How MNOPS inspectors ensure safety and quality on the pipeline replacement
July 29, 2021
Minnesota Office of Pipeline Safety (MNOPS) inspectors have been making regular trips to different parts of the Enbridge Line 3 replacement project since construction began last year. One of the main activities MNOPS inspectors have been checking on this summer is horizontal direction drills (HDD). MNOPS does not and will not operate the pipeline, and they don't grant any permits for its construction or operation. Their job is to make sure HDDs – and other work on the pipeline – are completed safely and correctly.
HDD is used throughout the utility industry to install pipe and cables. It allows for installation without digging trenches or breaking up roadways. In the case of Enbridge Line 3, HDD is being used to install pipe under bodies of water such as rivers, creeks and lakes, as well as under roadways.
They start with a pilot bore using temporary segments of pipe. The permanent segments of pipeline attach to the end of the pilot bore and get pushed (or sometimes pulled) through. Once the temporary segments are fully exposed on the other side, they are removed leaving the permanent segments in place. This process prevents damage to the permanent pipeline segments.
It works like this: Once all the utilities have been located and marked (to make sure no power or other lines are damaged during the HDD), MNOPS reviews Enbridge's procedures and plans for the bore. MNOPS also checks the amperage range of the welding crew. The welding crew is there to weld the front end of the next section of pipe to the back end of the current section, and they have to be within a certain amperage range for the weld to hold. MNOPS reviews the amperage range and monitors the ultrasonic test on each weld after it's done to make sure it's thorough. If it's not, Enbridge had to cut out the weld and perform a new one.
MNOPS makes sure workers follow the proper two-part epoxy coating application procedures over the welds. Under MNOPS's observation, workers run a jeeping tool (so called because of the sound it makes if it finds a problem) across the outside of the pipe to make sure it's coated properly.
MNOPS inspectors are working tirelessly to ensure that the plans, construction processes and materials, and workers on the Enbridge Line 3 pipeline replacement project are of the best possible quality so that the finished product will be the safest it can be.
