Feature Story

SEA CONPrecisions Development of

Umbilical Distribution
By Fernando Hernandez, SEA CON Technical Advisor

Umbilicals & Tethering

Umbilicals are a critical link to an ROVs functionality as
much as they are to Umbilical Distribution Assemblies
(UDA). The more both technologies are creatively expanded,
the more technological advancements can go from science
fiction to fact. Both technologies share a common feature:
they allow for communication between topside facilities
(multi-service vessels, rigs, etc.) and subsea architecture (Xmas trees, subsea pumps, etc.), expanding the capabilities for
data distribution.

distribution center for data and power (hydraulic capabilities

can also be applied). Both data and power are distributed
through flying leads with subsea-deployable connectors on
both ends and are linked by a Pressure Balanced Oil Filled
(PBOF) conduit hose. The PBOF hose (typically 13mm or
20mm) with connectors extends the UDA by allowing communication with subsea assets.
Despite apparent similarities between the deployment of
ROVs and UDAs, there are many differences. For example,
an ROVs TMS is terminated on the surface at the umbilical
to enable tethered travel, but UDA terminations do not have a
built-in TMS; therefore, flying leads serve as the critical component to connect UDAs to existing subsea assets. Such connections are complex because they are done in open water,
but a successful connection ensures operators can maximize
the potential of a single umbilical.

Figure 1: Visual of UDA with ROV tether

Unification of Tethering
The work of an Ultra-Deepwater ROV begins when it is
overboarded via a Launch and Recovery System (LARS).
The ROV will be tethered to a Top Hat or Cage Assembly via
a Tether Management System (TMS) where the umbilical terminates. Once the ROV reaches operational depth, the ROV
can tether out to its subsea focal point. The production
umbilical is terminated at the UDA and serves as the communication link between mudline and surface. The UDA is similarly overboarded and installed into its designated position on
the ocean floor. Upon landing, the UDA can be utilized as a

Figure 2: LARS deployment

of ROV

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Figure 3: Umbilical reel

Figure 4: Flying lead with splice box

Both ROV and production umbilicals extend communication paths, enhancing the capability of subsea equipment and
fields. Subsequently, current flying lead connector technology
expands a fields capability by eliminating the need to build,
manufacture, and deploy additional umbilicals

Optical & Electrical Flying Leads

Before electrical and optical flying leads became a staple
for open-water communication, the PBOF conduit hose
underwent extensive analysis and development via qualification testing, design, and engineering. John Johansen,
Technical Manager for SEA CONPrecision, was instrumental in the development of PBOF hoses to ensure they met
the offshore demands of the early 90s. Today, the PBOF hose
assemblies continue to meet operational requirements for
deepwater operations.
ROV pilots continue to demonstrate the worth of PBOF
hoses, as flying leads have to be engaged and recovered from
deployment frames while being handled by an ROVs manipulator to install at destination points. Pilots must manage the
tether as it travels on an XYZ axis with a flying lead, increasON&T July 2012

Subsea Fiber Optics

Figure 5: Handling of PBOF hose with SEA CON HydraLight

ing the possibility of tangling the ROVs tether or the flying

lead. The flying lead is also at risk of being dropped to the
ocean floor or becoming snagged and inadvertently damaged.
To allay these concerns, the outer jacket, inner liner, strain
elements, and armor elements of the PBOF hose assembly
underwent extensive development. SEA CONPrecisions
PBOF hoses are now designed to handle inadvertent stretching during subsea operations to mitigate potential damage to
fiber or copper lines. Extensive stress and pull tests ensure
that a 2% stretch of hose is permissible during operations.

Figure 8 illustrates the spatial constraints when an ROV

and skid are mated, caused by
the skid being enclosed between
the LARS deck and ROV. Skid
technology has been influenced
by the need for these skids to
host additional equipment when
ROV tooling and intervention
equipment exceeds the space an
ROV has for auxiliary components. Hydraulic lines (hardplumbed/soft-plumbed) and
electrical and fiber optic
whips for equipment on skids
Figure 7: Work on ROV
are under the same spatial limiwithout skid
tations. Should a drymate connector or fiber optic whip be placed under excessive stress in
order to fit in a confined area, the stress can severely damage a
bulkhead connector or cause the whip to break from the mating area. The potential for further damage increases when
equipment must be removed to carry out repairs or maintenance, which requires the removal of components and compact equipment, including fiber optic and electrical whips.

