Research On Techniques Of Measuring Cathodic Protection Current For Buried Pipelines

Pipeline in conveying gas, liquid and slurry due to its advantages of large volume,economic, fast, safe, reliable and low cost has become one of the five importanttransportation means necked with railway, highway, aviation, water transport andplays an irreplaceable role in national economic construction and national defenseconstruction. At present, cathodic protection of the long-distance buried pipelinegenerally uses impressed current method. It has advantages of continuously adjustableoutput current, large scope of protection, not restricted by environment resistivity,long service life and so on.Pipeline cathodic protection current density refers to the required protectioncurrent per unit area of the protected pipeline, which is an important indicator forestimating the insulation performance of the anticorrosion coating of pipeline. Theintegrity and insulativity of the anticorrosive coating is directly related to cathodicprotection, the better the integrity and insulativity, the smaller the cathodic protectioncurrent density is, conversely, the greater the cathodic protection current density is.Cathodic protection current density is also the important parameter of the entirecathodic protection system of pipeline, it can primely reflect the working conditionsof the pipeline anticorrosion coating and cathodic protection system, the magnitude ofthe cathodic protection current density is associated with the variety of metal and thesurface state of metal, which directly affects the effect of cathodic protection.At first, in this paper a pipeline cathodic protection current detection devicewhich is called magnetic collecting ring is designed, the mechanical structure of themagnetic collecting ring is designed through software simulation and experimentalverification, then the measurement of pipeline cathodic protection current is throughmeasurement for the magnetic field of the gap between the opening of the magneticcollecting ring. On the basis of the magnetic collecting ring and its experimentcathodic protection comprehensive evaluation system of buried pipeline is design.The whole system is divided into data acquisition module, wireless transmissionmodule, data processing module, power supply module, etc. Core hardware of thesystem is magnetoresistive sensor HMC1001and MCU C8051F310, the softwaremainly realize data acquisition, wireless transmission and other functions. Experiment results show that the device can effectively detecting pipelinecathodic protection current, the scheme of multiple detection devices in parallel canrealize real-time monitoring for cathodic protection current of long-distance pipeline,and the buried pipeline cathodic protection comprehensive evaluation system canmake a reasonable evaluation and prediction for the cathodic protection condition ofone section of buried pipeline.