Two major heavy lifting and heavy transport challenges faced by contractors in cities and industrial complexes influenced Mammoet’s product development strategy and led to the development of the Focus30 crane. Firstly, as population growth and urbanisation increase pressure on infrastructure planning and construction, complex lifting and transport operations need to be executed in highly congested areas without disrupting daily life and public transport networks.
Secondly, with increase in demand for energy, governments prioritising sustainability are imposing restrictions on permits for new industrial complexes and emission and noise limits for existing facilities. Nevertheless, industrial complexes such as petrochemical plants need to be maintained, rebuilt and upgraded periodically without loss of production. Like cities, refineries and chemical plants face the problem of congestion. As they expand over time, they tend to operate beyond their intended life cycle, often within the same footprint. Refineries across Europe and the US between 50 and 60 years of age are reaching the end of their design lives. This presents owners with two choices: to shut down existing facilities and rebuild, or to expand and revitalize them. Until recently, both these options would result in a significant downtime, and therefore, costs.
While maintaining and upgrading such facilities, the biggest challenge faced by heavy haulage companies is the lack of space to transport and lift oversized loads. Contractors can overcome regulatory and logistics challenges by reducing civil preparation work, utilising fewer equipment to do more work, and planning for just-in-time transportation. However, none of these approaches can be adopted with crawler cranes.
Jacques Stoof, head of global market development and innovation, Mammoet, elaborates on the challenges facing plant operators and contractors, particularly during refinery upgrades.
“Maintaining and upgrading refineries require cranes. While this is good for our business, it comes with the risk of disrupting production as a result of transporting, erecting and operating a large crane at a fully operational refinery. Conventional crawler cranes need a large laydown area during assembly with their booms raised over existing workspaces. Assembly of such cranes may require clearing space on the site for lifting, demolishing buildings, reinforcing the ground, closing roads, building the boom over existing pipe racks and interfering with the refinery processes. Sometimes we have to compromise on the crane capacity due to limitations in the available area and ground bearing pressure and the challenges involved in the assembly of the crane. This is not a feasible option considering that such facilities must be maintained or upgraded every five to seven years and that downtime is more critical than ever,” he explains.
Jacques Stoof, head of global market development and innovation, Mammoet.
The product development strategy adopted by Mammoet for heavy lifting in confined spaces was centred on vertical assembly.
“We asked ourselves why a vertical assembly mechanism had not been developed for heavy-duty cranes the way it has for tower cranes. This led to the concept of the Focus30, which we envisioned as a heavy-lift crane that builds itself. We designed the Focus30 to be erected vertically and manoeuvred with flexibility, while delivering the size of lifts required for modular construction. By enabling heavy lifts with no loss of production, the Focus30 can accelerate refinery upgrade and maintenance projects with a lower total cost of refurbishment,” says Jacques.
Features of the Focus30
Capacity
The Focus30 is a 2500t class crane with maximum load moment of 30,000 tonne-metre. The crane can lift 1000 tonnes at 30m radius with a 90m main boom and 18m jib. The maximum lift radius is 98m, and the boom angle varies from 30 degrees to 85 degrees.
The high capacity of the crane facilitates modular construction: larger modules can be pre-fabricated off-site and then transported and installed in single lifts.
Assembly
As a vertically self-erecting crane, the Focus30 can be assembled up to a height of 150m. No part of the crane overhangs surrounding people, buildings and roads during its assembly and disassembly. The following systems and mechanisms enable vertical assembly:
• The main boom mast sections are supplied in sections and erected using a guidance system that allows vertical mast build-up
• A specific masthead enables hoisting or lowering of the back mast during crane erection or disassembly
• A feed system on the crane’s upper structure allows safe and convenient insertion of mast sections
• The erection frame allows stable vertical mast erection, based on a proven methodology for tower cranes. Boom stop cylinders, integrated in the support brace of the erection frame, keep the main boom mast sections vertical and stable.
The total area required for assembly, including assisting cranes and support equipment, is 35m x 35m. After the assembly, the crane requires an area of only 22m x 22m to operate. The small footprint allows more work to continue around the Focus30, thus increasing productivity on the job site.
Vertical assembly also allows the crane erection methodology to be consistent on every project. The Focus30 can be erected within 10–14 days by a crew of six people including supervisors and riggers and by using locally available 400t and 100t mobile cranes and a 30m access platform.
Ground bearing pressure
The pedestal design of the Focus30 creates stability and keeps the ground bearing pressure of the crane within 6–10t/m2. These low values limit the impact on the surrounding as well as underground infrastructure and reduces the amount of civil work required to start lifting operations.
Wind speeds
The Focus30 can be erected at wind speeds up to 40m/s and operated at speeds up to 10m/s. An out-of-service crane can withstand up to 35m/s; beyond that speed, several tie-down configurations can help the crane withstand severe storms and up to category 3 hurricanes.
Relocation
The Focus30 has a variable and splittable superlift system which enables swift relocation of the crane without disassembly. Where the surface allows, the Focus30 can also be skidded to additional lifting positions. This allows more lifts to be made using the same crane.
Testing and availability
Testing of the Focus30 took place in two phases, under the supervision of Lloyd’s Register, an independent third-party surveyor that worked alongside Mammoet during design of the Focus30. First, the crane was assembled in its SFSL fixed jib configuration and subjected to 125% of its maximum recommended load.
Next, the crane was re-assembled, this time to its SSL configuration, with 90m boom but no jib, and again loaded with 1,250t. Testing of the crane in its SFSL configuration lasted for approximately one week, while testing in its SSL configuration lasted for three days in total.
Side load, swing load and maximum radius testing was performed during both the phases. Repositioning of its superlift between tests took just two hours each time, rather than one to two days, a feature that will reduce plant downtime when the crane starts project work.
Following the two phases of testing, the crane is now fully compliant with the EN 13000 standard for mobile cranes, and with F.E.M. 5.004, which governs the design of steel structures of general use.
Mammoet has announced the Focus30 will be available in 2021. The Focus30 will belong to a series of cranes that will include the Focus6, Focus8, Focus15, and Focus50 (50,000 tonne-metre) models.