Pipe rehabilitation near St. Gallen using the TERRA-HYDROCRACK HC 625

Approximately 100 meters of pipeline replaced trenchlessly

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Outside of St. Gallen, the TERRA-HYDROCRACK HC 625 was used for the trenchless replacement of an existing pipeline. Over a stretch of approximately 100 meters, the old pipe was burst while a new 200 mm diameter HDPE pipe was pulled in simultaneously. The job site was located in a meadow. Instead of exposing the entire length of the existing line and digging a 100-meter trench, the existing pipe route was used for the new installation. Excavation pits were only required at the machine's location and at the opposite end of the stretch.

TERRA-HYDROCRACK HC 625 – 62.5 tons of pulling force

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The TERRA-HYDROCRACK HC 625 was used for the pipe replacement. This powerful rod-based pipe burster was specifically developed for demanding trenchless pipe rehabilitation tasks, combining high pulling power with a compact design. With a maximum pulling force of 62.5 tons, existing pipes made of ductile iron, lamellar cast iron, steel, vitrified clay, or plastic can be burst and replaced with new pipes. Depending on the application, new pipe diameters of up to 350 mm and rehabilitation lengths of up to 150 m are possible. With a 100-meter rehabilitation stretch, the site near St. Gallen provided ideal conditions to demonstrate the performance of the HC 625 in practice.

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Bursting and pipe installation in a single pass

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At the start of the bursting process, the threaded bursting rods were pushed through the existing pipeline to the opposite excavation pit. There, the bursting tool and the new HDPE pipe were connected to the rod string. The HC 625 then pulled the bursting rods back. As it did so, the bursting tool broke the existing pipe in a controlled manner and displaced the pipe fragments into the surrounding soil. Directly behind the bursting tool, the new 200 mm HDPE pipe was pulled into the existing pipe route. In this way, the 100 meters of pipeline were replaced using a trenchless method. Extensive earthworks along the entire route were not necessary.

Compact design for efficient site operations

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The HC 625 consists of a 2.30 m long carriage and a 2.45 m long front box. Together, they have a compact footprint of just 4.75 × 0.90 × 1.40 m. A special feature is the handling of the threaded bursting rods. During the pull-back, they are removed from the side of the machine rather than from behind, which allows the required excavation pit to be kept relatively short. The hot-dip galvanized front box and the front support plate ensure that the high pulling forces generated during the bursting process are safely transferred into the ground. At the same time, the design allows for the smooth installation of the new pipe through the front box.

100 meters with threaded bursting rods

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The HC 625's threaded bursting rods are 0.80 m long, 50 mm in diameter, and weigh approximately 11 kg each. With a minimum bending radius of 20 m, they can reliably follow the path of the existing pipeline. For a fast workflow, the rod magazine can be positioned directly on the machine. A fully loaded magazine holds 114 bursting rods, or approximately 91 m of rod length. Additional rods can be added for longer rehabilitation stretches. Especially over a 100-meter stretch, the easy handling of the rods contributes to an efficient and continuous workflow.

Pipe rehabilitation with minimal disruption

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The site near St. Gallen demonstrates the advantages of the static bursting method even outside of densely built-up areas. Instead of breaking up the meadow along the entire pipeline route for an open trench, earthworks were limited to just a few areas. Using the TERRA-HYDROCRACK HC 625, the 100-meter-long existing pipeline was burst and simultaneously replaced with a new 200 mm diameter HDPE pipe. High pulling force, compact dimensions, and easy rod handling make the HC 625 a powerful solution for the economical and trenchless replacement of existing pipelines.

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