carriage of liquified gas - p& i club ion
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1
Introduction
The renewed interest in gas, which started in the
1990s due to its excellent environmental
credentials, has seen an increase in the order
book for LNG carriers – LNG carriers being the
leviathans of the gas carrier fleet. Yet, while
attracting great interest, the gas trade still
employs relatively few ships in comparison to oil
tankers, and hence its inner workings are little
known except to a specialist group of companies
and mariners.
Considering the fleet of gas carriers of over
1,000 m3 capacity, the total of nearly 1,000 ships
can be divided into 5 major types according to the
following table:
By contrast, the world oil tanker fleet for a
similar size range is over 16,000 ships!
Given the relative paucity of knowledge on gas
tankers in comparison to oil tankers, the purpose
of this article is to describe the gas carrier genre,
its particularities within each type and its
comparison with other tankers. The aim is to
provide basic knowledge about gas carriers and
an overview of their strengths and weaknesses,
both from design and operational viewpoints.
A second article, on page 8, describes the
liquefied natural gas (LNG) carrier in more detail
and a third article, to be published later, will
describe the liquefied petroleum gas (LPG) carrier.
“The carrier shall properlyand carefully load, handle,stow, carry, keep, care forand discharge the goods
carried.”
Hague Rules, Articles iii, Rule 2
CAREFULLY TO CARRY
> continued over
UK CLUB FEBRUARY 2005 ISSUE 8
The carriageof liquefied gases
IN THIS ISSUE PAGE
The carriage ofliquefied gases 1
Liquefied natural gas 9
Bulk liquid cargoes– sampling 13
Carriage of potatoes 15
Fumigation of shipsand their cargoes 19
Scrap metal 24
Hold cleaning– bulk cargoes 26
Direct reduced iron 35
The introduction of a tanker designed to carry
compressed natural gas (CNG) is anticipated in
the near future. A number of designs have been
produced but, due to the relatively low
deadweight and high cost of these ships, the first
commercial application of this technology cannot
be predicted.
The gas carrier is often portrayed in the media
as a potential floating bomb, but accident
statistics do not bear this out. Indeed, the sealed
nature of liquefied gas cargoes, in tanks
completely segregated from oxygen or air,
virtually excludes any possibility of a tank
explosion. However, the image of the unsafe ship
lingers, with some administrations and port state
control organisations tending to target such
ships for special inspection whenever they enter
harbour. The truth is that serious accidents
related to gas carrier cargoes have been few,
and the gas carrier’s safety record is
acknowledged as an industry leader. As an
illustration of the robustness of gas carriers,
when the Gaz Fountain was hit by rockets in the
first Gulf War, despite penetration of the
containment system with huge jet fires, the fires
were successfully extinguished and the ship,
together with most cargo, salved.
Source: Braemar Seascope Gas (all information given in good faith but without guarantee).
The gas carrier fleet (end 2004)
Pressurised Semi-pressurised Ethylene Fully refrigerated LNG carriersLPG carriers LPG carriers carriers LPG carriers
Ship numbers 336 189 103 185 175
Total capacity (m3) 1,045,970 1,378,690 755,620 11,171,705 20,683,798
2
Carriage of liquefied gases continued
The relative safety of the gas carrier is
due to a number of features. One such,
almost unique to the class, is that cargo
tanks are always kept under positive
pressure (sometimes just a small
overpressure) and this prevents air
entering the cargo system. (Of course
special procedures apply when stemmed
for drydock). This means that only liquid
cargo or vapour can be present and,
accordingly, a flammable atmosphere
cannot exist in the cargo system.
Moreover all large gas carriers utilise a
closed loading system with no venting to
atmosphere, and a vapour return pipeline
to the shore is often fitted and used
where required. The oxygen-free nature
of the cargo system and the very serious
limitation of cargo escape to atmosphere
combine to make for a very safe design
concept.
The liquefied gases
First let us consider some definitions in
the gas trade. According to the IMO, a
liquefied gas is a gaseous substance at
ambient temperature and pressure, but
liquefied by pressurisation or
refrigeration – sometimes a combination
of both. Virtually all liquefied gases are
hydrocarbons and flammable in nature.
Liquefaction itself packages the gas into
volumes well suited to international
carriage – freight rates for a gas in its
non-liquefied form would be normally far
too costly. The principal gas cargoes are
LNG, LPG and a variety of petrochemical
gases. All have their specific hazards.
LNG is liquefied natural gas and is
methane naturally occurring within the
earth, or in association with oil fields. It is
carried in its liquefied form at its boiling
point of -162°C. Depending on the
standard of production at the loading
port, the quality of LNG can vary but it
usually contains fractions of some
heavier ends such as ethane (up to 5%)
and traces of propane.
The second main cargo type is LPG
(liquefied petroleum gas). This grade
covers both butane and propane, or a
mix of the two. The main use for these
products varies from country to country
but sizeable volumes go as power station
or refinery fuels. However LPG is also
sought after as a bottled cooking gas and
it can form a feedstock at chemical
plants. It is also used as an aerosol
propellant (with the demise of CFCs) and
is added to gasoline as a vapour pressure
enhancer. Whereas methane is always
carried cold, both types of LPG may be
carried in either the pressurised or
refrigerated state. Occasionally they may
be carried in a special type of carrier
known as the semi-pressurised ship.
When fully refrigerated, butane is carried
at -5°C, with propane at -42°C, this latter
temperature already introducing the
need for special steels.
Ammonia is one of the most common
chemical gases and is carried worldwide in
large volumes, mainly for agricultural
purposes. It does however have particularly
toxic qualities and requires great care
during handling and carriage. By
regulation, all liquefied gases when carried
in bulk must be carried on a gas carrier, as
defined by the IMO. IMO’s Gas Codes (see
next section – Design of gas carriers)
provide a list of safety precautions and
design features required for each product.
A specialist sector within the trade is
the ethylene market, moving about one
million tonnes by sea annually, and very
sophisticated ships are available for this
carriage. Temperatures here are down to
-104°C and onboard systems require
perhaps the highest degree of expertise
within what is already a highly specialised
and automated industry. Within this group
a sub-set of highly specialised ships is able
to carry multi-grades simultaneously.
Significant in the design and operation
of gas carriers is that methane vapour is
lighter than air while LPG vapours are
heavier than air. For this reason the gas
carrier regulations allow only methane to
be used as a propulsion fuel – any minor
gas seepage in engine spaces being
naturally ventilated. The principal
hydrocarbon gases such as butane,
propane and methane are non-toxic in
nature and a comparison of the relative
hazards from oils and gases is provided in
the table below:
Comparative hazards of some liquefied gases and oils
GASES OILS
HAZARD LNG LPG GASOLINE FUEL OIL
Toxic No No Yes Yes
Carcinogenic No No Yes Yes
Asphyxiant Yes (in confined spaces) Yes (in confined spaces) No No
Others Low temperature Moderately low Eye irritant, narcotic, Eye irritant, narcotic,temperature nausea nausea
Flammability limits 5-15 2-10 1-6 Not applicablein air (%)
Storage pressure Atmospheric Often pressurised Atmospheric Atmospheric
Behaviour if spilt Evaporates forming a Evaporates forming an Forms a flammable Forms a flammablevisible ‘cloud’ that explosive vapour cloud pool which if ignited pool, environmentaldisperses readily and is would burn with clean-up is requirednon-explosive, unless explosive force,contained environmental clean-up
may be required
3
3,200 m3 coastal LPG carrier with cylindrical tanks.
78,000 m3 LPG carrier with Type-A tanks
16,650 m3 semi pressurised LPG carrier
135,000 m3 LNG carrier with membrane tanks
137,000 m3 LNG carrier with Type-B tanks (Kvaerner Moss system)
> continued over
Design of gas carriers
The regulations for the design and
construction of gas carriers stem from
practical ship designs codified by the
International Maritime Organization
(IMO). This was a seminal piece of work
and drew upon the knowledge of many
experts in the field – people who had
already been designing and building such
ships. This work resulted in several rules
and a number of recommendations.
However all new ships (from June 1986)
are built to the International Code for the
Construction and Equipment of Ships
Carrying Liquefied Gases in Bulk (the IGC
Code). This code also defines cargo
properties and documentation, provided
to the ship (the Certificate of Fitness for
the Carriage of Liquefied Gases in Bulk),
shows the cargo grades the ship can carry.
In particular this takes into account
temperature limitations imposed by the
metallurgical properties of the materials
making up the containment and piping
systems. It also takes into account the
reactions between various gases and the
elements of construction not only on
tanks but also related to pipeline and
valve fittings.
When the IGC Code was produced an
intermediate code was also developed by
the IMO – the Code for the Construction
and Equipment of Ships Carrying
Liquefied Gases in Bulk (the GC Code).
This covers ships built between 1977 and
1986.
As alluded to above, gas carriers were
in existence before IMO codification and
ships built before 1977 are defined as
‘existing ships’ within the meaning of the
rules. To cover these ships a voluntary
code was devised, again by the IMO – the
Code for Existing Ships Carrying Liquefied
Gases in Bulk (the Existing Ship Code).
Despite its voluntary status, virtually all
ships remaining in the fleet of this age –
and because of longevity programmes
there are still quite a number – have
certification in accordance with the
Existing Ship Code as otherwise
international chartering opportunities
would be severely restricted.
Cargo carriage in the pressurised fleet
comprises double cargo containment –
hull and tank. All other gas carriers are
built with a double hull structure and the
distance of the inner hull from the outer
is defined in the gas codes. This spacing
introduces a vital safety feature to
mitigate the consequences of collision
and grounding. Investigation of a
number of actual collisions at the time
the gas codes were developed drew
conclusions on appropriate hull
separations which were then
incorporated in the codes. Collisions do
occur within the class and, to date, the
codes’ recommendations have stood the
test of time, with no penetrations of
cargo containment having been reported
from this cause. The double hull concept
includes the bottom areas as a protection
against grounding and, again, the
designer’s foresight has proven of great
value in several serious grounding
incidents, saving the crew and
surrounding populations from the
consequences of a ruptured containment
system.
So a principal feature of gas carrier
design is double containment and an
internal hold. The cargo tanks, more
generally referred to as the ‘cargo
containment system’, are installed in the
hold, often as a completely separate
entity from the ship; i.e. not part of the
ship’s structure or its strength members.
Herein lies a distinctive difference
between gas carriers and their sisters, the
oil tankers and chemical carriers.
Cargo tanks may be of the
independent self-supporting type or of a
membrane design. The self-supporting
tanks are defined in the IGC Code as
being of Type-A, Type-B or Type-C.
Type-A containment comprises box-
shaped or prismatic tanks (i.e. shaped to
4
Carriage of liquefied gases continued
fit the hold). Type-B comprises tanks
where fatigue life and crack propagation
analyses have shown improved
characteristics. Such tanks are usually
spherical but occasionally may be of
prismatic types. Type-C tanks are the
pure pressure vessels, often spherical or
cylindrical, but sometimes bi-lobe in
shape to minimise broken stowage.
The fitting of one system in
preference to another tends towards
particular trades. For example, Type-C
tanks are suited to small volume carriage.
They are therefore found most often on
coastal or regional craft. The large
ballast tanks and if problems are to
develop with age then the ballast tanks are
prime candidates. These ships are the most
numerous class, comprising approximately
40% of the fleet. They are nevertheless
relatively simple in design yet strong of
construction.
Cargo operations that accompany such
ships include cargo transfer by flexible
hose and in certain areas, such as China,
ship-to-ship transfer operations from
larger refrigerated ships operating
internationally are commonplace.
Records show that several ships in this
class have been lost at sea because of
collision or grounding, but penetration of
the cargo system has never been proven.
international LPG carrier will normally be
fitted with Type-A Tanks. Type-B tanks
and tanks following membrane principles
are found mainly within the LNG fleet.
The pressurised fleet
The first diagram, on the previous page,
and the photograph above show a small
fully pressurised carrier. Regional and
coastal cargoes are often carried in such
craft with the cargo fully pressurised at
ambient temperature. Accordingly, the
tanks are built as pure pressure vessels
without the need for any extra
metallurgical consideration appropriate
to colder temperatures. Design pressures
are usually for propane (about 20 bar) as
this form of LPG gives the highest vapour
pressure at ambient temperature. As
described above, ship design comprises
outer hull and an inner hold containing
the pressure vessels. These rest in saddles
built into the ship’s structure. Double
bottoms and other spaces act as water
Pressurised LPG carrier with cylindrical tanks.
In one case, a ship sank off Italy and
several years later refloated naturally, to
the surprise of all, as the cargo had
slowly vaporised adding back lost
buoyancy.
The semi-pressurised fleet
In these ships, sometimes referred to as
‘semi-refrigerated’, the cargo is carried in
Semi-pressurised LPG carrier.
pressure vessels usually bi-lobe in cross-
section, designed for operating pressures
of up to 7 bars. The tanks are
constructed of special grade steel
suitable for the cargo carriage
temperature. The tanks are insulated to
minimise heat input to the cargo. The
cargo boils off causing generation of
vapour, which is reliquefied by
refrigeration and returned to the cargo
tanks. The required cargo temperature
and pressure is maintained by the
reliquefaction plant.
These ships are usually larger than the
fully pressurised types and have cargo
capacities up to about 20,000 m3. As
with the fully pressurised ship, the cargo
tanks are of pressure vessel construction
and similarly located well inboard of the
ship’s side and also protected by double
bottom ballast tanks. This arrangement
again results in a very robust and
inherently buoyant ship.
The ethylene fleet
Ethylene, one of the chemical gases, is
the premier building block of the
petrochemicals industry. It is used in the
production of polyethylene, ethylene
dichloride, ethanol, styrene, glycols and
many other products. Storage is usually
as a fully refrigerated liquid at -104°C.
Ships designed for ethylene carriage
also fall into the semi-pressurised class.
They are relatively few in number but are
among the most sophisticated ships
afloat. In the more advanced designs
they have the ability to carry several
grades. Typically this range can extend to
ethane, LPG, ammonia, propylene
butadiene and vinyl chloride monomer
(VCM), all featuring on their certificate of
fitness. To aid in this process several
5
independent cargo systems co-exist
onboard to avoid cross contamination of
the cargoes, especially for the
reliquefaction process.
The ships range in size from about
2,000 m3 to 15,000 m3 although several
larger ships now trade in ethylene. Ship
design usually includes independent
cargo tanks (Type-C), and these may be
cylindrical or bi-lobe in shape constructed
from stainless steel. An inert gas
generator is provided to produce dry
inert gas or dry air. The generator is used
for inerting and for the dehydration of
the cargo system as well as the inter-
barrier spaces during voyage. For these
condensation occurs on cold surfaces
with unwanted build-ups of ice. Deck
tanks are normally provided for
changeover of cargoes.
The hazards associated with the
cargoes involved are obvious from
temperature, toxic and flammable
concerns. Accordingly, the safety of all
such craft is critical with good
management and serious personnel
training remaining paramount.
The fully refrigerated fleet
These are generally large ships, up to
about 100,000 m3 cargo capacity, those
above 70,000 m3 being designated as
VLGCs. Many in the intermediate range
(say 30,000 m3 to 60,000 m3) are suitable
for carrying the full range of hydrocarbon
liquid gas from butane to propylene and
may be equipped to carry chemical liquid
gases such as ammonia. Cargoes are
carried at near ambient pressure and at
temperatures down to -48ºC.
Reliquefaction plants are fitted, with
> continued over
substantial reserve plant capacity
provided. The cargo tanks do not have to
withstand high pressures and are
therefore generally of the free standing
prismatic type. The tanks are robustly
stiffened internally and constructed of
special low temperature resistant steel.
All ships have substantial double
bottom spaces and some have side
Fully refrigerated LPG carrier.
ballast tanks. In all cases the tanks are
protectively located inboard. The ship’s
structure surrounding or adjacent to the
cargo tanks is also of special grade steel,
in order to form a secondary barrier to
safely contain any cold cargo should it
leak from the cargo tanks.
All cargo tanks, whether they be of the
pressure vessel type or rectangular, are
provided with safety relief valves amply
sized to relieve boil-off in the absence of
reliquefaction and even in conditions of
surrounding fire.
