The Williams Companies’ Northwest Pipeline was fined $100,000 last week by the Department of Transportation’s Office of Pipeline Safety (OPS) for exceeding pressure restrictions that were placed on a segment of its damaged 26-inch diameter pipeline in Washington in 2003.

The pipeline had two ruptures last year, one in May near Lake Trapps and one in December near Toledo, and the system, which includes several other parallel pipelines, has been operating at reduced capacity under order from the OPS ever since. Both of the pipeline ruptures were caused by a metallurgical condition known as stress-corrosion cracking, according to Northwest.

Williams said the excess pressure incident occurred on July 15, 2003, between the Sumner and Snohomish, WA, compressor stations. It did not occur as part of normal operations, but during a system test. As work crews were making preparations to run an internal inspection tool (smart pig) to test the integrity of the line in response to the line break in May 2003, Northwest inadvertently allowed the operating pressure to exceed for three hours the maximum operating pressure set under a Corrective Action Order (CAO) by the OPS following the pipeline rupture. The CAO had directed Northwest to lower the operating pressure on its 26-inch line in western Washington in the area of the incident by 20%.

According to OPS Notice of Probable Violation, Northwest allowed the operating pressure in the line to reach 701 psig when it should have been less than 539 psig. Northwest immediately reported the incident to the OPS, and more than a year later OPS handed down its fine, the maximum allowed for such an incident.

There was no impact on pipeline facilities and no additional sections of the pipeline were affected, Northwest said. After investigating the incident, new protocols were adopted to ensure that a similar situation would not occur in the future. OPS also issued amendments to Northwest safe operating procedures.

Since July 2003, Northwest said it has completed the testing of 137 miles of pipeline in Washington without encountering a similar situation or violating the CAO. The Sumner to Snohomish segment is currently idle while Williams moves forward with plans to replace the 26-inch pipeline with a new 36-inch diameter pipeline.

About 111 miles of the 26-inch line is currently in service. While 150 miles of the line remains idled, the pipeline has been able to operate at normal capacity by utilizing parallel lines. Northwest expects to file an application for adding the 36-inch diameter line this winter. It will replace the 26-inch line’s 360,000 Dth/d of capacity when placed into service.

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