Page 35 - Analysis Report of Global Market in the Submarine Cable Field (2017)

& C) during deployment & recovery operations. The deployment two separate operations and to take advantage of vessel availability or
will demonstrate that the BU will not spin and twist Legs B&C during different geographical locations. Hengtong decided to complete all trials
deployment, due to the cable torsional characteristics of Leg A. A worst from the same cable-ship platform and to mobilise all personnel, test
case scenario is the deployment and recovery of a BU in deep water using equipment and cable systems at one time from the Hengtong Marine
LW cable (where cable tensions will be much closer to the cable NTTS), Port in Changshu, China.
rather than an armoured BU in shallow water, where there is a much
larger factor of safety over cable working tensions. 3.6 Which Cable Types and lengths of cable: Sufficient cable lengths
should be supplied to allow the cable ship to deploy the system safely,
The relative size and shape of Cable Joints, Repeaters and Branching Units
using industry standard cable working procedures. The system cable
should be a mix of cable types, including in-line transitions, cable joints
and bodies.

3.6.1 For surface lay operations there should be sufficient cable length to
allow the cable ship to generate a steady state cable deployment catenary
in surface lay mode and to control the cable slack deployed. The distance
between optical amplifier bodies should be planned so that one body is
on the seabed, before the next body is deployed from the cable-ship.

3.6.2 For branching unit deployment, sufficient lengths of cable, should
be provided to allow cables to be laid & buoyed off, picked up and
for offshore shipboard joints to be made, with system integration the
Branching unit on-board the cable ship.
3.2 Sea Trial Location & water depth: The selection of the sea trial
location is critical in that it can affect permits & permissions to operate
and transit distance from Port. An open exposed location will give 3.6.3 For Plough burial of cables, the armoured cables should be
a good test of products (dynamic tension variation due to swell and sufficiently long to allow the plough to be launched from the vessel
waves), at the risk of weather delays, while a sheltered location will without any joints or other bodies being deployed through the plough
provide calmer seas (relatively steady tensions) and low risk of weather during this process. The selected water depth for this operation will also
delays. To be a realistic sea trial for international clients the selected have a major influence on cable lengths required.
location should tend to be open and exposed, as this will offer a more
severe test of the cable system. The water depth will dictate the cable 3.7 Which Optical Fibre types and number: The cable used on the sea
tensions applied to the cables. Hengtong Marine chose to complete a trial should incorporate a wide range of fibre types (different suppliers
5000m water depth surface lay trial, a 4000m water depth Branching and specifications) and fibre counts. The Hengtong Marine sea trial used
Unit trial and a 500m water depth plough burial trial. 5 types of optical fibres from 3 suppliers, including the Hengtong G654
& G652D fibres, and cables with fibre counts ranging from 8, 16 and 24
fibres.
3.3 Sea trial seabed survey: Is it necessary to complete a full bathymetric
and plough burial assessment survey of the sea trial area? This would Hengtong Marine FibreIn Metal Tube (FIMT) production line
be a costly exercise both in terms of timescales (separate mobilisation
in advance of the system sea trials) and also costs incurred. The survey
requirements will also be influenced to a great extent by the marine
installer selected for the trials. For the Hengtong Marine Sea trials the
marine installer selected was satisfied to carry out an onsite sounding
run to determine the seabed profile (slopes) and water depth (in deep
water) and to select a separate location for ploughing operations close
to existing in service international systems where geophysical seabed
parameters where know, and cable burial could be achieved (while
respecting the International Cable Protection Committee (ICPC)
operational recommendations). 3.8 Which cable features &repairs to be included: The sea trial
operation is an excellent opportunity to include some standard cable
3.4 Timing of the sea trial, weather considerations: Some cable features, splices and repairs (which have already passed land based testing
operations are more weather sensitive than others, for example plough as part of the qualification process). High strength fibre splicing, in-line
burial (launch & recovery operations) are much more weather sensitive tube joints, copper weld repairs, inner armour wires welds, insulation
(vessel motion) than deep water surface lay operations. There is little repairs (heat shrink and moulded repairs), outer armour wire welds and
point in completing the sea trial when weather conditions are perfect, inline cable transitions should all be sea trialled.
as the cable system products will not see a realistic test of actual marine
deployment conditions & the trial results could be open to criticism 3.9 Location and type of cable joints: The location of cable joints
by future clients. Likewise, it is pointless to select a time window when should be carefully selected so as not to affect marine deployment
weather conditions are so severe that no cable work can be achieved operations (such as planned plough launch activity, or planned plough
(and the cable ship is on downtime due to weather delays). At Hengtong recovery positions). Most clients will use the Universal Cable Joint for
Marine we waited for a reasonable time period which was considered system maintenance so they usually expect to see this type of joint in the
early in the cable working season, where the risk of some weather delays sea trial, together with any supplier propriety factory cable joint designs.
was expected, but this was tempered by the requirement to achieve a Stages in the assembly & build of a Universal Cable Joint
good dynamic test of the cable system products.
3.5 Duration of sea trial, one operation or several separate trials? It
is possible to split the plough burial trials and the surface lay trials into
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