The repair method of trenchless pipe replacement includes air sourcing, chemical stabilization, flushing, jetting, joint sealing and testing, patch repair systems, pigging, pointing, pressure scraping, resin injection and robotic systems.
Air sourcing is a cleaning method that uses compressed air, blown into a flowing stream of water to remove loose pipe deposits and small animals and improve water quality.
Chemical stabilization is the renovation of a pipeline and ancillary features by sealing, between two access points by the chemical reaction of added compounds to the surrounding ground.
Flushing is a method for cleaning water mains by allowing a high flow of water through a pipeline to improve water quality.
Jetting is a method for cleaning water mains using pressurised water directed onto the inside of the pipeline to remove deposits including encrustation, corrosion deposits and damaged or faulty linings.
JOINT SEALING AND TESTING
This method is used to test and seal defective pipe joints with a grout using a packer which combines the functions of leak testing and grout injection.
PATCH REPAIR SYSTEMS
This is a localised pipe repair system that involves positioning a short sleeve of resin-impregnated material within the host pipe and curing it.
Pigging is an aggressive cleaning technique which involves passing abrasive pigs through a pipeline along with a jet of water and ensures maximum removal of encrustation.
Pointing and chemical grouting of joints is a repair method to prevent infiltration and exfiltration through joints or deteriorated mortar in brick sewers that are structurally intact but suffer infiltration.
Pressure scraping is a technique which uses a cylindrical scraper unit, driven through the pipeline to remove deposits and encrustation.
Resin Injection is the localised repair of pipes by injection of a resin formulation such as epoxy resin or mortar into defects and the subsequent curing to prevent leakage and further deterioration.
Robotic systems for gravity pipelines comprise of grinding and filler robots that remove encrustation and intrusions and mill out cracks to provide a good surface and key for the repair materials.
PIPE AND CABLE PLOW SYSTEMS
Pipe and cable plow systems include: pipe and cable plow and the rocket plow.
The plowing technique is especially suitable for sparsely populated rural areas where long pipelines with few connections are required. Up to now only pressure lines are installed with this technique. Due to the plow design and its universally adjustable extensions, even small, flat waters can be crossed and pipes can easily be installed in embankments. Applying the plowing technique to install pipes below ground water level has proved to be very economic and environmentally friendly. The terrain should not be fortified and should be free of larger obstacles. Prior to the installation the exact position of crossing lines and the prevailing soil conditions have to be investigated.
PIPE AND CABLE PLOW
An all terrain traction unit (Unimog or tracked vehicle) pulls the plow by aid of a cable winch. Bumpy terrains are levelled by universally adjustable extensions and hydraulically adjustable rubber tyres. At the starting point of the bore path the plow lamella is placed in the starting pit at a level with the installation depth. Being pulled by the rope, the plow lamella displaces the soil in the pipeline zone, settling the ditch bottom with its own high weight. That way a hollow space for installing the pipe is created. By means of an automatic sanding cart attached to the plow, the hollow space can be filled with sand. Then the pipe is installed on the bottom of the ditch at the desired depth free of any mechanical stress. The pipe and cable plow installs PE and PE-X pipes up to OD 255 mm.
When using the rocket plow, the installation box is exchanged for a displacement and extending piece. The rocket plow installs PE and PE-X pipes up to OD 335 and ductile cast iron pipes up to ND 250. The pipe is attached directly to the displacement and extending piece and pulled into the hollow space the piece has created. Additional protection pipes, cables and trace bands can be pulled in simultaneously. A bentonite mix can be applied to fill the annulus around the pipe and to minimize the friction. Monitoring the pulling forces affecting the pipe string is possible as well.