Papers by Keyword: Corrosion Defect

Abstract: Storage tank is an essential vessel in petrochemical industry, and the corrosion of tank is an important reason for the safety hazard. The corrosion of tank bottom plate is more serious than the tank wall, and it is not easy to check and repair, when damaged to a certain extent it will cause the leakage of the media, then lead to waste of energy, environmental pollution, at the same time it will cause a major accident. Magnetic flux leakage testing is widely used in the field of tank floor inspection with the advantages of fast scanning speed, accurate results and so on. In this paper, the finite element simulation and analysis of the corrosion defect leakage magnetic field is used to obtain the data, and the characteristic of the leakage magnetic field is extracted. The effect of defect depth and width and shape on the magnetic flux leakage field is studied, and the distribution curve of the magnetic flux leakage field is obtained.

Abstract: Corrosion is a very common defect for pipes under the sea after some service time, and it causes a deterioration of a pipe’s strength due to the reduction of the tube wall thickness. To provide a reliable assessment on the residual strength of a pipe after corrosion is very important in the safety evaluation of such pipes. This study presented both experimental and numerical investigations on the static strength of corroded pipes. Flexural test on a corroded pipe is carried out, and the tested results prove the decrease of the static strength for this corroded specimen. Furthermore, a finite element modeling method is proposed, and the reliability of this model is evaluated through the comparison with experimental results. Using this finite element model, effect of some corrosion sizes on the residual strength of the pipes has been analyzed and discussed.

Abstract: The finite element analysis method was used to analyze the seismic response of two oil pipelines, which have corrosion defects and no defects correspondingly. The velocity, displacement and acceleration time history of the two pipelines and the contrastive analysis of the maximum stress of two pipelines were obtained. The results show that the displacement, velocity and acceleration of the pipeline with corrosion defects are larger than those of the pipeline without corrosion defects, the corrosion has great influence on the bottom of the pipeline, and the influence also has certain wide, the farther away from the corrosion, the smaller the influence is.

Abstract: Importance on the detection of corrosion-related defect is undeniable from the fact that it can prevent significant economic loss and enhanced safety in mechanical equipments, pipes, ships, bridges, and other applications. Conventionally researched measurement methods for defect and thinning from corrosion are acoustic emission, EMAT using ultrasound, laser induced ultrasound, etc. However, these non-destructive testing methods have the shortcoming of accessibility to on-site. For instance, EMAT should be close to several millimeters to generate magnetic field in structure. For laser application, it can be applied to remote non-destructive testing, but some defect might not be possible to be detected by the surface condition of structure. In this study, infrared thermography camera is utilized to determine the degree of corrosion on paint-coated metal. In addition, fundamental researches to develop corrosion detection system for on-site metallic structure are conducted to provide the applicability of IR camera and possibility of thermal analysis method.

Abstract: Pipelines have the highest capacity and are the safest and the least environmentally disruptive means for transmitting gas or oil. Recently, failures due to corrosion defects have become a major concern in maintaining pipeline integrity. A number of solutions have been developed for the assessment of remaining strength of corroded pipelines. In this paper, a Fitness-For-Purpose (FFP)type limit load solution for corroded city gas pipelines is proposed. For this purpose, a series of burst tests with various types of machined defects were performed. Finite element simulations were carried out to derive an appropriate failure criterion. Based on such solution along with existing solutions, an integrity evaluation program for corroded city gas pipeline, COPAP-CITY, has been developed.