'Dual-diameter pig' harnesses technology, boosts pipeline safety

This "dual-diameter pig" is an inline inspection tool with ultrasonic capabilities.

Enbridge develops one-of-a-kind inline inspection tool

There’s building a better mousetrap. And then there’s building a better pig.

At Enbridge, we’re constantly harnessing the latest technology to boost safety across our pipeline network. Inline inspection tools, otherwise known as “smart pigs” in the industry, are sent through our pipelines at regular intervals, inspecting the pipe millimetre by millimetre – with a level of detail similar to that provided by MRIs, ultrasound, and X-ray technology in the medical industry.

But how do you handle inspections for a unique line like Enbridge’s Line 4, which consists of 28 segments of varying sizes – some of them 36 inches in diameter, and some 48 inches – as it travels nearly 1,100 miles, or 1,765 kilometres, from Edmonton to Superior, Wis.?

You create a better pig. An ultrasonic pig.

A dual-diameter pig.

“We needed a tool that could inspect all sections of Line 4 using complementary ultrasonic techniques. And because of Line 4’s unique design, we needed a tool that could expand and contract multiple times without losing the inspection coverage,” notes Garry Sommer, a manager in Enbridge’s Pipeline Integrity division, who led development of this specialized tool.

Sommer and his colleagues approached Germany-based NDT Global, an international leader in the production of ultrasonic pipeline inspection equipment, to develop a tool that could meet the unique challenges of Line 4.

After years in the design, development, and testing phases, and a $4.4-million investment by Enbridge, NDT Global produced a dual-diameter inspection tool that uses an ultrasonic inspection technique. Because it expands and collapses within the line like an umbrella, sensors on this dual-diameter tool provide 100-per-cent coverage of the pipe wall – whether it’s running through a 36-inch-diameter section, or a 48-inch-diameter portion.

Inspection of all 28 segments of Line 4 was completed in 2014. And after results from field excavations verified data collected from the dual-diameter pig’s travels, we were able to lift a self-imposed pressure restriction on Line 4 this spring. That means fewer operational outages, more cost savings, and decreased pressure cycling.

Ultimately, the development of this dual-diameter pig means more valuable knowledge about running ultrasonic inspection tools on heavy crude lines. It also serves as another example of our ongoing investment in advanced technology to optimize safety and operational reliability. At Enbridge, we believe all incidents are preventable – and we’re aiming for 100 per cent safety.

The dual-diameter inspection tool is currently being stored in Nisku, Alta., allowing for quick access should it be needed. While it’s designated as a “dedicated” Enbridge tool, meaning other pipeline companies require Enbridge approval to use it in their systems, our approach to safety is based on collaboration. We don’t compete when it comes to safety.

At Enbridge, we’re committed to helping advance pipeline industry safety and technology – and the dual-diameter pig is helping us get there, one millimetre at a time.