Experimental Study And Application About Key Technologies On Pipelines With Pressure Under Security

Pressure pipeline is a pressure-bearing component which has certain risk,containing medium with high temperature, high pressure,flammable and explosive.Once the pipeline leaking or exploding, it always lead to the occurrence of disastrous accidents, which threaten the life and property of people and directly influence the social stability.The pressure pipeline under the conditions of high temperature,high pressure and high corrosive always generate cracks inevitably in the service period.The extension of these cracks may lead to serious safety accidents and threaten the safe operation of the pressure pipeline.In order to ensure the continuity of the actual petrochemical production,the pressure pipeline with cracks can not replace immediately. The development of fracture mechanics and modern materials science has already confirmed: the materials containing certain defects still has a certain ability to bear pressure.To ensure the safe operation of the pressure pipeline with cracks, the key is to understand the extension of cracks and calculate the cracks’ fracture mechanics parameters,and by comparing the fracture and toughness of materials to judge whether the pipeline under the safe operation. Based on this situation, this paper has done the following research on pressure pipeline containing internal longitudinal crack: Using the method of finite element analysis, the influence of the pressure pipe inner surface crack length and depth to the crack surface circumferential strain was discussed,and to the pressure piping containing internal longitudinal crack, the variation of the outer surface of the circumferential strain at the center of the crack along with the length and depth of crack was obtained; And the monitoring device to pressure pipeline containing crack was set up by using optical fiber grating sensing technology, the test and analysis to the crack surface circumferential strain at the center of the crack of pressure pipeline containing internal longitudinal crack were done by the device, the test results are in good agreement with the results of finite element analysis; The monitoring system of the safe operation to the pipeline with crack was established, it can calculate the fracture mechanics parameters of crack-- stress intensity factor by the crack surface circumferential strain at the center of the crack which obtain by the monitoring device to pressure pipeline containing crack,and the calculated value can be compared to the material fracture toughness for safety assessment to the pipeline containing crack, so as to ensure the safe operation of pressure pipelines containing crack;On account of the safety evaluation work of the pressure pipeline involves material science, mechanics, failure analysis and comprehensive knowledge in many aspects,and the process of analytical method for evaluating is more complex, it is difficult to master for general engineering and technical personnel. The monitoring system of the safe operation to the pipeline with crack studied in this paper can be used in practical production if it is perfected,and it can help the engineering and technical personnel to monitor the crack propagation situation for the pressure pipeline containing crack and control for the safe operation of pipelines.