According to experts in the failure of oil and gas pipelines, there
are a handful of factors that can contribute to a pipeline rupture, like
the one on Exxon Mobil's Pegasus pipeline that spilled toxic diluted
bitumen or dilbit from the Canadian tar sands into a Mayflower, Arkansas lake and subdivision.
Those
factors include pressure swings within the pipe, reversing the
direction of the flow of oil, the quality of the original pipe
construction and a build-up of hydrogen atoms inside tiny cracks in the
pipe.
Elizabeth Douglass reports at The Arkansas Times that all of these factors were in play in the Pegasus pipeline rupture.
Some
operators may change their pumping pressures and their cycles to
accommodate customers or to push more crude through the pipe faster,
which generates more fees. Exxon, for example, increased the amount of
dilbit flowing through the Pegasus by 50 percent in 2009. To accomplish
that without installing larger pipe, Exxon had to send oil through the
pipe faster, either by adding pumping stations or increasing the overall
operating pressure, or a mix of the two.
Three years earlier, in
2006, Exxon also reversed the direction of the pipeline's flow, a move
that would automatically alter the impact of pressure cycles by changing
where the highest and lowest pressures hit along the pipeline. MORE
No comments:
Post a Comment