KNOCK-DOWN OR FULLY ERECT – A TERMINAL VIEW
There are two main methods of delivering quay and yard cranes, either fully-assembled or in knock-down form. Barry Cross investigates which option terminal operators prefer and why
Colombian port operator, SPR Buenaventura received all of its new quayside gantry cranes fully assembled, explains Gustavo Florez, VP for Strategy and Infrastructure. “We simply don’t have enough space to erect cranes on site,” he says.
When a delivery is scheduled, Buenaventura only has to set aside a 150-metre area on the quay into which the crane can be positioned. “That’s the only disruption we face,” he stresses, pointing out that the crane is effectively already in position and can commence operations from the very spot it came ashore once commissioning is complete.
All of Finnish terminal operator Steveco’s cranes have been delivered fully-assembled. Heikki Jääskeläinen, who is the head of Steveco’s repair shop, Suomen Satamatekniikka Oy, says there are several reasons for preferring this method of delivery, but like Buenaventura, confirms that there is no need to set aside a special area in the terminal where crane parts will be stored, or for the crane to be assembled. “It is also a much faster way of subsequently getting cranes into service,” he agrees.
One major international terminal operator contacted by Port Strategy said that it generally prefers to receive new cranes not only already assembled but also fully tested at the manufacturing site prior to shipment. “This helps us ensure quality,” said a spokesperson. “Furthermore, receiving cranes and assembling them on-site safely requires the terminal to have the space to do so and may require an area to be set aside as a “factory”, which implies additional regulations.”
One UK-based container terminal operator confirmed that that, “Receipt fully-assembled reduces the overall time of delivery and commissioning. However, there is not a lot of difference in price between fully-assembled or knock-down formats, but the former involves less preparation, particularly in respect of planning and site supervision.”
Significantly, since 2008, ICTSI has only received one shipto-shore crane in knock-down or semi-erect form. This involved two out of a batch of four cranes acquired for CMSA (Mexico), which were shipped thus for purposes of vessel stability. “The crane manufacturer didn’t have its own vessels and had to use a third party,” recalls Johan Swart, ICTSI’s VP Global Engineering Equipment Maintenance. “In this case, once the cranes were discharged, the boom and girder were strand jacked into their final position.”
In terms of RTGs, ICTSI, has never received knock-down or semi-erect units, although in some instances, RTGs are shipped in what is called “leg-shift configuration”. This is where RTG legs (engine-side) are shifted and bolted to the middle of the girder, on specially fabricated flanges. This configuration is used for reducing the RTG footprint when the company is taking delivery of a large shipment of ship-to-shore and RTG cranes, with TecPlata, in Argentina, being a good example.
Here, there was the simultaneous movement of four gantry cranes and nine RTGs on a single vessel. “Some crane manufacturers offer a discount for knock-down or semi-erect delivery as the vessel used for shipment is often significantly smaller,” explains Mr Swart. “However, in my opinion it is never easier to receive semi-erect cranes as on-site erection and commissioning is more complicated and significantly longer than that of fully erect cranes.
Furthermore, there are many items to consider prior to on-site erection, including sufficient paved area or hard-standing for the duration of works, a reputable mobile equipment supplier being available in the region, as well as reliable and competent sub-contractor availability.”
According to Mr Swart, preparation work starts very early on in the crane manufacture process (which can be a 14-16-month project) as the crane design is dependent on which format the cranes will be shipped as. If it is to be semi-erect, the design often utilises bolted flanges, while for fully-erect welded flanges are used.
ICTSI reviews and approves the crane manufacturers design typically within the first 6-8 weeks of the project. “We maintain a presence at the crane manufacturer’s facility from the cutting of the steel plate right up until shipment,” says Mr Swart. “In addition, we review and approve sea-fastening calculations and drawings, as well as the discharge method to be used, which involves approving the jacking and wheel loads. We typically assist the crane manufacture with local approved sub-contractors and mobile equipment companies for required discharge, removal of sea-fastenings and the commissioning works.”
In terms of how quickly cranes then enter service, he says this would be four to six weeks for a ship-to-shore crane and 10 to 14 days for an RTG, although for RTGs shipped in leg shift mode a further 10 days are necessary.
Mr Swart is adamant that fully-erect units will always be preferred by ICTSI, albeit with four caveats. If the price differential was significant then knock-down would be considered, as it would be if ample space to erect the cranes was available. Time for completion would also not have to be a limiting factor and there would have to be no or minimal interruption to commercial operations.
