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Leading Fibre Rope Solutions
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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, GAMA 98® ropes include up to 12 sub-ropes, each sub-rope being a long lay length 8 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, but a present our limiting capacity is the reel take-up stand which is designed to handle single piece weights of up to 80 tonnes gross (rope and reel). This can be upgraded if warranted by projectsspecific 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.
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| 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 J oint 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)
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Stiffness |
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Minimum
Breaking
Load
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Ø |
Mass
in
air
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Mass
in
water
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Cycling Between
10-30% MBL
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Cycling between
20-30% MBL
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Cycling between
40-50% MBL
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| (TF) | (mm) | (kg/m) | (kg/m) | MN | MN |
MN |
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| 450 | 125 | 10,8 | 2,8 | 68 | 100 |
121 |
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| 500 |
132 | 12,2 | 3,1 |
76 |
111 |
134 |
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| 600 | 144 | 14,4 | 3,7 | 91 | 134 |
161 |
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| 700 |
156 |
16,7 |
4,3 |
106 |
156 |
187 |
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| 800 |
167 |
19,3 |
4,9 |
121 |
178 |
214 |
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| 900 |
177 |
21,6 |
5,5 |
136 |
200 |
241 |
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| 1000 |
186 |
24,0 |
6,2 |
151 |
223 |
268 |
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| 1100 |
196 |
26,5 |
6,8 |
166 |
245 |
295 |
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| 1200 |
201 |
28,3 |
7,3 |
181 |
267 |
321 |
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| 1250 |
203 |
29,0 |
7,4 |
189 |
278 |
335 |
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| 1300 |
208 |
30,4 |
7,8 |
196 |
289 |
348 |
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| 1400 |
217 |
33,0 |
8,5 |
212 |
312 |
375 |
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| 1500 |
223 |
34,8 |
8,9 |
227 |
334 |
402 |
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| 1600 |
232 |
37,7 |
9,7 |
242 |
356 |
429 |
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| 1700 |
238 |
39,5 |
10,1 |
257 |
379 |
455 |
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| 1800 |
246 |
42,4 |
10,9 |
272 |
401 |
482 |
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| 1900 |
251 |
44,2 |
11,3 |
287 |
423 |
509 |
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| 2000 |
259 |
46,8 |
12,0 |
302 |
445 |
536 |
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| 2100 |
266 |
49,7 |
12,7 |
317 |
468 |
562 |
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| 2200 |
274 |
52,5 |
13,5 |
332 |
490 |
589 |
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| 2300 |
279 |
54,6 |
14,0 |
347 |
512 |
616 |
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| 2400 |
286 |
57,4 |
14,7 |
363 |
534 |
643 |
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| 2500 |
290 |
59,2 |
15,2 |
378 |
557 |
670 |
