Line 5 in-line inspection results



The Straits of Mackinac is a special place, and that’s why we take extraordinary precautions to continue the safe and reliable operation of Line 5 as it crosses underwater. Our in-line inspection program is one of many protective measures we use to help keep the Straits crossing safe.

Internal inspections are done every five years using sophisticated tools that run through the pipe and examine it from the inside, inch by inch. These tools use imaging technology, with a level of detail similar to that of MRIs, ultrasound and X-ray technologies used in the medical industry. The tools alert us to any issues in the pipeline that may require immediate attention, further analysis or maintenance. Data collected from those scans is analyzed by specialized computer programs and expert engineers, and is continually compared to get a full picture of what’s happening in the pipes.

In the past five years, the four-plus miles of pipe under the Straits have been internally inspected by three different tools, checking for everything from deformations to girth-weld features to metal loss in the pipe wall. A total of 13 in-line inspections have been done since 1987.

The next in-line inspections—for metal loss, deformation and circumferential cracking—are planned for 2018.

Interested in the technical data? Learn more about the findings from in-line inspections for:


Click here for an optimized for print version of our inspection results web pages.