MKII Fitting Assembly

The engineering of the MKII fitting assembly was instrumental in ensuring sustainability of the PBOF hose. The MKII
assembly is a two-layer design with tension and pressure armor
in between and a break-load tension of 10,000 newton meters.
Engineered to handle volumetric expansion and elongation, the
MKII assembly, coupled with PBOF hoses, decreases the risk
of potential downtime during the installation of flying leads in
a dynamic application. SEA CONPrecision would revisit
the MKII fitting and associated PBOF assembly to apply such
technology to a static application.
Figure 8: ROV with mounted skid

Despite the limitations of using ROV skids, skid technology continues to be a necessary extension for ROVs. Skids
have been developed for contingent and non-contingent situations that involve actuation of BOPs, hydrate remediation,
dewatering of flowlines, auxiliary functionality to control
modules, etc. Therefore, when telemetry and power are essential for these operations, flying lead technology can be applied
to this static application to expand the ability of an umbilical.

Figure 6: SEA CONPrecision MKII offerings

This answer was found in the development of an 8mm

MKII fitting with a proprietary hose that resembles clear, flexible tubing for ROV static and limited special applications.

ROV Intervention
The small profile of the 8mm MKII assembly reduces
harm to fibers or connection points in constrained areas and
allows it to serve as a bridge for the skid and tooling to tap
into the power and telemetry of an ROVs umbilical. It also
allows for distribution within the constrained area between an
ROV intervention skid and tooling.
ON&T July 2012

Figure 9: PBOF hose constraints on intervention skid

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Subsea Fiber Optics

Feature Story
tor can distribute data and
power through two different
paths using 8mm, 13mm, or
20mm hoses on either end.
Figure 12 illistrates the application of such combination
options. The accumulation
of these technologies is
essential in bridging static
and dynamic operational
requirements and creates a
viable solution for openwater and drymate/surfaceterminated communication.

Figure 12: IDA with 13mm

and 8mm PBOF

Figure 10: Troubleshooting of intervention skid

8mm, 13mm, and 20mm PBOF Assemblies

SEA CONPrecisions intimate involvement with data

distribution led to the development of 8mm, 13mm, and
20mm conduit hoses with MKII technology. These advancements led to the development of another product, the IDA
(Inline Distribution Assembly), to creatively distribute data to
actual subsea assets such as X-mas trees and Subsea Pumps.
This ability is credited to the field-installable IDAs
hybridization of the 8mm, 13mm, and 20mm technologies,
which can be applied to those assets that need internal, nonopen water (drymate) distribution.

Figure 13: IDA assembly

48-Channel HydraLight

Figure 11: Cross-section of typical bulkhead mounting

To achieve this, the IDA is terminated to a bulkhead on an

asset that matches the opposite end of a bulkhead on a UDA in
order to correspond with the bridging flying lead. When communication is bridged to an independent subsea asset, the IDA can have
a single 13mm PBOF that comes from an assets bulkhead. By terminating the bulkhead on an asset to the IDA assembly, an opera-

Advancement of subsea distribution continues today as

demand increases for this technology to do even more. To
accomplish this, great energy is focused on connector development. The concept of utilizing a higher-channel capacity for an
already proven technology led to the development of the 48channel HydraLight. The 48-channel connector has already
been designed to meet these needs, and a 24-channel version
of this design is in its qualification stage. The 48-channel fiber
optic connector builds on the proven track record and fieldtested technology of its 8-channel predecessor a connector
that is already internationally-recognized and qualified and
will offer a greater degree of confidence and success in the
field. What developments this will lead to in the future remain
unknown, but promises to be interesting regardless.
For more information, visit www.seaconworldwide.com.

Figure 14: 24 channel HydraLight during testing

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ON&T July 2012