TAPS repair shows value of deformation monitoring
For Arctic pipelines, especially those built in river and floodplain areas, a monitoring system is essential for detecting impending pipe damage. This was a major lesson derived from last year's repair and rerouting of a section of the Trans-Alaska Pipeline (TAPS) at milepost (mp) 200. The line at this point crosses a river and floodplain area in which any surface evidence of pipe damage is obliterated, thus making ground surface conditions unreliable indicators of pipe settlement. The wintertime repair project, with rerouted pipe of about 4,000 ft long, cost $27 million. The affected pipe was buried beneath the main channel of the Dietrich River, 200.6 miles from the beginning of the pipeline at Prudhoe Bay, and 84 miles above the Arctic Circle. As part of Alyeska's continuing monitoring program, a corrosion and deformation (C/D) pig traverses the TAPS pipe at regular intervals. This pig has proven helpful in locating places where excessive settlement has caused deformation of the pipe. The C/D pig detects pipe diameter changes as small as 0.25 in. The radial and longitudinal locations of the pipe change have proven quite accurate. A review of the results of the June 1984 C/D pig run revealed a pipe wall ovality anomaly with a sinusoidal shape indicating a wrinkle. This wrinkle was small when compared with other wrinkles Alyeska had found and subsequently repaired. A comparison of previous C/D pig runs for this location revealed a wrinkle with an amplitude of 0.25 in. which had developed in previously smooth pipe in the space of a year.
- Research Organization:
- Alyeska Pipeline Service Co., Anchorage, AK
- OSTI ID:
- 5755012
- Journal Information:
- Oil Gas J.; (United States), Vol. 84:14
- Country of Publication:
- United States
- Language:
- English
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