NOVEMBER 2022 Ӏ BELOW THE HOOK


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Making Your Connections


A business that works in the shadows of hulking cranes every day must also appreciate components, especially those below-the-hook. Casper, Phillips & Associates (CP&A) are a multi-discipline engineering fi rm located in Tacoma, Washington State, USA. They began in 1987 as structural engineers specialising in container cranes. Since then they have expanded their expertise to include most types of dockside cranes from RTG, RMG, and Goliath cranes to B.O.P handlers on drill ships. Ports and crane manufacturers around the world use their services to design and procure all types of load handling equipment, for which reason container handling remains a core expertise. The company recently completed a project where rail-mounted gantry (RMG) cranes had a lifting capacity of 40 long tons (2,240 lbs.), and


both the trolley and gantry could travel at 150 m/min. The cranes spanned 175 ft. (approx. 53.34m) over nine rail tracks. They had a cantilever, giving the trolley a total travel distance of 213 ft. (approx. 65m) and the cranes a total length of 245 ft. (approx. 74.67m). Given all that, what happens below the hooks of that might seem rather minor. “Who cares about the minutiae when we’ve got the mighty?”


says Richard Phillips, CP&A’s mechanical engineer. But “container handling is a bit different in terms of below-the-hook,” he says. “Actually, we can use the industry as something of a barometer by which to measure safety and effi ciency under the jib.” Most cranes have a single hoist rope, with the load dangling freely at the end. That, of course, does not give you a lot of control. “Container


cranes are different, though, in that you have you have four independent hoist ropes” – essentially one at each corner of the load. “This enables the lift system to perform controlled trim, list, and skew operations to precisely pick up and place containers. Container cranes are built to pick up and move as much cargo as possible. The standard design of containers allows for much faster loading and unloading. “The standard lifting device on a container crane is called a spreader; it can lift standard containers. There can also be special spreaders that


rotate the container or tilt the container to dump bulk material such as grain or coal. They are attached to the crane through the headblock. You can think of the headblock as a universal mount where different lifting devices can be swapped in or out. The headblock also allows quick swapping of spreaders during normal operation if a spreader needs maintenance in the middle of unloading a ship; this minimises interruption. “But typically, container cranes are purchased also with a second lifting device called a cargo beam. The beam connects to the headblock with either twist-locks or pins. The cargo beam has either a single hook or multiple hooks and is used for general non-containerised cargo.” From then on down, things can get interesting. “Below-the-hook lives from the point where the standard crane hook starts, and it ends at the


load,” says Phillips. There are ‘lots of reasons’ he says, for fi tting special attachments between them. “One of the more common reasons is that the object being lifted needs to be supported in a certain way. A simple example would be a long span truss; if you pick it up from the middle it is being loaded in a way that it may not be designed for. A special lifting device can help spread the load out and lift the truss from hard points. “When we are involved,” he says, “there is usually a unique lifting requirement. This makes it obvious that specialty equipment is required.


We only get involved when it’s a one-off or has special requirements where off-the-shelf products won’t work. Contractors are very motivated to try to fi nd the cheapest way to lift something, so I’m sure there is some effort to fi nd a way to lift the load with the standard setup without a special attachment. A common arrangement is that a specialist doesn’t have any available engineers for a project, so they subcontract the above- or below-the-hook engineering to companies like us.” At this sharp end of the industry, Phillips sees some good—exemplary, even—practice. And he points to slowdowns as a moment where the


smart get to work and start to consider their below-the-hook engineering. “Smart companies take advantage of slowdowns to put their engineers to work designing new, innovative equipment. If there are no slowdowns and a company needs to innovate, they can hire outside engineers like us. Many countries recognise and understand the importance of having a licensed engineer from a country with a reputation for engineering excellence, and some of the best engineering out there resides between hook and load.” As an example of that best practice CP&A still


likes to revisit the Hong Kong-Zhuhai-Macau Bridge (HZMB) project when it consulted on below-the-hook engineering. Hong Kong, Macau, and Zhuhai are three major cities on the Pearl River Delta and the bridge between them is 34 miles-worth of bridge. CP&A was onsite in 2011 to observe the fabrication of the lift system that held the eight pile drivers, which was named ‘The Ocktakong’. Its tasks included driving a 72-ft. (22m) diameter steel pile—a world record at the time. “We designed a custom lift system that holds an


This was the largest pile driven, albeit back in 2010. Pic credit: American Piledriving Equipment


array of eight vibrating pile drivers for driving the main columns of the bridge,” recalls Phillips. “A fl oating crane was used, which presented a huge area exposed to the wind load in addition to the motions of the vessel. Our team was able to overcome these challenges and the project was a success.”


f 128 CRANES TODAY


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