The LNG fleet
Although there are a few exceptions, the
principal ships in the LNG fleet range from
75,000m3 to 150,000m3 capacity, with
ships of up to 265,000 m3 expected by the
end of the decade. The cargo tanks are
thermally insulated and the cargo carried
at atmospheric pressure. Cargo tanks may
be free standing spherical, of the
LNG carrier with Type-B tanks (Kvaerner Moss system).
LNG carrier with membrane tanks.
6
membrane type, or alternatively, prismatic
in design. In the case of membrane tanks,
the cargo is contained within thin walled
tanks of invar or stainless steel. The tanks
are anchored in appropriate locations to
the inner hull and the cargo load is
transmitted to the inner hull through the
intervening thermal insulation.
All LNG carriers have a watertight
inner hull and most tank designs are
required to have a secondary containment
capable of safely holding any leakage for
a period of 15 days. Because of the
simplicity and reliability of stress analysis
of the spherical containment designs, a
full secondary barrier is not required but
splash barriers and insulated drip trays
protect the inner hull from any leakage
that might occur in operation. Existing
LNG carriers do not reliquefy boil-off
gases, they are steam ships and the gas is
used as fuel for the ship’s boilers. The first
ships to burn this gas in medium speed
diesel engines will be delivered in 2005/6,
and ships with reliquefaction plant and
conventional slow speed diesel engines
will enter service late in 2007. It is likely
that gas turbine propelled ships may
appear soon after this.
Crew training and numbers
As they did for oil tankers and chemical
carriers, the IMO has laid down a series of
training standards for gas carrier crews
which come in addition to normal
certification. These dangerous cargo
endorsements are spelt out in the STCW
Convention. Courses are divided into the
basic course for junior officers and the
advanced course for senior officers. IMO
rules require a certain amount of
onboard gas experience, especially at
senior ranks, before taking on the
responsible role or before progressing to
the next rank. This can introduce checks
and balances (say) in the case of a master
from the bulk ore trades wanting to
convert to the gas trade. The only way,
without previous gas experience, to
achieve this switch is to have the
candidate complete the requisite course
and sail as a supernumerary,
understudying the rank for a specified
period on a gas carrier. This can be costly
for seafarer and company alike.
Accordingly, as the switch can be difficult
to manage, especially at senior ranks,
current requirements tend to maintain a
close-knit cadre of ‘gas men or women’
well experienced in the trade.
In addition to the official certification
for hazardous cargo endorsements, a
number of colleges operate special
courses for gas cargo handling. In the UK
a leader in the field is the Warsash
Maritime Centre.
While this situation provides for a
well-trained and highly knowledgeable
environment the continued growth in the
fleet currently strains manpower
resources and training schedules and it is
possible that short cuts may be taken.
While the small gas carriers normally
operate at minimum crew levels, on the
larger carriers it is normal to find
increased crewing levels over and above
the minimum required by the ship’s
manning certificate. For example, it is
almost universal to carry a cargo
engineer onboard a large gas carrier. An
electrician is a usual addition and the
deck officer complement may well be
increased.
Gas carriers and portoperations
As gas carriers have grown in size, so too
has a concern over in-port safety.
Indeed, the same concerns applied with
the growth in tanker sizes when the
VLCC came to the drawing board. The
solutions are similar; however, in the case
of the gas carrier, a higher degree of
automation and instrumentation is often
apparent controlling the interface
between ship and shore.
Terminals are also protected by careful
risk analysis at the time of construction
so helping to ensure that the location
and size of maximum credible spill
scenarios are identified, and that suitable
precautions including appropriate safety
distances are established between
operational areas and local populations.
Regarding shipping operations, risk
analysis often identifies the cargo
manifold as the area likely to produce the
Hard arm quick connect/disconnect coupler
(QCDC).
Hard arms at cargo manifold, including
vapour return line (below, centre arm).
Hard arm connection to manifold, showing
double ball valve safety release.
Carriage of liquefied gases continued
7
maximum credible spill. This should be
controlled by a number of measures.
Primarily, as for all large oil tankers, gas
carriers should be held firmly in position
whilst handling cargo, and mooring
management should be of a high calibre.
Mooring ropes should be well managed
throughout loading and discharging. Safe
mooring is often the subject of
computerised mooring analysis, especially
for new ships arriving at new ports, thus
helping to ensure a sensible mooring array
suited to the harshest conditions. An
accident in the UK highlighted the
consequences of a lack of such procedures
when, in 1993, a 60,000 m3 LPG carrier
broke out from her berth in storm
conditions. This was the subject of an
official MCA/HSE inquiry concluding
that prior mooring analysis was vital to
safe operations. The safe mooring
principles attached to gas carriers are
similar to those recommended for oil
tankers (they are itemised in Mooring
Equipment Guidelines, see References ,
page 13).
The need for such ships to be held
firmly in position during cargo handling is
due in part to the use of loading arms
(hard arms – see photos opposite) for
cargo transfer. Such equipment is of
limited reach in comparison to hoses, yet it
provides the ultimate in robustness. It also
provides simplicity in the connection at the
cargo manifold.
The use of loading arms for the large
gas carrier is now quite common and, if
not a national requirement, is certainly an
industry recommendation. The alternative
use of hoses is fraught with concerns over
hose care and maintenance, and their
proper layout and support during
operations to prevent kinking and
abrasion. Further, accident statistics show
that hoses have inferior qualities in
comparison to the hard arms. Perhaps the
worst case of hose failure occurred in
1985 when a large LPG carrier was loading
at Pajaritos, Mexico. Here, the hose burst
and, in a short time, the resulting gas
cloud ignited. The consequent fire and
explosion impinged directly on three other
ships in harbour and resulted in four
deaths. It was one of those accidents
which has led directly to a much increased
use of loading arms internationally. The
jetty was out of action for approximately
six months. Fortunately the berth was in
an industrial area and collateral damage
to areas outside the refinery was limited.
As ships have grown in size the
installation of vapour return lines
interconnecting ship and shore vapour
systems has become more common.
Indeed, in the LNG industry it is required,
with the vapour return being an integral
part of the loading or discharging
system. In the LPG trades, vapour returns
are also common, but are only opened in
critical situations such as where onboard
reliquefaction equipment is unable to
cope with the loading rate and boil-off.
A feature common to both ship and
shore is that both have emergency
shutdown systems. It is now common to
interconnect such systems so that, for
example, an emergency on the ship will
stop shore-based loading pumps. One
such problem may be the automatic
detection of the ship moving beyond the
safe working envelope for the loading
arms. A further refinement at some
larger terminals is to have the loading
arms fitted with emergency release
devices, so saving the loading arms from
fracture (see centre photo opposite).
Given good moorings and well-
designed loading arms, the most likely
sources of leakage are identified and
controlled.
Hazards to shore workers andcrewmembers at refit
While the gas carrier accident record is
very good for normal operations, and
exemplary with respect to cargo
operations and containment, the same
cannot be said for the risks it faces in
drydock. Statistics show that the gas
carrier in drydock presents a serious risk
to personnel, particularly with respect to
adequate ventilation through proper
inerting and gas-freeing before repairs
begin. Most often the risk relates to
minor leakage from a cargo tank into the
insulation surrounding refrigerated LPG
tanks. A massive explosion occurred on
the Nyhammer at a Korean shipyard in
1993 for this very reason, where
considerable loss of life occurred.
Although the ship was repaired, it was a
massive job ■
Checklist
The following checklist, made
available from SIGTTO, may be
used as guidance in a casualty
situation involving a disabled gas
carrier.
● What cargo is onboard?
● Is specialist advice available in
respect of the cargo and its
properties?
● Are all parties involved aware of
cargo properties?
● Is the cargo containment
system intact?
● Is the ship venting gas?
● Is the ship likely to vent gas?
● What will be the vented gas
and what are its dispersal
characteristics?
● Is a gas dispersion modelling
tool available?
● Is the ship damaged?
● Does damage compromise the
ship’s manoeuvring ability?
● What activities and services are
planned to restore a seaworthy
condition?
● Is ship-to-ship transfer
equipment available if
required?
● When is it expected the ship will
be seaworthy again?
● Is prevailing shelter (and other
dangers) suitable for the
intended repairs?
● What contingency plans are
required?
● Who will control the operation?
● How will the ship operator and
port or public authorities
co-operate?
● Will customs and immigration
procedures need facilitation for
equipment and advisers?
8
Liquefied natural gas
Background
It was as far back as 1959 that the
Methane Pioneer carried the first
experimental LNG cargo, and 40 years
ago, in 1964, British Gas at Canvey Island
received the inaugural cargo from Arzew
on the Methane Princess. Together with
the Methane Progress these two ships
formed the core of the Algeria to UK
project. And the project-based nature of
LNG shipping was set to continue until
the end of the 20th century. LNG carriers
only existed where there were projects,
with ships built specifically for
employment within the projects. The
projects were based on huge joint
ventures between cargo buyers, cargo
sellers and shippers, all in themselves
large companies prepared to do long-
term business together.
The projects were self-contained and
operated without much need for outside
help. They supplied gas using a purpose-
built fleet operating like clockwork on a
CIF basis. Due to commercial constraints,
the need for precisely scheduled
deliveries and limited shore tank
capacities, spot loadings were not
feasible and it is only in recent years that
some projects now accept LNG carriers as
cross-traders, operating more like their
tramping cousins – the oil tankers.
Doubtless the trend to spot trading will
continue. However, the co-operative
nature of LNG’s beginnings has led to
several operational features unique to
the ships. In particular there is the
acceptance that LNG carriers burn LNG
cargo as a propulsive fuel. They also
retain cargo onboard after discharge (the
‘heel’) as an aid to keeping the ship
cooled down and ready to load on arrival
at the load port. Thus matters that would
be anathema to normal international
trades are accepted as normal practice
for LNG.
Again, looking back to the early days,
there was also great interest in this new
fuel in the USA and France. Receiving
terminals sprouted. However, gas pricing
difficulties in the USA saw an end to early
American interest while Gaz de France
consolidated rather than expanded.
Indeed, the American pricing problems,
and the failure of an early US-built
shipboard Conch containment system on
newbuildings, blanketed any spectacular
progress in the Atlantic basin until the
regeneration of interest initiated by the
Trinidad project in 1999.
At that time, the stifling of European
interest was also due to the discovery of
natural gas in the North Sea, so quantities
to replace town gas were available in
sufficient volume on the doorstep
without the need for imports. This being
so, the first LNG project from Algeria to
UK eventually faltered, with the receiving
terminal at Canvey Island switching to
other interests. The stagnation of LNG in
the 70s and 80s applied the world over,
with the singular exception of imports to
Japan and Korea. Here interest in LNG’s
potential as an environmentally-friendly
fuel stayed vibrant; as it does today.
LNG projects are massive multi-billion
dollar investments. Major projects in the
Far East included Brunei to Japan,
Indonesia to Japan, Malaysia to Japan and
Australia to Japan, comprising some 90%
of the LNG trade of the day.
Consequently, the Japanese defined
much of what is seen best today in way of
safety standards and procedures. It is
worthy of note, however, that some early
safety standards and practices are being
questioned today in the light of
experience in a more mature industry.
LNG as a fuel
Because the ships, terminals and
commercial entities were all bound
together in the same chain, advantages
could be seen in limiting ‘unnecessary’
shipboard equipment, such as
reliquefaction plant, and allowing the
boil-off to be burnt as fuel. One way or
another the ship would need fuel, be it oil
or gas and, if gas, it was only then a
matter to quantify usage and to direct the
appropriate cost to the appropriate
project partner.
Interestingly, this concept was
recognised in the IMO’s Gas Codes from
the very earliest days, and with the
appropriate safety equipment in place
the regulations allow methane to be
burnt in ship’s boilers. This is not the case
for LPG, where reliquefaction equipment
is a fitment, but specifically because the
LPGs are heavier than air gases and use
in engine rooms is thereby disallowed.
LNG quality
LNG is liquefied natural gas. It is sharply
clear and colourless. It comprises mainly
methane but has a percentage of
constituents such as ethane, butane and
propane together with nitrogen. It is
produced from either gas wells or oil
wells. In the case of the latter it is known
as associated gas. At the point of
production the gas is processed to
remove impurities and the degree to
which this is achieved depends on the
facilities available. Typically this results in
LNG with between 80% and 95%
methane content. The resulting LNG can
therefore vary in quality from loading
terminal to loading terminal or from
day-to-day.
Other physical qualities that can
change significantly are the specific
gravity and the calorific value of the
LNG, which depend on the
characteristics of the gas field. The
specific gravity affects the deadweight
of cargo that can be carried in a given
volume, and the calorific value affects
both the monetary value of the cargo
and the energy obtained from the boil-
off gas fuel.
These factors have significance in
commercial arrangements and gas
quality is checked for each cargo, usually
in a shore-based laboratory by means of
gas chromatography. LNG vapour is
flammable in air and, in case of leakage,
codes require an exclusion zone to allow
natural dispersion and to limit the risk of
ignition of a vapour cloud. Fire hazards
are further limited by always handling
the product within oxygen-free systems.
Unlike oil tankers under inert gas, or in
some cases air, LNG carriers operate
with the vapour space at 100%
9
methane. LNG vapour is non-toxic,
although in sufficient concentration it
can act as an asphyxiant.
Gas quality is also significant from a
shipboard perspective. LNGs high in
nitrogen, with an atmospheric boiling
point of -196°C, naturally allow nitrogen
to boil-off preferentially at voyage start
thus lowering the calorific value of the
gas as a fuel. Towards the end of a
ballast passage, when remaining ‘heel’
has all but been consumed, the
remaining liquids tend to be high on the
heavier components such as the LPGs.
This raises the boiling point of the
remaining cargo and has a detrimental
effect on tank cooling capabilities in
readiness for the next cargo.
The good combustion qualities
attributed to methane make it a great
attraction today as a fuel at electric
power stations. It is a ‘clean’ fuel. It
burns producing little or no smoke and
nitrous oxide and sulphur oxide
emissions produce figures far better than
can be achieved when burning normal
liquids such as low sulphur fuel oil.
Natural gas has thus become attractive
to industry and governments striving to
meet environmental targets set under
various international protocols such as
the Rio Convention and the Kyoto
Protocol. The practice of firing marine
boilers on methane provides the further
environmental advantage of lesser soot-
blowing operations and much fewer
carbon deposits.
Cargo handling
The process of liquefaction is one of
refrigeration and, once liquefied, the gas
is stored at atmospheric pressure at its
boiling point of -162°C. At loading
terminals any boil-off from shore tanks
can be reliquefied and returned to
storage. However, on ships this is almost
certainly not the case. According to
design, it is onboard practice to burn
boil-off gas (often together with fuel oil)
in the ship’s boilers to provide
propulsion. In the general terms of
seaborne trade this is an odd way to
handle cargo and is reminiscent of old
tales of derring-do from the 19th century
when a cargo might have been burnt for
emergency purposes. It is nevertheless
the way in which the LNG trade operates.
Boil-off is burnt in the ship’s boilers to the
extent that it evaporates from its mother
liquid. Clearly cargo volumes at the
discharge port do not match those
loaded.
Accounting however is not
overlooked and LNG carriers are outfitted
with sophisticated means of cargo
measurement. This equipment is
commonly referred to as the ‘custody
transfer system’ and is used in preference
to shore tank measurements. These
systems normally have precise radar
measurement of tank ullage while the
tanks themselves are specially calibrated
by a classification society to a fine degree
of accuracy. The system automatically
applies corrections for trim and list using
equipment self-levelled in drydock. The
resulting cargo volumes, corrected for
the expansion and contraction of the
tanks, are normally computed
automatically by the system.
Cargo tank design requires carriage at
atmospheric pressure and there is little to
spare in tank design for over or under
pressures. Indeed, the extent to which
pressure build-up can be contained in a
ship’s tanks is very limited in the case of
membrane cargo tanks, although less so
for Type-B tanks. Normally this is not a
problem, as at sea the ship is burning
boil-off as fuel or in port has its vapour
header connected to the terminal vapour
return system. Clearly, however, there are
short periods between these operations
when pressure containment is necessary.
This can be managed. So taken together,
shipboard operations efficiently carried
out succeed in averting all possible
discharges to atmosphere, apart that is
from minor escapes at pipe flanges, etc.
Certainly this is part of the design criteria
for the class as it is recognised that
methane is a greenhouse gas.
