API RP 2SM-2001 pdf free download
API RP 2SM-2001 pdf free download.Recommended Practice for Design, Manufacture, Installation, and Maintenance of Synthetic Fiber Ropes for Offshore Mooring.
3.3.4 Durability and Fatigue Factors which may limit the life of synthetic fiber ropes for deepwater mooring and which should be checked include hydrolysis, heating and internal abrasion, tension-tension fatigue and axial compressive fatigue. The possibility of creep rupture was commented on in the previous section. 3.3.5 External Abrasion and Cut Resistance Jacketing should be used on fiber ropes where external abrasion is expected to occur while in service and during installation and recovery (if applicable for movable tempo- rary moorings). Certain rope constructions may need a pro- tective jacket to keep the strength core strands together, such as parallel strands. In case a protective jacket is used, the interaction between the jacket and the rope core should be considered when evaluating rope properties, service life and installation/recovery procedures. Braided HMPEs, which have demonstrated to possess high wear resistance may be used without jacketing if it can be shown that the wear resis- tance will be adequate for the intended application. To date there have been no recorded incidents of detrimen- tal fishbite damage to large diameter fiber ropes, and there- fore this is not expected to be a concern for large deepwater fiber rope moorings. If damage due to fishbite becomes a concern for a specific application and/or location, means for minimizing such damage should be considered in the selec- tion and design of the fiber rope, and the frequency of subsea inspection may have to be increased. 4 Rope Design and Properties 4.1 GENERAL This section provides an overview of typical rope materi- als, rope constructions, rope termination types and indications of their effect on final rope assembly properties. The principal components of synthetic fiber ropes are yarns supplied by fiber makers, which are used in the main load-bearing core of the rope. The rope core may also contain marine finishes such as lubricants and fillers, and other materials.
4.2 ROPE MATERIAL 4.2.1 Fiber Types and Properties The choice of a particular fiber material depends on the nature of the application and on the level of confidence in the material. Polyester and aramid ropes do not have potential creep rupture problems. HMPE and aramids have better strength to weight ratios and are stiffer than polyester and nylon, which has different wet and dry abrasive properties. Nylon’s low stiffness (lower than polyester) may be useful where a more compliant system is desired. 4.2.2 Yarn Quality Quality control procedures stated in Section 7 of this docu- ment should be used to ensure that yarn quality is maintained. 4.2.3 Marine Finish Typically, synthetic fiber manufacturers apply a non-water soluble marine finish coating to polyester, nylon, and aramid marine ropes to enhance performance. Purposes of the marine finish include: • Increasing the initial strength (translational efficiency) of the rope. • Providing lubrication to assist bedding-in of the rope during initial tensioning. • Increasing the rope’s service life by reducing yarn-to- yarn abrasion. Minimum requirements on the quality of marine finish and its long-term durability are described below. A more detailed discussion on these requirements can be found in Appendix E.
4.2.3.1 Quality of Marine Finish Due to the potential importance of marine finishes on deepwater moorings, the following should be followed: a. Fiber, yarn and rope data used for design of deepwater moorings should explicitly denote whether the data was gen- erated from samples which included a marine finish, and give the descriptive designation of the marine finish with the man- ufacturer’s fiber certification. b. As part of the prototype rope fatigue qualification testing (6.3.6), post-test analysis of the fibers (see 4.2.3.2) should demonstrate that the finish remains effective during wet cyclic fatigue for at least the duration of the testing. In addi- tion, as part of the rope specification (6.2) the fiber or rope supplier should demonstrate that the marine finish remains effective in seawater for at least one year. c. As part of deepwater mooring procurement quality control, metrics of finish quality such as yarn-on-yarn abrasion resis- tance or overfinish add-on level should be used to confirm that the yarn used in the production ropes has characteristics comparable to yarn used in the prototype rope (see 7.2.2).
