By David John Smith
The Rjukan-Notodden Industrial Heritage Site builds upon 97 associated objects that include power plants, factories, building, transportation lines and equipment, rail ferries and ports – and not in the least – technological industrial innovations.
The Vemork Penstock & Penstock Valve House is just one example:
Vemork Penstock & Penstock Valve House
Vemork Power Plant’s position on a plateau approximately 125 metres above the valley floor is quite unusual for a power plant. This was the result of a decision to utilise the total water’s fall in height of approximately 570 metres between Skarsfoss and Rjukan in first Vemork, and then Såheim.
This is where the placement of the Penstock and the Penstock Valve House became critical to success.
The power plants Hydro built in Vestfjorddalen before 1920 were engineered to fully utilize the fall of the Måna River from Møsvatn, and included a system of tunnels, adits and spillways. The Penstock Valve House and the Penstock were the final key element that ensured the water would be effectively brought down to Vemork.
Penstock Valve House
The Penstock Valve House was built using carved stone of the same type as Vemork. Automatic throttle valves supplied by I. M. Voith of Heidenheim in Germany were installed in a separate building, where the pipe dimension of ten pipes was reduced to 1,250 mm and the eleventh pipe to 1,600 mm.
The valves closed automatically if the water in the pipe increased beyond a set limit, but they could also be controlled manually or by using the instruments inside the station.
The 11th Pipe
Eleven pipelines comprise the Vemork Penstock, positioned above ground, each with a length of approximately 720 metres. The first ten are held together by riveted collars, with an external diameter of 1,450 mm, which is reduced to 1,250 mm down by the station.
Originally there were ten pipes planned, but hydrological surveys carried out during the construction of the plant suggested that the water flow was greater than first estimated.
An outlet for an eleventh water pipe was therefore installed in the distribution reservoir in preparation for a possible expansion of the plant. The eleventh pipe with a diameter of 2,000 mm was later welded along its whole length.
Engineering Feat
The final completion of Vemork and the penstock technology was an epic feat of technical engineering and logistics. A labour force of up to 600 was employed, supervised by engineers and foremen.
A separate railway track, the Vemork Line, had to be built across a mountainside that was prone to landslides in order to transport the pipelines and generators, each weighing 5,000 and 300 tonnes, respectively.
The pipelines have now been replaced by a pressure shaft for the new underground turbine generator hall, but they have not been removed.
Photos 2, 3 and 5 - Thanks to NIA Photos 1 and 4 - Ian Brodie