Jonel introduces world renowned Enerpac stressing technology

Enerpac stressing technology for infrastructure projects

Enerpac Stressing Technology

Some of the world’s most advanced precision stressing technology for construction, resources and infrastructure projects will become more widely available in New Zealand following the introduction by Jonel Hydraulics of specialist Enerpac ranges from Europe.

The stressing technology – used on some of Europe and Asia’s major projects – includes prestressing and constant tensioning technology as well as heavy lifting expertise that was used in the lifting of the Russian submarine Kursk.

Now part of the Enerpac family of extreme force technology and integrated solutions, it is produced at a specialist plant in Europe has been a leader in developing and manufacturing precision parts for prestressing and stressing systems for decades, often working with major concrete and pre-stressing companies  who manage major construction projects around the world.

The technology has been employed on projects such as: stay cable prestressing for windmills in Europe and Asia; pre-stressing on the Palm Island project in Dubai and on the Dubai Highway in the United Emirates; pre-stressing on the Roertunnel and at Schipol Airport in the Netherlands; bridge launching in Malaga, Spain and pre-stressing on a major Rhine bridge, Germany; and heavy lifting on the London Eye and of the Kursk.

Jonel Hydraulics recently introduced the first specialist 900-tonne hydraulic stressing cylinder from the range to be introduced to Australia or New Zealand, which includes cylinders in capacities from 110 to more than 1000 tonnes with stroke lengths typically from 150-300mm.

The rugged cylinder, supplied and customised by Jonel Hydraulics at its Auckland headquarters, will be used by Post Tensioning and Grouting Ltd to simultaneously tension dozens of high tensile stressing strands for bridge sections of the new $NZ250 million-plus Tauranga Harbour Bridge crossing.

Enerpac National Marketing Manager Tony Brooks said the integration of this advanced technology into the global Enerpac organisation following its acquisition last year meant that both Australia and New Zealand would  have expanded access to advanced technologies and nation-wide sales and service backup.

“Enerpac is already the global leader in extreme force technologies used by construction, infrastructure and resources companies, with a history of innovation in these sectors extending back more than 50 years in Australia and New Zealand. These specialist stressing technologies add to our inventory of innovation and are one of many advances flowing from our global resources and capabilities into the products and integrated solutions we provide throughout Australia and New Zealand,” he said.

The advanced stressing and lifting technologies involved offer advantages such as:M

  • Mass production of prefabricated segments, providing more quality control
  • Shorter construction times
  • Construction independent of climatic conditions
  • Structures can be fully loaded immediately after being prestressed
  • Prestressed cables can be inspected and replaced at all times
  • Superstructures can be raised without underlying infrastructure having to be stopped
  • Low weight due to thin bridge sections
  • Strengthening using pre-stressing possible at any time
  • Distortions of structures can be controlled better

The extreme force hydraulic cylinders of the type introduced by Jonels are manufactured at a specialist plant in Europe that has built a worldwide reputation for manufacturing stressing cylinders and heavy lifting technology.

The range of stressing cylinders are used in prestressing operations for the stressing of single and multi-strand systems. Many, including the 900 tonne jack, are equipped with hydraulic nose cones which, after the cylinder’s initial extension, push the locking wedges in place mechanically while the cylinder retracts then extends again to repeat the operation as many times as necessary for the job in hand.

Depending on the client requirements, multi-strand stressing heads of any configuration can be supplied. Stressing cylinders are tested for both safety and function and can be calibrated for the stressing load required.

Because of the widely differing requirements of different projects and customers, Enerpac stressing cylinders are typically customized to individual requirements, with adaptations in this case being undertaken in New Zealand by Jonel Hydraulics to save time and simplify setup.

Jonel Hydraulics Enerpac Product Manager says Jonels supplied and fitted inner guide tubes for the high tensile strand to pass through – “This shortens set up time by a considerable amount before the stress is applied. It means there is no need to manually line up the strand to the wedge head assemblies.

“We also modified the cylinder’s wedge plate and fixed it to the ram, which means everything is in place to make it quick and simply to perform the task.” An anti-rotational guide was also fitted which stops the ram from rotating during the extending process.  Jonel Hydraulics also supplied and fitted Enerpac high flow couplings and adaptors to suit the customer’s pump.

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