Offshore Lifting Company Carves Tracks In Canadian Ski Field

The equipment sold by Australian company Tensa Equipment is usually seen in the high wind, wild sea conditions of offshore oil and gas fields such as the North Sea or Bass Strait. So it was something of a surprise to Tensa management to get a tender request from engineers hundreds of miles from any ocean - the Canadian ski fields.

Tensa’s Dynamic Load Reducers (DLR) are usually used in offshore lifting operations to reduce the sometimes catastrophic loads on cranes when operating in adverse sea conditions. The DLR can also be used in other crane applications such as pile driving.

It was the similarities between the wild offshore seas and the turbulent conditions around the turbine outlet of the Brilliant Dam hydroelectric facility in British Columbia, Canada (right) that led the Columbia Power Corporation (CPC) engineers to talk to Tensa.

The vast volumes of water from the melting snowfields that feed the Kootenay River near Castlegar, British Columbia, often generate waves up to three metres in the spillway near the turbine outlet of the plant. This was potentially dangerous for the CPC crane and its operator so the Canadian powerco turned to the offshore sector and its many years of dealing with dynamic loads in adverse conditions. Thus it found Tensa and its range of Dynamic Load Reducers.

After making some customisations for its proposed new terrestrial application, Tensa was subsequently successful against international competition in supplying a DLR to Columbia Power Corp for the Kootenay River plant to reduce the dynamic loads on its crane, particularly when operating around the turbine outlet.

Tensa owner Derick Markwell said: “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.”

Technical Notes
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.

Design is in accordance with American Petroleum Institute spec 2C Specification for Offshore Cranes as well as other relevant 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 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 which allows it to absorb more energy.

Tensa is a Perth-based company that provides tensioning, gripping, lifting, heave compensation and motion monitoring products primarily for the offshore oil and gas and drilling industry.