Boil-off gas (BOG) is limited by tank
insulation and newbuilding contracts
specify the efficiency required. Usually
this is stated in terms of a volume boil-off
per day under set ambient conditions for
sea and air temperature. The guaranteed
maximum figure for boil-off would
normally be about 0.15% of cargo
volume per day.
While at sea, vapours bound for the
boilers must be boosted to the engine
room by a low-duty compressor via a
vapour heater. The heater raises the
temperature of the boil-off to a level
suited for combustion and to a point
where cryogenic materials are no longer
required in construction. The boil-off
then enters the engine room suitably
warmed but first passes an automatically
controlled master gas valve before
reaching an array of control and shutoff
valves for direction to each burner. As a
safety feature, the gas pipeline through
the engine room is of annular
construction, with the outer pipe purged
and constantly checked for methane
ingress. In this area, operational safety is
paramount and sensors cause shutdown
of the master gas valve in alarm
conditions. A vital procedure in the case
of a boiler flameout is to purge all gas
from the boilers before attempting
re-ignition. Without such care boiler
explosions are possible and occasional
accidents of this type have occurred.
Cargo care
The majority of LNG shippers and
receivers have a legitimate concern over
foreign bodies getting into tanks and
pipelines. The main concern is the risk of
valve blockage if (say) an old welding rod
becomes lodged in a valve seat. Such
occurrences are not unknown with a ship
discharging first cargoes after
newbuilding or recently having come
from drydock. Accordingly, and despite
discharge time diseconomies, it is
common practice to fit filters at the ship’s
liquid manifold connections to stop any
such material from entering the shore
system. The ship normally supplies filters
fitting neatly into the manifold piping.
> continued over
10
In a similar vein, even small particulate
matter can cause concerns. The carry-
over of silica gel dust from inert gas driers
is one such example. Another possible
cause of contamination is poor
combustion at inert gas plants and ships
tanks becoming coated with soot and
carbon deposits during gas freeing and
gassing up operations. Subsequently, the
contaminants may be washed into gas
mains and, accordingly, cargoes may be
rejected if unfit. Tank cleanliness is vital
and, especially after drydock, tanks must
be thoroughly vacuumed and dusted.
A cargo was once rejected in Japan
when, resulting from a misoperation,
steam was accidentally applied to the
main turbine with the ship secured
alongside the berth. The ship broke out
from the berth, but fortunately the
loading arms had not been connected.
This action was sufficient however for
cargo receivers to reject the ship, and the
cargo could only be delivered after a
specialised ship-to-ship transfer operation
had been accomplished. The ship-to-ship
transfer of LNG has only ever been
carried out on a few occasions and is an
operation requiring perfect weather,
great care and specialist equipment.
Another case of cargo rejection, this
time resulting in a distressed sale,
involved a shipment to Cove Point in the
USA, where the strict requirements which
prevail on in-tank pressures on arrival at
the berth were not adhered to. The ship
had previously been ordered to reduce
pressure for arrival. This is a difficult job
to perform satisfactorily and, if it is to be
successful, the pressure reduction
operation must progress with diligence
throughout the loaded voyage by forcing
additional cargo evaporation to the
boilers. This cools the cargo and hence
reduces vapour space pressure. The
process of drawing vapour from the
vapour space at the last moment is
ineffective, because the cargo itself is not
in balance with that pressure and once
gas burning stops the vapour space will
return to its high equilibrium pressure.
This process is known in the trade as
‘cargo conditioning’.
Ship care
A temperature of -162°C is astonishingly
cold. Most standard materials brought
into contact with LNG become highly
brittle and fracture. For this reason
pipelines and containment systems are
built from specially chosen material that
do not have these drawbacks. The
preferred materials of construction are
aluminium and stainless steel. However
these materials do not commonly feature
over the ship’s weatherdecks, tank
weather covers or hull. These areas are
constructed from traditional carbon
steel. Accordingly, every care is taken to
ensure that LNG is not spilt. A spill of LNG
will cause irrevocable damage to the
decks or hull normally necessitating
emergency drydocking. Accidents of this
Moss design (courtesy of Moss Maritime).
LNG carrier with Type-B tanks (Kvaerner Moss system).
Liquefied natural gas continued
11
nature have occurred, fortunately none
reporting serious personal injury, but
resulting, nevertheless, in extended
periods off-hire.
LNG carriers are double-hulled ships
specially designed and insulated to
prevent leakage and rupture in the event
of accident such as grounding or
collision. That aside, though
sophisticated in control and expensive in
materials, they are simple in concept.
Mostly they carry LNG in just four, five or
Membrane design (GTT).
within the double hull where the water
ballast tanks reside. The world fleet
divides approximately 50/50 between the
two systems.
Regarding spherical tanks, a very
limited number were constructed from
9% nickel steel, the majority are
constructed from aluminium. A
disadvantage of the spherical system is
that the tanks do not fit the contours of a
ship’s hull and the consequent ‘broken-
stowage’ is a serious diseconomy. In
general terms, for two LNG ships of the
same carrying capacity, a ship of Moss
design will be about 10% longer. It will
also have its navigating bridge set at a
higher level to allow good viewing for
safe navigation. On the other hand the
spherical tanks are simple in design and
simple to install in comparison to the
membrane system, with its complication
of twin barriers and laminated-type
construction.
Tank designs are often a controlling
factor in building an LNG carrier.
Shipyards usually specialise in one type or
the other. Where a yard specialises in the
Moss system, giant cranes are required to
lift the tanks into the ships and limits on
crane outreach and construction tooling
facilities currently restrict such tanks to a
diameter of about 40 metres.
Early LNG carriers had carrying
capacities of about 25,000 m3. This
swiftly rose to about 75,000 m3 for the
Brunei project and later ships settled on
125,000 m3. For some years this
remained the norm, giving a loaded
draught of about 11.5 metres, thus
stretching the port facilities of most
discharge terminals to their limits. Since
then, however, there have been some
incremental increases in size, usually
maintaining draft but increasing beam,
resulting in ship sizes now of about
145,000 m3. That said, one of the newest
in class is the Pioneer Knudsen, trading at
only 1,100 m3 capacity from a facility
near Bergen to customers on the
Norwegian west coast. At the end of
2004 the first orders were placed for LNG
carriers of more than 200,000m3 and
ships to carry over 250,000m3 are
expected to be delivered by the end of
2008.
six centreline tanks. Only a few have
certification and equipment for cross
trading in LPG. The cargo boils on
passage and is not re-liquefied onboard
– it is carried at atmospheric pressure.
Although there are four current methods
to construct seaborne LNG tanks, only
two are in majority usage. There are the
spherical tanks of Moss design and the
membrane tanks from Gaz Transport or
Technigaz (two French companies, now
amalgamated as GTT). Each is contained
LNG carrier with membrane tanks.
> continued over
12
Large modern LNG carriers have
dimensions approximately as follows:
recognise this and, together with
inspection regimes, the overall quality of
LNG tonnage is kept to a high standard.
Age for age, they are probably the best
maintained ships in the world. Of course
some of these ships are now old and only
a few have ever been scrapped; some are
over 30 years old. This is very old for a
large tanker trading all its life in salt
water, when 25 years is already
Glossary
Administration The Administration is the national authority responsible for
shipping safety in the country concerned
Certificate of Certificate of Fitness for the Carriage of Liquefied Gases in
Fitness Bulk, an essential gas carrier certificate required by, and
defined in, the IGC Code
DCE Dangerous Cargo Endorsement
Heel The amount of liquid cargo remaining in a ship’s cargo tank
at the end of discharge. It is used to maintain the cargo
tanks cooled down during the ballast voyage by
recirculating through the sprayers. On LPG ships such
cooling is carried out via the reliquefaction plant and on
LNG ships by using the in-tank spray pumps.
IGC Code International Code for the Construction and Equipment of
Ships Carrying Liquefied Gases in Bulk
IMO International Maritime Organization (a United Nations
agency)
LNG Liquefied Natural Gas (methane with traces of heavier
gases)
LPG Liquefied Petroleum Gas (typically butane and propane)
SIGTTO Society of International Gas Tanker and Terminal
Operators Ltd
SMS Safety Management System – a company-wide SMS as
required under the ISM Code
STCW Convention International Convention on Standards of Training,
Certification and Watchkeeping for Seafarers
STCW Code Seafarers’ Training, Certification and Watchkeeping Code
USCG United States Coast Guard
Capacity (m3) 145,000 215,000
Length 295m 315m
Beam 48m 50m
Loaded draft 12m 12m
Liquefied natural gas continued considered by many as a cut-off date. On
termination of their original projects we
are now seeing many of the older ships
as surplus to requirements. Sometimes
the project wishes to continue but only
with new ships. So the older ships are
laid-off. In the past this would have been
their death knell but today this is not
necessarily the case. The slow
development of a spot market has
LNG having a typical density of only
420 kg/m3 allows the ships, even when
fully laden, to ride with a high freeboard.
They never appear very low in the water
as a fully laden oil tanker may do. Ballast
drafts are maintained close to laden
drafts and, for a ship having a laden
draft of 12 metres, a ballast draft of 11
metres is likely. This means that for
manoeuvring in port in windy conditions
the ships are always susceptible to being
blown to one side of the channel, and
restrictions on port manoeuvring usually
apply with extra tug power commonly
specified.
Another salient feature of the LNG
class is the propensity to fit steam
turbine propulsion. This is an
anachronism brought about by a
reluctance to change over the years,
together with a fear that a system as yet
untried on LNG carriers may not find
favour with the principal charterers – the
Japanese. Most other ship types of this
size have diesel engines and the
engineers to run diesel equipment are
plentiful and suitably trained. On the
other hand, engineers knowledgeable in
steam matters are few and their training
base is the ship itself. This situation is
changing though, with both diesel
electric dual fuel systems and slow speed
diesels now finding favour. With slow
speed diesel propulsion, reliquefaction
plants will be required onboard to
handle boil-off gas, and all diesel
systems will require back-up gas disposal
facilities – also known as ‘gas
combustion units’ (GCUs) – for when
either the reliquefaction plants or the
duel fuel diesel engines are not available
to process boil-off gas.
LNG ships are expensive to build.
They comprise very valuable assets:
generally far too good to let rust away.
Shipowners and ship managers alike
13
.............................................................................................................................................................................................
Introduction
Sampling is a vitally important factor in
the custody transfer of bulk liquid
cargoes. Acquisition and subsequent care
and retention of representative samples
can provide an important means of
rebutting unfounded allegations of cargo
contamination. This applies equally to
chemical, petrochemical, petroleum
product and crude oil shipments.
Cargo surveyors attending the loading
or discharge of any given cargo are often
working on behalf of shippers or
consignees (or both, on a joint basis) and
are not obliged to provide samples to the
ship, albeit that it is common practice to
place samples in the custody of the
master at the loadport for delivery to the
disport receivers. However, these samples
are not the property of the ship and only
on rare occasions are official-sealed
custody transfer samples provided.
Whether samples are provided by the
cargo interests to the ship or not, it is
recommended that the vessel’s crew
draw samples for the ship’s protection.
Retention and sealing
Due to the inability of the ship’s officers
to undertake analysis of samples, only
the most obvious contamination
problems will be apparent at the outset,
such as:
● Change in colour.
● The presence of water (if water is not
soluble in the cargo).
● Foreign particulate matter.
● Odour taint.*
Samples taken at the initial stages of
cargo operations showing such obvious
cargo quality deviations should give
cause to halt cargo operations in order to
carry out further investigations** and to
note protest.
All samples drawn should be sealed,
labelled, retained and recorded.
Wherever possible, samples drawn by the
* Safety: Odour is not an issue on all cargoes. Toxic and
highly odiforous cargoes should not be tested for
odour.
** A P&I surveyor should be summoned.
Bulk liquid cargoes– sampling
ship’s crew should be clearly labelled with
the following:
● Ship’s name.
● Operational status
i.e. before loading, after Ioading,
before discharge.
● Product.
● Sample source
i.e. tank number, manifold number.
● Sample type
i.e. top, middle, bottom, dead
bottom, running, composite.
● Identity of sampler
i.e. surveyor, crewmember.
● Date and time.
● Location
i.e. port, berth, anchorage.
● Seal number.
Seals are customarily applied to samples
by an independent surveyor in order to
> continued over
SIGTTO
Valuable assistance in the preparation of
these articles has come from the Society
of International Gas Tanker and Terminal
Operators (SIGTTO).
SIGTTO is the leading trade body in
this field and has over 120 members
covering nearly 95% of the world’s LNG
fleet and 60% of the LPG fleet. SIGTTO
members also control most of the
terminals that handle these products.
The Society’s stated aim is to
encourage the safe and responsible
operation of liquefied gas tankers and
marine terminals handling liquefied gas;
to develop advice and guidance for best
industry practice among its members and
to promote criteria for best practice to all
who have responsibilities for, or an
interest in, the continuing safety of gas
tankers and terminals.
The Society operates from its London
office at 17 St. Helens Place EC3.
Further details on activities and
membership is available at
www.sigtto.org
References
Liquefied Gas Handling Principles on Ships
and in Terminals – SIGTTO
Safe Havens for Disabled Gas Carriers –
2003, SIGTTO
Mooring Equipment Guidelines – 2001,
OCIMF
Ship-to-Ship Transfer Guide (Liquefied
Gases) – 1995, SIGTTO
The International Code for the
Construction and Equipment of Ships
Carrying Liquefied Gases in Bulk,
(IGC Code) – IMO
A Contingency Planning and Crew
Response Guide for Gas Carrier Damage
at Sea and in Port Approaches – 1999,
SIGTTO
The aforementioned publications are
available from Witherby & Company Ltd,
London.
allowed the shipowner to consider life
extension programmes of considerable
cost; all this set against the value of a
very expensive newbuilding. Today life
extension programmes are common with
old ships making handsome profits in the
spot market ■
14
preserve sample provenance in the event
of dispute. Nowadays, seals are widely
available and relatively inexpensive and it
is increasingly common for ships to be
equipped with their own seals.
Alternatively, some owners use self-
sealing tamper-evident bottle closures
which may not be individually numbered
but, nonetheless, preserve sample
provenance.
Marked samples should be retained in
a dedicated locker, ideally for at least 12
months. Space considerations may make
this impractical in which case the samples
should be retained for as long as
possible. However, where the cargo is
known or expected to be the subject of
dispute, samples should be retained for
at least 12 months in any event. Samples
should not be exposed to extremes of
temperature and should be kept in
darkness. When no longer required,
disposal should be by appropriate means;
many owners use the services of local
cargo surveyors who invariably have
disposal methods already in place.
Sample bottles
Sample bottles vary in size and in the
materials from which they are made.
Glass and plastic bottles can be dark or
clear. Most samples can generally be
stored in clear glass bottles. Light
sensitive samples, however, should be
stored in brown bottles*. Certain
samples, such as caustic soda or potash
require plastic containers. Petroleum
products/crude oil samples are often
retained in lacquer-lined tinplate
containers. These types of containers are,
in general, unsuitable for retention of
chemical cargo samples. Where possible,
a range of containers should be available.
Sample bottle closures vary in the
chemical resistance of the sealing insert.
Waxed cardboard disc type should only
be used for petroleum products/crude
oils. Aluminium foil-faced cardboard
discs are unsuitable for acid or alkaline
samples. Preferred inserts are
polypropylene or PTFE.
Sample bottle size may be
determined, to some extent, by storage
capacity, balanced against the need to
retain sufficient sample volume to allow
analysis in the event of a dispute arising.
Generally, 500ml is a realistic
compromise.
Where to take samples
During the custody transfer of a bulk
liquid cargo, the principal sampling
points where cargo quality can be
adequately monitored are:
1 Loadport shore tank(s).
2 Shoreline sample following any
‘packing’ or flushing operation.
3 Vessel’s manifold at commencement
of loading and spot checks during
loading.
4 Vessel’s cargo tanks first foots.
5 Vessel’s cargo tanks post-loading.
6 Vessel’s cargo tanks pre-discharge.
7 Vessel’s manifold at commencement
of discharge.
8 Disport shore tank(s) pre- and post-
discharge.
Ideally, all of these samples should be
taken on each cargo carrying voyage, but
in any event, onboard ship samples 3 to 7
should always be taken by the crew for
protection of the owner’s interests.
