The Research Of Scientific Thickness Measurement Method For Pipeline Of Crude Distillation And Vaccum Distillation Unit

Recently, the fire and explosion accidents which related to piping or equipment corrosion happened frequently. In November2013, Sinopec raw oil pipeline in Qingdao exploded, and caused large number of people died and huge property loss. As an efficient methodology to prevent the accident and enhance the inherent safety, corrosion protection is playing more and more important roles.Take the crude distillation unit and vacuum distillation unit in Lanzhou Petrochemical Company as an example; Use science thickness measurement method to analysis the pipelines and select TML. Using the thickness data, some result, such as corrosion rate, can be given. According to the calculation result of pipelines, correct the test scope used for the next time.Combining RBI result, corrosion type analysis, and the corrosion inspect, to optimize the distribution of resources in pipeline, and can also focus on those pipeline associated with high risk, high probability of failure. According to the operation process, compare the demanded corrosion condition and operating parameters to find the inspection scope. For the inspection scope, the study is carried out on the local corrosion of component, and erosion. Firstly, a C-scan is used to check the components of pipelines, and according to the scanned image, find out the most serious corrosion position and take it as the TML. Based on the extreme value distribution of Gumbel type I, the reliability of TML is proven. Secondly, use the computational fluid dynamics to simulate fluid flow. Through this method, it can show that the impact of the tube wall of high speed and gas-liquid two-phase flow, including the distribution pressure, velocity distribution and the wall shear stress.Use PCMS software from PAC to analyze the large number of thickness date. According to the thickness data, such as the corrosion rate, retirement date, inspection interval, can be given. According to the result, some pipelines with higher corrosion rate or approaching retirement date should be put into the inspection scope for next time.