The world’s most creep-resistant, ultra-high molecular weight polyethylene fibre is even better than previously thought. Producer DSM Dyneema unveiled DM20, based on its new Dyneema Max Technology, at the OTC Offshore Technology Conference in 2012, for use in mooring ropes for offshore production platforms. Since then, the company has been carrying out extensive characterisation studies on the lifetime and tensile properties of this groundbreaking fibre. DM20 is fully commercial, with a set of final specifications that exceed the data presented at OTC 2012.
Dyneema Max Technology is an innovative platform technology that will extend the use of Dyneema, which was already the world’s strongest fibre. DM20 is designed for long-term permanently loaded systems, such as mooring offshore production platforms. Mooring ropes made with DM20 outperform all alternatives, surpass industry standards for deep-water permanent moorings and will outlast the operational life of the installation.
The new technology also opens the door for applications outside the scope of offshore permanent mooring, where designers need the excellent dynamic properties of high modulus polyethylene (HMPE) fibre for high-strength tension members that are under permanent load. DSM Dyneema is currently supporting potential customers in the development of totally new applications for Dyneema Max Technology, in such areas as industrial and renewable energy. In addition, the company is working on further developments based on the Dyneema Max Technology platform.
One major existing customer, Lankhorst Ropes, has already used DM20 to produce a special version of its Gama 98 mooring rope. Working with a 34mm subrope produced by Lankhorst, DSM Dyneema has been carrying out endurance tests according to ISO/TS norm 14909 at Norwegian classification society DNV GL’s facilities. These involve subjecting the rope to 10,000 cycles of between 5% and 50% of break load stress. The rope passed the tests without problem. Lankhorst also verified the creep characteristics of its Gama 98 rope with DM20.
In addition, DSM Dyneema has been building a broad database. This confirms that the behavior of DM20 is just as good as the company’s existing class-leading fibers Dyneema SK75 and SK78. Furthermore, it has also proven its capability to produce DM20 consistently on an industrial scale.
With DM20, Dyneema has taken a major step forward in the development of fibres with extremely low creep. Whereas in 2012, the company predicted creep of 0.2%, the new data now shows that in normal operating conditions (below 40°C and below 20% of rope break strength) the creep of the fibre is almost non-existent.
DSM Dyneema offshore segment manager Jorn Boesten said: "No other HMPE fibre comes even close to the creep properties of DM20 and we are confident that no other failure mode dominates over creep in DM20."
Key points:
- First use of Dyneema in a complete set of offshore mooring lines was in 1999
- The longest-running project with synthetic deep-water mooring rope is in the water for almost 20 years
- The creep performance of average HMPE is significantly poorer than the creep value of Dyneema Max Technology
- A typical mooring for an FPSO will show close to zero rope creep in 25 years when using Dyneema Max Technology
- At OTC 2014 there will be several rope manufacturers showing mooring lines with Dyneema Max Technology