MONDAY, JULY 9, 2018
A rupture last fall in TransCanada’s Keystone Pipeline near Amherst, South Dakota, was the result of damage inflicted by a construction vehicle during installation, according to a report released Thursday (July 5) by the National Transportation Safety Board.
|
|
| PHMSA |
|
The NTSB’s accident report relates that the fatigue crack that eventually grew and ruptured began as damage from a “metal-tracked vehicle.” |
A metallurgical analysis ruled out the theory that concrete weights installed over the pipeline to prevent buoyancy due to groundwater were to blame, a possibility broached in the Pipeline and Hazardous Materials Safety Administration’s initial Corrective Action Order.
Metal-Tracked Vehicle
The NTSB’s accident report relates that the fatigue crack that eventually grew and ruptured began as damage from a “metal-tracked vehicle.” Materials scientists analyzed grooves in the pipe’s exterior in the area of the rupture, finding traces of metal inconsistent with the pipeline itself, but likely a match for metal-tracked construction equipment. Coating material was “present and intermixed with the sliding groove marks,” according to the report.
The shape and size of the grooves, along with the metallurgical analysis, led to the conclusion that it was construction equipment, and not the concrete weights, that ultimately led to the leak.
 |
| TransCanada |
|
The report says the Nov. 16, 2017, rupture resulted in the release of about 5,000 barrels of oil, but in April, TransCanada officials told the Aberdeen News it was actually 9,700 barrels. |
According to the accident report, TransCanada was conducting in-line inspection with a pig and an acoustic leak detection tool at the time of the rupture; it was the first ILI for the detection of cracks since the pipeline was installed in 2008.
The area of the pipeline where the failure occurred is a 30-inch API 5L X70 steel pipe coated with fusion-bonded epoxy.
The report says the Nov. 16, 2017, rupture resulted in the release of about 5,000 barrels of oil, but in April, TransCanada officials told the Aberdeen News it was actually 9,700 barrels, which would make it one of the 10 largest crude-oil spills onshore in the U.S. since 2010.
Keystone XL Project
The spill came just as TransCanada gained approval from Nebraska for its Keystone XL project, the long-delayed Keystone extension that would connect the Alberta oil sands with Steele City, Nebraska. TransCanada has since confirmed commercial interest in Keystone XL but has yet to officially announce whether it will move forward with the project, first proposed in 2008.
Keystone XL was rejected by the administration of former President Barack Obama in 2015 but was revived soon after President Donald J. Trump took office in 2017.
TransCanada has signaled that the construction of Keystone XL is commercially viable and the company has plans to begin clearing brush for the project this fall, but it has yet to make a formal decision as to whether it will build the pipeline.
Tagged categories: Fusion bonded epoxy; Oil and Gas; Pipelines; Quality Control
