Project Report Bayernwerk: Operation under High Pressure

To increase capacity in its high-pressure network, Bayernwerk Netz GmbH used the HexelOne® SLM gas pipe. The new high-pressure pipeline transports gas with a pressure rating of 16 bar. By using trenchless technologies, civil engineering costs were kept low and interventions in the landscape were reduced to a minimum.

High-pressure transmission pipeline with a pressure rating of 16 bar – HexelOne® SLM

As part of this construction project, various companies were also integrated into the existing gas network, including a mega-greenhouse. In the high-pressure transmission pipeline, gas will be transported to consumers with a pressure rating of 16 bar in the future. Due to the required operating pressures, the HexelOne® SLM gas pipe with dimensions 160 x 14.6 mm was chosen. The routing of the pipeline and the local conditions required the use of various laying technologies. By using trenchless technologies as needed, the construction time could also be significantly reduced compared to open trench installation. Peter Hößl from Bayernwerk Netz GmbH: “By using the HexelOne® system, we were able to reduce the total costs of the construction project and halve the construction time compared to using other materials.” Karl Krumpholz Rohrbau GmbH was commissioned with the overall civil engineering and pipeline construction work. The plowing and milling work was awarded to selected subcontractors.

Preißinger Bau GmbH & Co. KG laid approximately 2,100 m of pipeline using the plowing method, with a daily output of about 1,000 m. Fräsen Schmid GmbH from Neumarkt took over the milling of 5,500 m of pipe material. The route passed through quite challenging terrain along roads and through wooded and stony areas. 600 m were laid using the horizontal directional drilling method by Richter-Bau GmbH & Co. KG from Altenkunstadt. The remaining part of the total approx. 9,000 m of HexelOne® SLM pipeline was laid using open trench installation. The earthworks and laying work were carried out by Krumpholz GmbH from Kronach.

Short construction time due to long coils

Due to the long delivery lengths—coils of 100 m each—the number of connection points was immensely reduced compared to other materials (approx. 100 connections compared to more than 750 necessary connections for steel). The permissible connection technologies for HexelOne® SLM pipes include welding using combination welding and connection using press fittings. On the long sections laid using plowing, milling, or horizontal directional drilling methods, combination welding, a combination of butt and electrofusion welding, was primarily used. Press fittings were used in the entry and exit pits of the horizontal directional drilling measures to connect the individually flushed pipe strings. The construction project was intensively supervised by egeplast’s technical field service throughout the entire construction period. The pipeline was successfully put into operation in September 2020 after a five-month construction period, to the satisfaction of all involved. Meanwhile, Bayernwerk has carried out over half a dozen construction projects with over 30 km of HexelOne® SLM high-pressure pipe system.