Ring crane

{{Short description|Type of construction crane}} {{Use dmy dates|date=January 2025}} [[File:Mammoet ring crane (51516326449) (crop to crane).jpg|thumb|Mammoet crane (red) set up in Nigg Energy Park, Scotland to load jacket foundations (yellow) for the Seagreen Offshore Wind Farm.]] A '''ring crane''' is a form of large construction crane with a luffing jib. It is distinguished by its slew pivot{{efn-lr|Slewing is the sideways rotation of the crane.}} being in the form of a ring-shaped track, rather than a narrow central spindle. The broad base this gives to the slewing section above allows it to slew whilst carrying extremely heavy loads.

Ring cranes are rare. There are very few of them, and these are operated by specialised heavy lift companies. They may be shipped around the world, as needed. Mammoet Transport operates three PTC ring cranes.<ref name="CRO" /><ref name="Mammoet " /><ref name="Mammoet, PTC 200-DS datasheet" /> Belgian heavy-lift company Sarens has also operated such cranes since 2011.<ref name="Sarens" /><ref name="Sarens, SGC-120" />

==Operation== [[File:Mammoet crane - Dubai - United Arab Emirates - 14 Nov. 2014.jpg|thumb|Mammoet PTC200-DS in Dubai, 2014.]] Ring cranes are used either when exceptionally large single lifts are essential, or when the ability to perform such lifts would accelerate a construction project sufficiently to make the use of such a specialised crane cost-effective. Other crane types, such as gantry or Goliath cranes may have similar capacities, but the jib reach of the ring crane allows them to work over a large area. This ability for a single crane to make lifts over a large area may reduce the amount of other expensive high-capacity plant needed, such as self-propelled modular transporters (SPMT).<ref name="OSI, Sarens, Newcastle" />

Typical loads include petrochemical plant modules, nuclear reactor vessels, bridge components or offshore equipment.<ref name="Sarens, Smulders" /><ref name="OSI, Sarens, Newcastle" /> They combine lifting capacity - up to 5,000 tons - with a long reach. Jib lengths of up to {{convert|160|m}} give a lifting radius of up to {{cvt|100|m}}. They also have a small footprint compared to gantry or Goliath cranes. The performance of super-heavy jib cranes is measured in tonne-metres, the product of weight and lifting radius, typically as much as 100,000 tonne-metres for large cranes.<ref name="Huisman" /> Sarens offer a range of such cranes from 90,000 to 250,000 tonne-metres.<ref name="Sarens" /><ref name="Sarens, SGC-120" /> Lifting a 3,200 ton load to a height of {{cvt|120|m}} may take up to 15 minutes.{{efn-lr|A power requirement of around {{convert|5000|kW|hp}}.}} Slewing in a complete rotation takes a similar time.<ref name="CRO" />

When a large load is lifted, particularly a tall vertical load, additional tailrope equipment may be needed to control the lower end swinging around. Although fixed winches may be adequate with smaller cranes, for the extremely large lifts performed by ring cranes this may need equipment such as an SPMT.<ref name="Heavy Lift News, July 2013" />

==Development== The first heavy ring crane was developed by Huisman in 1996, for petrochemical plant construction in Dubai. A Van Seumeren{{efn-lr|In 2000 Van Seumeren bought Mammoet and adopted their name.<ref name="Cranes Today, Van Seumeren buys Mammoet" />}} Demag CC4800 crawler crane, which had been used by Huisman on other worldwide contracts since 1992, was adapted by being placed on a ring track.<ref name="Heavy Lift News, July 2013" />

==Transport== They can offer flexible configuration and quick mobilisation. When dismantled for shipping they may either be moved as large units or broken down further to the size of standard freight containers.<ref name="Huisman" /> On assembly, a modular design allows choices of how much reach or lifting capacity to provide.<ref name="Huisman" /> The Sarens SGC-120 can be assembled with either the main boom alone or with either a heavy-duty or light-duty jib in addition to this.<ref name="Sarens, SGC-120" /> The counterweight for the crane is composed of a series of open steel boxes, based on standard {{convert|40|ft|adj=on}} freight containers, which can be filled with low-cost, locally sourced material such as sand, rubble or scrap metal.<ref name="LA, Sarens" /> The ring itself has a footprint diameter of {{cvt|45–55|m}} and a ground pressure of 20 tons / m<sup>2</sup>.<ref name="CRO" />

