The Inspection Methods for Corroded Butt Welded Bends
Posted: 01/13/2017 02:25:03 Hits: 16
The incorrect use of butt welded bends can cause corrosion, when this occurs, the wall thickness will be thinner; concave and pit will happen partially. The inspection method for corroding butt welded bends: the fundamental principle of magnetic flux leakage inspection is based on the basic characteristics of high permeability for ferromagnetic materials.
The magnetic permeability of the butt welded bend corrosion defect is much lower than the butt welded bend. so the butt welded bend would magnetize under the action of an external magnetic field.When there is no defect in butt welded bend, most of the magnetic lines can pass through steel pipes and are uniformly distributed; when there is defect in butt welded bends, the magnetic lines will curve and part of the magnetic lines will leak out on the surface of the steel pipe. Check the leakage flux on the butt welded bends, you will know whether there is defect or not.
The test of ultrasonic is to use pulse reflection principle of ultrasonic to measure the thickness of the corroding butt welded bends. You can put the probe vertically into the butt welded bend to launch ultrasonic pulse, the probe will firstly receive pulse reflection from the inner wall, then another pulse reflection from the external wall. The distance between the inner and external wall pulse reflections shows the wall thickness.
The magnetic permeability of the butt welded bend corrosion defect is much lower than the butt welded bend. so the butt welded bend would magnetize under the action of an external magnetic field.When there is no defect in butt welded bend, most of the magnetic lines can pass through steel pipes and are uniformly distributed; when there is defect in butt welded bends, the magnetic lines will curve and part of the magnetic lines will leak out on the surface of the steel pipe. Check the leakage flux on the butt welded bends, you will know whether there is defect or not.
The test of ultrasonic is to use pulse reflection principle of ultrasonic to measure the thickness of the corroding butt welded bends. You can put the probe vertically into the butt welded bend to launch ultrasonic pulse, the probe will firstly receive pulse reflection from the inner wall, then another pulse reflection from the external wall. The distance between the inner and external wall pulse reflections shows the wall thickness.
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