Page 344 - Pipeline Pigging Technology

Bi-directional ultrasonic pigging

BI-DIRECnONAL ULTRASONIC

PIGGING: OPERATIONAL EXPERIENCE

HAVING SUCCESSFULLY inspected a 48-in 11-km offshore pipeline using
a bi-directionally-travelling ultrasonic inspection pig, NKK has proven its
technological ability to provide valid data for efficient, cost-saving mainte-
nance.

INTRODUCTION

The natural environment will be severely affected in the event of a leak
from an offshore crude-oil loading pipeline. To prevent such leakage due to
corrosion, an inspection of the development of pipeline corrosion by means
of an inspection pig is effective. Most offshore loading pipelines are installed
between the shore with storage tanks, and the PLEM (pipeline-end manifold)
on the sea bottom, permitting connection to a tanker via a flexible rubber
hose. At present, however, difficulties are always encountered in carrying out
the inspection of offshore pipelines by means of an inspection pig, because
the structure of the offshore crude-oil loading line is not suited for installing
a launcher or a receiver.
NKK has developed an inspection pig that makes it possible to inspect the
state of corrosion of a pipeline by travelling bi-directionally in the line
provided there is a sufficiently-large area at the shore end of the line to install
a launcher/receiver.
This paper outlines how the inspection of the inside of an offshore pipeline
was conducted by a bi-directional ultrasonic inspection pig currently in use
in Japan.

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