High Modulus Polyethylene is widely considered to be the most suitable material for longer, ultra deepwater mooring lines beyond 2,000 m. The fibers are characterized by high strength and high modulus, producing lighter and smaller diameter high stiffness ropes, compared with polyester mooring lines for the same MBL. However, HMPE's creep performance has prevented its use in long-term deepwater moorings. Systematic improvements in creep performance by DSM Dyneema have led first to the development of SK78 fiber for semipermanent MODU moorings, and now DM20 fiber for offshore permanent production moorings. The long-term creep properties of DM20 match industry requirements for the duration of permanent moorings. As requested by various industry guidelines and standards, a creep estimation model based on fiber data has been developed for DM20 to demonstrate the fiber's ability to meet creep performance requirements, and thus limit the need for full size rope testing. The fiber creep rate properties were confirmed by creep tests on subropes. Because of its extreme low creep elongations, the discard criterion of 10% permanent elongation - suggested in industry guidelines and standards for general HMPE types and MODU grade SK78 - needs to be re-considered for DM20 Dynamic stiffness of DM20 equals SK78, while secant stiffness of DM20 is higher than SK78, confirming the reduced creep of this new fiber. It is advised to determine stiffness values on (sub)rope level.


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    Title :

    Development of HMPE Fiber for Permanent Deepwater Offshore Mooring


    Contributors:
    Vlasblom, M.P. (author) / Boesten, J. (author) / Leite, S. (author) / Davies, P. (author)

    Published in:

    Publication date :

    2014


    Size :

    7 Seiten, 6 Bilder, 4 Tabellen, 20 Quellen



    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




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