Analysis and Trend Estimation of Geometry Defects and Metal Losses in the Pipeline Wall Based on UT Intelligent Pig Inspection
Proceedings Publication Date
In the past 20 years, CDRiA has performed a series of inspections of crude oil and liquid fuel pipelines. Some of these inspections were repeated inspections of the same pipeline after several years. By repeating inspections, the growth rate of both geometry defects and metal losses can be estimated. The KORSONIC high resolution ultrasonic intelligent pig was used for the inspection. The applied solution is characterised by placing sensors on a rigid cylinder body. Such solutions allow for the simultaneous measurement of the pipeline’s internal geometry parameters and the wall thickness. Owing to its high resolution, the tool allows for the precise imaging of any of the pipeline’s defects while ultrasonic technology application is used to detect and estimate not only metal losses but also several material defects such as lamination, including particularly dangerous angular laminations, and inclusions. Material losses in girth welds can be measured by the adjustment of longitudinal resolution combined with the precise measurement of a stand-off. This paper presents some examples of different applications of the images, including 3D images, offering the presentation of characteristic features of various types of defects detected in pipelines. Additionally, the usefulness of the high resolution results generated from the tool to estimate the impact of the defects detected on the operational parameters of the pipeline was emphasised by using the finished element method (FEM), as well as the application of different types of standards defining the durability of defective pipelines such as ASMR B31G or RSTRENG. By repeating inspection runs in the same pipeline, comparative material can be collected for the purpose of estimating the development rate of the geometry defects as well as the corrosion rate. This study presents some examples of estimating the growth rate of specific defects. It also proposes to adopt the statistical approach for the purpose of the comprehensive assessment of changes occurring in the pipeline as a whole. This solution allows for predicting the future condition of the pipeline, which signifies that the dates for future inspections, maintenance and repair works may be scheduled.