Page 282 - Pipeline Pigging Technology

Pigging for pipeline integritit analysis

Earth Movements Improper Construction
Sea Currents Hydrostatic Tests
Wash Outs Improper Back Fill
Mechanical Interference Unsupported Spans

Table 2. Deformation/slope change cause factors.

Dents Ovality
Mashes Construction Damage
Wrinkles Third Party Damage
Buckles Flat Spots
Generalized ID Changes Hydrostatic Test Expansions

Table 3. Defect detection capability.

Girth Welds Insulating Flanges
Valves Spiral Welds
Tee's Scraper Detectors
Transition Joints Stopple Fittings

Table 4. Pipeline appurtenance detection.

Deformation of the pipeline can be caused by mechanical force (ditching
machines, anchors, etc.) or by a change in slope. The D/S tool is sensitive to
both types of change. Table 2 lists some of the causes that effect the area or
slope of the pipeline. Table 3 lists some of the mechanical defects that are
detectable.
In addition to deformation or mechanical damage, the log clearly indicates
many other pipeline appurtenances which help in defining pipeline configu-
ration. Some of the appurtenances detected are listed as the second part of
Table 4.
Tables 3 and 4 are not inclusive of all deformation, mechanical damage or
pipeline appurtenances that can be detected, but provide an indication of the
tool's ability. The D/S tool is sensitive to any factor that would cause a change
in the pipeline ID or change in direction of travel.
The tool cannot 'see' the cause of the pipeline change, but rather looks at
symptoms. Symptoms can then lead the operator to a cause.
In addition to the capabilities described above, the tool has options that
allow further definition of the pipeline system. A brief description of each
option follows:

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