Further samples might be considered,
such as 3, following changeover of
shoretanks at a mid-loading stage.
Method of drawing samples
Samples should be drawn in compliance
with industry practice as set out in
publications such as those issued by
ASTM, API and BS (see References). In
general, a ‘running’ sample taken by use
of a bottle and sample cage is the
preferred method of obtaining a
representative sample in a homogeneous
bulk cargo. Where the cargo may not be
homogenous, careful zone sampling is
required to produce a representative
composite sample. The properties of
some chemical cargoes require that
special sampling procedures are adopted
such as excluding air, using specialist
sample valves or indeed ‘closed’
sampling methods due to the toxicity or
flammability of the cargo. Here, the
sampling procedure is prescribed by the
specialist equipment in use. Appropriate
safety procedures must be observed and
the sampler protected from exposure to
the cargo during sampling.
Conclusion
It is unquestionably the case that a
vessel’s adherence to the above sampling
procedure can provide the necessary
evidence to rebut cargo quality claims in
circumstances where unfounded
allegations are made against shipowners.
A rigorous sampling system should form
an essential part of a vessel’s ISM
operational procedures ■
References
ASTM D 4057
Standard Practice for Manual Sampling
of Petroleum and Petroleum Products.
ASTM E 300
Standard Practice for Sampling Industrial
Chemicals.
BS 3195
Methods for Sampling Petroleum
Products.
BS 5309
Methods for Sampling Chemical
Products.
IP
Petroleum Measurements Manual Part IV
Sampling – Section I Manual Methods.
API
Manual of Petroleum Measurement
Standards Ch 8, Standard Methods of
Sampling Petroleum and Petroleum
Products.
* Brown bottles impede inspection of the sample for
colour/water/particulates. It is suggested that clear
glass bottles are used initially and, after inspection,
the sample transferred to a dark brown bottle for
storage.
Sampling bulk liquid cargoes continued
15
> continued over
Carriage of potatoes
Introduction
The potato tuber, Solanum tuberosum L.,
is an annual of the Solanaceae family and
originally native to South America.
The edible tuber forms at the end of
the underground stems or stolons of the
plants and within which the starch-rich
nutrients are stored. Colour together
with other criteria form important
characteristics for identifying the
numerous varieties of potatoes:
● Skin colours – brown, russet, white,
yellow, pink or red.
● Skin textures – rough or smooth.
● Flesh colours – white, cream, yellow,
blue/purple/red or striated.
● Tuber shape – round, oblate, oval, or
kidney shaped.
● Usage – table, processing or seed.
● Harvest time – early/new or immature,
or late/mature.
Potatoes are grown throughout the
world, except in humid tropical lowland
areas. They are one of the worlds most
important food crops, and thus are an
important commodity of trade.
For the purposes of this article we
shall refer to three basic types of potato,
which are:
● Early/new or immature.
● Late/mature.
● Seed.
All of which require special
considerations for stowage and carriage.
Early or new potatoes have thin,
relatively loose, skins that are easily
removed and are thus readily liable to
damage. Over more recent years,
demand for this type of potato has
increased and large quantities are
shipped from Cyprus, Greece, Israel,
Turkey and the Canary Islands during the
northern winter and spring seasons.
Late/mature potatoes have firm skins
and are therefore more resistant to
damage and much easier to carry than
immature potatoes.
Seed potatoes for shipment comprise
small whole tubers each with at least one
eye to produce the new growth. Seed
potatoes are grown under a regulated
certification programme to ensure that
they are as disease-free as possible.
Pre-shipment considerations
Once potatoes have been harvested they
must be stored under optimal conditions
until released for shipment. However no
storage is able to improve the product
placed therein, but much can be
achieved to minimise losses.
High temperatures cause the tuber
respiration rate to increase, whereby
oxygen and food reserves are used,
potentially resulting in excessive
shrinkage. Freezing or chilling
temperatures can damage and kill tuber
cells. If the air surrounding the tubers has
a low humidity then water will move
from the tubers to the air, resulting in
weight loss. Should the oxygen content
of the air fall to a low level, cells within
the tubers die and ‘blackheart’ forms.
Sprouting is a natural function of the
tuber, however, during shipment it is not
desirable as, in the event, quality and
condition will suffer. Sprout suppressant
chemicals or other methods
may be used prior to
shipment to preclude
sprouting but control in
stowage can only be
maintained by application
of the correct
temperature(s).
Potato tuber diseases may be the
result of micro-organisms or adverse
preshipment storage conditions.They
may also be the result of improper
stowage and conditions of carriage.
Potatoes are grown under the soil
and, as such, when harvested will always
contain on their surfaces spores of
invading micro-organisms, which will
attack the tubers if the natural defence
mechanism is ruptured. This can result
from mechanical damage, either during
harvesting or subsequent handling or,
alternatively, can result from other forms
of deterioration such as sun-scald. It may
also result if the tuber is subjected to
wetting such that a film of water is
present over its surface.
Some of the principal diseases found
at the time of harvesting may include
Phytophthora infestans (potato blight); a
dry mealy rot due to species of Fusarium
(dry rot); a bacterial soft rot caused by
Erwinia ssp. (black leg); or brown rot
caused by the bacterium Ralstonia
solanacearum and ring rot caused by the
bacterium Clavibacter michiganensis
subsp. sepedonicus, both of which are
Three basic types of potato, left to right: early/new; late/mature and; seed (notice fragile ‘eyes’
which produce new growth).
15
16
Carriage of potatoes continued
notifiable diseases in the UK and other
countries.
Post-harvest deterioration i.e. storage/
stowage deterioration will normally result
from the development of bacterial soft
rot, usually the result of infection by
Erwinia ssp. which causes collapse of the
cells of the infected potatoes exuding
heavily infected fluid and gives rise, by
contact, to soft rot developing in adjacent
tubers. Hence over a period of time the
contents of whole bags may collapse to a
malodorous slime.
Another cause of deterioration is
infestation by insects, which has been a
problem since potatoes have been grown.
The two most serious infestants of potato
crops are the North American black and
yellow striped beetle (Colorado Beetle)
and the Potato Tuber Moth (Phthorimaea
operculella).
It is necessary for shippers or charterers
to provide phyto-sanitary certificates,
attached to the bill(s) of lading or other
trade documents. These certificates are
produced by the Authority of the country
of origin indicating that the specified
consignment(s) have been inspected or
treated according to the importing
country’s requirements. Recent legislation
The Potatoes Originating in Egypt
(England) Regulations 2004 came into
force on 15 May 2004.
Whereas the master should be able to
rely upon a valid phyto-sanitary certificate
he does have a continuing duty in relation
to cargo in his charge. For example, if
infestation is noticed during the voyage,
the master/owners must take reasonable
steps to deal with the situation.
Fumigation prior to berthing at an arrived
port, or alternatively rejection of a cargo
of potatoes as a result of infestation or
infection by serious bacterial diseases,
not only may cause massive delays to a
vessel but also considerable additional
problems for the shipowners.
Greening may occur in any part of a
tuber exposed to light. Exposure to bright
light during post harvest handling, or
longer periods (7 to 14 days) of low light,
can result in the development of
chlorophyll (greening) and bitter, toxic
glycoalkaloids, such as solanine. Experts
advise that whereas in cultivated varieties
green discolour of the flesh does not
cause substantive harm to health, it
undoubtedly will, depending upon
extent, result in a loss of value of
consignments. Green flesh of potatoes
tastes bitter and must be cut away before
cooking.
When presented for shipment,
consignments should be inspected for
external condition of the packaging.
Evidence of wet patch staining of the
bags, or any associated malodours,
should alert crewmembers to likely
problems and the vessel’s P&I association
should be requested to appoint an expert
surveyor to investigate and ensure only
healthy and undamaged potatoes are
shipped. Since potatoes have been
shipped in woven polypropylene bags of
varying dark colours it has become
extremely difficult to recognise wet
patches from superficial examinations;
close inspections are thus recommended.
Mechanical damage is one of the
most important factors affecting potato
condition, since it is largely preventable.
Special care is therefore essential during
handling to and from the vessel,
especially when immature/new potatoes
are being shipped. Bags of potatoes
should not be walked over or handled
roughly, with special care taken if
palletised units of bags are over-stowed
by a second tier of pallets. In light rain,
snow, or damp weather cargo must be
protected from moisture to preclude the
onset of premature spoilage by bacterial
soft rot. Do not load or discharge
potatoes during heavy rain.
Summary
Subsequent to harvesting and prior to
packing for shipment:
Early or new potato tubers should
be graded and sorted:
● without mechanical damage;
● sound, without disease;
● dry;
● without greening;
● free from adherent soil and stones;
● and stored at optimum temperatures.
Late or mature potato tubers
should, in addition to the above:
● be fully mature and firm skinned;
● have been stored for a specific post
harvest period of 10 to 14 days
(wound healing and curing).
Seed potato tubers may, in
addition to those points noted
under ‘early potatoes’:
● consist of unwashed tubers and may
contain loose soil and foreign material
but should generally be free of caked
soil.
Left: Bacterial soft rot in potatoes can,
through contact, infect adjacent tubers.
Potato tubers infested with Colorado Beetle. Signs of infestation by the Potato Tuber Moth.
17
> continued over
Packaging
Potatoes may be packed in hessian bags,
woven polypropylene bags, sacks lined
with an internal perforated polyethylene
bag and sometimes cartons or crates.
Various sizes of bags are utilised,
however the bags will usually contain
about 25 kg of tubers.
A more recent innovation is to pack
potatoes in large open-top lift bags
weighing some two to three tonnes.
New potatoes are frequently packed in
moist or dry peat moss. The main
purpose for including moist peat moss
within the bags is to protect the ‘new’
tubers and to preclude skin-set and thus
maintaining their value. However, excess
free water or release of water from the
peat moss during carriage can cause
problems leading to bacterial soft rot of
the tubers.
Stowage
As for any product which may enter the
human food chain, preparation of
stowages will include ensuring that the
cargo spaces are clean and dry. Potatoes
are highly sensitive to odours and readily
absorb foreign smells from chemicals,
mineral oils, and some fruits, etc. All
compartments destined for stowage of
potatoes must be free from malodours
and volatile substances.
Potato tubers are living organisms
that consume oxygen and evolve carbon
dioxide, water and heat. The principal
problem as far as stowage and carriage
is concerned is the heat produced, and
therefore good climate control is
required to maintain the condition of
tubers. Condensation in the form of ship
or cargo sweat should not be allowed to
develop during a voyage. Long voyages
therefore demand more critical control
than short-term voyages.
An example of the heat produced by
cargoes of potatoes is noted in the table
below.
From these figures it is evident that
new / immature potatoes
produce considerably more heat per
1000 kg than late / mature potatoes and
are commensurately more difficult to
carry.
When potatoes are presented for
loading in bags, stow heights of up to
eight tiers are preferable. To ensure
adequate ventilation of cargo blocks,
maximum stow heights of twelve to
thirteen bags should never be exceeded.
The stowage must be so arranged to
ensure a free flow of air throughout the
compartments.
Bags shipped on pallets are usually
stacked to a height of eight/nine bags
and are often secured to the pallet base-
boards by means of nylon netting. Care
must be taken, (especially when the
bags are constructed of woven
polyethylene) to ensure that the
contents of pallets are fully and properly
secured.
The frictionless nature of this type of
outer bag frequently results in the pallet
loads becoming deformed and, in some
cases, detached from the base-boards.
This slippage can result in additional
stevedoring costs for re-making the
pallets. Slippage of woven polyethylene
bags from pallets, and also when loose
stowed, into ventilation channels will
cause restrictions of air flow and must be
prevented by the use of timber dunnage
or dunnage nets.
Stowages in refrigerated cargo
vessels
As previously noted, not only do growing
and harvesting conditions influence the
post harvest/pre-shipment behaviour of
potatoes but, additionally, post-harvest
storage conditions are also critical to the
optimum temperature requirements for
their carriage. Therefore written
instructions for the carriage temperature
regime should always be obtained from
the shippers and should be complied
with throughout the voyage. Transport
temperatures must be such that
respiration and weight losses due to
evaporation are maintained to a
minimum.
The approximate lowest safe
temperature for the carriage of potatoes
is plus 4o Celsius (39o Fahrenheit) and
carriage is usually recommended at plus 4o
to 5o Celsius (39o to 41o Fahrenheit) at a
relative humidity of between 90 and 95%.
However potatoes destined for processing
will require to be carried at temperatures
depending upon their cultivar. In these
cases, it is thus essential for shippers to
provide detailed instructions and for those
instructions to be rigorously followed.
The exact stowage patterns adopted
for potatoes will depend upon the
permanent air circulation systems
incorporated in a vessel. Strict supervision
of cargo stowage must ensure that airflow
will be evenly distributed throughout the
compartments for maintenance of
optimal temperature control.
Detailed records of cargo
compartment / flesh temperatures should
be maintained throughout the transit
period.
At the time of discharge from
refrigerated stowages, the cargo should
ideally be landed to stores at similar
temperatures to that of carriage. If cold
cargoes are discharged into ambient
warm humid conditions then a risk of
condensation forming on the tubers may
exist and bacterial soft rot will ensue.
Some shippers/consignees will request the
vessel to undertake a dual temperature
regime during transit and require the
vessel to slowly raise the temperature of
the cargo, to above the anticipated
ambient dew point at the discharge port,
commencing some two to three days
before discharge is due to commence.
Type of potatoes kcal per 1000 kg per 24 hours
At OC 5O 10O 15O 20O
Immature 735 1070 1380 1930
Mature 370 520 550 735
Potatoes packed in large open-top lift bags.
18
Blackheart is formed when the oxygen
content of the air falls to a low level.
Stowages in mechanically ventilated
general cargo spaces
The usual system adopted is to use block
stowage with air channels around each
cargo block. This system relies on
convection cooling. The cargo is stowed
clear of the deck either by placing it on
double dunnage or alternatively on pallet
boards. Cargo blocks should normally not
exceed 3 metres by 3 metres square.
Smaller blocks may be preferred under
certain circumstances; however stability
of each block is critical and when loose
stowed, bags must be key-stacked to
construct a locking stow precluding
slippage or collapse of bags into the air
channels potentially causing a breakdown
in the air circulation.
High stows may not only cause
compression damage/bruising to the
potatoes (especially new/immature
tubers) but may also result in excessive
heating due to metabolic processes. Bags
should be stowed ideally to eight tiers in
height, but never more than twelve to
thirteen. The width of the air channels
around the cargo blocks should be in the
order of 20 to 30 cms. constructed using
dunnage and/or the locking stow noted
above. Cargo should be stowed clear of
transverse bulkheads and ship’s sides to
promote air circulation with exposed steel
work protected by paper mats or other
sheeting to preclude condensation
damage.
Potato cargoes should be kept well
clear of engine room bulkheads and any
other local heat source situated on the
vessel.
The stowage on any vessel should be
designed to suit the type of permanent
ventilation system fitted. Potato cargoes
make heavy demands on ships’ ventilation
systems and a capacity of at least fifteen
air changes per hour in each empty hold is
required. At these rates the ventilation
system should be run continuously except
when weather and climatic conditions
prevent e.g. risk of shipping water
through the weatherdeck ventilators or
condensation forming on the cargo or
internal ship’s structures. At higher rates
of air changes per hour consideration
should be given, especially on longer
voyages, to either run the fans on lesser
power (reduction of speed) or for lesser
times (ventilate intermittently) in order to
maintain humidity and preclude water
loss from the tubers (desiccation).
Details of ambient air wet and dry
bulb temperatures, hold wet and dry bulb
air temperatures / flesh temperatures and
the ventilation regime undertaken
according to the acquired data regularly
obtained must be recorded in a dedicated
ventilation logbook or alternatively the
deck log book.
Ro-Ro vessels
Cargoes of new/immature potatoes have
for some time been shipped from Eastern
Mediterranean ports in the holds of
Ro-Ro vessels. Packed in woven
polypropylene bags, shipped on pallet
boards with bags secured by nylon nets,
losses and/or additional costs have been
experienced due to the displacement of
bags from the pallet boards.
Bearing in mind the practice of
keeping the Ro-Ro deck lights illuminated
throughout the voyage the problem of
tuber greening has been experienced.
