Intelligent inline inspections (ILI) are widely used to guarantee a safe operation of pipelines. The inline inspection provides reliable data in an economic way. Historically, magnetic flux leakage technology (MFL) was one of the main technologies applied in pipeline systems. Within the last few years some minor improvements have been introduced in the existing MFL tool fleets, mainly focusing on a higher resolution. Nevertheless, a general restriction based on the physical basics finally limits the sizing capabilities of corrosion defects, esp. for complex shaped defects.
Ultrasonic (UT) is currently the most accurate and reliable In-Line Inspection technology available in the market. These UT ILI Tools record data while travelling through the entire pipeline from Launcher to Receiver. In most cases, the Pipeline Operator does not need to make major adjustments to their pipeline.
The latest generation of UT tools offers high inspection velocities — consequently a reduction of medium flow and loss of production can be avoided. In addition, a very high resolution of transducers in axial and circumferential direction provides excellent input for accurate pressure calculations, e.g. based on Riverbottom profiles or even 3D Finite element modeling.
Using UT as the inspection method greatly increases the confident level of the inspection survey results. This in turn will give Pipeline Operators a greater peace of mind that their true pipeline condition is known thereby reducing unnecessary and costly digs and repairs.
The authors will present some basic background information about ultrasound inspection technologies. State of the art solutions are presented for crack and wall thickness tools.
Combining different technologies in one tool offers additional benefit. One single inspection tool with corrosion and crack transducers enables pipeline operators to operate their system safe with a minimized impact. Finally, the authors will present some special solutions for high pressure deep water applications and multi diameter pipeline systems.