A North American pipelinecontracted NDT Global to inspect an 18" Natural Gas Liquid ( ) pipeline for cracks, including hook cracks. The pipeline transported blended NGL, which made the process complicated by the nature of the medium.
Performing ultrasonicinspections in a challenging medium such as blended NGL requires a thorough understanding of certain parameters. One of the biggest challenges is determining the sound velocity in the medium as changes in operational and environmental conditions such as pressure and temperature can affect propagation angles and lead to measurement degradation.
Typically, when faced with a challenging medium, thetool is deployed in a batch of a standard medium, such as diesel. However, in this instance, the sought a solution that could be deployed directly in the product. Working closely with the pipeline operator, an extensive testing and validation process was initiated.