How to detect the corrosion performance of flanges

The use of steel flanges in industrial structural parts is mainly to improve the connection effect and keep the pipeline sealed without leakage. However, many steel flanges will experience corrosion and aging after a period of use, thus losing the sealing effect, so It is very necessary to periodically test the steel  flanges for corrosion resistance. Here I will share with you the process of measuring the corrosion of steel flanges.

First of all, it must be affirmed that the steel flange should be regularly maintained and inspected. After corrosion occurs, the pipe wall of the steel flange is usually thinned, and local pits and pits appear. The causes and methods of internal corrosion of stainless steel flanges need to be carried out according to certain methods and principles. The steel flange corrosion detection methods that can be widely used at home and abroad are the magnetic flux leakage method and the ultrasonic detection method.

Ultrasonic method Ultrasonic detection method uses the principle of ultrasonic pulse reflection to measure the thickness of the pipe wall after corrosion. The basic principle of leakage flux method detection is based on the high permeability of ferromagnetic materials. The permeability of the steel flange corrosion defect is much smaller than that of the steel flange. It is magnetized under the action of an external magnetic field. When there is no defect in the steel flange, most of the magnetic force lines pass through the steel pipe, and the magnetic force lines are evenly distributed; when there is a defect inside the steel flange, the magnetic force lines bend, and some of the magnetic force lines leak out of the steel pipe surface. By detecting the leakage flux escaping from the surface of the magnetized steel flange, it can be judged whether the defect exists.

In addition, when testing, the probe transmits ultrasonic pulses vertically to the inner wall of the steel flange. The probe first receives the reflected pulse from the inner surface of the pipe wall, and then the ultrasonic probe receives the reflected pulse from the outer surface of the pipe wall. This pulse and the reflected pulse from the inner surface The distance between paths reflects the thickness of the pipe wall. In the actual inspection, the elbow needs to be carried out according to the actual situation and instructions, and it can be inspected according to the ultrasonic method.

The ultrasonic testing method is also suitable for measuring the thickness and metal properties of other metal structural parts.