Attempts to prevent this have included
covering stowages with polythene
sheets, which unfortunately reduce the
effectiveness of the hold ventilation
system. Hold lights should never remain
continuously illuminated throughout a
voyage, even of short duration.
Transport of potatoes in ISO
containers
Cargoes of potatoes may be carried in
fan assisted ventilated containers, open
sided containers, insulated refrigerated
containers and ‘port-hole’ insulated
containers. For voyages of a short
Carriage of potatoes continued
duration, closed cargo containers may be
used but doors should remain open
when ever possible to promote
ventilation. Stowage on deck must
include provisions to protect the cargo
from rain, sea-spray and sunlight.
Flat racks are also used for below-
deck stowages in well-ventilated compar,
provisions should be made to afford
exposed bags protection against rain and
sunlight prior to loading and subsequent
to discharge.
Seed potatoes
Seed potatoes are usually shipped
around the world in smaller
consignments than those of new or
mature potatoes. The value of seed
potatoes is much greater than potatoes
destined for consumption and special
care should be taken as any loss in
quality or condition will potentially result
in substantial claims. They may be carried
in a mechanically ventilated stowage but
for longer voyages involving any
prolonged period in warm climatic
conditions, say in excess of 20o Celsius,
they should be carried under
refrigeration at a temperature of 2o to 4o
Celsius.
Safety
Inadequate, or failure of, ventilation in
spaces containing cargoes of potatoes
can cause life threatening concentrations
of carbon dioxide (CO2) or oxygen (O2)
depletion to arise. Thus under these or
suspected conditions the
compartment(s) must be fully ventilated
and a gas measurement conducted. The
threshold limit value (TLV) for CO2
concentrations is 0.49 % by volume ■
Greening occurs when tubers are exposed to
bright light or long periods of low light.
19
Fumigation of shipsand their cargoes
Introduction
Fumigation is a procedure that is used
throughout the world to eradicate pests
that infest all types of goods,
commodities, warehouses, processing
factories and transport vehicles including
ships and their cargoes.
1 What are fumigants andhow do they work?
Fumigants are gases, which are toxic to
the target infestation. They can be
applied as gas, liquid or in solid
formulations, but after vaporisation from
liquids or reaction products from solids,
always act in the gaseous phase. They act
either as respiratory poisons, or as
suffocants in the case of controlled or
modified atmospheres. On release, they
mix with air at a molecular level. They are
capable of rapidly diffusing from one
area to another and through
commodities and buildings.
Fumigants should not be confused
with smokes, which are solid particles in
air, or with mists, aerosols or fogs, which
are liquid droplets, of various sizes, in air.
Smokes, mists, aerosols or fogs are not
fumigants as they are unable to diffuse
(i.e. they do not mix with air at a
molecular level) and do not reach deep-
seated infestations in commodities or
structures.
The fumigant gases used to carry out
the fumigation process are numerous,
but the most commonly used currently
for the treatment of ships cargoes are
phosphine and methyl bromide. Others
used are carbon dioxide and more
recently sulfuryl fluoride, which is
starting to replace the use of methyl
bromide.
1.1 How does a fumigant gas work
effectively?
The critical parameters, which need to be
considered for fumigants to be effective
are:
● Nature of infestation (type of pest e.g;
rodent, insect or beetle, and stage of
its life cycle).
● Type of fumigant applied.
● Concentration and distribution of gas.
● Temperature.
● Length of time fumigant must be
applied.
● Method by which fumigant is
administered.
● Containment of fumigant.
● Nature of commodity.
● Nature of commodity packaging.
● Monitoring system.
● Ventilation system.
1.2 Aim of fumigation
Fumigation aims to create an
environment, which will contain an
effective concentration of fumigant gas
at a given temperature, for a sufficient
period of time to kill any live infestations.
Both the time measured (hours or
days) of exposure and concentration of
gas is critical to fumigation efficiency.
Dosages applied are usually expressed as
grams per cubic metre, concentrations
measured during the fumigation are
usually expressed in parts per million
(PPM) or grams per cubic metre, and total
concentrations actually achieved, as
concentration-time-products (CTPs).
The fumigation process is not
completed until ventilation has been
effectively carried out, and removal of
any residues is completed.
2 When can ships’ cargoes befumigated?
The ship’s cargo can be fumigated and
ventilated:
● In warehouse or storage silos before
loading.
● In freight containers before loading.
● In the hold of the ship with fumigation > continued over
and ventilation completed before
sailing.
or
● In the hold prior to sailing with
fumigation continued during the
voyage (intransit).
● In freight containers before loading
with fumigation continuing during the
voyage (intransit).
In these situations the fumigation
continues during the voyage and is not
finished until the ventilation and removal
of residues is completed, which is
normally at the first discharge port.
3 Rules, regulations andguidelines that affect thefumigation process
3.1 The United Nations International
Maritime Organization (IMO) Safety of
Life at Sea (SOLAS) Convention places an
obligation on all governments to ensure
all shipping activities are carried out
safely.
3.2 The Recommendations on the Safe
Use of Pesticides in Ships (IMO
Recommendations) published by the IMO
(revised 2002) are intended as a guide to
all those involved in the use of pesticides
and fumigants on ships and are
recommended to governments in respect
of their legal obligations under the
SOLAS Convention.
These recommendations are referred
to throughout this document as within
the IMO Recommendations.
3.3 Individual countries (e.g. US and
Canadian Coastguard) have their own
requirements, but some governments
have chosen to make the IMO
Recommendations mandatory on all
vessels in their territorial waters (e.g. UK).
3.4 The IMO International Maritime
Dangerous Goods (IMDG) Code, which is
20
✔ Statement of vessel suitability for
fumigation and fumigant application
compliance.
✔ Manufacturers information or safety
data sheet.
✔ First aid and medical treatment
instructions.
✔ Fumigation certificate.
✔ Fumigation plan.
✔ Instructions for the use of the
phosphine gas detecting equipment.
✔ Precautions and procedures during
voyage.
✔ Instructions for aeration and
ventilation.
✔ Precautions and procedures during
discharge.
✔ Also to provide sufficient additional
respiratory protective equipment (RPE)
where necessary to the vessel, to
ensure the requirements of IMO in
respect of RPE are available for the
duration of the voyage. (Note; the RPE
may consist of SCBA or canister
respirators or a combination of both
but the minimum requirement is for 4
sets of RPE).
Refer also to IMO Recommendations
Annex 4.
5.2.2 Master
✔ Appoint a competent crewmember to
accompany the fumigator during the
inspections/testing of empty holds
prior to loading to determine whether
they are gas tight, or can be made gas
tight and, if necessary, what work is to
be carried out to ensure they are gas
tight.
✔ Ensure the crew is briefed on the
fumigation process before fumigation
takes place.
✔ Ensure the crew search the vessel
thoroughly to ensure there are no
stowaways or other unauthorised
personnel onboard before fumigation
takes place.
✔ Appoint at least two members of the
crew to be trained by the fumigator to
act as representatives of the master
during the voyage to ensure safe
Fumigation continued
mandatory in many parts of the world
under SOLAS, specifically relates to the
fumigation of packaged goods only and
will be referred to under section 8 on
freight container fumigation.
The fumigation of packaged goods
and freight container recommendations,
are referred to throughout this document
as within the IMDG Code.
3.5 The International Maritime
Fumigation Organisation (IMFO) Code of
Practice (COP) provides clear guidance to
fumigators and ships’ masters in respect
of bagged and bulk cargoes, in addition
to packaged goods.
IMFO is an organisation of
independent maritime fumigation
servicing companies with members in
many countries. See Annex 2.
4 Fumigants that can be usedfor intransit fumigation ofbulk and bagged cargoes inships’ holds
4.1 The most widely used fumigant for
intransit fumigation is phosphine (PH3).
The gas is normally generated from
aluminium phosphide or sometimes
magnesium phosphide, but can also be
applied direct from cylinders.
4.2 Methyl bromide should never be used
for fumigation intransit (IMO
Recommendations, Annex 1D).
4.3 Insecticides such as dichlorvos,
pirimiphos-methyl, malathion,
permethrin and others may be sprayed
on to the grain during loading. These are
not fumigants and should be allowed
provided data is provided to the master as
set out in IMO Recommendations 6.2 and
6.4 and Annex 1A.
5 Intransit fumigation of bulkand bagged cargoes withphosphine gas
5.1 Phosphine is only fully effective if a
lethal concentration is maintained for a
period of time that can be as little as 3
days or as much as 3 weeks.
The actual time needed will vary
according to the cargo temperatures,
insect species that may be present, and
the system of fumigation (refer to Annex
1 of this article for brief details of the
types of system).
This is the reason why fumigation with
phosphine is almost always carried out
during the voyage (intransit) so that the
voyage time can be used to ensure a fully
effective treatment.
5.2 When the owners/charterers/master
agree to fumigation being carried out
intransit with phosphine, the master
should ensure he is familiar with the
requirements of IMO Recommendations
3.4.3.1. – 3.4.3.20. This will enable the
master to be clear what the obligations of
both fumigator and master are.
A checklist of these obligations is as
follows:
5.2.1 Fumigator
To provide written documentation in
respect of the following:
✔ Pre-fumigation inspection certificate.
✔ Standard safety recommendations for
vessels with fumigated grain cargoes.
✔ Gas tightness statement.
Probing aluminium phosphide in retrievable sleeves into a bulk cargo.
21
conditions, in respect of the
fumigations, are maintained onboard
the ship during the voyage.
✔ After the fumigant has been applied
and appropriate tests have been
completed, the master should provide
his representative to accompany the
fumigator, to make a check that all
working spaces are free of harmful
concentration of gas (IMO
Recommendations 3.4.3.11).
✔ When the fumigator has discharged
his responsibilities, the fumigator
should formally hand over in writing
responsibility to the master for
maintaining safe conditions in all
occupied areas, which the master
should accept (IMO
Recommendations 3.4.3.12).
✔ It must be clearly understood by the
master that, even if no leakage of
fumigant is detectable at the time of
sailing, this does not mean that
leakage will not occur at some time
during the voyage due to the
movement of the ship or other
factors. This is why it is essential the
master ensures regular checks are
carried out during the voyage.
✔ During the voyage, the master should
ensure that regular checks for gas
leakage should be made throughout
all occupied areas and the findings
recorded in the ships log (IMO
Recommendations 3.4.3.13). If any
leakage is detected appropriate
precautions to avoid any crew being
exposed to harmful concentrations
must be taken. If requested to do so
by the fumigator, the master may,
prior to arrival at the first discharge
port, start the ventilation of the cargo
spaces.
✔ Prior to arrival at the first discharge
port the master should inform the
authorities at the port that the cargo
has been fumigated intransit. (IMO
Recommendations 3.4.3.16).
✔ On arrival at the discharge port the
master should not allow discharge of
the cargo to commence until he is
satisfied that the cargo has been
correctly ventilated and aluminium
phosphide residues that can be
removed have been removed, and
that any other requirements of the
discharge port have been met (IMO
Recommendations 3.4.3.17).
Refer also to IMO Recommendations,
Annex 4.
6 Fumigation of bulk andbagged cargo with ventilationin port
This procedure can be used either after
loading and prior to sailing (6.1) or on
arrival at the discharge port prior to
discharging (6.2).
6.1 After loading and prior to sailing
Phosphine fumigation is the only
fumigant that should be accepted for this
procedure, as methyl bromide
(though frequently used) is not
recommended (IMO Recommendations,
Annex 1D).
Phosphine fumigation and ventilation
in port, prior to sailing, will normally take
from 1-2 weeks to complete and
therefore is only occasionally specified.
All procedures as for intransit fumigation
should be followed to ensure a safe and
effective fumigation.
6.2 At discharge port prior to
discharge
Methyl bromide is the most common
fumigant used for this purpose as it is
normally possible to achieve an effective
fumigation of the cargo in 24-48 hours.
The crew should be landed and remain > continued over
Checking the gas concentrations in the cargo
prior to discharge.
Ventilating the cargo prior to discharge.
ashore until the ship is certified ‘gas free’
in writing by the fumigator in charge.
The fumigator is responsible for the
safety and efficiency of the fumigation,
though crewmembers may remain in
attendance to ensure the safety of the
ship provided they adhere to safety
instructions issued by the fumigator in
charge.
The ventilation of methyl bromide
from cargoes can be a very slow process
if sufficient powered ventilation is not
available and the master (or his
representative) should ensure that the
fumigator has ensured that residues of
gas are below the TLV (IMO
Recommendations, Annex 2) throughout
all parts of the cargo and holds.
Phosphine fumigation and ventilation
in port, prior to discharge, will normally
take from 1-2 weeks to complete and
therefore is only occasionally specified.
All procedures as for intransit fumigation
should be followed to ensure a safe and
effective fumigation.
7 Fumigation of empty cargoholds and/or accomodation toeradicate rodent or insectinfestation
7.1 Methyl bromide is the most common
fumigant used for this purpose (although
hydrogen cyanide (HCN) or sulfuryl
fluoride may be used in some countries)
22
Fumigation continued
as it is normally possible to achieve an
effective fumigation of the empty spaces
in 12-24 hours.
7.2 The crew should be landed and
remain ashore until the ship is certified
‘gas free’ in writing by the fumigator in
charge as for 6.2 above.
8 The intransit fumigation offreight containers
8.1 The reason for the fumigation of
containers is normally to try to ensure
that when the goods arrive at the
discharge port they are free of live pests/
insects.
8.2 Containers are normally fumigated
and subsequently ventilated prior to
being loaded onboard the ship.
Containers that have been fumigated
and subsequently ventilated and where a
‘certificate of freedom from harmful
concentration of gas’ has been issued,
can be loaded onboard ships as if they
had not been fumigated (IMO
Recommendations 3.5.2.1).
8.3 Frequently containers are fumigated
but not ventilated prior to loading and
these containers are therefore fumigated
intransit, as the ventilation process will
not take place until after they have been
discharged from the ship. The carriage of
containers intransit under fumigation is
covered by the IMDG Code whereby
these containers are classified in Section
3.2 Dangerous Goods List as ‘Fumigated
unit Class 9 UN 3359’. Also refer to the
IMDG Code Supplement Section 3.5.1
and 3.5.2 of chapter called ‘Safe use of
pesticides in ships’.
WARNING – Containers are still
sometimes shipped under fumigation
with no warning notices attached and
no accompanying documentation
stating they have been fumigated.
This process is in direct contravention
of the IMDG Code. There may be
dangerous levels of fumigant gas
inside the container when it arrives at
its destination which is both illegal
and dangerous.
8.3.1 Obligations on the fumigator
✔ The fumigator must ensure that, as far
as is practicable, the container is made
gas tight before the fumigant is
applied.
✔ The fumigator must ensure that the
containers are clearly marked with
appropriate warning signs stating the
type of fumigant used and the date
applied and all other details as
required by the IMDG Code and IMO
Recommendations Annex 3.
✔ The fumigator must ensure the agreed
formulation of fumigant is used at the
correct dosage to comply with the
contractual requirements.
8.3.2 Obligations on the exporter
✔ The exporter must ensure that the
containers are clearly marked by the
fumigator with appropriate warning
signs stating the type of fumigant used
and the date applied and all other
details as required by the IMDG Code
and IMO Recommendations Annex 3.
✔ The exporter must ensure that the
master is informed prior to the loading
of the containers.
✔ The exporter must ensure that
shipping documents show the date of
fumigation and the type of fumigant
and the amount used all as required in
the IMDG Code, volume 1, page 35
and specifically section 9.9.
8.3.3 Obligations on the master
✔ The master must ensure that he knows
where containers under fumigation
are stowed.
✔ The master must ensure he has
suitable gas detection equipment
onboard for the types of fumigant
present, and that he has received
instructions for the use of the
equipment.
✔ Prior to arrival of the vessel at the
discharge port the master should
inform the authorities at the discharge
point that he is carrying containers
under fumigation.
✔ If the master (or his representative)
suspects that unmarked containers
may have been fumigated and loaded
onboard they should take suitable
precautions and report their suspicions
to the authorities prior to arrival at the
discharge port.
