Advanced precision bolting technologies from Outotec

Outotec’s use of Enerpac hydraulic torque wrenches and pumps, in combination with Boltstress ultrasonic technology, mean each bolt can be fastened in just a couple of minutes to the exact required tension, saving time and ensuring precision across the hundreds of bolts required on a construction project.
Peter Nilsson, global installation manager - grinding at Outotec in Australia, said that the technique was employed when assembling the critical load-bearing frames. The bolts varied in size from 30-60 mm diameter, with up to 1000 bolts being tightened to the correct tension in each mill.
Outotec’s SAG (Semi-Autogenous Grinding) and ball mills - grinding mills that tumble large ore rocks, sometimes in association with steel balls - are part of the metal extraction process for minerals that include gold, copper, platinum, lead, silver, zinc, alumina and nickel.
“Installations can be undertaken anywhere around the world, for a wide variety of safety conscious clients. A recent construction project was at a mine in Bolivia,” said Nilsson.
Outotec can either construct and install the mills for clients, or alternatively supply the technology and training and work in partnership with clients to complete the installation.
Outotec had employed Boltstress bolt testing for about two years before being able to further enhance the precision bolting task by teaming it with the Enerpac ZU4208TE-Q pump and W-Series torque wrenches and socket accessories.
W-Series low profile hexagonal wrenches, weighing just 1.4-5 kg, have precisely repeatable torque from 2712 to 20337 Nm. Coupled with the high-speed ZU4208TE-Q pump, they are used to ensure correct power, precision and repeatability in loosening and tightening nuts.
The ZU4 Pro Torque wrench pumps, engineered for high duty cycles, incorporate the latest Firmware 7.0 programming that cuts out an entire step in the bolting process by enabling users to directly display torque in foot-pounds or Newton metres instead of having to convert them from conventional pressure output readings.
The pumps supplied to Outotec were engineered for optimum compatibility with Boltstress’ ultrasonic bolt tension measurement for safety and reliability.
Nilsson said that the combined Boltstress and Enerpac technology saved time and gave precision to the bolting operation.
“We were one of the first to adopt the Boltstress-Enerpac combination. The advantage of the technique is that our engineers can pre-set all the parameters – the information that needs to go to the tools. The actual bolting job can then be done by a trained operator who doesn’t have to worry about setting up the correct data properties,” he said.
The Boltstress G5 bolt loading tool employs ultrasonic measurement of bolt stretch to ensure the correct pre-load is applied, safeguarding joint integrity and preventing bolted joint failure. Ultrasonic bolt tension measurement assesses true joint performance by using real (not assumed) data. It is designed to eliminate costly downtime, potential safety hazards and guesswork.

For more information about Enerpac equipment in Australia, contact tel: +61 (0)2 9743 8988; email: info@enerpac.com.au; or for New Zealand email: neville@enerpac.co.nz