Page 346 - Pipeline Pigging Technology

Bi-directional ultrasonic pigging

PIPELINE, PIG AND OTHER DETAILS

A 48-in diameter crude-oil loading offshore pipeline with an approximate
length of 11km was required to be inspected (see Fig.l).

Pipeline details

Nominal diameters: 42-48in
Fluids: crude oil, product oil, seawater, fresh water
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Fluid pressure: 10 kg/cm and less
Fluid temperature: normal temperature
Bend radius of pipe: 1.5 times pipe diameter

Specification of inspection pig

Type: ultrasonic
Measuring method: inspection of inside wall and outside surface
for corrosion
Total number of sensors: 240
Travelling method: bi-directional
Weight: 1,800kg
Overall length: 2.125m

Data analysis system

Inspection data from the designated areas can be regenerated by an on-site
data-analysis system. The data regenerated is output to a monitor display in the
form of a picture image as if seen from inside the pipeline. Following analysis
on the monitor display, data for the whole line is transferred to an engineering
work station at the NKK Engineering Centre, where a complete and detailed
analysis is conducted, using reporting formats such as tabulating corrosion,
and providing a planar view (plane pattern), a longitudinal cross-section, a
circumferential cross-section, a contour map, and a colour planar view. Fig.3
shows the data-analysis system.

Reporting formats

With an internal, natural corrosion sample patched on the NKK test loop,
the detection capability of the bi-directional ultrasonic inspection pig has

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