he latest stainless-steel sliding-guided bearings from Hercules Engineering respond to expanding demand for long-term, no-maintenance protection for buildings, plant and infrastructure against structural disruption from shock, impact, vibration and thermal movement.
The 316-grade stainless steel bearings – which are also particularly applicable to aggressive, damp, chemically laden or salty environments producing rust – are custom-fabricated developments of Hercules’ proven HLD-SG bearings, used throughout Australasia and the Asia-Pacific in applications ranging from commercial, civil and steel and concrete beam infrastructure projects, including small-span bridges, conveyor overpasses and pipeline supports.
The long-life stainless bearings align with new international moves to ensure building resiliency under the impact of climate change, with the Australian Building Codes Board teaming up with The National Research Council of Canada, the New Zealand Ministry of Business, Innovation and Employment and the International Code Council (US) to launch a Global Resiliency Dialogue.
Stainless HLD-SG bearings enclose a sandwich of Teflon on mirror-finish stainless steel bonded to a special grade rubber sub-stratum. They are engineered to offer optimum no-maintenance lifespans of decades for developments in aggressive environments, such as marine, oil and gas, mining, ports, power plants and water and waste water infrastructure, says Mr David Booty, Manager, Hercules Engineering (a division of Cut To Size Plastics).
They also respond to construction engineers’ and specifiers’ ongoing need to help protect structures against disruption from sources as diverse as subterranean shock and vibration, rust, chemical ingress and greater thermal movement of structures with climate change. Examples of uses include:
- Buildings and plant located near increasing sources of urban vibration and shock, including civil engineering projects such as tunneling and foundation excavation as cities grow more crowded and projects move closer together.
- Mining, oil and gas structures, ranging from conveyors and bridges to buildings such as mill houses and plant subject to widely varying loads and climatic conditions. Such conditions can range from extreme heat and cold, through to marine and tropical situations subject to salt, violent windstorms and chemical ingress
- Machinery, building, plant, tanks and pipelines involved in process engineering applications including food and beverage, agriculture, primary production, resources development and gas and liquid distribution.
Stainless bearings can be custom-tailored to to configurations that best suit installations and site conditions. All Type D Herculon Bearings (HLD-SG) are designed to accept a lateral load of 30 per cent of the vertical rated load, which can be up to 600 kN per bearing in stock sizes, with higher capacity available custom-engineered for specific applications.
Herculon Type D Sliding Guided (HLD-SG) bearings have been developed to fulfil the need for a low friction bearing on corbels and columns where a continuous slipjoint is inappropriate.
They can be used under beams and slabs and also under pipes, ducts, conveyors, pressure vessels and small-span bridges. HLD bearings typically offer no-maintenance service lives of decades, depending on applications, and are removable and replaceable to ensure ongoing performance.
“The stainless HLD-SG provide an extra layer of security, longevity and risk management that engineers and developers are increasingly looking for, even beyond the excellent performance of standard HLD-SG bearings,” says Mr Booty.
Compared with more expensive heavy alternatives, such as pot bearings and roller bearings, HLD bearings offer benefits such as lower initial cost, easier installation and no maintenance typically for decades. They minimise maintenance and optimise service life by flexibly accommodating the thermal issues and the vertical and horizontal stresses imposed by the shuddering and vibration of varying loads.
Performance characteristics include
- Outstanding stick-slip performance, to provide smooth, easy movement under load
- Friction co-efficient 0.05 – 0.08 depending on stress
- Expansion capacity up to ± 40mm for standard Bearings. (Larger movements can be accommodated upon request)
- Maximum contact stress 10-12 MPa
- Maximum rotation up to 0.02 radians
- Maximum temperature 80 deg C (with higher temperatures accommodated by thermally insulating bearings or using high temperature materials, both as recommended by Hercules).