Several decades ago, a U.S. operator connected two existing pipelines of differently-sized diameters. The 29-mile-long onshore pipeline was built in 1957 and, due to its age, in need of an inspection.
It was determined that it must be inspected for long seam cracks as well as pipe body cracks. The pipeline had never previously been inspected for cracks because no inline inspection (ILI) vendor had been able to deliver a suitable solution that could safely travel the length of the pipeline while gathering a high-quality dataset.
Ultrasonic (UT) crack detection is a well-known ILI service that can be used for a wide range of applications. For almost 25 years, the industry has offered large-diameter UT crack detection tools that have been successfully applied all over the world. However, when the diameter of the tool becomes smaller, especially multi-diameter, the demanding design requirements of this technology present particular challenges. The available space for measurement systems in a pipeline significantly decreases with the diameter of the pipeline. Mathematically, it is a simple quadratic equation; for tool designers and measurement engineers, however, it is a major challenge to overcome.
The number of sensors required to fulfill the specification for an 8”/10” multi-diameter solution is the same as for a single-diameter 10” tool. However, it must contain the bore restriction capability of an 8” tool. Measurement units, as well as electronic and battery segments, must be able to travel through multiple reducers from 10” to 8” and vice-versa. Furthermore, in order to obtain a high-quality dataset, the incident angle must remain inside the allowable tolerances during the journey through the pipeline.
Spatial limitations on the small diameter tool meant that a standard tool design was no longer feasible. A new configuration of the electronics and cabling was required. The development team therefore created a highly miniaturized solution that connected the sensors to a brand-new electronic segment, which was positioned inside the measurement unit. To create the space necessary for the collapsibility of the measurement units, a decentralized data storage concept with easily accessible storage devices was realized.
These modifications demanded less overall space and allowed for new possibilities in tool design. Multiple functionalities, like ultrasonic data acquisition and analysis, as well as system controller functionality with location detection, were implemented in the new electronics. In addition, exceptionally reduced power consumption, in combination with the new cabling concept, helped to ease the entire tool assembly and maintenance process. Consequently, there was no need for extra electronic segments, which helped to limit the tool length and comply with the launching and receiving space provided by the operator.
With the newly-developed multi-diameter tool, multiple RoCD UT ILI services for axial crack detection were successfully performed. The data quality was very high, and the tool remained in good condition with no damages. The operator was pleased with the results, as they fulfilled the previously agreed upon requirements of the inspection.
For the first time, it was possible to collect high-quality data about this aging pipeline system, enabling the operator to ensure its safe operation. Additionally, thanks to this new compact solution, there was no need for temporary launchers and receivers to be installed, which saved the operator those unnecessary costs. Furthermore, the results gathered allowed for the implementation of the data in ROSEN’s Crack Management Framework to further serve the operator with additional integrity modules and assessments throughout the integrity management cycle.