MENCK MHU 3500S makes a strong impression in North Sea development.
The world’s largest underwater hydraulic hammer, the 3500-kJ MENCK MHU 3500S, has played a key role in the successful installation of subsea jackets at the Clair Ridge development, west of Shetland.
Operated by BP, Clair oilfield lies 75 km west of Shetland in water depths to 140 m. Clair Ridge is a $7.3 billion investment in the second phase of development at the field. The project will comprise two new bridge-linked platforms and new pipeline infrastructure to connect to processing facilities on Shetland. The installation of the topsides is scheduled for 2015, and production is expected to commence in late 2016.
Heerema Marine Contractors (HMC) was responsible for installing the jackets for the linked platforms at Clair Ridge and used the MHU 3500S to complete a 32-pile foundation operation. Jost Pokelsek, MENCK’s key account manager for HMC, says, “The piling work conducted at Clair Ridge was the first commercial application for the MHU 3500S and we are delighted to see the system performing as it was designed to.”
HMC approached MENCK in 2009 to discuss the possibility of developing a hammer that offered significantly more power than the 3000-kJ hammers that were the largest available at the time (the MENCK MHU 3000 hammers). After these discussions, MENCK started exploring the possibility of designing a larger hammer.
“MENCK hydraulic underwater hammers have established a reputation for performance and reliability over the years,” Pokelsek continues. “They also offer a modular design that ensures flexibility in terms of size adaptation, simple mobilisation and ease of access for maintenance. HMC was convinced that MENCK could deliver what was needed.”
MENCK engineers started with a blank sheet of paper because, although the new hammer basically looks like a normal MENCK MHU hammer, the energy level required made new designs in numerous technical components necessary. The new design involved a comprehensive programme of engineering and customisation to meet HMC and the offshore market’s needs: a hammer that would be perfectly suited to the task of driving piles up to 500 m into the toughest seabed.
During the development process, MENCK had to conduct much detailed modelling. “We had to extrapolate the performance of the original hammer to the upscaled system and to ensure that the materials we used would behave as predicted,” Pokelsek explains. “As part of this process, MENCK identified the need to introduce new materials into the hammer design to ensure that it delivered the high-energy performance HMC required. The resultant system, which has a submerged weight of just over 425 t, sets a new benchmark in offshore piledriving.”
The current trend for offshore installation in the North Sea is towards larger hammer systems. “North Sea operations are taking place in areas with rougher seas and more demanding soil conditions, so this has encouraged field developers to use large piles and large hammers to secure them in the seabed,” Pokelsek explains.
Specialist companies across Europe manufactured the components for the MHU 3500S: cast material was supplied by a forge in Spain and various other components came from Germany and Italy. MENCK assembled the components and tested all functions and electronics in-house before sending the system to HMC for field testing.
A key feature of the design and construction process was the quick turnaround from contract award in July 2011 to delivery of the system in January 2013. The hammer was the subject of comprehensive testing at HMC’s Caland Canal facility in Rotterdam. This test programme aimed to ensure that the hammer achieved the designed energy level. In an 800-blow test programme, the energy performance of the hammer was measured by an independent company, TNO (the Dutch organisation for applied scientific research), and was shown to have reached the required 3500-kJ rating.
The multimillion dollar contract to build the MHU 3500S is part of a business relationship between HMC and MENCK that dates back to the late 1970s. As part of the MHU 3500S contract package deal between the companies, MENCK undertook upgrading of two MHU 600i hammers (to the MHU 600iS version) and a MHU 2100i (to the MHU 2100iS version). At the same time, HMC also awarded MENCK a master services agreement to provide on-site services for its entire fleet of MENCK hydraulic hammers.
The MHU 3500S has proved successful on a demanding oil and gas project, but it could also deliver significant benefits for companies that are conducting installation work for offshore wind projects in Europe and elsewhere. Underwater noise during piling operations is an environmental issue for offshore wind installations, particularly in Europe, but, despite its size, the MHU 3500S is helping to address this, as Pokelsek explains.
“We call the MHU 3500S the gentle giant,” he says, “because the improved ratio between the mass of the pile and that of the hammer ram weight helps to achieve a noise reduction of up to 2–3 dB at the source of the noise. This is a significant reduction and helps us and our clients to meet the required noise emission values.”
This is part of MENCK’s ongoing commitment to developing technologies that reduce the noise of offshore installation operations. HMC is looking to apply the system to other North Sea projects. The company transports, installs and removes all types of offshore facilities, including fixed structures, complex infrastructures and floating facilities in shallow, deep and ultra-deep water, so the MHU 3500S is expected to play a key role in HMC's operations.
"The new hammer is a product of the strong ties between HMC and MENCK,” Chris de Ruiter, senior asset equipment manager at HMC, adds. “These go back almost 50 years to the very early days of HMC, when we started with lifting and piledriving. HMC has always been innovative, entrepreneurial and a setter of world records in piledriving. This new hammer will enable us to serve our customers in more demanding circumstances.”
“We are delighted that HMC is happy with our products and services, and that we have justified the company’s confidence in us. As a technical leader in the marine contracting industry, HMC has a strong track record in applying state-of-the-art equipment, and the MHU 3500S certainly falls into that category,” concludes Pokelsek.