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Message Subject ****Raw Video: San Bruno Surveillance Cameras Capture meteor strike followed by fireball detonation****
Poster Handle Anonymous Coward
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Max life expectancy for these pipes is 40-50 years. They are in the range. Now, add to that:
Thread: With the accumulative action of many magnetic disturbances pipeline corrosion is significantly accelerated

from: SPACE WEATHER EFFECTS CATALOGUE
[link to www.esa-spaceweather.net]
2.4.3. Pipelines

Buried oil and gas pipelines are prone to corrosion, which may occur at points where an
electric current flows from the metal into the surrounding earth. Therefore pipelines are
covered by an insulating coating. The insulation is, however, not perfect, and particularly
problematic are possible holes in the coating. To avoid corrosion, pipelines are equipped
with a cathodic protection system (Von Baeckamn et al., 1997) which tries to keep the
pipeline in a negative potential of roughly 1 V with respect to the soil. Different harmful
processes may take place if the negative potential becomes too large, so the adjustment of
the potential has to be careful.
GIC flowing along pipelines are accompanied by voltages between the pipeline and the
Earth (Boteler, 2000; Brasse and Junge, 1984; Campbell, 1980). GIC are not hazardous
regarding corrosion issues but the pipe-to-soil voltage variations related to GIC can easily
exceed the cathodic potential making the protection thus invalid
(Gummow, 1999). Today’s coatings have orders of magnitude higher resistance than those used earlier. This
results in larger pipe-to-soil potentials, thus significantly increasing the risk of corrosion
at defects in the coating.
How much pipe-to-soil voltages induced by space weather effects
really increase the corrosion rate of a pipeline is still a somewhat open question, and
estimates about times before the wall of a pipeline is seriously damaged vary in a wide
range
(Martin, 1993; Campbell, 1978; Henriksen et al., 1978; Gideon, 1971). Besides a
direct contribution to corrosion, geomagnetically induced pipe-to-soil voltages are a nuisance
when measuring cathodic protection parameters and making control surveys
(Barker and Skinner, 1980). The measurement results may be completely incorrect and
thus lead to erroneous conclusions.

Similarly to a power system, the magnitudes of GIC along a pipeline network and of
pipe-to-soil voltages depend both on the geophysical situation and on the details of the
network. Model calculations supported by measurements of geomagnetic variations can
be performed to reveal the most problematic regions in a pipeline network (Boteler and
Seager, 1998). In general, the pipe-to-soil voltages are larger at in homogeneities of the
system, such as ends, bends and branches of the pipeline, changes in the material or size
of the pipeline, or variations in the Earth’s conductivity.
The adjustment distance that expresses
the length of the area in which the inhomogeneity affects is typically in the order
of tens of kilometres. Long pipelines experience larger geomagnetically induced pipe-tosoil
voltages than shorter ones.
Therefore, pipelines are sometimes electrically interrupted
by installing insulating flanges in series with metallic pipeline parts (Camitz et al., 1997).
Such a procedure may really decrease the largest voltages appearing but at the same time
increases the number of inhomogeneities. Therefore, all effects of insulating flanges have
to be carefully analysed, and the final solution is a compromise.
To avoid the problems caused by geomagnetic storms to buried pipelines, the industry
has to be aware of the risk produced by GIC and induced pipe-to-soil voltages. A possibility
of forecasting geomagnetic storms will help avoid making control measurements
during times of a high probability of disturbances.
A forecast of a magnetic storm also
gives a reason to check that the corrosion protection systems are in full operation.
In general, space weather risk has not been investigated as much in pipelines as in power
systems. Recent investigations (Pirjola et al., 1999) containing improved tools for model
calculations are improving the situation, and at present an international “pipeline-GIC”
study with eight companies involved is being finished.
 
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