Robotic Ultrasonic Inspection of Dual-Diameter Pipeline
Overcoming the challenges of unpiggable liquid pipelines with self-propelled robots
Through robotics, automation, and advanced sensor technology, self-propelled systems can navigate complex pipelines without needing traditional access points or product flow. In the following case, our experts deployed a self-propelled robotic ultrasonic wall measurement (UTWM) system in the 20” segment of a dual-diameter pipeline to verify the integrity while eliminating the need for pipeline modifications or pumping equipment.
Pipeline information:
- Diameter: NPS 16/20
- Length: ~1,411ft/430m (~1,138ft/347m 20”/ ~272ft/83m 16”)
- Minimum bend radius: 90° (assumed 1.5D)
- Wall thickness (normal): 0.25’’/6.35mm
- Pipeline product: Distillate and Gasoline
- Diameter: NPS 20/16
The challenge
The underground lateral line between a fuel distribution terminal and a third-party pipeline operator supplies multiple storage tanks with distillate and gasoline. This pipeline consists of a dual-diameter segment on the third-party facility’s land, accessible via aboveground risers equipped with tool launching and receiving infrastructure.
Despite this launching and receiving infrastructure, the pipeline was not designed for conventional pigging, so several challenges had to be overcome:
• Limited access points
• Unsuitable operational conditions for conventional ILI
• Limited space and environmental risks associated with setting up temporary pumping equipment
• The transition between the 16” and 20” sections at a bend
Prior to inspection of the line, boundary conditions with the customer were established, including the following:
• Carrying out the inspection during a planned shutdown window
• Ensuring high-resolution corrosion measurement performance
• Minimizing activities, modifications, and equipment use whenever possible
Our solution
Several critical factors had to be considered when developing a solution: selecting the suitable propulsion components, choosing the right measurement technology for the asset, and integrating robust fail-safe mechanisms for the inspection tool itself.
A self-propelled tethered inspection tool emerged as the optimal solution, allowing autonomous traversal of the dual-diameter line without needing liquid or gas propellants. Ultrasonic Wall Measurement (UTWM) was chosen due to the relatively clean oil in the pipeline, which aids in the propagation of ultrasonic signals. The tethered tractor self-propelled inspection system consists of a UTWM module, propulsion/tractor unit, umbilical winch, and a computer system for communication and control of the inspection vehicle.
The tool was deployed at the 20” entry point, avoiding modifications at the tank farm end. It navigated the line, pausing at the 16”/20” transition point, and was retrieved using a winch system at the entry point. This method eliminated the need to install pumping equipment at both ends so that the product no longer had to be drained from the line and operational interventions at the tank farm end could be avoided. This approach effectively mitigated potential environmental or safety risks while ensuring high-quality data collection.
Your Benefit
Throughout the inspection process, the collected data was accessible in real-time, enabling onsite analysts to adjust to enhance data quality. Moreover, analysts could conduct additional passes on areas of concern, providing a dynamic and adaptable approach to the inspection procedure.
The elimination of the need for temporary pumping, thanks to the inspection design concept, increased operational and environmental safety. In addition, the robust fail-safe mechanism provided by the tethered connection ensured that the tool could be retrieved from the pipeline if required.
Reference:
This case study was first published at the Pipeline Pigging and Integrity Management Conference in Houston in February 2024