Development Of The Portable Instrument For Magnetic Flux Leakage Testing Of Storage Tank Floor

As the lack of energy becomes more and more serious in our country, the safety of oil storage tank attracts greater attention. The corrosions on the tank floor caused a lot of accidents during the past years. Based on the country's basic technology and social commonweal research"Development of Instrument for Magnetic Flux Leakage (MFL) Testing of Storage Tank Floor", the principle and instrument for MFL testing of storage tank floor are studied in this thesis.The peak value of the testing signal is used to evaluate the magnetization intensity of the tank floor. Based on theoretically research and experimental analysis, the influences of the parameters(the length,width and thickness of the magnets) in the magnetic path are compared. The conclusions show that the width of the magnets has the most important influence on the magnetization intensity, and the thickness has the least. At the same time, the relationship between the magnetic flux leakage signals and the physical characters (including the width,depth and position) of the corrosions are studied. The results identify that, if the floor is saturated, the magnetic flux leakage intensity changes linearly with the changing of the corrosion diameter. When the corrosion is in the surface, the peak value of the signal is higher than it's in the back. On the other side, faced to the local application, the influence of the lift-off of the sensor to the signal is studied. It shows that the sensor can be lifted to get stable signals if the floor is saturated. And then, according to the above research, a portable instrument, based on PC-104 embedded technique, is designed for the inspection of the corrosions on oil storage tank floor. Some problems occurred during the testing, such as straightly walking,turning and installing of the instrument are solved. At last, the instrument is applied in the storage tank of ZhenHai chemical plant. It shows that the portable MFL instrument can detect 4mm diameter,0.5mm deep hole in 6mm thick plate and 8mm diameter,1.1mm deep hole in 12mm thick plate. The whole instrument is about 22kg heavy. The battery can keep on working for 6.5 hours. It is an efficient way for the testing of the corrosion on oil storage tank floor.