1.Detection objects of mfl equipment
The above ground storage tank is composed of bottom plate (lap welding), tank wall, tank top (with fixed top and floating top) and pipes around the tank. The material is generally ordinary carbon steel. The thickness of tank bottom plate is generally 8-12mm. As the oil contains moisture or H2S and other chemical components, the bottom plate will be corroded, and anti-corrosion coating will be added during the manufacturing process. Under the influence of various factors, the damage of the anti-corrosion coating will cause different degrees of corrosion on the upper surface of the bottom plate, while the corrosion on the lower surface is more serious. The corrosion defect is also the main defect of the tank bottom plate. The volume of the tank is different, and the diameter of the bottom plate is from tens of meters to tens of meters.
2.Detection process of the mfl equipment
(1) before inspection, tank cleaning shall be carried out first, including tank emptying, replacement and cleaning, so as to meet the requirements of entering the tank for inspection.
(2) start the instrument for preheating, and adjust the probe lift off value according to the thickness of the base plate to ensure the accuracy of the test results.
(3) calibrate the instrument. Use the calibration test board to test the function of each independent channel of the instrument. By scanning and comparing the artificial defects of the test plate, the set value of the instrument and the height of the sensor are adjusted to make the signal indication of the instrument consistent with the percentage of the required artificial defect depth of the plate thickness.
(4) determine the tank benchmark, number the bottom plate (draw the floor map), so as to determine the scanning mode conveniently during scanning.
(5) select scanning mode. Scanning can be carried out in manual and automatic mode, and the scanning speed shall be kept as uniform as possible.