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GAMA 98 ROPE FOR DEEP WATER TETHERS

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Design
GAMA 98® polyester rope tethers are made from high efficiency sub-rope cores laid parallel within an outer  braided jacket. Each sub-rope is computer monitored during tether manufacture to ensure all sub-ropes have equal tension and length, Typically, GAMA 98® ropes include 7 to 18 sub-ropes, each sub-rope being a long lay length 8 x 1 or 12 x 1 construction, which gives a 100% torque free rope.
 
Particle Filters
Filter elements are included between jacket and sub-rope cores. They are effective in filtering out particles greater than 5 microns whilst allowing free flooding of the rope. Filter systems can be provided to allow for ropes to be pre-installed on the seabed prior to vessel hook-up.
 
Length
Lankhorst Ropes' equipment can in theory manufacture ropes of infinite length. Recent investment in a new reel take-up stand brings our capacity to handle single piece weights of up to 150 tonnes gross (rope and reel). This can be upgraded if warranted by project specific requirements. Maximum length is a function of the maximum reel weight and the linear weight of the rope which is dictated by the required breaking load.
 
 Axial Stiffness
Stiffness is the ratio of rope load to strain variations between the lower (trough) and upper (peak) stresses imposed during testing. GAMA 98® is probably the stiffest rope construction currently available in the market for deepwater tether applications. This will result in less constructional stretch during the rope bedding-in and lower overall elastic stretch. These advantages translate into smaller platform offset and lower pre-tensioning during installation.
 
 
Fatigue Life
The fatigue life of polyester rope is typically quoted as being approximately 80 decades superior to steel wire tope. The fatigue life curve of GAMA 98® rope was established during the durability of polyester in Joint Industry Projects. The rope gets up to 10% stronger during initial cycling as the molecule chains in the individual yarns straighten out under constant cycling loading before losing strenght and returning to initial Minimum Breaking Load after approximately 30% of the fatigue life.                                                                        
 
Key Projects
Lankhorst Ropes executed the design and manufacture of GAMA 98® polyester rope tethers for major projects such as the Tahiti spar for Technip (Operator : Chevron), Thunder Hawk semi-submersible for SBM Atlantia (Operator : Murphy) and Cascade & Chinook FPSO for APL / BW Offshore (Operator : Petrobas Americas), Lucius spar for Technip (Operator: Anadarko), and Goliat FPSO for Eni Norge (Operator: Eni Norge). Gama 98® polyester tethers manufactured for the Goliat FPSO set a world record for the highest Minimum Breaking Load (MBL) ropes ever produced and tested.
 
 
 
 Minimum
Breaking 
Load                 
 Ø              
 Mass
in 
air                 
 Mass
in 
water  
 Cycling Between
10-30%  MBL
 
 Cycling between
20-30% MBL
Cycling between
40-50% MBL
 (TF) (mm) (kg/m) (kg/m) MNMN
MN
 450 125 10,8 2,8 68 100
 121
 500
 132 12,2 3,1
 76
 111
 134
 600 144 14,4 3,7 91 134
 161
 700
 156
 16,7
 4,3
 106
 156
 187
 800
 167
 19,3
 4,9
 121
 178
 214
 900
 177
 21,6
 5,5
 136
 200
 241
 1000
 186
 24,0
 6,2
 151
 223
 268
 1100
 196
 26,5
 6,8
 166
 245
 295
 1200
 201
 28,3
 7,3
 181
 267
 321
 1250
 203
 29,0
 7,4
 189
 278
 335
 1300
 208
 30,4
 7,8
 196
 289
 348
 1400
 217
 33,0
 8,5
 212
 312
 375
 1500
 223
 34,8
 8,9
 227
 334
 402
 1600
 232
 37,7
 9,7
 242
 356
 429
 1700
 238
 39,5
 10,1
 257
 379
 455
 1800
 246
 42,4
 10,9
 272
 401
 482
 1900
 251
 44,2
 11,3
 287
 423
 509
 2000
 259
 46,8
 12,0
 302
 445
 536
 2100
 266
 49,7
 12,7
 317
 468
 562
 2200
 274
 52,5
 13,5
 332
 490
 589
 2300
 279
 54,6
 14,0
 347
 512
 616
 2400
 286
 57,4
 14,7
 363
 534
 643
 2500
 290
 59,2
 15,2
 378
 557
 670
These data are forguidance purposes only and are subject to change without prior notice