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Corrosion inspection of the Trans-Alaska pipeline

CORROSION INSPECTION OF THE

TRANS-ALASKA PIPELINE

THE ALYESKA Pipeline Service Company operates an 800-mile pipeline
which transports crude oil from Alaska's large reserves on the North Slope to
the ice-free port at Valdez. The pipeline, which carries approximately 25% of
the US domestic crude, was put in service in July, 1977. This paper describes
the use and preliminary results of the last four years of corrosion inspection
of the 48-in diameter mainline pipe by state-of-the-art, intelligent pipeline-
inspection devices.

INTRODUCTION

Pipeline operators have many choices in a fast-changing pipeline-inspec-
tion industry. Technological advancements in computer, data-processing and
electronic industries in the past 10 years have permitted vast leaps in
advanced-pig inspection systems. Mature monitoring systems have been
improved and advanced, and capabilities and systems which were not
possible 10 years ago are now out of the experimental stage and are being
used as commercial production systems.
Two of the primary technologies representing pipeline corrosion-inspec-
tion systems are the magnetic-flux and the ultrasonic corrosion pigs. There
are many companies which provide various types of magnetic-flux corrosion
pigs, and they have by far logged the majority of corrosion-pig mileage today.
However, two companies in the world pig market have pioneered commer-
cially-available corrosion pigs using ultrasound. These companies are NKK,
the Japanese steel producer, and Pipetronix, a subsidiary of Preussag (previ-
ously known as IPEL-KOPP).

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