Assembly on site is itself a complex process, involving a number of smaller cranes and several weeks of effort,<ref name="Sarens, Assembly" /> and a cost of perhaps $500,000.<ref name="Heavy Lift News, July 2013" />

==Variants== ===Twin boom cranes=== Twin boom ring cranes can be supported by the wide lateral base of the ring track, giving extra lateral stability, similar to an A-frame derrick, but with the ability to slew around. As the base of this derrick is broad, comparable to the radius of the ring, this reduces the peak ground loading by spreading the load into two separate areas. Twin boom ring cranes are used for the largest ring cranes: up to 5,000 tonne load for the latest Sarens SGC-250.<ref name="Sarens SGC-250" />

ALE (merged with Mammoet) is planning to release the SK10,000 (10,000 tonne capacity) with double twin booms and twin rings in Q4 2020.<ref>{{Cite web|url=https://www.ale-heavylift.com/sk10000/|title=SK10,000 {{!}} World's biggest crane|website=ALE|language=en-US|access-date=2020-03-22}}</ref>

===Ringers=== A '''ringer''' is a similar device, although intended as an optional add-on for crawler cranes.<ref name="Manitowoc Cranes, Ringer" />

==''Big Carl''== The world's largest crane{{efn-lr|As of 2019.}} is ''Big Carl'', the Sarens SGC-250.<ref name="Sarens SGC-250" /> The name is a reference to Carl Sarens. In September 2019, it began work at the construction site for the Hinkley Point C nuclear power station in Somerset, England,<ref name="BBC, Big Carl" /><ref name="BBC, Big Carl2" /> lifting the first 245-tonne reactor dome into place<ref name="BBC, Big Carl 2023" /> and in July 2025 the second.<ref name="BBC, Big Carl 2025" /> This is a double ring crane with a reach of {{cvt|275|m}} and maximum lift of 5,000 tonnes.<ref name="Sarens SGC-250" />

