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Corrosion of welded pressed bends if used incorrectly
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Corrosion of welded pressed bends if used incorrectly

Soldering pressed bends can cause corrosion if not used properly. After the corrosion of welded pressed bends, the wall of welded pressed bends is usually thinned and localized pitting and pitting appear. Detection method after welding pressed bend corrosion: The basic principle of magnetic flux leakage detection is based on the basic characteristics of high magnetic permeability of ferromagnetic materials.

pressed bend

The magnetic permeability of the welded pressed bend corrosion defect is much smaller than that of the welded pressed bend, and the welded pressed bend is magnetized under the action of an external magnetic field. When the pressed bend is welded without defects, most of the magnetic lines of force pass through the steel pipe, and the magnetic lines of force are evenly distributed; when the welded pressed bend is defective, the magnetic lines of force are bent, and some of the magnetic lines of force leak from the surface of the steel pipe. The presence of defects can be judged by detecting magnetic flux leakage escaping from the surface of the magnetized welded pressed bend. The ultrasonic testing method uses the pulse reflection principle of ultrasonic waves to measure the thickness of the corroded pipe wall. This process adopts the method of self-propagating centrifugal casting, which mainly uses the chemical reaction of the substance itself to generate high temperature through exothermic combustion, and synthesize new substances during the propagation of combustion waves. During inspection, the probe emits ultrasonic pulses perpendicular to the inner wall of the welded pressed bend. 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. The distance between this pulse and the pulse reflected from the inner surface reflects the thickness of the tube wall.

Maintenance method of pressed bend: The bolts of the pressed bend valve packing gland should be tightened evenly, and should not be pressed into a bent state, so as to avoid collision, hinder the movement of the valve stem or cause leakage. The pressed bend should be a handwheel, do not use levers or other tools to avoid damage to valve parts. Clockwise rotation of the handwheel is closed, otherwise it is open.