Preparation before inspection
Equipment and calibration: Select 2 - 5MHz flaw detector, calibrate according to the standard, and use CSK - IA and other test blocks to adjust the gain, time base and vertical linearity.
Probe selection: For thin pipes (<20mm), choose straight probes, and for thick pipes or welds, use oblique probes (45°, 60°, etc.), and set the angle according to needs. Clean the oil, rust, etc. on the surface of the pipeline to ensure good contact of the probe.
Test parameter setting
Scanning speed: Calculate the ratio of pipe thickness and probe refraction angle, and adjust the flaw detector scanning speed to locate the defect depth.
Sensitivity: According to the standard and acceptance level, adjust the gain with artificial defects such as flat bottom holes, and set a suitable sensitivity benchmark (such as the signal reaches 80% of the full screen).
Testing process
Scanning method: Scan the pipe body along the circumference, axial spiral or zigzag shape, and scan the weld with oblique parallel and cross scanning, with a speed of ≤150mm/s.
Signal processing: Observe the flaw detector signal, record the amplitude, position, shape, and store abnormal signal waveforms.
Defect assessment and judgment
Positioning and quantitative: Calculate the axial, circumferential and depth positions of defects according to the signal position, and compare the quantitative analysis of artificial defect signals (equivalent method, etc.).
Qualitative: Determine the nature of defects (pores, slag inclusions, cracks, etc.) according to signal characteristics.
Test report preparation
Record basic information: pipe diameter, wall thickness, material, batch, etc.
Equipment parameters: flaw detector, probe model specifications and test parameters.
Defect details: location, size, nature, conclusions and treatment suggestions based on the results.
