Since January of this year, the network company of Osnabrücker Stadtwerke AG, as SWO-Netz GmbH, has been renewing the wastewater and stormwater sewers in Scharnhorststraße. The old pipelines date back to 1915 and were correspondingly deteriorated. Furthermore, the dimension of the storm sewer was no longer sufficient for a planned change of the gradient in the storm water. Construction time for the overall measure (sewer construction, new installation of gas, water and electricity lines and subsequent road reconstruction) is planned until March 2018.
A special feature of this measure is its location directly in front of the VFL stadium in Osnabrück. In close cooperation with the security experts from the VFL and the police, the security requirements of the construction site were also adapted to the requirements in order to protect the fans from the construction site and the construction site from the fans during the construction work.
Due to age and corresponding damage, the existing pipelines could not be rehabilitated in a closed construction method. At present, the main sewers (DN 200 to DN 800) are being completely renewed in order to meet the required technical demands, both in hydraulic and structural terms. The original pipe material of the wastewater sewers was stoneware DN 200. The storm sewers were made of concrete DN 250 to DN 400. Due to the large number of damaged areas found and the need for protection against root ingrowth and long-term stability of the entire pipelines, only a welded plastic pipe system was considered for the drainage of the wastewater. For several years, SWO Netz GmbH has favored PE pipes for wastewater sewers because of their impermeability, explains Daniela Fiege, head of the sewer construction department at SWO Netz GmbH. In the storm sewers, concrete/reinforced concrete pipes will continue to be used for economic and technical reasons.
The house connection pipes in the protection water channel are usually also welded PE pipes and for the rainwater house connection SWO Netz GmbH relies on PP pipes (KG2000).
Due to the high groundwater level, SWO Netz GmbH decided to also weld the PP pipes (KG 2000) for the stormwater pipes. From the BI UmweltBau No. 5 from October 2014 we could learn that there is a possibility to simply shit PP pipes (KG 2000) if necessary. We contacted the SABUG company and arranged a demonstration appointment. The simple method convinced us and the foreman on the construction site at the time, and so we quickly integrated the system (IP-plus welding system from SABUG) into a construction project, continues Daniela Fiege.
In addition to the technically high-quality solution, the IP-plus welding system reduces the cost of pipe construction compared to conventional welding solutions. It can also shorten the construction time due to quick and easy installation of the welding rings.
When using this welding system, the rubber sealing ring is simply removed from the pipe bead and replaced by the welding ring. Modification of the existing pipe system is not necessary. TheIP-Pluswelding ring is preformed for easy insertion and individually welded in. It can be inserted into the bead of the tube without force.
The operation of the IP-plus welding system differs from the systems of conventional heating coil welding sleeves. Due to the design of this welding system, the joining pressure required for welding is generated during the welding process itself. The basis of the welding system is a torus made of modified PP, to which a heating wire is applied thermally. When the temperature is increased, the torus heats up and thus sets itself up, causing the two tube partners to weld together and even tolerances in the millimeter range can be reliably compensated. The PP material surrounding the torus, serves as a welding filler. The multi-voltage welding process offers the possibility to model the temperature and the added power during the welding process to obtain a perfect welding result. Removal of the oxide layer is not necessary with this system, as it is safely destroyed by the “setting up” of the welding ring. Only cleaning with PE/PP cleaner is necessary. This was proven, among other things, by the peeling tests at the MPFA-Leipzig. The individual packaging also guarantees high quality of the delivered IP-Plus welding rings.
By using a bar code, the required welding parameters are read into the device and processed accordingly. In conventional welding processes in the field of plastic filament welding, the voltage is kept constant during the welding process. In the multi-voltage welding process, this is changed in a defined way. Quality assurance and welder training are set high for this system. As with PE-HD heated spiral butt welding, a high standard of quality and cleanliness is essential on the construction site, when processing the components. For this reason, the specific training of welders for the IP-Plus welding system is desirable and necessary.
Corresponding seminars are offered by the company SABUG GmbH. This involves theoretical and practical training in the use of the IP-plus welding system. All proofs of the functionality of the IP-plus welding system were, of course, verified in advance by corresponding expert reports. Furthermore, the entire system is protected by the German Institute for Building Technology (DIBt) approved for use in wastewater pipes. Approval : Z-42-5-553.
Initial experience from the current construction site promises a functional and safe system for welding PP sewer pipes from a wide range of manufacturers. Based on the positive experience, SWO Netz GmbH will probably also consider this system for sewer construction measures in the future.