8.3.4 Obligations on the receivers
✔ The receiver (or his agent) must ensure
that any fumigant residues are
removed, and the container checked
and certificated as being free from
harmful concentrations of fumigant by
a suitably qualified person before the
cargo in the container is removed ■
For further information:
International Maritime Organization
4 Albert Embankment, London, SE1 7SR
Tel: 0207 735 7611. Fax: 0207 587 3210
www.imo.org
International Maritime Fumigation
Organisation
Friars Courtyard, 30 Princes Street,
Ipswich, Suffolk, IP1 1RJ or any member
worldwide. See – www.imfo.com.
Annex 1
A summary of the various methods of
phosphine application methodology
that can be considered for intransit
fumigation of bulk or bagged cargoes
in ships’ holds.
23
1 Application of tablets or pellets to
cargo surface (or into the top half
metre).
High concentrations of gas build up in
the head space, potentially resulting in a
lot of leakage through the hatchcovers
unless they are very well sealed. Very
little penetration down into the cargo.
Powdery residues cannot be removed.
Good kill of insects in top part of
cargo but negligible effect on eggs or
juvenile or even adults in lower part of
cargo.
2 Application of tablets or pellets
by probing into the cargo a few
metres.
Less loss of gas through hatchcovers
than in 1. Better penetration of gas than
when applied on surface only but unlikely
to be fully effective unless holds are
relatively shallow and voyage time
relatively long. Powdery residues cannot
be removed.
3 Application of tablets or pellets by
deep probing into the full depth of
the cargo.
This is difficult to achieve and currently
practically impossible if the cargo is more
than 10 metres deep. Ensures effective
fumigation provided voyage time is
relatively long to allow gas to distribute.
Powdery residues cannot be removed.
4 Application of aluminium
phosphide in blankets, sachets or
sleeves, placed on the surface of the
cargo (or into the top half metre).
All points the same as 1, except that with
this method powdery residues can be
removed prior to discharge.
5 Application of tablets or pellets by
probing into the cargo a few metres in
retrievable sleeves.
All points as for 2, except that with this
method powdery residues can be removed
prior to discharge.
6 Fitting of an enclosed powered
re-circulation system to the hold and
application of aluminium phosphide
tablets or pellets to the surface.
This will ensure the gas is distributed
throughout the cargo evenly and rapidly
making maximum use of the fumigant in
the shortest possible time. Powdery
residues cannot be removed.
7 Fitting of an enclosed powered
re-circulation system to the hold and
application of aluminium phosphide in
blankets, sachets or sleeves on the
surface or probed into the top one or
two metres.
As for 6, except that with this method,
powdery residues can be removed. Also
gaseous residues can be removed more
easily than with other methods, as once
the powdery residues have been removed
the re-circulation system can be used to
assist this to happen rapidly.
8 Deep probing into the full depth of
the cargo (however deep) with tablets
or pellets (in retrievable sleeves when
required).
This is being developed in Canada but is
not yet available. Also deep probing using
pre-inserted pipes.
Will enable good distribution of gas to be
achieved without the requirement for a
powered re-circulation system, provided
the voyage is long enough.
9 Use of powered re-circulation
system with phosphine from
cylinders.
This is not yet available but could be in
the future and will enable phosphine
fumigation to be carried out without
using aluminium phosphide. This will
mean no powdery residues to deal with
and therefore residue and safety
problems at the discharge port will be
minimised. A powered re-circulation
system will be needed to enable this
system to work with maximum efficacy.
Annex 2
References
International Maritime Organization
Recommendations on the Safe Use of
Pesticides in Ships revised 2002.
Published by IMO, 4 Albert Embankment,
London, SE1 76R
International Maritime Organization
The International Maritime Dangerous
Goods Code (IMDG Code) Volumes 1, 2
and Supplement (which includes the
Recommendations on the Safe Use of
Pesticides in Ships referred to above).
Published by IMO London as above. Refer
to Dangerous Goods List under entry UN
3359.
The International Maritime Fumigation
Organisation (IMFO)
Code of Practice (COP)
Obtainable from the IMFO website
www.imfo.com ■
Manhole
Phosphine drawn from thesurface to bottom of hold
Phosphine permeatesthrough cargo asre-circulation continues
Fan
Phosphine applied to surface
Fumigation of cargo in ship’s hold usingphosphine and the J. System.
Traditional fumigation of cargo in ship’s holdusing phosphine.
Phosphine applied to surface or probeda few metres into cargo
Gas moves down veryslowly from surface
After 5-7 days some gasshould reach 10-12 metresat effective concentrations
Gas unlikely to reach 15-20metres in effectiveconcentrations howeverlong the voyage
>
>
>
>
24
Ferrous materials in the form of iron
swarf, steel swarf, borings, shavings or
cuttings are classified in the IMO Code of
Safe Practice for Solid Bulk Materials as
materials liable to self heating and to
ignite spontaneously.
Turnings are produced by the
machining of steel, turning, milling,
drilling, etc. When produced the turnings
may be long and will form a tangled mass
but they may be passed through a
crusher or chip breaker to form shorter
lengths. Both forms of turnings are
shipped and shipments are frequently a
mixture of short and long chips. The
density of the short chips is of the order
of 60 pounds per cubic foot, twice the
density of the longer chips as they tend
to compact more readily.
Borings are produced during the
making of iron castings. Because of the
nature of the parent metal, borings break
up more readily than turnings. They tend
to be finer and the bulk density is greater
than turnings.
Turnings and borings may be
contaminated with oils – cutting oils for
instance – used in the manufacturing
processes. Oily rags and other
combustible matter may also be found
among the loads.
Iron will oxidise, (rust) and iron in a
finely divided form will oxidise rapidly.
This oxidation is an exothermic reaction,
heat is evolved. In a shallow level mass of
turnings this heat will be lost to the
surrounding atmosphere. However in
large compact quantities as in a cargo
hold this heat will be largely retained and
as a result the temperature of the mass
will increase. This oxidation process is
accelerated if the material is wetted or
damp, contaminated with certain cutting
oils, oily rags or combustible matter.
The turnings may heat to high
temperatures but will not necessarily
exhibit flames. In one incident
temperatures in excess of 500ºC were
observed six feet below the surface of
the cargo. Temperatures of this order
may cause structural damage to the
steelwork of the carrying vessel. Flames
Scrap metal(borings,shavings,turnings,cuttings,dross)
are frequently seen in cargoes of metal
turnings but these flames are usually the
result of ignition of the cutting oils, rags,
timber and other combustible materials
mixed with the turnings.
Spontaneous heating of metal
turnings has caused several major
casualties. In the incident mentioned
above spontaneous heating was
detected, the vessel was moved from port
to port in attempts to agree discharge.
After weeks of delay all the holds were
eventually flooded to reduce the heating
for safe discharge of cargo. Following
discharge of the turnings the vessel
loaded a cargo of conventional scrap.
During the subsequent voyage rough
weather was encountered, cracks
developed in the shell plating, the holds
flooded and the vessel was lost with 29
lives.
In another incident heated turnings
formed a solid mass in the hold which had
to be mechanically broken into pieces
before discharge by grab. In a further
incident, following a normal passage it
was not possible to discharge the cargo
by grabs. The surface of the stow had
crusted to a hard mass. Bulldozers were
used to loosen the surface of the cargo
and several hours later fire was observed
in all of the holds.
The IMO Code of Safe Practice for
Solid Bulk Cargoes has special
requirements for the loading of turnings
and borings which include:
1 Prior to loading, the temperature of
the material should not exceed 55ºC.
Wooden battens, dunnage and debris
should be removed from the cargo
space before the material is loaded.
2 The surface temperature of the
material should be taken prior to,
during and after loading and daily
during the voyage. Temperature
readings during the voyage should be
taken in such a way that entry into the
cargo space is not required, or
alternatively, if entry is required for this
purpose, sufficient breathing
apparatus, additional to that required
by the safety equipment regulations,
should be provided.
If the surface temperature exceeds
90ºC during loading, further loading
should cease and should not
recommence until the temperature
has fallen below 85ºC.
The ship should not depart unless the
temperature is below 65ºC and has
shown a steady or downward trend in
temperature for at least eight hours.
During loading and transport the bilge
of each cargo space in which the
material is stowed should be as dry as
practicable.
3 During loading, the material should be
compacted in the cargo space as
frequently as practicable with a
bulldozer or other means. After
loading, the material should be
trimmed to eliminate peaks and
should be compacted.
Whilst at sea any rise in surface
temperature of the material indicates
a self-heating reaction problem. If the
temperature should rise to 80ºC, a
potential fire is developing and the
ship should make for the nearest port.
Water should not be used at sea. Early
application of an inert gas to a
smouldering fire may be effective. In
port, copious quantities of water may
be used but due consideration should
be given to stability.
4 Entry into cargo spaces containing this
material should be made only with the
main hatches open and after adequate
ventilation and when using breathing
apparatus.
It will be noted that compacting the cargo
as loaded with a bulldozer is
recommended. This will tend to form a
dense mass, pushing the short turnings
into the bundles of long turnings, tending
to exclude air from the stow. However
some authorities argue that compacting
the stow tends to break up the long
turnings, creating greater surface areas
for the oxidation process. However
25
shorter turnings should compact more
readily than the longer forms and thus
reduce the area exposed to oxidation.
The reference to trimming level
ensures that there is less cargo surface
exposed to the air than cargo in a peaked
condition. Furthermore, theoretically air
will pass across the top of a level trim, but
can pass through the stow if loaded in a
peaked condition creating a ‘chimney’
effect, thus accelerating the heating
process.
The requirements for entry into cargo
spaces are very important, many lives
have been lost by officers and
crewmembers entering a hold to inspect
a heating problem without taking
adequate precautions. Oxygen is
essential for the oxidation process and in
a sealed space the oxygen is reduced by
the heating reaction of the turnings or
borings. The concentration of oxygen in
air is 20.8%. Exposure to an atmosphere
of 16% oxygen concentration causes an
impairment of mental and physical state.
Concentrations of 10% will cause
immediate unconsciousness and death
will follow if not removed to fresh air and
resuscitated. The symptoms which
indicate an atmosphere is deficient in
oxygen may give inadequate notice to
most people who will then be too weak
to escape when they eventually recognise
the danger. Ventilation of the hold and
testing the atmosphere or use of
breathing apparatus is essential for safe
entry to a hold which is loaded with these
cargoes.
Metal dross and residues
Aluminium dross
Aluminium dross is formed during the
recovery of aluminium from scrap and in
the production of ingots. Dross may
constitute about 5% of the metal where
clean mill scrap is involved but will
constitute greater quantities where
painted or litter scrap is recovered. The
main components of dross are aluminium
oxide and entrained aluminium. Small
amounts of magnesium oxide, aluminium
carbide and nitride are also present.
The dross is recovered and re-melted
under controlled conditions to provide
aluminium metal which is then treated to
remove hydrogen and other impurities
including trace elements. Storage or
transport of aluminium dross should be
conducted under carefully controlled
conditions. Contact with water may
cause heating and the evolution of
flammable and toxic gases, such as
hydrogen, ammonia and acetylene.
Hydrogen and acetylene have wide
ranges of flammability and are readily
ignited.
Aluminium dross, aluminium salt slags,
aluminium skimmings, spent cathodes
and spent potliner as aluminium smelting
by-products are included in the IMO Code
of Safe Practice for Solid Bulk Cargoes.
The Code recommends that hot or wet
material should not be loaded and a
relevant certificate should be provided by
the shipper stating that the material was
stored under cover or exposed to the
weather in the particle size in which it is
to be shipped for not less than three days.
The material should only be loaded under
dry conditions and should be kept dry
during the voyage. The material should
only be stowed in a mechanically
ventilated space. In our opinion the
ventilation equipment should be
intrinsically safe.
Zinc dross
Zinc dross, zinc skimmings, zinc ash and
zinc residues are all materials obtained
from the recovery of zinc. The zinc types
may be recovered from galvanised sheets,
batteries, car components, galvanising
processes, etc. Zinc ashes are formed on
the surface of molten zinc baths, and
whilst primarily zinc oxide, particles of
finely divided zinc will also adhere to the
oxide. The various types of zinc are
treated by processes to produce pure zinc
metal.
The ashes, dross, skimmings and
residues are all reactive in the presence of
moisture liberating the flammable gas
hydrogen and various toxic gases.
The materials are also listed in the
IMO Code for Solid Bulk Cargoes which
states that any shipment of the material
requires approval of the competent
authorities of the countries of shipment
and the flag state of the ship.
The Code recommends that any
material which is wet or is known to have
been wetted should not be accepted for
carriage. Furthermore the materials
should only be handled and transported
under dry conditions. Ventilation of the
holds should be sufficient to prevent
build up of hydrogen in the cargo spaces.
All sources of ignition should be
eliminated which would include naked
light work such as cutting and welding,
smoking, electrical fittings etc.
We have knowledge of one incident
where the cause of an explosion in a hold
containing zinc ashes was said to be a
lamp used to warm the sealing tape used
to seal the hatchcovers. The flame of the
lamp was stated to have ignited
hydrogen gas leaking from the hold. The
flame flashed back into the hold to ignite
an explosive concentration of hydrogen/
air. The explosion lifted the hatchcovers
and collapsed a deck crane.
Unfortunately there was also loss of life.
The hydrogen had been generated by
reaction of the zinc ashes with water,
zinc ashes which had been loaded in a
damp condition.
The zinc ashes were discharged and
later spread on the quayside in a thin
layer to dry. Seven days later hydrogen
was still being evolved to the
atmosphere, as proved by tests with a
hydrogen gas detector ■
Surface temperature reading.
26
Hold cleaning: bulk cargoes– preparing a ship for grain
Surveyors inspection/requirements
Prior to loading grain, all ships are usually
subject to a survey by an approved
independent surveyor. The surveyor will
require the vessels particulars and details
of at least the last three cargoes carried.
He will then inspect the holds for
cleanliness and infestation, or the
presence of any material which could
lead to infestation.
When the surveyor is satisfied with
the condition of the hold, he will issue
the ship with a certificate stating which
holds are fit to load grain.
Purpose:
To ensure cargo holds are prepared to
receive the next cargo.
Large claims have arisen when cargo
holds have not been cleaned sufficiently
to prevent cargo contamination.
The requirements for cleaning the
holds are dependent upon the previous
cargo carried, the next cargo to be
carried, charterers’ requirements, the
requirements of shippers and/or the
authorities at the port of loading and the
receivers.
It is becoming common practice for
receivers to have an inspector at the load
port.
General
Regardless of the previous cargo, all
holds should be thoroughly cleaned by
sweeping, scraping and high-pressure
sea water washing to remove all previous
cargo residues and any loose scale or
paint, paying particular attention to any
that may be trapped behind beams,
ledges, pipe guards, or other fittings in
the holds.
If the ship has been carrying DRI
(direct reduced iron), the dust created by
this particular cargo during loading or
discharging, will be carried to all areas of
the ships structure and the reaction
between iron, oxygen and salt will create
an aggressive effect wherever the dust
may settle. This is particularly noticeable
on painted superstructures. (The IMO
Bulk Cargo Code contains guidelines).
Whenever salt water washing is used
to clean hatches, the relevant holds
should always be rinsed with fresh water
to minimise the effects of corrosion and
to prevent salt contamination of future
cargoes. In this respect, arrangements
should be made in good time to ensure
sufficient fresh water is available for this
operation.
Before undertaking a fresh water
rinse, the supply line (normally the deck
fire main or similar) will need to be
flushed through to remove any residual
salt water. Accordingly, it is suggested
that fresh water rinsing of the holds is
left until the end of hold cleaning
operations to minimise the amount of
fresh water required.
Grain preparation andsafe carriageOne of the most difficult hold cleaning
tasks is to prepare a ship for a grain
cargo after discharging a dirty or dusty
cargo such as coal or iron ore,
particularly if the last cargo has left ‘oily’
stains on the paintwork or other
deposits stubbornly adhering to the steel
surfaces. Greasy deposits which remain
Cargo hold, coal sticking and discharging salt.
on the bulkheads will require a
‘degreasing chemical wash’ and a fresh
water rinse in order to pass a grain
inspection. The degreasing chemical used
should be environmentally acceptable for
marine use, and safe to apply by ships
staff, who have had no special training
and do not require any specialised
protective equipment. Product safety
data sheets of the chemical should be
read, understood and followed by all
persons involved with the
environmentally friendly degreasing
chemical.
