Production of two aluminum 420 kV transmission towers

Statnett is currently developing an aluminium 420 kV transmission line tower, with the design phase due to be finalized by the end of October 2018. Installation of two towers of this type are planned in Norway during the summer of 2019. These pilot towers will provide experience with the new tower design. If successful, the tower design will be available for general use in Statnetts transmission line projects, with demand in the range of 10 – 100 towers per year.
Description of tower manufacturing
The two aluminium towers will be appr. 30-35 m height. The geometry and beam profiles will resemble that of the prototype tower, constructed and tested in 2017, ref attachment 1. Despite the updates currently made to the tower geometry, the prototype design gives good insight into the general tower geometry and principles. These describe typical beam sizes, lengths and weights, in addition to weld and bolt hole details.
The tenderer is expected to take full responsibility for the manufacturing of the tower, including material quality, extrusion, cutting, bolt hole drilling, welding and transport.
General requirements
The tower shall be constructed with en-aw 6082 T6 material, with the exception of the footplate (SBP30401) which is made of en-aw 5083 H111. The weld filler material is of grade 5083. In general, the material specifications shall be in accordance with EN1999-1-1. Furthermore, the requirements in EN1090-3 shall be complied with.
The quality of galvanised bolts, nuts and washers shall be according to iso 898-1 cl. 8. 8 and iso 898-2 cl. 8, and shall be documented with Test Report Type 2. 2 in accordance with en 10204. Bolts, nuts and washers shall be galvanized according to iso 10684 (minimum coating thickness 40µm).
Attachments
1. Manufacturing drawings of prototype tower, constructed and tested in 2017