Page 455 - Pipeline Pigging Technology

Pipeline Pigging Technology

pipeline where SCC was discovered in the vicinity of a removed dent, and to
excavate selected locations on several other pipelines.

Slope instability projects

Total expenditures related to pipelines with slope stability problems
amount to 12% of programme costs, with nearly half of those costs attributed
to one location where river bank movement has caused a previous failure. For
the past three years, pipe movement at that location has been monitored
using a satellite global positioning system installed on the pipeline [16], which
indicates that reconstruction will be required within the next year to protect
the pipeline from continuing soil loading. Monitoring of slope movement is
expected to continue at another nine river crossings where slope movement
is occurring. Costs for these other slope monitoring projects are compara-
tively low, at less than $25,000 per year for each site.

COSTS AND BENEFITS

Costs

The total cost of the programme will be approximately 2% of the opera-
tions and maintenance costs for the pipeline system for the years 1988 to 1990
inclusive. As mentioned earlier, just over half the expenditures have been on
assessing lines with anticipated integrity problems, with the rest spent on
monitoring lines with known integrity problems and a risk of recurring
failures.

Benefits

The need to periodically assess the condition of lines recognized to have
a risk of recurring failures is almost self-evident. Failure to do so would likely
result in regulatory action as a minimum, and would not be consistent with
NOVA's commitment to operate a safe and reliable system. The benefits of an
established programme for monitoring the integrity of such lines includes:

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