EoW May 2009

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EuroWire – May 2009 58
technical article
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.
A deployment at sea can 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/mm2 (13,400psi) of water
pressure.
All of the equipment was tested to
6,096metres (20,000 ft) or 61 N/mm2
(8,900psi) of water pressure. Oceaneering
tested the Deep-Sea ROV cable on site
with a small hydrostatic chamber.
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.
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 56th IWCS,
held in Florida in 2007, and is reproduced
with the permission of the organisers.
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:
Oceaneering International, Inc
Hanover
Maryland USA
Website:
Set Distance (m) Maximum Number of Turns
before Attn. Failure
Maximum Number of Turns
before Fibre Break
0.50 20 40
0.75 40 50
1.00 50 60
1.25 70 70
1.50 70 80
Table ▲ ▲ 5: Hockle Test Results