Experimental And Analysis Method Study On Pipeline Testing

Pipeline which is one of the five leading transportation tools plays an important role in transiting liquid and gas .Transportation by pipeline can never be replaced in petro-chemistry and natural gas industry . Now there are thousands and thousands kilometers of pipeline in service all over the world , and in China, till the end of 1994 the longness of main pipeline in service for the transportation of petroleum and gas had been more than twenty thousands kilometers. At the same time, with the policy to exploit westward being carried into execution , the exploitation of petroleum field in southeast area and the enlargement of the oil, gas and water service system in cities in China, the transportation industry using pipeline will develop quickly. To maintain so large number of pipeline will coat enormously .As a result ,the method to test pipeline in long range economically and effectively is needed. The problem to be solve in this paper bases on this kind of engineering backdropIn this paper, any fundamental studying has been introduced on long-range pipeline NOT by method of exciting longitudinal stress wave which is base on analyzing domestic and overseas studying development in this domain. For the reason of the complexity of the problem, this study is hard.The main work introduced in this paper is as follows:K The dynamics equation of pipeline (arbitrary rotary shell) has been simplified and by which the calculating result by eigenline theory has tallied well with the result by experiment. It can be drawn that the one dimension equation is fit here and the simplification make the equation more close to the engineering application.2 Transmission of longitudinal stress wave in non-defect pipelineexcited by axial symmetry Impact has been studied by the numbers. The reflection, attenuation of the wave and the effect on wave by the form of excitation or restrict has been studied. What can be drawn from the study is that under the condition in Lab longitudinal planar stress wave can be excited successfully and the SNR for the wave excited is good enough to do farther analysis.3 In experiment the common electrical-resistance strain gages is used as receiver to replace the PZT or velocity and acceleration transducer which is frequently used in pipeline NOT. Experimental result shows that electrical-resistance strain gages can respond well in the frequency range of artificial excitation by impact hammer , at the same time , the experimental scheme brought forward in this paper makes the experimental setting simple and can be manipulated easily as well as can display the excitation and response expediently and synchronously on digital oscillograph .The impact hammer can implement half-sine load.4 Attenuation of the stress wave propagating in non-defect pipeline has been studied by experiment. The experimental result tells that in non-defect pipeline the stress wave excited in this way can propagate more than 100 meters , and then, the method put forward in this paper can serve the purpose to test pipeline in long-range .5 Experimental study about the influence that is resulted from the artificial crack flaw on the propagation of longitudinal stress wave in pipeline has been done. Experimental result make us know that the signal collected can reflect the defect' s influence which will provide the important basic for the next analysis in this paper.6 Based upon a large number of experiments , for the first time introduce the method of reflecting wave used to testing the integrity of pile into testing pipeline in long range. System impulse response and the relation between layers of pipeline units are used and the wave' s converseas well as the aim to recognize the position of defect has been achieved. 7 Wavelet transform analysis is applied to extract the feature of collected signal and the aim to recognize the position of defect has been achieved. 8 Chebyshev-I digital filter is used to process experimental data .The result can meet the need of next process.