NEW IN INDUSTRY
Safe, efficient heavy lifting with Enerpac strand jacks The Enerpac strand jacking system has been designed to provide a highly safe and accurate method of heavy lifting. The HSL Series strand jacks – in individual capacities from 15 to 1,250 t – are now being further advanced with a sophisticated SCC smart cylinder control system software programme, which synchronises the motion of the strand jacks and adjusts the motion to the loads per lifting point. The system was recently employed on projects in Indonesia, Singapore and the Philippines. It is ideal for projects such as bridge lifting, aircraft hangars, oil and gas plant and rigs, silo maintenance and marine applications including ship thruster installation and maintenance. Each HSL system is supplied with the SCC hardware and software package as standard. The SCC system not only monitors progress, but also controls the operation within safe working limits specific to the particular job and client demands. For example, the system governs maximum permissible load and synchronous position at each lifting position and between them, which are key parameters that the SCC uses to precisely manage the lifting operation, explained Enerpac. Powered either by electrical or dieseldriven hydraulic power packs, the HSL system also features: control by a single operator from a central location for increased safety; automatic locking/unlocking operation for optimum load control and load holding; telescopic nickel-plated strand guide pipes to prevent bird-caging, enhancing smooth and reliable operation; anti-corrosion Lunac coating of internal components for aggressive and marine environments; long strokes from 250 to 600 mm within compact high-pressure cylinders (up to 350 bar); lifting anchors included with each cylinders for convenient mounting and safety; and Lloyds witness tested to 125 percent of maximum working load. According to Enerpac, a strand jack can be considered to be a type of linear winch. In a strand jack, a bundle of steel strands passes through a main hydraulic cylinder, which acts as the lifting or lowering jack. The strands in the HSL are either 15.7 mm or 18 mm diameter each, with multiple strands supporting the load. Above and below the main hydraulic cylinder are mini jacks with anchor systems of wedges that grip the strand bundle when the load is being lifted or lowered.
Lifting and lowering a load is achieved by hydraulically controlling the main jack and both mini jacks alternately, feeding the strands through the cylinders in steps equivalent to the cylinders’ strokes (which range from 250 to 600 mm). The wedges close automatically to lock the suspended load in place if the hydraulic system loses pressure, further ensuring safety. Enerpac said strand jacking delivers compact high capacity lifting capabilities that are easy to deploy, compared with mobile and crawler cranes. The technology offers a high lifting height, with true vertical lift and no drift. n Website: www.enerpac.com
Right: The Enerpac HSL Series strand jacks are designed to offer a highly safe and accurate method of heavy lifting. They feature individual capacities from 15 to 1,250 t. Left: The HSL strand jacks are being matched with a sophisticated SCC smart cylinder control system software programme, which synchronises the motion of the strand jacks and adjusts the motion to the loads per lifting point.
Strand jacks are in operation here to lift two Songdo cable-stayed bridge pylons in Incheon, South Korea.
Southeast Asia Construction : Nov-Dec 2017