Page 72 - Reliability and Maintainability of In service Pipelines

Pipeline Inspection and Maintenance 61

The process of CCTV involves the human operators continually playing and
stopping the camera footage to determine regions of interest (ROI). ROI are
defined as those areas where potential defects may occur. After determining these
areas, the operators must then make a decision as to whether further examination
is required for that particular image.
Even collecting large amounts of data and visual images, the pictures are still
viewed by human operators and therefore the error prone factor of the inspection
is still a concern for CCTV inspection.
Fig. 2.5 presents the types of defects which professional CCTV operators who
are responsible for identifying defects are looking for. These defects are in accor-
dance with Pipeline Assessment and Certification Program (PACP).
Until a proven automated method of assessment is developed, we can only
improve the quality of evaluations by improving the human operators through
experience, knowledge, and training in specific working conditions to acquire the
best possible outcome.

Longitudinal
Circumferential
Hole Collapsed
Multiple cracks Fracture Broken
Spiral
Surface
Crack
damage
Structural defects
Deformed
Joint
Joint offset
Lining failure Joint
Weld failure separated
Point repair Brick work
Joint angular
Construction defects Operation and
maintenance defects
Tap
Roots Deposits
Access points Infiltration Obstacles
Intruding seal material Line Vermin

Material change Survey abandoned
Lining change Miscellaneous defects Dye test visible

Shape change Water level change
Figure 2.5 Types of defects detected in pipeline structures (Guo et al., 2009).