Columbia Power uses offshore dynamic load reducer to protect dam

Tensa, an Australian company, usually works in the high wind, wild sea conditions of offshore oil and gas fields such as the North Sea or Bass Strait.

The similarities between the wild offshore seas and the turbulent conditions around the turbine outlet of the Brilliant Dam hydroelectric facility in Canada led the Columbia Power Corporation (CPC) engineers to involve Tensa in this project.

The large amount of water from the melting snowfields that feed the Kootenay River near Castlegar, British Columbia, often generates waves up to 3m in the spillway near the turbine outlet of the plant. This was potentially dangerous for the CPC crane and its operators so the Canadian power company turned to the offshore sector and its many years of dealing with dynamic loads in adverse conditions.

After making some customisations for its proposed new terrestrial application, Tensa was able to beat the competition in supplying this DLR to Columbia Power Corporation.

The dynamic load reducer is a damped air spring with spring rate, energy absorption and damping tailored to absorb the energy from a moving load and bring it gracefully to rest with minimal recoil. With the DLR, the dynamic load factor for boat lifts can be significantly reduced, allowing the crane capacity to be increased by up to 50% depending on the sea state and load. The capacity increase is determined once the specific crane design and operating parameters, load and sea state have been calculated.

In compliance with American Petroleum Institute spec 2C Specification for Offshore Cranes, API and AS codes covering the mechanical construction, the design has been certified by Lloyds Register.

The Tensa DLR series are modular and can be adapted quickly to different strokes and operating conditions. Two units can also be used in parallel to double the capacity. Additional accumulators can be added to further improve the operating performance for extreme conditions.

The DLR60L has extra energy absorption needed for demanding applications such as piling operations. This is achieved by increasing the length and stroke, allowing to absorb more energy.

Derick Markwell, managing director at Tensa, says: "Our DLRs are accepted as being extremely robust, competent and reliable pieces of equipment for working in harsh environments.

"It was Tensa's ability to provide a customised version of one of its standard products and our ability to quickly do a numerical analysis to simulate the loadings and the performance of our equipment that won us this job in its unusual surroundings."