Mammoet’s SK6000, billed as the world’s strongest land-based crane, has passed its test programme in the Netherlands.
The ring-mounted SK6000 crane, with a rated maximum lifting capacity of 6,000 tonnes, has been certified as safe by Lloyd’s Register, which oversaw the load testing.
After reviewing the SK6000’s engineering design earlier during its development, Lloyd’s Register confirmed that the test programme was suitable to prove its capacity charts. Testing was then carried out at Mammoet’s Westdorpe facility in the Netherlands over a three-month period late last year, confirming that the crane operates to specification.
After verifying its performance specification, the SK6000 was subjected to structural and stability testing, during which it was subjected to a range of lift weights and conditions to prove that all components can withstand at least 125% overload.
These tests covered the extreme limits of all the load charts for the crane and for all main boom configurations, from shortest (127 metres) to longest (171 metres).
The testing regime exerted a maximum load moment of 520,000 tonne-metres on the crane – substantially more than one-and-a-half times greater than the rated load moment of Mammoet’s SK350, which was previously the company’s most powerful crane and also once a claimant to the title “strongest land-based crane”.
Besides verifying the SK6000’s prodigious lifting capabilities, the three-month testing regime also tested the machine for fully electric operation. Instead of relying on a bank of diesel generators to power the machine, Mammoet’s new behemoth can operate directly from grid power or, at sites without power network access or with supply stability issues, via batteries or hydrogen generators.
This allows Mammoet to boast that its flagship crane can offer zero-emission capability to projects taking place anywhere in the world.
Fully-electric operation allows customers to reduce the emissions profile of large projects; it also reduces the noise generated by crane operations, resulting in a better work environment where communication is easier.
Large projects are therefore made safer, cleaner and easier to finance, says Mammoet.
Electric testing was carried out using two 600kWh battery boxes from power supply specialist Bredenoord, connected in series to deliver 1,200kWh, around the same output as 20 electric cars .
Connection took a day and was carried out alongside test weight reconfiguration activity.
Battery packs capable of operating the SK6000 are becoming widely available, says Mammoet. The Bredenoord battery boxes come in standard 20ft shipping containers that can be transported easily to and from site.
“Thanks to this test we can now say that the SK6000 operates fully zero-emissions on-site,” says Mammoet’s global sustainability advisor Niek Bezuijen.
“Electrification isn’t a matter for the future of heavy lifting – it is needed now and, through innovations like this, Mammoet can help its customers lead on safety, efficiency, sustainability and cost,” he adds.
By plugging into a medium-voltage network – commonly available in heavy industry – the SK6000 can operate directly from the grid. At port facilities, so-called ‘shore power’ connections, typically used to prevent cargo vessels idling at port, are also capable of powering the crane.
Battery power offers a further option, says Mammoet, and has the additional benefit of being chargeable from lower-power networks. And because rigging and preparing massive ring-cranes like the SK6000 for each lift is a lengthy process, there’s always plenty of time for battery packs to recharge.
Hydrogen generators can be used where neither grid power nor battery power is an option, for example at remote sites without significant infrastructure.
With SK6000 electric functionality confirmed, Mammoet says it can now offer a fully zero-emission, low-noise marshalling service to customers in the offshore wind sector.
Oil and gas projects – not without some irony – can now benefit from complete elimination of carbon impact during their heaviest lifting operations, at the same time as realising the largest possible economies of scale from modular construction methods.
And in the nuclear sector, reduced noise levels will enhance safety levels at complex sites while allowing projects to deliver low-carbon energy in a sustainable way.
Development of the SK6000 was part-funded by the Subsidy Scheme for Clean and Emission-free Construction Equipment (SSEB), a Dutch government scheme to promote research and development of zero-emission construction equipment.
With testing now complete, the SK6000 will be stripped down and stowed away in standard containers ready for shipping to its first project – which has yet to be revealed – in a few weeks’ time.
Not just your average battery
Electric power for Mammoet’s new SK6000 can be provided by a local mains network, but in remote areas where this isn’t available, the machine will operate using two 600kWh “battery boxes” supplied by Dutch mobile power specialist Bredenoord.
The BB600 battery boxes – the largest in the Bredenoord range – comprise lithium-ion cells housed in standard 20ft shipping containers. They are designed specifically for locations where there is insufficient grid capacity and where extremely high peaks in power demand are likely – such as a super-heavy crane lift.
The BB600 Battery Boxes used to power the SK6000 are connected in series and run through a 600kW inverter to give approximately 1,200kW of power, enough for the SK6000 to operate at maximum capacity.
Bredenoord designs its battery boxes so they can be used as standalone units or as part of a hybrid setup. This allows power installations that are tailored to the client’s power demand and is more sustainable than a traditional installation based solely on the peak demand, the company says. There are several possible combinations.
They can be used in combination with gensets to handle peak demand and allow more sustainable use of diesel power.
Or they can be used alongside the grid to increase peak capacity when using a small grid connection. And for maximum sustainability, they can be used in combination with solar panels, storing solar energy during the day for later use.
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