Elbow after corrosion, usually show the elbow pipe wall thinning, a partial pits and pitting.
Now bend corrosion detection method is widely used at home and abroad is the method of magnetic flux leakage and ultrasonic test.
(1) the method of ultrasonic ultrasonic testing technique is to use ultrasonic pulse reflection principle to measure the thickness of pipe wall corrosion after. Detection will launch ultrasonic pulse probe perpendicular to the elbow wall, probe first received by the inner surface of tube wall reflection pulse, then ultrasonic probe will receive from the reflection of the surface outside wall pulse, the pulse and the distance between the internal surface reflection pulse spacing reflects the thickness of tube wall.
(2) the method of magnetic flux leakage magnetic flux leakage method is based on the basic principle of the high permeability of the properties of ferromagnetic materials, elbow corrosion defect of permeability is far less than the permeability of elbow, elbow in the applied magnetic field under the action of magnetized, when no defect of the bend, for the most part lines by steel tube, the lines of magnetic force uniform distribution; When bend internal flaws, the lines of magnetic force bent, leaking pipe surface and a part of the field lines. Escape detection by magnetization bend surface of magnetic flux leakage, can determine whether defects exist.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)
