Arctic technology: Winterisation of FPSO 38 Cruise ... - Ship & Offshore

SHIPBUILDING & EQUIPMENT | GREEN SHIP TECHNOLOGY
Effi ciency
tests
EEDI | European Maritime Safety
Agency (EMSA) has awarded Finish
service provider Deltamarin a
contract for a study on tests and
trials of the Energy Effi ciency Design
Index (EEDI) as developed
by the IMO. The main objective
of the contract is to provide
EMSA with a technical study on
the EEDI, in order to refi ne its
application for certain categories
of RoRo ships and to identify the
potential application of the index
or any alternative method to
improve the energy effi ciency of
purpose-built vessels from a technical
and design point of view.
Deltamarin’s commission includes
fi rstly the refi nement of
the EEDI formula for RoRo and
RoPax vessels. In this context,
Deltamarin shall assess the current
baselines approach for volume
and weight carriers and
consider the various IMO submissions
at previous MEPC sessions.
If necessary, a refi nement
or an adjustment of the baselines
for the volume and weight carriers
will be proposed. Deltamarin
is also to identify possible correction
factors to be included in
the EEDI formula for RoRo and
RoPax vessels. In case no correction
factor is suitable, Deltamarin
has to develop an alternative
approach to address energy effi
ciency for the applicable vessel
types, arrange test/trials of
the proposed approach, and
draw conclusions on its suitability.
The study will also include
a comparative analysis looking
at the greenhouse gas emission
reduction potential between the
current EEDI approach and the
potential new proposal.
Secondly, according to the contract,
Deltamarin will develop a
frame work to address the energy
effi ciency of purpose-built vessels
and specialised ships. Based
on representative samples establishing
baselines for these vessel
categories, requirements for any
additional correction factors will
be identifi ed. The main goal will
be to develop methods on how to
improve energy effi ciency of these
vessels during the design phase.
20 Ship & Offshore | 2011 | N o 1
Corrosion studies on ballast water
CLEANBALLAST | Germanybased
RWO, a worldwide supplier
of systems for water and
wastewater treatment aboard
ships and offshore rigs, in cooperation
with a leading European
corrosion institute
(SWEREA KIMAB) and the classifi
cation society Germanischer
Lloyd (GL), has carried out
thorough accelerated corrosion
studies in treated full-salinity
sea water with the CleanBallast
ballast water treatment (BWT)
system. The tests simulated operation
over an approximate
entire lifetime of a ballast water
tank/piping structure of approximately
40 years.
Functionality of
CleanBallast
CleanBallast has been designed
to operate in waters with low
and full salinity. The natural
corrosiveness of those environments
differs signifi cantly, with
full salinity (>32PSU) being a
very corrosive medium to common
construction materials. A
larger quantity of active chlorine
also has further negative
effects on corrosiveness, such
as the increase of the wear rate
of non-passivated metals.
The disinfection unit “Ecto-
Sys®” utilised by the Clean-
Ballast system is based on
electrochemistry but operates
very differently compared with
conventional chlorination or
electrolysis systems using salt
water (containing chloride),
where a maximum production
of active chlorine is desired.
Instead, EctoSys® produces
short-lived mixed oxidants,
which have a more striking
and powerful effect compared
with active chlorine. Thus, the
EctoSys® is not dependent on
chloride content (salinity) but
produces oxidants directly
from the water. The negative
effects of active chlorine on
corrosiveness can effectively
be avoided.
In natural brackish and full-salinity
seawater, the disinfection
unit EctoSys® will – besides the
short-lived oxidants hydroxyl
radicals – only produce low
levels (up to maximum 2mg/l)
of more persistent oxidants,
summarised as TRO (Total
Residual Oxidants). Being oxidising
agents, such substances
in higher concentrations are
relevant for corrosive properties
of water. TRO will decay
via interactions with dissolved
organic matter. Fig. 1 illustrates
a typical decay curve of TRO,
showing that the natural blank
level of 0.2 – 0.3mg/l of TRO is
reached within approximately
two hours.
Simulation of entire
lifetime
The studies undertaken by
RWO, SWEREA-KIMAB and
Fig. 1: Natural decay of residual oxidants TRO produced by
CleanBallast, T=22°C, pH=7.9, salinity 15PSU
GL included accelerated comparative
studies (treated and
untreated seawater) using both
uncoated steel test specimens
but more importantly test
specimens with two-coat paint
systems according to NOR-
SOK Coating 3B approved according
to DNV Classifi cation
Note 33.1 class B1, common
and approved for use in ballast
water tanks, for instance,
the Jotun system ‘Balloxy HB
light’. The tests included parallel
tests with both continuous
exposure to the water and
intermittent cyclic exposure
to water and air. Intermittent
exposure better resembles the
real conditions in ballast water
tanks and a corrosive case
worse than continuous exposure.
The tests were accelerated,
that is, the exposure of the
test panels was set to simulate
an approximate entire lifetime
of a ballast water tank/piping
system, regarding initial maximum
concentration of TRO
and natural decay.
The evaluation of the exposed
test panels was performed according
to the following standards:
� SS-EN ISO 9227:2006 (salt
spray 1440 h)
� SS-EN ISO 6270-1 (condense
1440 h)
� SS-EN ISO 2812-2 :2007
(immersion 3000 h)
�
EN ISO 15711:2004 (ca-
thodic 3000 h).
Based on the result of these
tests, both SWEREA KIMAB
and Germanischer Lloyd concluded
that there are no additional
corrosive properties of
seawater treated with CleanBallast,
compared with untreated
seawater. These studies were
later recommended by the IMO
technical group GESAMP-BW-
WG, as part of the guidance for
other vendors developing ballast
water treatment analysis, to
be included in their respective
approval process (ref. MEPC
59/2/16, §4.5.1).
CleanBallast is certifi ed and
classifi ed by GL as compatible
with epoxy-based ballast water
tank coating systems.