Regularly inspecting your undersea cables will give you peace of mind, minimize downtime, and save the cost of replacing damaged equipment. In this blog series, we present a 5-step plan for inspecting and testing your cables, along with some general handling advice for storing and using them safely:
In this blog, we’ll explain how you know when you should call DeRegt Field Service for help with any cable issue.
DeRegt has developed a Practical Guide to help extend your seismic cable life and prevent equipment downtime through proper handling and inspection procedures. Once you have performed the recommended actions and discovered possible issues, the Guide includes an easy-to-follow decision-making chart that helps you identify likely causes for damaged cables. The chart then provides recommendations on steps to take in situations that commonly occur on seismic vessels.
In the chart, each type of damage to the cable is given a color code, either Green, Orange, or Red. Green issues indicate that field service might be needed in the future, but for now, you can continue to use the cable or termination. Make sure to continue following all the steps provided in the Guide, as well as in the handling, reeling, and installation instructions provided by your cable manufacturer.
One example of a Green issue is loss of the grease cover on the cable armor wires, which could lead to corrosion of the wires. Be sure to re-grease the cables before using.
Orange issues indicate that the cable is degrading, if thorough inspections show deviating values from the last results taken and from original manufacturing results. In these cases, it is expected that the cable or termination will begin to show faults in the future, so contacting a field service representative for advice is recommended.
An example of an Orange issue is observing nicks or gouges in the cable armor wires, which could be caused by rough handling or contact with sharp objects. This should have a minimal effect on the safe workload but keep the cable under observation and note the location on the log book.
Red issues are those that show significant damage to the cable and require immediate field service. One type of Red issue is visible corrosion or rust on the cable armor wires. The possible cause could be a loss of zinc plating or grease cover. The effect could be a reduction in the safe workload capability of the cable, and so the cable should not be used. Take a photo of the damage and contact DeRegt immediately.
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Damage
|
Test / Inspection
Procedure
|
Possible cause
|
Effect on
functionality
|
Recommendation
(general repair)
|
|
Nicks or
gouges in the
armour wire
|
Visual
|
Rough handling,
contact with sharp
objects
|
Minimal effect
on SWL
|
Keep under observation
|
|
Broken wires
|
Visual
|
Tight armour wire
coverage, or high
torque build up on cable, extreme
bending.
|
Lead to armour
wire damage
and loss in
SWL.
|
Contact De Regt Marine Cables for
advice; SWL and torque balancing
must be recalculated.
Check coverage, repair-push back in
to position and lash. Reel out and
back in, under no load to remove torque build up
|
|
Z-kinks in
armour wires,
twisted or
kinked wires.
Bird caging.
|
Visual
|
Torque build-up,
extreme bending,
cables experiences
severe compressive
forces, or cable loaded
past elastic yield
strength
|
Reduced SWL,
possible
damage to
internal
components
|
Photograph and contact De Regt
Marine Cables for advice.
|
|
99% or higher
coverage of
outer layer of
armour wires
over inner
layer.
|
Measure the cable diameter
of the HTC. The coverage will be 99% or higher when the cable diameter reduced to
21.2 mm or lower.
|
Cycling over sheave
wheels, torque build-up
|
May lead to
armour wire
damage, loose
riding wires.
|
Contact De Regt Marine Cables for
advice. High coverage suggests
significant torque build-up in outer
layer of armour.
Repair-reel cable out under minimal
load and reel back in with end free
to rotate and release torque.
|
|
Corrosion of
galvanising ZN
coverage.
|
Visual
|
Loss of grease covers.
|
Lead to
corrosion of
armour wires
|
Re-grease wires
|
|
Corrosion of
armour wires
|
Visual. Check cable for signs
of pitting corrosion and / or red rust
|
Loss of ZN plating. Loss
of grease cover
|
Reduction in
SWL.
|
Cable must not be used. Photograph and contact De Regt
Marine Cables for advice.
|
|
Circularity
|
Measure diameter of cable
at right angles using Vernier
callipers
|
Crushing, bending over sheave wheels
|
Increased wear
to cable.
|
Keep under observation.
Contact De Regt Marine Cables if
cables become obviously oval.
|
|
Cleanliness,
sand, grit, salt
residues in armour wire
interstices
|
Visual
|
General use
|
Increased
armour wear
|
Wash salt and grit off with fresh
water during every recovery.
Clean regularly.
|
|
Grease cover
|
Visual
|
General use
|
Increased wear
and corrosion
of armour
wires
|
Re-grease after cleaning
|
By regularly inspecting and testing your undersea cables and terminations, you can save on downtime and expensive repairs or replacements. Working with a manufacturer that can support all your cable needs and provide responsive field service gives you the best opportunity to avoid unnecessary problems with your equipment.
For a fresh look at how to inspect marine cables in the field along with directions on knowing when to call DeRegt for help, download our Practical Guide to Seismic Cable Handling.