No trip to Alaska would be complete without seeing the oil pipeline. This part of the pipeline in the photo passed by Fairbanks. The pipes are not rigidly attached to the support structure and rest on slides which permit for motion from thermal expansion. Careful design also insulates the pipeline from the vertical supports in order to avoid transmission of heat into the support columns with the undesired effect of the melting of the permafrost and the certain sinking of the support columns into the ground. The vertical units visible on top of the dark support posts are radiator units which are attached to heat pipes which transfer any heat in the support column to the surrounding air to further guarantee that the posts are not warmed and sink into the permafrost.
The pipe line is a collection of 40 foot long sections of 48 inch internal diameter pipe. The line is laid out in a zig-zag to permit linear expansion. At start up, the thermal expansion produced a growth in line length of 4 feet per mile. This pipeline now accounts for 20% of all US production. It is owned to the order of 70% by BP.
Oil comes from the ground at 180 degrees F and averages about 60 to 72 degrees F inside the pipeline. There are a total of 5 pumping stations over the entire length.
The estimated cost of construction was $900 million. The actual cost was $8.8 billion with a total of 2000 contractors working on the job. The cost of the pipeline was recovered by the oil revenues collected from the first 14 months of operation.
The problems confronting the pipeline construction:
1) Mountain ranges
2) Perma frost
3) 13 major rivers to cross
4) 3 earthquake faults to cross
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