The paper presents results of experimental and numerical tests over research and development of the numerical Finite Elements Method (FEM) based methods of pipeline strain/stress condition assessment. The research is inspired by certain circumstances accompanying domain of safe exploitation of pipeline systems used for gas and crude oil transportation [1]. Currently, we observe the increase in hazard originated not only by typical pipeline operations but the third party activities understood as terrorist threats and warfare activities, especially in regions that are of significant value for the stability of the world’s energy supplies. Methods used in the scope of the research may be applied also to such events as disturbances of normal pipeline operation by seismic or mining activities, as they need the analysis of shock waves influence on pipeline installations. Elements of these methods may be used in wider range of construction types like pipelines in power plants (especially nuclear) that are at leading locations on the list of any threats. The research is focused on the two topics: • establishing the method of fast numerical assessment of stress state in deformed pipes with the use of data possessed from inline inspection pipeline intelligent tool (PIG); • establishing methods of numerical simulations of influence of shock waves (caused by explosions, seismic as well as mining activities) on pipeline systems (buried, ground based, underwater). The research includes an investigation of geometric flaws which may be detected in oil or gas transporting pipeline by a caliper PIG during inline inspection. Such typical flaws are dents, folds and bucklings [2]. The research method is based on numerical simulation and analysis with the use of FEM (Finite Elements Method). But it must be verified experimentally. To achieve experimental verification of the numerical method, preliminary tests were conducted in a laboratory scale. Artificial dents, folds, and ovalizations were created with the use of material strength testing machine in the sample of weldless thin-walled pipes. The experiment was conducted under strict control, enabling measurements of deformations and strains in selected points located on the external surface of the pipe wall. Experimental research on deformations and strains, conducted for bended pipes, allows for verification of strain and stress distributions obtained from numerical calculations. This will allow improving methods of numerical simulations [3].

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