EoW May 2009

technical article

The test results from Oceaneering assure the ROV team that the cable will meet the rigorous demands of the deep-sea environment. n 7 Acknowledgments Special thanks to the CommScope fibre optics product engineering staff for all of their hard work, namely Robert D Paysour Jr, Kevin Sigmon, Chris Rogers and Joe Lichtenwalner. This paper was presented at the 56 th IWCS, held in Florida in 2007, and is reproduced with the permission of the organisers.

Maximum Number of Turns before Attn. Failure

Maximum Number of Turns before Fibre Break

Set Distance (m)

0.50 0.75 1.00 1.25 1.50

20 40 50 70 70

40 50 60 70 80

Table ▲ ▲ 5 : Hockle Test Results

The standard attenuation requirement was used for this test. The standard stated that the change in attenuation should remain less than 0.05dB for 90% of the fibres under test and less than 0.15 for 100% of the fibres under test. If the fibre met the change in attenuation requirements, then the procedure was repeated until a failure occurred. From the results it can be seen that the cable will withstand an extreme hockle situation. The results far exceeded expectations, eclipsing the results from previous cable designs. With other cable designs, a predictable number of twists would form a hockle in the cable. Once a hockle was formed, cable failure was almost guaranteed. In the current case a hockle had to be combined with excessive twisting in order to initiate a failure. This was definitely a more robust cable than any of the previous iterations. 5.2 Oceaneering International testing In addition to CommScope testing, Oceaneering performed a few internally created tests in order to build confidence in the cable design. cost millions of dollars, so Oceaneering methodically tests all components of the ROVs. The Deep-Sea ROV cable was a small but vital component; therefore, Oceaneering engineers were uncompromising re- garding any poor test results. 5.2.1 Specialised hydrostatic pressure test In order to simulate the extreme depths of the ocean, a hydrostatic pressure tank was utilised by the Oceaneering team. These tanks are capable of simulating 9,100metres (30,000 ft) depths with a pressure of 92N/mm 2 (13,400psi) of water pressure. All of the equipment was tested to 6,096metres (20,000 ft) or 61 N/mm 2 (8,900psi) of water pressure. Oceaneering tested the Deep-Sea ROV cable on site with a small hydrostatic chamber. A deployment at sea can

Immediate feedback on the pressure performance allowed for quicker turn around time for any necessary design changes or process alterations. 5.2.2 Buoyancy test This test was performed within the Oceaneering facility. It was extremely important to the Oceaneering team that the new cable was neutrally buoyant, so as not to affect the buoyancy of the vehicle itself. The spooled cable located onboard the ROV makes up a large percentage of the overall weight of the vehicle. As the cable is paid out it can potentially cause a shift in the buoyancy of the vessel. This test was performed by weighing the spool of cable on a gravimetric scale located in a salt water bath. 5.2.3 Fibre pack payout test A third party was used to pack the fibre onto the spool, therefore an acceptance test needed to be performed on the finished fibre packs which had both a second party supplier and a third party supplier for one piece of equipment. The quality of this cable has to be flawless to meet the requirements of both Oceaneering and the spool manufacturer. Even if the cable met all of Oceaneering’s requirements, it did not mean approval from the spooling manufacturer. The fibre pack was tested underwater with a take-up spooling out the cable and an attenuation measuring device to monitor the cable’s attenuation values as it was paid out. 6 Conclusion From the testing completed at the CommScope Claremont facility developers had a good understanding of the capabilities of the new cable. This data can be compared to any future cable designs to see if a change in design or material will really improve the performance of this cable.

8 References

[1] ANSI/ICEA S-87-640-1999, “Standard for optical fiber outside plant communications cable” [2] GR-20-CORE Issue 2, “Generic requirements for optical fiber and optical fiber cable” [3] EN 187105:2002,“Single mode optical cable (duct/ direct buried installation)” [4] Random House Unabridged Dictionary, copyright© 1997

CommScope, Inc Fiber optic cable division Hickory North Carolina USA

Website : www.commscope.com Oceaneering International, Inc Hanover Maryland USA Website : www.oceaneering.com

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EuroWire – May 2009