It was stated on another thread yesterday that sand is pumped out of the ground along with the oil. Over time, it corrodes, or creates thin spots along the pipeline.
What kind of maintenence does one do to prevent corrosion of this nature from happening?
Well, sand is certainly very corrosive. That must be the answer. However, I would think that some fairly high-tech coatings would be used in this instance. Do you remember when this pipeline was put in?