“Crane manufacturers, such as ZPMC, use their own fleet of specially modified vessels and have been shipping fully-erect cranes for over 20 years,” he says. “As a consequence, they are extremely competent.”
Over the past 20 years, the loading and discharge method of the equipment from ships has not changed significantly. Although there are various techniques, the principle is the same when discharging, namely sliding, skidding or rolling gantry cranes off the vessel onto the quay.
On very rare occasions, floating cranes can also be deployed. According to Mr Swart, advances in technology have not had a significant impact on the crane loading and discharge method because the operation itself is very simple. “Receiving new cranes can be disruptive to terminals as berthing space has to be blocked for approximately 7-10 days for discharge, or longer if more cranes are to be delivered. This prevents customers from berthing and being serviced,” he states.
In addition, a certain amount of quay space is required for gantry crane commissioning, with four units needing more than 100 metres plus a further 50 metres of safety exclusion zone. While fully-erect RTGs take up less space and are less disruptive, they still occupy yard space that could otherwise be potentially used for operations.
“Air-draft must be considered prior to delivery of any crane (especially gantry cranes). However, to date, this has not been an issue for ICTSI, and we have not had to modify crane design or delivery method because of such restrictions,” he adds.
Interestingly, ICTSI will always consider shipping equipment fully-erect, regardless of the type of project (refurbished, relocation or new). The company has shipped MHCs for relocation in knockdown form, but Mr Swart says it is unlikely it would consider this for refurbishment or relocation of gantry cranes.
Although some manufacturers and terminal operators believe that fully-erect crane deliveries are the way forward, others remain more cautious.
Trevor O'Donoghue of Liebherr Container Cranes Ltd takes a quite distinct view, pointing out that, “On-site erection or knocked down delivery can be considered an advantage in some customer locations. This is especially true in countries where they are trying to promote employment for local communities, so the local spend on hotels, car hire and local labour is seen as a big advantage.”
Furthermore, in cases where contracts specify fully-erect delivery, Liebherr typically ships the cranes in knock-down form and erects them at remote sites nearer to the final operational site. “This delivery method minimises stresses associated with long sea voyages and eliminates any ambiguity with respect to the remaining operational life of the crane,” he says.
Academic studies undertaken following long sea journeys involving fully-erect crane deliveries seem to reinforce Liebherr’s delivery philosophy. “What has been discovered is that, once some cranes have been put into service, they have developed unexpected cracks in both booms and girders. Attempts have been made to explain this away by claiming the cranes had been deployed in handling materials they were not designed for, but strain gauge measurements have ruled that out as the cause.”
Worryingly, the cracks may well be caused by the extended ocean transit element of the delivery. “During the sea voyage, cranes are tension-lashed, braced and strut supported, which means they effectively use up part of their fatigue life prior to being put into operation. In other words, they can’t be considered to be entirely brand new,” explains Mr O'Donoghue.
“To date, there has been very little discussion in the industry about this potential problem. However, by delivering our own ship-to-shore cranes in knock-down form and then erecting them as close as possible to the operational area, Liebherr can justifiably claim that the cranes it delivers are definitely and unambigiously “new”,” he says.
What do manufacturers think?
Ilkka Annala, who is VP Intelligent Cranes Solutions at Kalmar, says that for sea ports, shipping cranes fully-assembled is a convenient way to deliver them, whereas at intermodal terminals knocked-down delivery is a must.
He points out that Kalmar’s Chinese Operation has its own port/jetty that can be used for direct international shipping and therefore the company is happy to undertake either knocked-down or fully-assembled crane deliveries based on individual customer requests.
“Typically, delivering fully assembled cranes is slightly more expensive than it would be in knock-down form, but that rule does not apply in all cases,” he says.
Furthermore, Mr Annala confirms that when delivering fully assembled cranes, the time spent at the customer’s site is shorter but the factory time is respectively longer. So, there isn’t a big difference in total delivery time between the delivery types.
“When delivering fully assembled cranes certain part of the testing can also be done at the factory, if the customer is willing to accept that.”
In answer to the question about whether more customers are now asking for fully assembled delivery of cranes, he says that Kalmar is not seeing any big difference compared to previous years.
As for shipping line capacity, there are differences, he says. “There seems to be very good capacity to transport yard cranes fully assembled, but when delivering fully assembled ship-to-shore cranes we sometimes see a shortage of equipment.” Irrespective of the way in which a Kalmar crane is delivered to a terminal,
Mr Annala says that, in terms of pre-delivery work that must take place at the terminal, there is no big difference between delivering cranes fully assembled or knocked-down.
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