![]() ![]() ![]() The four screen shots below show the AIM sensitivity maps for two pulse-echo propagation mode wave sets (2T and 4T) and two self-tandem propagation mode wave sets (3T and 5T).įor the P/E modes (2T and 4T) the flaw type is set to spherical while for the self-tandem modes (3T and 5T) the flaw type is set to planar at 0°. The OmniScan X3 instrument’s AIM tool takes into account all these parameters in its estimation of the sensitivity coverage, facilitating the selection of the proper wave set and the index offset. Selection of the optimal wave set while considering the probe focusing capabilities, the part geometry, and the expected flaw type and orientation is one of the biggest challenges that an inspector faces while setting up a TFM inspection. ![]() The ASME code requires that your FMC/TFM scan plan depict, at minimum, the examination volume coverage and the weld joint geometry, and it must include the wave sets that are used, the grid density information, and the scan pattern (index and scan offsets, zero datum point, and the number of needed scan lines). Optimizing Your Scan Plan Using a Modeling ToolĪn optimized scan plan is key to a successful inspection strategy. The better choice in this case is the second model because of its higher Sensitivity Index reading (25.20 vs 20.02), which indicates a higher decibel level for the red color waves covering the ROI.Ģ. In this example, of the four probes, only two offer adequate coverage in the region of interest (ROI) in TT mode-the 5L64-A32 and 5L64-A2 probes. Check out this application note for a simple explanation of AIM and the Sensitivity Index.Ĭomparison of these four AIM models tells us that the pitch and frequency have an important impact on the resulting sensitivity map. That is why the “Sensitivity Index” reading is given. It’s important to know how to correctly interpret the level of sensitivity that the colors represent since they are relative to the maximum expected amplitude of each map. The wave set (2T), input material velocity, and flaw type (spherical) are the same for all four maps. The AIM sensitivity coverage is shown for four different probe models. The images below show an example of how you can use the AIM tool to guide your probe selection for FMC/TFM inspection. The Acoustic Influence Map (AIM) tool in the OmniScan™ X3 flaw detector enables you to compare the sensitivity coverage in the region of interest between different probes, taking into consideration the material velocity and the flaw type and orientation. With TFM inspection, there are several wave sets (sets of beams grouped according to their propagation modes), so it is impossible to visualize the impact of these parameters on each one without a proper modeling tool. For example, a large aperture (element pitch times the number of elements) combined with a high frequency tends to result in better focalization at a deeper position in the part, while a smaller aperture combined with a lower frequency tends to produce better focalization in the near-surface area. Inspectors need to find the best combination of these characteristics to suit the type of application, the characteristics of the part to inspect, and the targeted region of interest in the part. The performance of a given probe depends on the combination of the following characteristics: Since TFM obeys the same principles of physics as PAUT, which probe you choose is equally important. With standard phased array ultrasonic testing (PAUT), the probe choice is crucial to the success of your inspection. ![]() Here are the 4 essentials for building a TFM strategy for weld inspection that complies with this code:
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