Sonar surveying enables survey of pipes that are partially full of liquid. Sonar surveys below the surface of the liquid and provides data of the profile of the pipe invert. This may show siltation and pipe defects that cannot be detected by CCTV.
Sonar surveying is utilised for inspection of pipes and ducts that cannot be entered by man-entry means either because they are too small or for safety reasons.
Systems are available for use on crawler-mounted CCTV systems or floated survey carriages from diameters into which the survey system will fit up to man-entry sizes and can be used over almost any length, this being dependant on the length and capacity of the umbilical cable to carry image data and the camera system to pull the cable through the inspected pipeline.
The pipeline should be as clean as possible but not necessarily totally clean as the sonar will detect siltation but this may obscure defects in the pipe invert.
Sonar system may be used independently or more usually in association with a CCTV survey system with the CCTV imaging the pipeline above any product flow level and the sonar imaging the condition of the pipeline below the product level and any silt in the invert.
Engineers w sonar survey data can to view the inner (usually invert) surface of a pipeline without the need for the pipe to be completely empty.
Data and images from currently available systems can often be accessed via the internet or Wi-Fi from almost any location enabling survey data to be viewed almost immediately after a survey is completed. This enables immediate responses to be made if any pipeline shows such serious defects that such a response is necessary.
Technology Description – what it is
Sonar survey methods may be used in a wide range of pipeline inspection circumstances, including pressure pipes as well as gravity sewer surveys and is particularly applicable in pipes where total cleaning or emptying is just not possible due to access or operational limitations.
Usually crawler-mounted or floatation system mounted along with a CCTV survey system, the sonar survey sends a sound wave from the sonar transducer through the coupling medium of the liquid in the pipe to the pipe wall. The reflection time of this sound wave indicates the distance of the pipe wall from the transducer. If the pipe wall is undamaged the reflected sound will show no discrepancy between the expected and recorded reflection time. Where displacement is found in the pipe wall at a crack or similar defect the sound reflected will arrive at the receiver at different than expected times and the image profile will show this as a deformation in the image created by the sonar software. This allows defects to be highlighted that cannot be viewed with a visual CCTV system.
Advances in Internet connectivity and Wi-Fi availability also enable survey results to be delivered directly to a client’s cloud storage facility or its own web-based storage platform for retrieval and immediate assessment should the survey highlight the need for such attention.
Specially designed software facilitates this recording (including images, defect assessment, distance down the survey line and notation process) as well as offering immediate access to survey results to the client software.
TISCIT (Totally Integrated Sonar and CCTV Inspection Technique)
TISCIT (Totally Integrated Sonar and Camera Inspection Technique) technology utilises sonar and CCTV technologies together to create a unique and valuable inspection.
TISCIT technology combines CCTV with sonar imaging to provide a comprehensive inspection of large diameter pipes. This dual sensor system allows the operator to inspect a pipe regardless of flow conditions as well as without removing sediments from the pipe invert. CCTV operates above the water level and sonar sensors below it. A Laser Profiler may also be included for the above-water level survey in some systems.
From low flow to surcharged, remotely controlled cameras capture video and pictures of internal pipe conditions while the sonar provides information below the water surface including the majority of structural defects and construction features detected by the CCTV above the surface. Sediment accumulation and locations of lateral connections are also detected. In some cases it may be possible to detect root intrusion, infiltration & inflow, and protruding lateral connections
The sonar sediment report provides graphs of the results of the TISCIT inspection, indicating the exact amount and location of deposits in a pipeline. This enables calculation of the amount of capacity that potentially may be reclaimed by cleaning the pipeline.