Insert – Weld – Tight: Faster Installation with Smart Connect
With its Smart Connect System, egeplast developed a joining technology which fulfills both the requirements of any kind of installation method as well as the technical specifications related to the laying of underground cables. After all, in order to meet the full range of requirements associated with cable protection systems used in the context of laying underground cables in an extra-high voltage range of up to 525 kV, the point is not only to select the right kind of pipe and pipe material, but also to chose a pipe connection which is optimally suited for the installation method of choice.
The driving force behind the development of the Smart Connect System was that, in recent years, many customers tackling projects involving underground cables kept inquiring about one single connection system which would be suitable for any installation method. Previously, in this segment of opentrench installation, systems with socket joints were used for straight stretches, whereas for bends, it was either electrofusion sockets or pipe connections were established by means of butt-welding.
1. Installation applying the ploughing method
The ploughing method primarily involves bending loads related to both the pipe and the connection system. To increase pipe stability, a meandering arrangement of the weld wire was developed for the Smart Connect joint to ensure that it would meet the special demands associated with alternative installation methods. Multiple ploughing tests on the test site of Frank Föckersperger’s in Aurachtal proved that this kind of connection technology stands the test in practice.
Frank Föckersperger (Managing Director) commented: “In the context of our research project, we have been able to develop a multi plough for ploughing in extra-high voltage power lines equipped with plough shafts designed to handle the pipe strings very delicately during insertion and thus help to preserve the quality of the pipe connections. Thanks to the rapid setting up of pipe strands without any bulging sockets and inside or outside weld beads which can be achieved using Smart Connect, the system has stood the test for pipe laying based on the ploughing method under field conditions, as confirmed by the results of various tests on Smart Connect connection following installation”
2. Installation applying the trenchbox method
On the Wahle-Mecklar route, the Smart Connect connection was successfully installed for pipe dimensions measuring d 250 mm SDR 17 in a particular segment where the trenchbox method was applied. It involves an excavator preparing a pipe trench as wide as the box and gradually pulling the box behind it. Three strands of cable protection pipes are guided laterally past the excavator and then inserted into the box via deflection rollers. For this installation method, too, it is primarily bending stress which can be expected to occur.
Stefan Kürzinger, foreman at Max Bögl, explained: “In the context of welding prefabricated pipe strings using hot-plate butt-welding, the inside weld bead cannot be removed afterwards. In the area of a road crossing, the Smart Connect system was used successfully to generate weld connections with flush transitions both inside the pipe as well as on the outer pipe walls, thus ensuring smooth insertion of the pipes into the trenchbox, followed by unobstructed pulling in of the power cables. Furthermore, fabricated meter sections allow for easy repair of defective spots in prefabricated strands when applying the Smart Connect system”.
3. Installation using the horizontal drilling method (HDD)
On the Ganderkesee route, the Smart Connect connection was the option of choice for a d 280 SDR 17 diameter pipe to be laid with the help of the HDD method. This procedure mainly involves tensile and to some degree bending loads which impact the pipe connection. In cooperation with the construction company, Bohlen & Doyen, Matthäi and Beermann, twelve pipes (totaling 432 m) were successfully installed as a road crossing in a 36-m route segment applying the HDD procedure. To assess the quality of the weld connection, Smart Connection connections were placed at the front ends of each of two pipe strands, to then be removed and subjected to a comprehensive QA test following installation of the pipe. For this kind of laying, too, Smart Connect was found to fulfill all related requirements.
As Philipp Oliv, the Project Manager of Landkabelbau & Bohrtechnik, commented: “Under certain conditions, pipe connections via Smart Connect can significantly reduce the time required to establish pipe strands applying the HDD method compared to hot-plate butt welding, resulting in a tangible reduction of the construction time and thus offering great potential”.
4. Open-trench installation
For open-trench installation along straight stretches without any changes of direction, modified double sockets featuring a large insertion-depth are the preferred option. Around bend areas, welding the pipes is inevitable. At BV Legden-Asbeck, Smart Connect was used for a pipe dimension of d 250 mm SDR 17 in the area of a road crossing.
As Niklas Nelsen, the Construction Manager of Rohrbau ARGE Schutzrohranlage Legden Asbeck, explains: “Utilising Smart Connect enables us to connect the pipes much faster compared to electrofusion welding with electrofusion sockets, since it does not require any machining of the surface, which in turn enables us to significantly reduce the overall construction time”.
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