RISP - Robot for the Internal Servicing of Pipes
Description
 RISP seals leaking joints from within an underground cast iron gas pipe.  |
Underground cast iron gas pipes contain joints that can develop leaks over time. A common repair procedure involves the injecting an anaerobic sealant into the jute packing of the joint. This requires an excavation at each joint to allow the utility to drill a hole through the joint, into the jute, and inject a measured quantity of sealant. Such a process is laborious and costly.
ESI has developed a novel technique to perform cast iron bell and spigot joint sealing from inside the pipe using a remotely controlled robot. The robot enters and travels along the interior of the pipe until a desired joint is reached, and then drills a hole into the joint spigot. The joint sealing is performed by injecting an anaerobic sealant into the jute packing of the joint, thus replicating the repair procedure currently done externally.
The new internal sealing system is capable of sealing several joints from a single excavation while keeping the main in service. The system has been designed for 15 cm (6 inch) diameter pipes. It can be inserted into the main for up to 45 metres (150 feet) in each direction, from the entry point. Since underground gas pipes contain joints at 12 foot intervals, up to 24 joints can be sealed from a single excavation. Adaptation of the system to other pipe diameters, both smaller and larger, is currently underway.
The joint sealing system consists of a miniature robotic working head equipped with a video camera for joint identification. It also contains an umbilical cable, cable insertion units, a system storage reel with the tool control components, and an operator's station, which includes a control panel and video monitor. In operation, the robot head is inserted into the main through a small tap, and pushed along the pipe with its umbilical cable. The operator visually locates the joint and positions the robot at the joint. The robot head is then raised into position and a small hole is drilled through the spigot into the joint cavity. The sealant head is then rotated into position and a measured amount of sealant is injected into the joint. The unit can then be moved to the next joint.
Extensive field tests have been conducted in two major cities in North America in order to evaluate the prototype and prepare specifications for the production version of the system. The development is funded by Consumers Gas of Toronto and Consolidated Edison Company of New York. A patent has been granted and applications have been made for further patents.
Features
- Operation does not require interruption of gas supply
- Robotic tool head is inserted through a small tap using a custom designed saddle
- Semi-rigid umbilical cable is used to push and control the tool head position
- Umbilical cable is stored on a custom designed reel
- Miniature video camera mounted on the tool head is used to locate each joint for sealing
- Operator's station is provided including control panel and video monitor
- Remote control of the tool head for drilling and sealant injection is provided
- System can seal joints up to 45 metres (150 feet), in each direction, from the entry point (24 joints)
- Current system has been designed for 15 cm (6 inches) diameter pipes
- Adaptation to other pipe diameters, both smaller and larger, is currently underway.