Closed circuit television (CCTV) inspections have become the standard method for inspecting the condition of the inside of underground pipe infrastructure, providing information about their condition and areas where deterioration and damage require pipes be repaired, rehabilitated or replaced. CCTV inspections also verify repairs are properly made and that new pipe has been correctly installed.
Recently, laser profiling technology is adding new dimensions to the inspection process and its potential caused a buzz at the most recent NASSCO (National Association of Sewer Service Companies) convention earlier this year.
Laser technology does not replace conventional CCTV inspections, but complements them, providing valuable data previously unavailable to system owners and project engineers.
“The technology can be used independently or in conjunction with CCTV inspection equipment,” says Gerry Muenchmeyer, P.E., Muenchmeyer Associates, and technical director of NASSCO.
Laser profiling usually is done by a separate piece of equipment that is attached to the inspection train as it is pulled through the pipe line.
“Whereas CCTV will provide a picture of the condition of the existing pipe,” Muenchmeyer continues, “the laser will provide a profile measurement of the existing pipe. Pipe defects such as partially collapsed or distorted pipe are very difficult to determine through a CCTV inspection, and the laser profile will provide detailed documentation of the pipe profile along the entire length of the pipe. This information can then be viewed in a strip profile format to determine the most badly deteriorated sections of the pipe. The engineer can use this information to design a renewal pipe that meets the exact requirements to restructure the old pipe.”
Muenchmeyer says with typical CCTV inspections, the old pipe is visually inspected and a best guess of the pipe distortion then is made by the engineer. For pipe rehabilitation, new liner pipe is designed based on this information. A laser profile will provide more detailed information about the host pipe’s circumferential profile allowing for a more accurate pipe liner design by the engineer. After the renewal pipe is installed, the laser profiler will then document the condition of the new pipe as it relates to the existing host pipe.
“State departments of transportation use laser profiling to inspect the installation of new culverts under highways,” Muenchmeyer continued. “For flexible plastic pipes, they measure the profile of the installed pipe to determine the amount of deflection in the new pipe and whether or not it meets the design criteria specified in the contract documents. For the installation of rigid concrete pipe the laser profiler can measure the width of a crack in the newly installed pipe to determine if it is within the allowable range as specified.”
Several companies are involved in the development of laser profiling for a variety of applications and some profiling systems are in use for profiling utility pipelines.
The July 2007 issue of Underground Construction published a First Look feature about the CoolVision laser profiling system.
The CoolVision profiler is mounted on four stainless steel wheels and can either be pulled behind a conventional pan and tilt CCTV camera to take profile and video surveys simultaneously or pulled through pipe independent of the camera system. With two distance encoders and sophisticated telemetry system, it is not necessary for the CoolVision unit to be centered in the pipe. Survey data are transmitted to a survey ground station by coaxial cable. CoolVision laser profilers are manufactured and distributed in the U.S. by Aries Industries and RS Technical.
Botts Consulting Group is the exclusive CoolVision consultant in the United States.
Aries manufactures and supports a variety of video inspection and rehabilitation products and is a major supplier of standard and custom built television inspection, grout and cutter equipment for internal inspection of sewer, gas and water pipelines and its laser profiling equipment is used in CoolVision systems.
CUES is a leading manufacturer of CCTV pipeline and inspection equipment and asset management software. The CUES laser profiler is a stand alone, snap on tool for use with the company’s CCTV survey system to collect survey data and create pipeline reports containing the measurement of faults and other features inside the pipeline. This includes measurements of pipe size, laterals, water levels and other features, as well as automatic analysis of pipe ovality and capacity up to 30 times per second. The Laser Profiler simply attaches to the existing CCTV Camera and the resulting CCTV images are analyzed using innovative machine vision software.
RedZone Robotics provides multi sensor inspection services delivering a 3D digital representation of pipes and is a leader in developing laser profiling technology. RedZone says that CCTV and laser complement one another – CCTV detects defects the laser is likely to miss, and laser picks up the defects that CCTV operators can’t detect or directly measure. Lasers also can be used to verify defects observed via CCTV and provide specific physical information on the size and shape of those defects. The net result is an inspection that provides a more accurate and comprehensive description of a pipe, which greatly increases the chances of discovering all defects.
RS Technical Services (RST)
RST is an established provider of CCTV pipeline inspection systems. Its laser profiling equipment is used in CoolVision systems and is capable of profiling pipe in diameters from 6 to 48 inches and can profile pipes that contain as much as 45 percent water. It has fixed optical and laser triangulation for +/ 0.25 percent accuracy with 99.9 percent repeatability for inspection comparison. The profiler takes 60,000 measurements per second of 2,000 radial measurement points. Data is analyzed and reports generated by the professional data analysis center.
“Laser profiling,” concludes Muenchmeyer, “appears to be a tool that has significant room for growth in the future. The major impediment at this time for the use of laser profiling, appears to be cost. As engineers begin to understand the value associated with laser profiling its use will increase significantly.”
FOR MORE INFORMATION:
CoolVision, Botts Consulting Group, (888) 747-3397, firstname.lastname@example.org
Aries Industries, (800) 234-7205, www.ariesindustries.com
RS Technical Services, (707) 778-1974, www.rstechserv.com
RedZone Robotics, (412) 476-8980, www.redzone.com
CUES, (800) 327-7791, www.cuesinc.com