Up in the Air
At any mine site with crane-assisted construction or overhead repairs under way, what goes up must come down — at the right time and under complete control. Here’s how the latest crane tech can help ensure that outcome.
By Russell A. Carter, Contributing Editor
The cost of lifting and overhead-safety- related mishaps can be staggeringly high, from both financial and personnel health aspects. A recent analysis by overhead crane manufacturer Konecranes of Occupational Safety and Health Administration- reported crane incidents in the United States, involving a study tracking 249 incidents over a 10-year period, showed that the average cost to an employer from a major crane-related injury was $200,000. A crane-related fatality costs an average of $4 million.
Cranes at mine sites are not considered primary production equipment, but without them, production can be adversely impacted when parts, supplies and other types of heavy material must wait to be lifted, shifted or loaded as part of ongoing maintenance and repair activities. Konecranes pointed out an important aspect of crane operation at mines and other industrial sites that can often be overlooked: the person controlling the crane may not be a full-time crane operator, but someone who handles crane work on a part-time basis in addition to his or her usual duty as a driver, millwright or field mechanic. Lifting-equipment manufacturers are becoming increasingly aware that their products must be designed to make it as easy as possible for these part-time operators to understand the limitations of the equipment and take advantage of built-in safety features — and at the other end of the load, for ground workers and riggers to be able to quickly reach and prepare a site for safe deployment and removal of lifting equipment that is generally only needed for specific, periodic duty.
As a result, Konecranes said it is committed to educating crane buyers about how its proprietary “safe” technologies address the issue of load swing, creating a safer crane that they believe will raise the bar for all overhead crane manufacturers. The company claims its Active Sway Control and Hook Centering are capable of dramatically reducing the number of crane-related accidents. Both require a PLC, variable frequency drive and Konecranes proprietary software to operate.
Active Sway Control stabilizes load movements in trolley traverse and/or bridge travel directions. It dampens load sway generated by normal motion to help the load remain stable at all times and in all conditions, making load-moving operations not only safer, but as much as 60% faster. Hook Centering is an innovation that was designed to automatically eliminate side pull situations and load swing caused by side pull. Side pull occurs when the hoist lifts an object that is not directly beneath it, which can cause violent load swing. When Hook Centering is activated, the crane automatically positions the trolley and bridge over the load. At the same time, the hoisting-up movement is limited until the crane and load are vertically aligned. Then, lifting can continue normally.
Mobile crane manufacturer Manitowoc noted that every model of its Grove all-terrain cranes since the release of its GMK3600 model in 2013 features the company’s Crane Control System, a user- friendly interface that is being deployed across Manitowoc’s brands for standardized training, operation and maintenance. CCS, said the company, features an intuitive Boom Configurator Mode that makes it much easier and quicker to select the optimum boom position for a specific lift.
The ability to maneuver in muck doesn’t apply just to cranes used in surface mining activities. Late last year, Manitowoc reported that PT Freeport Indonesia added three Grove cranes to its fleet. The RT765E-2 and two RT530E-2 rough-terrain cranes join the company’s operations at its Irian Jaya location, one of the world’s largest mine sites. The new units will replace two older Grove RT cranes that are being retired. The three new cranes will be applied primarily in underground expansion, where they will be used for steel erection work, and in supporting mill shutdown work or other tasks around the site.
“The RT cranes are the perfect size to operate in the underground environment and to support shutdown work around the mill area,” said Jason Smith, who works in mobile crane maintenance for PTFI. The RT765E-2 has a capacity of 60 metric tons (mt) and includes four-wheel multimode steering and a Full Vision cab. The RT530E-2 is a 30-mt capacity unit with a Tier III compliant 119-kW (160 hp) QSB 6.7L Cummins diesel engine. The crane also includes CCS, plus dual-axis electric joystick controllers.
“Compared to the older models, the initial crane setup is much easier, and therefore, getting the cranes to work is much faster. There are more options for slew limits and boom angle limits,” Smith said. “More importantly, it’s much easier to diagnose any faults with the software, so downtime is minimized, too.”
Designed to meet stringent safety requirements, the SL300 complies with standards set by ASME B30.1-2015. The SL300 is also CE-compliant.
Stopping the Drops
The potential impact from a crane accident can be catastrophic in terms of cost, damage and injury. However, smaller mishaps due to dropped tools and other items by workers overhead are much more common. Each year across the U.S., more than 50,000 recordable incidents involving workers “struck by falling object” are reported, according to the U.S. Department of Labor Statistics. That represents one injury caused by a dropped object about every 10 minutes, and OSHA has calculated that the average direct cost to an employer for a lost time injury such as a contusion resulting from being struck by a falling object is more than $27,000.
Tool restraint accessories are available from a number of sources, such as Proto’s Tethered Tool System, which employs heat shrink loops, tool collars and sealing tape with D-Ring web tethers to transform existing tools into tether-ready versions. According to Proto, with just a few simple steps, various wrenches, hammers, screwdrivers, punches, chisels, and hex keys can be retrofitted and used safely at height, or in work areas requiring foreign material exclusion (FME).
But what about the fasteners those tools are used with? A new tool has been developed by RToddS Engineering (rtodds-eng.com) to help reduce incidents of dropped fasteners and the related costs. The Washer and Nut Keeper is a flexible rubber socket set that can be loaded with any combination of nuts, bolts or washers of a given size. Once loaded, the fasteners stay in the flexible socket and in perfect alignment for starting them either in a tapped hole or on a stud or bolt. The flexible socket has ribs for easy gripping. Once the fastener stack is started, the Washer and Nut Keeper is removed and final torqueing is done with conventional sockets or wrenches.
Each socket is designed with a series of cavities that securely hold the fasteners in place, and the base has an opening for a standard ratchet drive or extension. A Washer and Nut Keeper can be designed for any combination of standard, metric or specialty fasteners.