Online Monitoring System Of Pipeline Stress Based On Fiber Bragg Grating

Currently,pipeline transportation has become one of the five transport industry to keep pace with the railway,aviation,waterways and highways.Pipeline transportation with the virtues of low transport costs and high reliability,compared to other modes of transport,has become the lifeblood of modern industry and the national economy.However,the pipeline is likely to cause aging in the long-term service process,and,with other inevitable factors such as wear and tear,corrosion and human destruction,pipeline leaks occur every now and then,consequently it is necessary to implement online monitoring to the pipeline.Now there are a variety of methods for testing the pipeline,including resistance strain gage method,X-ray method,photo-elasticity method and ultrasonic method,but these methods are not suitable for long-term online monitoring of the pipeline.First of all,the advantages and disadvantges of various methods are taken into account in this paper,and on the basis of knowing of the current development of online monitoring of pipeline stress at home and abroad,the fiber grating method is selected to implement online monitoring of pipeline stress.Secondly,during the online monitoring of pipeline stress,the temperature compensation technology and demodulation technology of fiber grating are important theoretical basis.In this paper on the basis of knowing of the sensing principle of fiber Bragg grating,a variety of temperature compensation methods and demodulation methods are exploed.Once more,two main online monitoring systems are described:hardware and software system.For hardware system,the overall design is given and at the same time each part of hardware system is introduced in detail.Then,on the basis of the selection of hardware systems,online monitoring software of pipeline stress is developed based on LABVIEW development platform.This software has the following advantages:stable and reliable,friendly interface,quick response,easy operation and so on.Then the scene of the construction is introduced in detail in this paper,including the installation and protection of sendors,the laying and protection of cable and the system debugging.For the paste location of the sensors,ANSYS is used in this paper to simulate the stress state in a pipeline of four different conditions and combining with the actual situation,the specific paste location of the sensors is determined.What is more,some protection measures of sensors and cable are elaborated.Finally the self-developed hardware and software system is applied to the real online monitoring of pipeline stress in this paper and the stress curve of 15 sensors on one pipeline during one month from 2012-1-11 to 2012-2-11 is analyzed.At last,one conclusion is drawn that the pipeline is in a safe operating status.The online monitoring of pipeline stress developed in this paper can achieve a variety of functions,and provides guidance to other stress online monitoring.