Cold storage pressure pipeline DR detection--signal to noise
Pipeline DR detection, signal to noise ratio
Pipe fittings - signal to noise ratio（1）

DR technology can be used for the detection of cold storage pressure pipelines, but the insulation layer of the cold storage pressure pipeline and the medium inside the pipeline will affect the test results.

Combined with the DR spot check of the cold storage pressure pipeline, the sensitivity of the DR detection of the cold storage pressure pipeline, the measurement of the defect geometry, and the geometric unsharpness were tested.

The thermal insulation layer will lead to an increase in geometric unsharpness, resulting in a decrease in sensitivity. The image quality index does not meet the requirements of NB/T47013.11-2015; geometric amplification will lead to distortion deformation amplification, and the blackness comparison test block measures the height of the defect itself. Consider the placement of the test block and the influence of the weld height

Non-destructive testing new technology detection signal-to-noise ratio has an impact on image quality meter identification. Take the double-wire image quality meter as an example. When the system is not corrected for a long time, the double-wired gauge number recognized by the 8mm test board is D8, which can be identified after calibration. D9, which improves the resolution. At the same time, multiple images are superimposed on the scene for detection, and the sensitivity is improved. However, if the number of superpositions is large, the on-site operation is inconvenient, the ray machine has a long working time, the dose is increased, and cooling may be required in the middle. Defect measurement Like film ray inspection, DR can easily measure the length and width of defects, but DR should fully consider the transillumination magnification. As shown in Figure (2):


Φ159×6mm pipe on the double wire image quality meter 3.2 line image quality test test(2)

The pipe specification is φ159×6mm, and its geometric magnification factor is 1.39. The length of the defect measurement is 67.3mm and the width is 8.9mm. The actual length is 48.4mm and the actual width is 6.4mm. The traditional film ray detection uses the blackness contrast method to estimate the height of the defect itself, but it is affected by factors such as uneven illumination field and inconsistent thickness of transillumination at different positions. If the comparison test block is far from the defect, the estimated defect height and actuality are estimated. Often there is a big difference.


Imaging of two different thickness common groove type test blocks placed(3)

Figure 3 is a DR image of a common groove type contrast test block with two different thicknesses placed on the workpiece. If the transillumination field is uniform and the thickness of the transillumination is uniform, the blackness of the two holes on the contrast test block at the same horizontal position is shown. It should be consistent, but the naked eye is clearly visible.

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