==References== {{Commons category|Ring cranes}} {{Notelist-lr}}

{{Reflist|refs=<ref name="LA, Sarens">{{Cite magazine |magazine=Lift and Access |title=The Sarens Group Introduces Heavy-Lift Crane System |date=5 April 2010 |url=http://www.liftandaccess.com/content/sarens-group-introduces-heavy-lift-crane-system }}</ref><ref name="Sarens">{{Cite web |title=Sarens Giant Crane |date= |website= |url=https://www.sarens.com/en/equipment/sarens-giant-crane.aspx }}</ref><ref name="Sarens, Smulders">{{Cite web |title=Massive SGC-120 crane used at Smulders Projects yard, Newcastle, UK |date= |website=Sarens Group |url=http://www.sarens.com/en/news/smulders-projects-yard-in-newcastle,-uk.aspx }}</ref><ref name="Sarens, SGC-120">{{Cite web |title=SGC-120: the new standard in super heavy lifting |work=Flyer |publisher=Sarens Group |url=https://www.sarens.com/media/catalog/Flyers/Flyer%20SGC%20120.pdf }} <br>{{Cite web |title=Sarens SGC-120 3200 Ton |work=Datasheet |publisher=Sarens Group |url=https://www.sarens.com/media/catalog/Sarens%20SGC-120/Sarens%20SGC120.pdf }}</ref><ref name="OSI, Sarens, Newcastle">{{Cite magazine |magazine=Offshore Industry |title=Ready for Any Lift |year=2017 |volume=10 |issue=17 |pages=36–37 |url=http://www.liftandaccess.com/content/sarens-group-introduces-heavy-lift-crane-system }}</ref><ref name="CRO">{{Cite web |title=Mammoet ADDINOL Eco Gear 68 S-T – the world's largest ring crane |date=3 October 2014 |website=Construction Review Online |url=https://constructionreviewonline.com/2014/09/mammoet-addinol-eco-gear-68-s-t-worlds-largest-ring-crane/ }}</ref><ref name="Mammoet ">{{Cite web |title=PTC 200-DS ring cranes |date= |website=Mammoet |url=https://www.mammoet.com/equipment/cranes/ring-cranes/ptc-200-ds/ }}</ref><ref name="Mammoet, PTC 200-DS datasheet">{{Cite web |title=PTC 200-DS Datasheet |date= |website=Mammoet |url=https://www.mammoet.com/siteassets/equipment/cranes/ring-cranes/ptc-200-ds/datasheet-ptc-200-ds.pdf }}</ref><ref name="Heavy Lift News, July 2013">{{Cite web |title=Mammoet Platform Twin Ring crane (2000 Tonner) in action in Saudi Arabia |date=18 July 2013 |website=Heavy Lift News |url=http://www.heavyliftnews.com/cranes/mammoet-platform-twin-ring-crane-2000-tonner-action-saudi-arabia-from-shoebox }}</ref><ref name="Huisman">{{Cite web |title=Huisman's new range of super heavy lifters Compact Ringer Cranes (CRC) enter the ring |date= |website=Heavy Lift Specialist |url=http://www.heavyliftspecialist.com/cranes/huismans-range-super-heavy-lifters-compact-ringer-cranes-crc-enter-ring/#more-9456 }}</ref><ref name="Sarens, Assembly">{{YouTube |id=BHwbu8iWrBo |title=This is how Sarens assembles one of the biggest cranes in the world, the SGC  }}</ref><ref name="Manitowoc Cranes, Ringer">{{Cite web |title=M-1200 72 RINGER |url=https://www.manitowoccranes.com/en/cranes/manitowoc/crawler-cranes/attachments/M-1200-72-RINGER |url-status=unfit |archive-url=https://web.archive.org/web/20150815152137/https://www.manitowoccranes.com/en/cranes/manitowoc/crawler-cranes/attachments/M-1200-72-RINGER |archive-date=2015-08-15 |website=Manitowoc }}</ref><ref name="Cranes Today, Van Seumeren buys Mammoet">{{Cite magazine |title=Van Seumeren buys Mammoet for 111m Euros |magazine=Cranes Today |date=1 June 2000 |url=http://www.cranestodaymagazine.com/news/van-seumeren-buys-mammoet-for-111m-euros/ }}</ref><ref name="Sarens SGC-250">{{Cite web |title=Sarens Launches the Largest Crane in the World: The SGC-250 |date=November 2018 |website=Sarens |url=https://www.sarens.com/en/news/sarens-launches-the-largest-crane-in-the-world-the-sgc-250.aspx |access-date=12 September 2019 |archive-date=17 September 2019 |archive-url=https://web.archive.org/web/20190917233737/https://www.sarens.com/en/news/sarens-launches-the-largest-crane-in-the-world-the-sgc-250.aspx |url-status=dead }}</ref><ref name="BBC, Big Carl">{{Cite web |title=Hinkley Point: World's largest crane begins work in Somerset |date=11 September 2019 |newspaper=BBC News Online |url=https://www.bbc.co.uk/news/uk-england-somerset-49673561 }}</ref><ref name="BBC, Big Carl2">{{Cite news |title=Big Carl: World's biggest crane starts work at Hinkley Point C |date=11 September 2019 |publisher=BBC News Online |url=https://www.bbc.co.uk/news/av/uk-england-somerset-49679073 }}</ref><ref name="BBC, Big Carl 2023">{{Cite news |title=Hinkley C nuclear reactor roof lifted into place |date=15 December 2023 |first=Dave |last=Harvey |publisher=BBC West |url=https://www.bbc.co.uk/news/uk-england-somerset-67702966 }}</ref><ref name="BBC, Big Carl 2025">{{Cite news |title=Huge dome lifted onto nuclear reactor |date=17 July 2025 |first=Bea |last=Swallow |publisher=BBC News, Somerset |url=https://www.bbc.co.uk/news/articles/c4g8yn07y10o }}</ref>

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Category:Cranes by type