Engineering Application Investigation Of Magnetic Flux Leakage Testing Equipment For Heat Exchanger Tubes

Heat exchanger tubes, the core component of the heat transfer equipment, are the most common heat exchange components in the production of the petrochemical industry, the exchanger tube bundle, the waste heat boiler tubes and so on are frequently used, its security state has a critical impact on the production and operation. The feed mixing and even fire accidents would occur in case of leaking, which would arouse upset or the extremely serious consequences. With an increase in the amount of high-sulfur oil, equipment corrosion exacerbates. There is no exception for the tube corrosion which leads to the tube leaks frequently. In Petrochemical Corporation, the frequent leaks often take over in ethylene plant TLE, waste heat boilers in hydrogen plant, air coolers and the common exchanger thermocouple, etc. The corrosion would take affect on the heaters once it reaches a certain level, and the repair and replacement need to be done. Exchangers would run with faults if corrosion defects can not be found in time, even the safe, stable and long-period running would be failed.Tubes were checked by the means of pressure test and endoscopy in the past.Pressure test could check the leaks and judge the current situation could stand the present work pressure or not. But the wall thickness could not be tested and life period could not be predicted. Only the condition of exchanger surface could be observed by Endoscopy, but not the covered corrosion flaws with the low efficiency. The corrosion state could not be accurately determined and given the life cycle by them. Advanced technologies such as remote field eddy current were adopted domestically and abroad for inspection. Imported equipments were expensive,800thousand per instrument, and the supporting probe had lots of specifications with high consumption. Signals of domestic instruments were unstable with high misjudgment rate and short life. The Ferromagnetic tubes are widely applied, therefore, research on NDT in-service for the ferromagnetic tubes and development of practical detection device had an important significance.According to the characteristics of ferromagnetic tubes, the magnetic flux leakage testing technology has been researched. The paper introduced its characteristics, technical principles, scope, advantages and disadvantages compared with other NDT methods. In this paper,the developpment of the testing device for ferromagnetic tubes and the software for magnetic flux leakage testing system were carried out,also the magnetism location and float support device for the detection device were systematicly designed.Different sizes of standard tubes were made to accumulate datas by on-site bundle inspection, to prove the capability of inspecting.This instrument is capable of finding corrosion pit flaws on in-outer wall and baffle signals on a certain level.