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Pipeline worker and welding unit throwing sparks

Pipeline construction worker with internal welding unit

Pipeline construction workers with internal welding unit

Welding shack being lowered on to pipeline

Pipeline welding technology: No. 1 of 13

In the field, crews working on major projects like the L3RP join together segments of pipe with girth welds, using the Gas Metal Arc Welding (GMAW) process.

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Pipeline welding technology: No. 2 of 13

Qualified welders operate automated welding units—one that performs an initial weld from the interior, another (pictured here) that completes the work from the exterior.

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Pipeline welding technology: No. 3 of 13

Enbridge’s L3RP supplier uses the Double Submerged Arc Welding (DSAW) process to assemble its pipe. This process is ideally suited to carbon-steel pipe, with high productivity rates, extremely low rejection rates, and quality results.

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Pipeline welding technology: No. 4 of 13

The heart of Enbridge’s business is the pipe in the ground—and the craftsmanship that keeps it strong. Enbridge uses the best available welding technology on our pipeline projects, like the Line 3 Replacement Program (L3RP).

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Pipeline welding technology: No. 5 of 13

The pipe steel we use is made of 96% recycled metal, including tons of Minnesota scrap steel for the Line 3 replacement pipeline. This alloy is not only a greener product, but also represents excellent chemistry for line pipe.

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Pipeline welding technology: No. 6 of 13

Enbridge has high demands for its pipe, requiring more rigorous and frequent testing than industry standards.

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Pipeline welding technology: No. 7 of 13

Weld quality in the pipe mill is examined by the manufacturer using automated ultrasonic devices. Enbridge inspectors audit those results.

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Pipeline welding technology: No. 8 of 13

An external unit or “bug,” circling the pipe on tracks, performs several passes from the exterior of the pipe to complete the weld and fill the ¼-inch gap. These “fill” and “cap” passes are performed in portable shacks that offer protection from the elements.

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Pipeline welding technology: No. 9 of 13

“There might be five or six shacks following the internal bug, and they just keep hopscotching down the line once they finish a weld,” says Joel McKim, a senior construction specialist on the Line 3 replacement project.

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Pipeline welding technology: No. 10 of 13

All welds are coated with the same fusion-bonded epoxy applied in the pipe mill to prevent corrosion.

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Pipeline welding technology: No. 11 of 13

Out on the pipeline right-of-way, an independent third party tests all welds, primarily using ultrasonic technology, with Enbridge auditors reviewing all of the scans as a second pair of eyes on the initial evaluations.

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Pipeline welding technology: No. 12 of 13

“Enbridge has an internal requirement that a certain percentage of our girth welds out in the field are delay-inspected—for enhanced quality assurance," says Andy Duncan, Technical Services Manager with Enbridge’s Major Projects group.

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Pipeline welding technology: No. 13 of 13

“I’m very, very confident in saying that we are using the best available welding technology to industry,” says Duncan, “and that we go far beyond the minimum requirements of existing codes and standards, wherever we build pipelines.”

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