1,Preparation before testing
①Familiar with the workpiece to be picked up (workpiece name, material, specification, bevelling form, welding method, heat treatment status, workpiece surface status, testing standards, qualified level, testing ratio, etc.);
② selection of instruments and probes (according to the standard provisions and site conditions, to determine the flaw detector, probe, test block, scanning ratio, detection sensitivity, detection mode)
③ Calibration of the instrument (determine the horizontal linearity and vertical linearity of the instrument when the instrument starts to be used).
④ Calibration of the probe (Perform calibration of leading edge, refractive angle, main beam deviation, sensitivity margin and resolving power).
⑤Instrument adjustment (The time base scale can be adjusted proportionally to represent the horizontal distance, depth, or acoustic range of the pulse return).
⑥ Adjustment of sensitivity (Sensitivity is calibrated on a comparison test block or other equivalent test block.)
2,Testing operation
① Inspection of base material: The thickness of pipe wall should be measured before inspection, at least one point every 90° for reference during inspection. Adjust the secondary bottom wave at the defect-free place to the full scale of fluorescent screen as the detection sensitivity;
② welded joints inspection: sweep sensitivity should not be lower than the evaluation line (EL line) sensitivity, the probe sweep speed should not exceed 150mm / s, sweeping the adjacent two probe movement interval should ensure that there is at least 10% overlap.
3, test results and rating: according to the nature of defects, amplitude, indication of the length of the rating based on relevant standards.
4,Calibration and rechecking of instruments and equipment.
5, issue a test report.
Note: There are excessive defects in the welded joints, the return part and the return of the affected area, should be in accordance with the original test conditions for re-inspection.