuation [ 11 , 13 ]. Research has focused on finding HTUT suitable couplants, yet high temperatures remain a demanding condition for probes and wedges, leading to their rapid degradation [ 14 , 15 ].…”