Inline inspection is a critical aspect of effective and efficient crack management in live pipelines. This encompasses the accurate detection, identification and sizing of such anomalies both to reliably validate the integrity of the pipeline and to also optimise subsequent in-field validation and repair programs.

Traditional pull-through tests (pull tests in air or static chamber tests) or pump tests in water are essential for ILI tool calibration, however they are limited in their ability to fully replicate the complexities and challenges of real-world pipeline inspections.

Advanced crack detection technologies using guided waves cannot be validated in water which requires going beyond conventional validation tests. DNV, in collaboration with NDT Global have developed a unique large-scale gas flow loop to validate the performance of NDT Global’s new gas crack detection tool.

The gas test loop includes a 30” diameter pipeline of approx. 100m in length and contains test sections with both real and artificial defects. The facility operates with natural gas at up to 65bar and can generate flow speeds up to 1.5m/s to replicate real pipeline operating conditions. The primary aims of the test program are to define the optimum operating window for the tool (speed, pressure) and to confirm tool calibration and performance prior to deployment in an operating pipeline.

This paper provides an overview of the design, construction, commissioning and operation of the 30” gas flow loop. Detailed results of the tool performance based on the artificial and real defects incorporated in the test loop are presented. A summary of key technical and cost benefits of this novel approach to accelerate tool validation prior to field deployment are presented.