To avoid taint problems, fresh paint
should not to be used in the holds or
under the hatch lids at anytime during
the hold preparation, unless there is
sufficient time for the paint to cure and
be free of odour as per the
manufacturer’s instructions. Most marine
coatings require at least seven days for
the paint to be fully cured and odour
free. All paint used in the holds and
underside of the hatchcovers should be
certified grain compatible and a
certificate confirming this should be
available onboard. Freshly painted
hatches or hatchcovers will normally
result in instant failure during the grain
inspection, unless the paint has had time
to cure.
Processed grains or grain cargoes that
are highly susceptible to discolouration
and taint should only be stowed in holds
that have the paint covering intact. It is
important that there is no bare steel,
rust, scale, or any rust staining in the
hold.
Dependent upon the quality of the
grain to be carried, the charter may
27
require the holds to be fumigated. This
may be accomplished on passage with
fumigant tablets introduced into the
cargo on completion of loading.
Fumigation can also be undertaken at the
port of loading (or occasionally
discharge). The ship will normally be
advised how the fumigation is to be
carried out and of any special
precautions that will have to be taken.
In all cases, the preparations (i.e.
inspecting the holds and hatchcovers for
gas-tight integrity) and fumigation must
be carried out in accordance with the
IMO document Recommendation on the
Safe Use of Pesticides on Ships. Gas-
detectors and proper personal protective
equipment should be available and
relevant ship’s officers should receive
appropriate training in their use. After
introduction of the fumigant, an
appropriate period should be allowed
(normally 12 hours) for the gas to build
up sufficient pressure so that any leaks
can be detected: the vessel must not
depart from port before this period has
expired. The entire process should be
certified by a qualified fumigator. The
holds must not be ventilated until the
minimum fumigation period has expired,
and care must be taken to ensure that
subsequent ventilation does not
endanger the crew.
Alongside the dischargeport
On non-working hatches, remove all
cargo remnants, loose scale and flaking
paint from the underside of the hatch lids
and from all steelwork within the hold,
provided safe access can be obtained.
Then commence washing the underside
of the hatchcovers using liquid soap
(such as teepol), followed by a fresh
water rinse with a high-pressure water
gun.
The hatch rubber seals should also be
washed to remove cargo grime.
However, caution is required to ensure
that the hatch rubber seals are not
damaged by the high pressure from the
fresh water gun.
probably assist the removal of cargo
remains from all of the holds using the
shore crane or other cargo-handling
facilities, which will avoid lengthy
difficulties for ships staff during the
ballast voyage.
Example: Portable high-pressure fresh water guns from Stromme.
Hatchcover underside and clean hatch rubber.
After washing, depending on weather
conditions, cargo dust may lightly
contaminate the underside of the hatch
lids; however, the dust particles can easily
be removed at a later date using a high-
pressure portable fresh water gun.
Ballast hold
If the ship has a ballast hold, this should
be discharged as soon as possible during
the discharge
sequence. This will
allow ships staff the
time to remove all
cargo debris and
prepare the hold for
ballasting.
A good working
relationship with the
stevedores will
Hatch undersides and rubber packing.
Shore bulldozer/cocoa beans and shore
personnel cleaning holds.
Discharging soya meal; tapioca cargo sticking
and; cargo hold after discharging minerals.
> continued over
28
Hold cleaning continued
The bilges and strums of the ballast
hold should be thoroughly cleaned and
all traces of previous cargo removed. The
bilge suctions should be tested and
confirmed as clear prior to any washing
out of the cargo holds and the bilge
spaces pumped out and secured with the
bilge blanks.
To prevent ballast water ingress into
the bilge area, it is essential that the
rubber joint/gasket is in good condition
and all the bilge-blank securing bolts are
fitted tightly. The un-seamanlike practice
of securing the bilge blank with four
bolts is unacceptable and may result in
pressurising the bilge line. This must be
avoided.
tightness should be attached by a chain
to the drain. These blanking caps or plugs
are provided if the drains do not have an
approved automatic means of preventing
water ingress into the hold.
If time permits, when the cargo has
been discharged from respective hatches,
all inner hatch coamings’ should be
teepol washed and fresh water rinsed
with the fresh water high-pressure gun
because it is more convenient to wash
this area in port rather than at sea.
If permitted by the port authority, all
hatch tops should be dock water
washed, ensuring that cargo remains are
retained onboard and not washed into
the dock. The fitting of plugs to all deck
scuppers should help prevent any
pollution claims alongside.
It is essential that permission is given
by the port authority for this washing
operation.
All hatch corner drains, including the
non return valves, should be proved clean
and clear. The blanking caps on the hatch
corner drains, used to ensure hold air-
Coaming/trackway covered in fertiliser.
Hatch drain with cap attached by small chain.
Under normal circumstances, when it
rains during cargo operations,
discoloured water from the decks will
flow into the dock and this is normally
accepted by the port authority. The
washing of cargo debris into the dock is
not acceptable.
In some loading ports, where
helicopter operations are used for
embarking and disembarking the pilot, it
is a normal requirement of the port to
wash down the helicopter area and at
least one hatch length either side of the
helicopter area, ensuring that cargo
debris is not washed into the dock.
Preparation at sea
To prevent cargo debris from the main
deck being walked into the
accommodation and tramped into freshly
washed cargo holds, wash down the
main decks and accommodation block as
soon as possible after clearing the port of
discharge, mindful of pollution from the
cargo remains.
Cement staining on decks and hatchcovers.
Prior to the commencement of the
hold-cleaning, a quick safety pre-brief
meeting should take place, which should
include all the personnel who will be
involved in the hold cleaning. During the
pre-brief the hold-cleaning schedule
should be discussed and the equipment
and chemicals to be used must be fully
explained and the safety data sheets
understood by all involved. Basic safety
routines should be established and the
wearing of suitable attire throughout the
hold cleaning must be of paramount
importance.
The wearing of oilskins, safety shoes/
safety seaboots, eye protection, hand
protection and safety helmets complete
with a chin strap, should be made
mandatory during the hold cleaning
process. The wearing of high visibility
waistcoats will help to improve safety in
the hold. The ‘permit to work’ should be
completed on a daily basis, as this will
help reduce the risk of accidents.
Ship’s main deck covered by previous cargo.
Scupper plug fitted.
Hatchcovers
Prior to closing the hatchcovers, all the
hatch track-ways should be swept clean,
then carefully hosed down. If a
compressed air gun is used, it should be
used with caution and suitable safety
equipment should be worn to ensure
both face and body protection.
Hold suction arrangement and filter.
29
Hold cleaning
Prior to high pressure hold washing,
excess cargo residue on the tank top
should be removed by hand sweeping
and lifted out of the holds via the use of a
portable mucking winch. As explained
earlier, a good working relationship with
the stevedores at the discharge port may
help to expedite this operation.
After all excessive cargo residue has
been removed then the holds can be
washed with salt water using a high-
pressure hold cleaning gun,
supplemented by the deck air line to
provide increased pressure. This is the
most commonly used method of hold
cleaning, however the hold cleaning gun
normally requires two seamen to safely
control the increased water pressure.
Some ships are fitted with fixed hold
cleaning equipment, normally fitted
under the hatchcovers. This method of
hold cleaning is less labour intensive.
A flexible high-pressure hose is
connected between a flange on the
hatchcover and the deck high-pressure
hold washing line.
All cargo residues washed down must
be removed via the hold eductors or
mucking winch. Special attention should
be given to cargo residues wedged
behind pipe brackets, hold ladders, and
on the under-deck girders and
transversals. Special attention should be
paid to ventilators to ensure that
remnants of previous cargo have been
removed and the area is grain clean.
Binoculars are quite useful for spotting
cargo remains in high places. Hold bilges
and recessed hatboxes should be cleaned
out and all cargo remains removed. Bilge
suctions must be tested both before and
after washing and the results entered in
the cargo notebook and/or deck log
book.
Salt water chemical wash andhand scraping
To remove any greasy deposits from the
hold steelwork, all the holds should be
high-pressure chemical washed using the
hold cleaning gun complete with air line
booster. The degreasing chemical used, as
previously advised, should be
environmentally acceptable for marine
use, and safe to apply by ships staff, who
have had no special training and do not
require any specialised protective
equipment.
Numerous degreasing chemicals are
available (eg. Sea Shield detergent) and
work quite effectively, if they are directly
injected into the firemain via the general
service pump strainer cover.
Manufacturer’s instructions must always
be followed, but in general the
recommended chemical injection rate is
approx. 5 litres/min.
A typical 110,000 dwt bulker will
require around 100 litres per hold, or 25
litres of degreasing chemical on each
bulkhead.
To avoid long lengths of hose
delivering chemical, the chemical station
should be situated as close as possible to
the injection point of the fire and GS
pump. The easiest way to control the rate
of chemical flow is by fitting a temporary
small hand operated valve on top of the
strainer cover. An alternative method is to
use an eductor system to suck the
chemical direct from the drum into the
Typical hold cleaning equipment: crew
operating a Toby gun and a Toby gun from
Stromme.
Other ships have permanent high-
pressure hold cleaning equipment that
can be lowered through a flange on the
main deck, turned ninety degrees and
bolted to the high-pressure deck wash
service line.
Fixed hold cleaning gun under hatch lids and
fixed hold cleaning connection on deck.
Hold cleaning equipment in the stowed
position above the deck. Note the flange on
the deck wash line.
> continued over
30
Hold cleaning continued
discharge nozzle. The quantity of
chemical introduced is controlled by the
operator or an assistant, lifting the
nozzle clear of the drum. However, this
method of educting the chemical from
the drum into the discharge nozzle is
time consuming and more awkward for
the operator and restricts his movement
around the hold. In addition it carries a
greater risk of an accident or spillage of
degreasing chemical because the
chemical drums have to be lowered into
each and every hold, whereas the first
method allows all the degreasing
chemical to be situated at one place i.e.
by the GS pump.
One degreasing chemical injection
station used successfully aboard a vessel
consisted of: a transparent container of
120-litre capacity, graduated in 10 litre
units; a 5 metre transparent length of
reinforced hose with one end fitted with
a 40cm long steel uptake branch pipe
and the other end open. The branch pipe
was inserted into the chemical container
and the open end of the transparent
reinforced pipe was connected to the
hand valve on the pump strainer cover
using two jubilee clips. The small hand
valve on the strainer cover was used to
control the flow of chemical into the fire
pump.
Prior to starting the high-pressure sea
water chemical wash, all fire hydrants
and anchor wash hydrants on deck
should be checked and confirmed as fully
closed.
The hydrant serving the hold cleaning
gun should be opened and the fire and
GS pump started.
To avoid unnecessary chemical waste,
predetermined times of injecting the
chemical into the fire main should be
agreed between the hold cleaning party
and the person controlling the rate of
chemical injection. On a 110,000 dwt
bulker it takes approx. 20 minutes to
complete a chemical wash in each hatch,
after which the chemical should be
washed off using high-pressure salt
water. Concurrent with the chemical
wash the hold should be hand scraped
with sharp long handled steel scrapers.
All loose scale and flaking paint must be
removed.
Fresh water rinse and holdpreparation
The final stage of hold washing is the
fresh water rinse. A ship preparing for a
grain cargo would be advised to carry
additional fresh water in a convenient
tank. This is often the after peak, which
can be pumped into the fire main via a GS
pump. A typical 110,000 dwt bulk carrier
will require around 30 tonnes of fresh
water per hatch. Prior to commencing
the fresh water rinse, the fire line is
flushed through with the after peak fresh
water to remove all traces of salt water. If
a GS pump is used, the flushing through
takes a few minutes and only uses a few
tonnes of fresh water. Once the fire main
is clear of salt, all deck fire hydrants and
anchor washers should be sighted and
confirmed that they are closed.
If a GS pump is to be used for the hold
rinse, to prevent possible pump damage,
a return line into the after peak should be
set up using a hose connected from the
fire main into the after peak vent.
On completion of the hold fresh water
rinse, all hatch entrances, hatch
trunkings and hand ladders should be
hand washed and fresh water rinsed
using the fresh water high-pressure gun.
It is not advisable to rinse and clean the
access ladders and hatches before
washing the main hold, because
splashings from the hold bulkheads will
often contaminate the freshly washed
ladders. Bulkheads either side of all the
hand ladders should be hand cleaned and
jet washed as far as one can safely reach,
using long handled turks heads. Safety
body harnesses and (if required) a bosun’s
chair should be used when undertaking
this task.
When it is safe to open the hatches, all
the hatch coamings should be hand
washed using long handled turks heads
and jet washed with fresh water using the
high-pressure fresh water gun.
With the hatch lids open, binoculars
should be used to sight the holds for any
cargo remains.
To prevent possible condensation in
the hold, all the recessed hold eductors (if
fitted) must be drained of any water
residue, be clean dry and odourless. There
is usually a small stainless steel drain plug
on the underside of the eductor which
can be temporarily removed to allow the
eductor water to drain into the bilge area.
When the eductor is empty the drain plug
must be replaced and secured. The
eductor hold plate must be secured with
all the securing bolts and duct tape
should be used to cover both the securing
bolts and recessed lid handles.
Hold bilges should be completely dried
out, odourless and in a fully operating
condition. The surveyor will usually
require to sight one bilge in each hold to
ensure that they have been cleaned out
correctly.
The tank top must be completely dry
and any indentations on the tank top
must be wiped dry. The hold should be
made completely odourless, by
maximising hold ventilation. Two layers of
clean hessian cloth should be fitted to the
bilge strainer plate to further restrict
cargo particles entering the bilge area.
Duct tape is used to cover the small gap
between the bilge strainer and tank top.
The hold hydrant area, if fitted, should be
cleaned and dried out. The steel cover
refitted and secured in place with all its
bolts/screws.
Hatch undersides
When it is safe to open the hatches all the
hatchcover undersides should be hand
washed and fresh water jet washed using
Holds drying after washing.
> continued over
31
the high-pressure fresh water gun. If all
the hatchcover undersides were hand
cleaned at the discharge port, this
operation will be completed very quickly
and a high-pressure jet wash may suffice.
All loose scale and any flaking paint
from the hatchcover undersides must be
removed. All ledges on the hatch
undersides must be checked to see that
they are clean. All hatch rubbers and
centre line drain channels should be
clean and clear of any cargo remains or
other debris.
Hatch watertight integrity
To prevent cargo claims due to water
ingress, all hatch seals (both longitudinal
and transverse), hold access lids and
seals around the hatch sides should be
chalk marked and water tested using
deck wash hoses.
Faulty or suspect sections of hatch
rubber should be replaced in their
entirety; localised replacement or
‘building up’ of hatch rubbers using
sealing tape is discouraged.
The first team to enter the open hold
should comprise the grain inspector, a
deck officer and a seaman. Under no
circumstances should grain inspectors be
allowed to inspect the hatches unescorted
by a deck officer.
A second team consisting of a deck
officer and some crewmembers should be
standing by at the top of the hatch being
inspected. The second team should have
available additional clean brooms, clean
mops, scrapers, buckets, clean heaving
lines and clean white rags.
The engineers should be on standby to
test the bilges (dry sucking only).
Radio contact is essential between all
three teams to prevent lengthy delays.
Any personnel entering the holds
should have clean safety shoes or clean
safety sea boots. It is essential that any
debris on the main deck is not walked into
the clean holds. Some ships issue
overshoes to personnel entering the hold.
If the inspector finds a fault with a
hold, if at all possible, the fault should be
identified and recorded, and remedial
action agreed with the inspector. If
possible the fault should be rectified
immediately and preferably before the
inspector leaves the ship. If this is not
possible a time should be agreed for his
re-inspection.
Ballast hold
The ballast hold is usually de-ballasted
and prepared alongside during the
loading period. If the hold and bilges were
cleaned at the discharging berth, the
ballast hold preparation will be quickly
completed.
Loading grain
Hatches not being loaded should be kept
closed. All hatches after passing the grain
inspection and prior to loading, must be
inspected on a daily basis to ensure that
they are still completely dry. Hatches
containing grain cargo must not be
entered due to a possible lack of oxygen.
During the load, it is important to keep
the grain cargo dry. If the grain is allowed
to become wet, high cargo claims will
result.
