Page 81 - Reliability and Maintainability of In service Pipelines

70 Reliability and Maintainability of In-Service Pipelines

TABLE 2.1 Comparison of Pipe Inspection Techniques
Method Description Advantages Disadvantages
CCTV Uses hard wire push systems Visual provision of Survey and review
and crawlers/tractors to pipe condition process is time-
drive the camera through Effective in dry test or consuming
sewer pipe. Inspection is with low flow Picture quality affects
based on operator decision Compatible with operator’s decision (is
or complex software autonomous fault subject to illumination,
detection systems humidity, etc.)
Intelligent fault Quantifying the defect
detection reduces size is a big challange
inspection time Tractor mobility is
Fault detection constrained by
software reduces time sediment, debris, hard
spent on pipe compacted solids, and
condition review and high flow levels
demonstrates Requires development
consistency between to operate in live pipes
image quality and in- Defect classification
pipe visibility relies on operator
All types of known competency
and new defects can Defect
be detected misidentification by
operator is high
High cost of supporting
software
Laser An external laser beam Easily incorporated Depends on sharp
scanning projector is placed on top of into existing CCTV images of projected
CCTV equipment. Special systems laser ring
software is required to Automated defect Depends on CCTV
interpret the data classification crawler smooth
algorithm mobility
Estimation of pipe wall ANN technique
roughness/loss requires defect
Cracks, pipe joints, signature database
and sedimentation can High cost of camera
be detected and laser
Image automate High cost of
processing using ANN comprehensive
technique software
Single inspection run Time-consuming
360 scanning angle survey

Ultrasonic Based on propagation delay Ability to inspect long High cost of the
intelligent time of acoustic wave distances in short time instrument
pigging emitted by ultrasonic Very high and Data storage problem
transducers accurate resolution
images
(Continued )