Explained: Ultrasonic Self-Propelled Robotic Inspection Solution for Unpiggable Dock Line
Authors: Richards Corey , Bolduc Cedric , Hamnes Børge 
Published: December 2022

While under various banners, Valero Energy Inc. has been a staple in the refining and marketing of products since 1961. Key facilities such as the Montreal East Terminal and the St-Romuald Refinery supply their carriers and customers (resellers and wholesalers) in the regions of Southern Quebec, the Maritimes, and the Greater Ottawa and Toronto areas, with smaller terminals in these areas serving the Northeastern United States market.

Guaranteeing that delivery orders are met and critical product is delivered on schedule requires Valero’s terminals to have comprehensive integrity programs in place. Comprehensive programs, which include risk modeling, in-line inspections and tank inspections, to name a few, help to ensure there is no unexpected downtime due to incidents.

While ensuring the integrity of any oil and gas pipeline network contains its own challenges, facility or terminal piping does not often contain the typical infrastructure to employ standard technologies. Accordingly, specialty solutions are often required. Such is the case for Valero’s 960-meter, 10inch dock line at the Gaspé Terminal, which is a critical supply link transporting refined products from shipping vessels to the terminal.

The technical challenges that needed to be overcome for the inspection of this underground dock line included:

• No pig launcher and pig receiver present; dock line not designed for conventional pigging

• Dock line only has flow when unloading to ships

• In-service operating conditions prohibited conventional ILI tool inspection

• Limited space available for equipment to support standard pigging operation

• Staging of equipment on the dock would pose additional risks for the environment in the event of loss of containment for any supporting pumping equipment

This paper will outline the validation, testing and execution of a self-propelled robotic tethered solution in combination with an ultrasonic wall measurement (UTWM) system capable of navigating the complexities of the Gaspé dock line. The inspection solution outlined in the paper did not require any major modifications to the dock line system, nor did any equipment need to be present on the dock side. The utilization of dedicated crawler units eliminated the requirements for flow or pressure in the dock line to propel the tool during inspection.

Overall technical and operations benefits of this solution are:

• Accurate and precise feature classification and sizing by quantitative ultrasonic measurement

• Two sets of data (from both the inbound and outbound run) with the outbound run providing a further verification for the inbound run

• Real-time data analysis and preliminary report on-site, followed by a thoroughly reviewed final report

The online self-propelled tethered crawler inspection system contained the actual inspection tool, the drive unit, the umbilical winch and a computer system to communicate with and control the inspection vehicle. The paper will outline in detail the workings of the inspection tool, particularly:

• The ridged ring UT sensor unit

• The modifications and testing to ensure the system could pass features in the line

• The electrically driven propulsion system

While the focus of this paper is the deployment of this inspection solution in the Gaspé dock line, it will also compare previous operational experiences with running a free-swimming tool. Overall, the paper will outline not only how this solution better ensured the integrity of the line itself, but also how its execution reduced safety and environmental risks, while still collecting indispensable, high-quality in-line inspection (ILI) data.