Wed, 2013-04-17 12:25 | 
Brief summary of PhD research
The present research aims at developing a systematic methodology for estimating the remaining structural capacity of oil and gas transmission steel pipelines with load distortions (dents and buckles). The necessity of inspection and examination of pipe wall deformations, caused by external forces, is crucial especially for safeguarding the integrity of existing pipeline networks. Numerical and experimental research will be carried out in order to investigate the residual structural integrity of dented and buckled steel tubes. More specifically, a series of full-scale experiments on steel 6-inch tubes of X52 steel grade are planned to be carried out, where the steel tubes will be buckled or dented using appropriate mechanical equipment. The deformed tubes will be subjected to further monotonic and cyclic loading in order to estimate the residual strength of the deformed pipe wall. Furthermore, small-scale cyclic tests will be conducted on longitudinal strips extracted from the steel pipe specimens aiming at the better understanding of the structural response of the damaged region under cyclic loading. Extensive numerical simulation of the small and full-scale experimental procedure will be conducted for each type of deformation and loading case in order to verify the experimental results and estimate the exact level of residual stress and strain distributions around the deformed area of the pipe wall. The objective of the present research is the utilization of the experimental and numerical results for the development of reliable guidelines and methodologies to be employed for the inspection, assessment and repair of structural damages in the form of local dents and buckles.
