A new generation of ultrasonic in-line inspection tools for detecting, sizing and locating metal loss and cracks in transmission pipelines

More than three million kilometers of high pressure liquid and gas pipelines are installed all over the world. Generally steel pipelines provide the safest means to transport large quantities of oil, oil related products and natural gas. However, just like any other technical component, they can deteriorate. As a result flaws can appear and grow until the pipeline fails. These flaws must be identified, before they endanger the integrity of the line. This paper introduces a new generation of high resolution inspection tools using ultrasonics to detect, size and locate metal loss and crack-like defects in the body and welds of transmission pipelines. These devices are pumped through the section of pipe to be inspected together with the medium being transported therein. They enable an inspection of the entire circumference and length of the pipe of up to several hundred kilometers in a single run. The paper describes the non-destructive testing principles applied and introduce the major components of the inspection system, tool and defect specifications and examples of features that can be found. Finally the improvements, which this latest generation of ultrasonic in-line inspection tools incorporates, is described and discussed.