Page 71 - Reliability and Maintainability of In service Pipelines

60 Reliability and Maintainability of In-Service Pipelines

Figure 2.4 Closed circuit television for pipe inspection.

without the need for extraction of the pipeline (Fig. 2.4). This means of inspec-
tion is cost-effective and reliable in identification of defects at the assessed
areas. The camera on the front can be rotated during the course of the naviga-
tion within the pipe to identify more than just what is directly in front of the
car. The machine is collaborated within the pipe and exact coordinates and dis-
tances are present in the footage to enable identification of damage within a
pipeline.
Damaged or defected pipes, generally can be treated in three ways: cleaning,
repairing, or replacing. This is all determined once the report has been provided
to the pipeline engineers/maintenance team from the contracted CCTV inspection
company. Once the reliability of the pipeline is determined from the testing, the
maintenance strategies are enforced to ensure the structure can rerun at its highest
efficiency.
Visual data from the CCTV devices is transmitted via cable in real time to the
operator and is recorded for further in-depth analysis in photo or video formats.
The CCTV is capable of detecting notable damage or defects within the pipe,
which is the subject of stream quality and fully relies on operator competency to
correctly record and classify the defect (Ahrary et al., 2007). Considering a num-
ber of influencing factors some research (Korving, 2004; Korving and Clemens,
2005a,b; Dirksen et al., 2013) concluded that CCTV data may lead to defect mis-
identification by an error rate as great as 20% 30%.
On its own, visual inspection produced by a CCTV module provides factual
evidence of certain pipe defects, i.e., the presence of a defect, its severity, and
longitudinal and circumferential location. However, time-consuming supportive
hardware and/or software is required to carry out an accurate quantitative assess-
ment of thescaleor depth of agiven defect.Inthisinstance, anumberofsup-
portive methods were developed to facilitate the numeric interpretation of the
CCTV data (Duran et al., 2007; Sarshar et al., 2009; Hao et al., 2012; Rogers
et al., 2012), however the direct use of measuring defects geometry has not been
mentioned.