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10 years of intelligent pigging
10 YEARS OF INTELLIGENT PIGGING:
AN OPERATOR'S VIEW
INTRODUCTION
Total Oil Marine pic has operated, for the last decade, a gas-transportation
system between the giant Frtgg field in the Northern North Sea and the
St.Fergus Gas Terminal on the NE coast of Scotland. The reserves of the field,
which straddle the Norwegian/UK boundary, have been exploited by the
construction of two large-diameter high-pressure gas pipelines to St.Fergus.
This paper looks at the background to the pipelines, and in particular at the
decision to use internal inspection by various types of intelligent pigs as an
element of internal condition monitoring devised for a gas-transportation
system.
PIPELINE DETAILS (SEE FlG.l)
The two lines from the Frigg field to St.Fergus were constructed during
1974-1976. One line is owned by the UK Association (see Acknowledgements
for definition of this group), and the other by the Norwegian Association (see
Acknowledgements). Both are opera ted by Total Oil Marine pic. Details of the
lines are as follows:
diameter 32in OD
wall thickness 0.75in
length (each) approx. 360km
steel API 5LX 65
maximum allowable operating pressure 149 bar
The pipelines run parallel to each other approximately 100m apart in
water depths of up to 155m. Approximately halfway to St.Fergus there is the
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