Tschar power station Lot A2; pressure pipeline

Project description:

An expansion and optimisation project comprising the renovation of the Tavanasa-Obersaxen power station, which had been in operation since 1946, while increasing the flow rate and expanding the plant by adding an additional uphill barrage. Kelag Systems AG was commissioned by ARGE KW Tschar c/o Prader AG to deliver and assemble the steel pressure pipeline for Lot A2.

Scope of work:

  • Engineering, delivery and assembly of the steel pressure pipeline
  • Engineering, delivery and assembly of cable ducts DN 150/50
  • 5 x expansion DN 1100 PN 28.5, executed as access pipe
  • 1 x expansion DN 1050 PN 32, executed as access pipe
  • 4 x manhole DN 800 PN 16 to PN 46
  • 32 x pipe support DN 1100

Technical data:

Steel pressure pipeline:320 m elevated assembly
Steel pressure pipeline:280 m buried assembly
Incline:Up to 100 %
Diameter:DN 1100/1050
Wall thicknesses:10 mm to 24 mm
Pressure:Max. 58 bar
Weight:255 tons
Material:P355 ML2

Buried corrosion protection: Exterior PE with fibre cement encasing, interior 2-component epoxy coating


  • 100 % UT, longitudinal and round seams (in-house)
  • 100 % MT, longitudinal and round seams (in-house)
  • 100 % RT, crossings (in-house)
  • 100 % UT, round seams (on-site)
  • 100 % MT, round seams (on-site)
  • Pressure test

Special construction conditions:

  • Assembly in very steep mountainous terrain
  • Pipe assembly with cable crane and helicopter
  • Construction year(s) 2016–2017
  • Owner Kraftwerk Tschar AG/ARGE KW Tschar c/o Prader AG