Magnetic powder detection method for large cast valve

Abstract

The invention relates to a new technique method for magnetic powder detection of a large cast valve, which comprises the following steps: 1), processing the surface of the valve body; 2), uniformly spraying contrast sensitivity on the surface of the valve body; 3), detecting whether the equipment is in the check validity period or not; 4), configuring a magnetic suspending liquid with the concentration within 10-25g/L; 5), fixing a Al-30/100 sensitivity test piece in a detected part through a standard test piece fixing device so as to assess the comprehensive performance of a detecting system; 6), wetting the surface of the workpiece by the magnetic suspending liquid, magnetizing the surface of the workpiece, and detecting the valve body according to a special magnetized path graph for the valve body inspection via an AC magnetic yoke continuous method; 7), utilizing an air pressure type sprinkling can with a lighting function and suitable for magnetic powder detection, directly performing observation once magnetic marks are formed, and achieving that magnetization, magnetic suspending liquid spraying and observation are performed at the same time; 8), recording detection parameters and defect magnetic marks, grading the workpiece quality according to the detection technique standard based on the displayed defect magnetic marks, and then determining whether the workpiece is qualified or not according to the acceptance quality level. Moreover, in case of reinspection, the sensitivity of the detecting system is readjusted, and the workpiece is detected again until the requirements are met. The method can be effectively used for detecting the magnetic powder of the large valve.

Description

technical field [0001] The invention relates to a new process method for magnetic particle detection of large casting valves. According to the process, effective magnetic particle detection can be carried out on large casting valves. technical background [0002] In recent years, large-scale casting valve leakage has occurred frequently in thermal power plants, which directly leads to equipment damage and unit shutdown. As special equipment accessories, valves are widely used in power plants, chemical plants, petrochemical plants, etc. Once they fail, they will cause major economic losses and serious social impact. At present, the ex-factory quality inspection of such valves is mainly based on appearance and size inspection, supplemented by random inspection of ordinary magnetic particle inspection process, and accepted according to the results of pressure test; however, the phenomenon of leakage caused by cracks in the valve body during operation recently shows that the abo...

AI Technical Summary

Problems solved by technology

At present, the ex-factory quality inspection of such valves is mainly based on appearance and size inspection, supplemented by random inspection of ordinary magnetic particle inspection process, and accepted according to the results of pressure test; however, the phenomenon of leakage caused by cracks in the valve body during operation recently shows that the above scheme There are serious deficiencies

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