Robotic systems play a significant part in trenchless technology construction. Not only are they used for surveying and monitoring, but also for localised repairs. The robots are inserted into the pipeline and remotely controlled by an operator on the surface. Essentially the robots comprise a wheeled motorised tractor/crawler, onboard lighting, CCTV camera, and a hydraulically, electrically or compressed-air driven rotating motor on an articulating arm that does the work.
Sealing Fractures and Holes
Epoxy resin or mortar is typically used for providing this type of structural repair in a localized defect. To accomplish the repair, a robot or sealing device is positioned at the repair site. The resin or mortar is inserted into the defect by injection, troweling or a combination. The intention is to allow the repair material to extend through the defect and lock in place on the outside of the pipe or joint. In some cases, this will require grinding or drilling out the defect before the grout is inserted and, in badly damaged joints or sections, some interior forming device is required to recreate the interior surface profile.
Opening Lined Laterals
Pipelines that have been rehabilitated by inserting a Cured-in-Place Pipe (CIPP) liner typically need for the existing lateral pipe connections to be re-opened. This is achieved by using a robot with a grinding head that cuts through the liner into the cavity and opens up the hole to the shape of the lateral and re-establish the flow. Usually, the locations of the laterals can be seen by dimples that form in the pressurised liner.
Grinding / Cutting Obstructions
Sometimes obstructions in pipelines cannot be removed by cleaning equipment from manholes (tools on rods, jets on hoses, buckets on cables). These obstructions can be concrete that has set in the pipe, protruding lateral pipes, heavy objects, objects that are jammed, mineral deposits, scaling, roots or structural defects. These can be tackled using robots fitted with mechanical grinding or cutting heads. They may take time but will get the job done.
High Pressure Water Jetting
This uses specialised robots with high pressure (over 500 bar), low volume water jets to break or cut obstructions up. They are suitable for removing roots, root balls, grease, fat, concrete, scaling, hardened calcium deposits, without damaging the pipe.
Object Removal
Loose larger objects found in pipes and other loose material from robotic operations, can be removed by a robotic gripper, that can grip the object and pull it down the pipeline to a manhole for retrieval.