Regular visual checks by ships staff
throughout the load should ensure that
Hose testing and a typical hose test.
A more accurate method of testing a
hatch for leakage is to use ultrasonic
equipment. However this is usually
completed by shore personnel who are
trained in the use of this equipment.
Ultrasonic hatch testing for leaks.
Grain inspection
Prior to the grain inspection all hatches
and access lids must be open and safely
secured with all locking pins/bars.
All hatches should be checked for
loose scale or flaking paint. Invariably
there will be a little scale on the tank top,
which can quickly be removed. If weather
conditions permit during the day, the
holds should be opened to allow fresh air
to assist the hold drying process. All small
pools of water should be mopped dry. All
hatch rubbers and centre line seals
should be wiped over with a clean dry rag
to confirm their cleanliness.
Poor practice: hatch tape used to build up
cross joints. This is discouraged.
Prior to the inspection, ships staff
should lower into the first hold an
aluminium ladder together with a small
number of clean brooms, scrapers,
dustpan and brush, a clean bucket and a
few clean white rags. If possible the
second hold to be inspected should also
be equipped with similar items.
Hold ready to load wheat.
> continued over
32
Hold cleaning continued
the grain being loaded is not in a wet
condition. These inspections should be
recorded in the deck log book.
Loading grain; other hatches closed.
During the loading of grain, dust
clouds often develop. These are a health
hazard and additional safety
requirements, such as the wearing of eye
protection goggles and dust masks
should be observed by all personnel in
the vicinity of the dust cloud.
If the master is in any doubt about the
condition of the grain during the load, he
must issue a note of protest and seek
advice from his operators and/or the UK
P&I Club.
Completion of a hatch
All holds to be filled must be absolutely
full. It is essential that the loading spout,
Grain dust cloud presents a health hazard.
Loading barley (bottom).
or other mechanism, is directed to all
corners, to avoid any void spaces. Time
should be allowed for the grain to settle
then refill any spaces (such as hatch
corners).
Grain settling in the cargo hold.
When the loading of a hatch has been
completed, the trackways, hatch drains,
and channel bars must be swept clean
and the hatch closed. Water must not be
used to wash down hatch trackways.
DRY compressed air is very useful, but
crew safe working practices must be
observed when using compressed air.
Ventilators should be tightly secured.
Loading grain to all corners.
are applied. Foam compound should not
be used to ensure hatch watertight
integrity.
Hatch vent to secure.
Loaded voyage
Regular checks of all hatch sealing tape (if
fitted) should be completed and damaged
or lifting tape immediately replaced.
During the voyage, entry into any cargo
space must be strictly prohibited.
Ventilation during the voyage will depend
on weather conditions and a comparison
between the dew point of the air inside
the hold and outside the hold. Under no
circumstances should hold ventilation be
permitted during adverse weather
conditions or before fumigation in transit
has been completed.
In good weather, basic cargo
ventilation rules should be observed.
Guidance can be obtained from Bulk
Carrier Practice: A Practical Guide (ISBN
928 0114 581).
If the vessel has any oil tanks adjacent
to or under the cargo holds, any steam
heating to these tanks should be
minimised, but in any case carefully
monitored and full records maintained to
Do not use foam to seal hatches.
Security seal in place.
If the voyage instructions require
hatch sealing tape to be used, as an
additional precaution to prevent water
ingress, then the hatch surfaces must be
scrupulously clean before the sealing
tape is applied. In cold climates, some
brands of tape will adhere better if
warmed in the engine room before they
To prevent unauthorised access to the
oxygen depleted grain holds, and where
fumigation in transit is to be undertaken,
all the hold access lids should either be
padlocked or have steel security seals
fitted.
33
prevent cargo heating and possible cargo
damage. This is a point that is often
overlooked by ships staff.
Grain cleaning ‘operational’checklist
Prior to commencing the grain clean the
master should check and confirm the
following:
✔ If the previous cargo is likely to cause
problems during the cleaning voyage,
the master must advise his operator
well in advance, so that sufficient
cleaning time, manpower and
materials can be planned. A lack of
communication between ship and
shore may result in difficulties for
the ship and costly off hire for the
operator.
✔ As soon as the ship starts cleaning
preparations, the master should make
regular daily reports of the hatch
cleaning progress to his operator.
✔ If the after-peak is to be used for the
carriage of additional fresh water –
confirmation that the after-peak tank
can be discharged via the deck service
line and, if after-peak is ‘filled’ with
fresh water, the ship can still maintain
the minimum bow height as per
classification rules. (Details in stability
book).
✔ The ship has fully operational mucking
winch.
✔ All bilge sounding pipes and
temperature sounding pipes (if fitted)
are clear with no ‘old’ sounding rods or
any obstructions or blockages.
✔ All sounding pipes have a fully
operational screw thread and the
gasket is in good condition i.e.
sounding cap that can be screwed
down tightly to prevent water ingress.
✔ The ship has no ballast tank leaks.
✔ Advise his operator if there are any
problems with the ship’s ballast pumps,
eductor(s) or general service pumps.
✔ The ship has a ‘grain certified’ paint
certificate for inside the hatches.
(assuming that the hatches were
previously painted some months
earlier).
✔ All hatch corner drains and non-return
valves are working correctly and are
complete in all respects.
✔ All hatch ladders on fwd and aft
bulkheads are in good condition to
allow safe access for all personnel.
✔ All hold bilge plates have all the
securing bolts fitted and the ships
approved ballast holds have the
blanks. This is often a spectacle piece
which can be rotated on deck.
✔ All ballast line hold cover plates have
all the bolts fitted and they are all in
good condition.
✔ All hatch access lids can have a hatch
seal or padlock fitted after loading, to
prevent unauthorised entry into
oxygen depleted area.
✔ No infestation is onboard. This
includes all the storerooms, as these
areas are also liable to be inspected by
grain inspectors.
✔ Approved grain stability books
onboard and the pre-calculated load
conditions (using appropriate grain
shift moments) have been completed.
In some ports, these calculations have
to be approved by the local authorities.
✔ A hold-cleaning schedule using
realistic times has been prepared.
The ‘simplified’ example, below, is not an
actual working schedule.
Under normal circumstances It often
takes one day to clean a hold.
This figure of one day per hold is
usually acceptable to charterers.
The ‘simplified’ schedule assumes that
the vessel’s previous cargo was coal or
iron ore. If the vessel’s previous cargo was
grain, then the chemical wash may not be
required, but the holds should still be
hand scraped to remove any loose scale
and paint.
Grain cleaning ‘equipment’checklist
✔ A fully working high-pressure hold
cleaning gun (Toby gun or Semjet or
similar) – complete with sufficient deck
wash down hoses and air-lines all in
good condition.
Fire hoses must not be used as wash
down hoses as they are part of the
ships safety equipment.
✔ Ship has a fully operational salvage
pump (Wilden pump) and approved
spares.
✔ Sufficient fresh water to complete a
high-pressure fresh water rinse of all
the holds. It will be more cost effective
to over-supply fresh water for hold
cleaning than the ship to run out
during the hold cleaning. (A typical
100,000dwt bulker requires around
30 tonnes per hatch).
Simplified schedule.
> continued over
Order of events Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day7
(In port)Hatch undersides
Wash downdecks
HP saltwaterwash holds
Chemical washholds – scrape –and SW rinse
FW rinse andhold preparation
Clean hatch lidsundersides
Check holdsand hatchwatertightness
x
x x
x
x x
x
x
x
x
34
✔ 1 x portable pressurised fresh water
gun, complete with extended handle
and 30 metres of pressurised hose.
✔ 6 x long handle steel scrapers
complete with handles.
✔ 3 x lightweight, strong, aluminium
extension poles with capability to
extend to approx 5 metres.
✔ 6 x long handled rubber squeegee
complete with 1 metre rubber blades.
✔ 10 x heavy-duty bass brooms, c/w
handles, suitable for hold cleaning.
✔ 6 x corn brooms c/w with handles.
✔ 6 x heavy-duty mops, c/w handles.
✔ 6 x spare mop heads suitable for above.
✔ 4 x galvanized, roller wringer, mop
buckets.
✔ 6 x turks heads, round head 4 inch,
c/w handles.
✔ 6 x small 6 inch wide, hand shovels,
steel, suitable for digging out hold
bilges.
✔ 3 x 25 metre length, lint free soogee
cloth, width approx 30cm.
✔ 1 x 50 metre length burlap, 1 metre
wide.
✔ 10 x rolls of 50 metre length, 10cm
wide, grey, industrial strength duct
tape.
✔ 6 x 20 metre length, ‘yellow’ wash
down hoses, duraline, 45mm dia
complete with couplings suitable for
ship’s fire main.
✔ 4 x plastic jet nozzles, suitable for
above hoses.
✔ 4 x 50 metre lengths, transparent
plastic, reinforced garden hose,
complete with male and female plastic
couplings to join each section.(for use
with Kew gun).
✔ 2 x universal tap connectors for above
reinforced transparent plastic garden
hose.
✔ Sufficient hatch sealing tape to comply
with operators instructions.
✔ 4 x 500 watt, portable lightweight
halogen lights to illuminate hatches
during cleaning. Each lamp to be
complete with 50 metres of cable and
have a waterproof plug fitted.
✔ 10 x spare halogen bulbs for above.
✔ 2 x 50 metre extension cables each
complete with three waterproof
outlet sockets and a waterproof plug.
✔ 5 x 20 litre drums concentrated
teepol.
✔ Sufficient drums of de-greasing
chemical wash suitable for use with
sea water (e.g. Sea Shield detergent
cleaner or equivalent).
Typical examples of holdfailures
The following images from a vessel which
failed a grain survey, would suggest that:
● Ships crew completed a very quick salt
water wash.
● No chemical wash was undertaken.
● No hard scraping of the bulkheads
was completed.
● Previous hold cleaning had not been
supervised (history of the ships
cargoes on the stiffeners).
Showing:
● Staining from the previous cargo
(coal).
● Cargo dust residues.
● Deposits of previous cargoes in hard
to reach places.
● Flaking paint and scale ■
Hold cleaning continued
References
Bulk Carrier Practice – A Practical Guide.
(ISBN 928 0114 581)
Recommendation on the Safe Use of
Pesticides on Ships. (ISBN 9280111205)
Product Safety Data Sheets – for
degreasing chemical used.
Bulk Cargo Code – IMO Publication. (ISBN
9280110616)
MARPOL. (ISBN 9280114174)
www.stromme.com
35
For a long period of time iron has been
produced in blast furnaces by reduction
of iron ore, that is removing the oxides of
the ore. High shipping costs are paid for
shipping the iron oxides from the ore
producing areas to the iron producing
furnaces. Reduction of the ore in blast
furnaces is then a high energy demand
process. Research in the steel making
industry has produced a method to
directly reduce the ores to metal, the
product known as direct reduced iron,
DRI. Iron ore is crushed and formed into
pellets. The pellets are then heated in a
furnace, at a temperature below the
melting point of any of the metal in the
ore, in the presence of reducing gases.
The ore is reduced to metal by the
removal of oxygen, leaving the metal in a
rigid but sponge-like structure. This
sponge-like structure has an extremely
high surface area to mass ratio, possibly a
thousand times greater than the surface
area of a piece of iron of the same mass.
It is well known that iron will readily
oxidise or ‘rust’. This ‘rusting’ process is
obviously increased with an increase in
surface area as exhibited by DRI pellets.
The rusting process is an exothermic
reaction, that is to say heat is evolved
during the process. Furthermore this
reaction is accelerated in the presence of
water or moisture and further
accelerated by the presence of an
electrolyte as in sea water. The reaction
between DRI and water results in the
production of the highly flammable gas
hydrogen.
Thus the safe carriage of DRI pellets
relies upon excluding oxygen and water,
particularly sea water, from the stow.
Certain manufacturers have developed
passivation techniques for the DRI pellets,
which supposedly prevent the effect of
moisture and oxygen reacting with the
pellets. However following a serious fire
in a ship carrying passivated pellets, there
are doubts whether the passivation
technique is satisfactory for the safe
carriage of the pellets.
During a period of six months in
2003/2004 there were three serious
casualties related to the carriage of DRI
and DRI fines including loss of life and
sinking of two of the ships.
The most positive method of carrying
DRI safely, free from the effects of
oxygen and sea water is to ensure that
the cargo compartments are effectively
sealed and inerted. The compartments
should be inerted to the extent that the
oxygen content of the atmosphere is less
than 5%.
Direct reduced iron such as lumps,
pellets and cold moulded briquettes are
included in the IMO Code of Safe
Practice for Solid Bulk Cargoes under BC
No.015. Direct reduced iron, briquettes,
hot moulded are included in the Code
under BC No.016. It is important to note
that the entries in the Code relate to:
“Direct Reduced Iron DRI” and “Direct
Reduced Iron”
Examples are indicated “such as
lumps, pellets, briquettes etc”. However
this does not exclude fines. Fines are fine
particles of direct reduced iron created
during the manufacturing, handling and
storage of the material. Fines as
marketed normally have specifications
relating to total iron and metallic iron.
The fines may thus evolve hydrogen if in
contact with water, which is also stated
in the Code.
Apparently one shipper and one
author considers that DRI fines and HBI
fines are not included in the IMO Code.
However this is not the case, the IMO
entry clearly states, direct reduced iron,
which would include fines derived from
direct reduced iron.
The IMO Code of Safe Practice for
Solid Bulk Cargoes under the title ‘Special
Requirements’ states:
“Certification: A competent person
recognised by the National
Administration of the country of
shipment should certify to the ship’s
Master that the DRI at the time of
loading, is suitable for shipment.
Direct reduced iron including DRI fines
Shippers should certify that the material
conforms with the requirements of this
Code.”
The Code continues with a section
‘Shipper’s Requirements’. This states that
prior to shipment the DRI should be aged
for at least 72 hours or treated with an air
passivation technique, or some other
equivalent method that reduces the
reactivity of the material to at least the
same level as the aged product.
It states under Paragraph A that the
shipper should provide the necessary
specific instructions for carriage either:
maintenance throughout the voyage of
cargo spaces under an inert
atmosphere containing less than 5%
oxygen. The hydrogen content of the
atmosphere to be maintained at less
than 1% by volume or
that the DRI has been treated with an
oxidation and corrosion inhibiting
process which has been proved to the
satisfaction of the competent authority
to provide effective protection against
dangerous reaction with sea water or
air under shipping conditions.
The provision of Paragraph A may be
waived or varied if agreed by the
competent authorities taking into account
the sheltered nature, length, duration, or
any other applicable conditions of any
specific voyage.
The Code then continues to describe
the relevant precautions, loading carriage
etc.
Despite all these problems, DRI cargoes
are safely carried to destination. However
if the precautions are not observed there
can be severe problems during discharge
of heated cargo. Expensive fire fighting
procedures involving the use of vast
quantities of solid inert materials, inert gas
etc, long delays to the discharge. Even
when removed from the ship’s hold a
heated cargo can cause problems on the
quayside. At one port there remained for
> continued over
36
Carefully to Carry
Edited by:
Karl Lumbers Tel: +44 (0)20 7204 2307
e-mail: karl.lumbers@thomasmiller.com
Colin Legget Tel: +44 (0)20 7204 2217
e-mail: colin.legget@thomasmiller.com
Fax: +44 (0)20 7283 6517
Published by:
Thomas Miller & Co Ltd
International House, 26 Creechurch Lane
London EC3A 5BA
Tel: +44 (0)20 7283 4646
Fax: +44 (0)20 7283 5614
http://www.ukpandi.com
For and on behalf of the Managers of
The United Kingdom Mutual Steam ShipAssurance Association (Bermuda) Limited
The United Kingdom Freight Demurrage andDefence Association Limited
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Carefully to Carry on-line
This newsletter and earlier editions
can be viewed on the Club’s website:
http://www.ukpandi.com
Acknowledgements
The UK P&I Club would like to thank theCarefully to Carry Advisory Committee forthe following articles:
The carriage of liquefied gases / Liquefiednatural gas – Wavespec Limited
Bulk liquid cargoes – sampling – CWAInternational Limited
Carriage of potatoes – John BanisterLimited
Fumigation of ships and their cargoes –Igrox Limited
Scrap metal – Minton, Treharne & DaviesLimited
Hold cleaning – UK Club Loss PreventionDepartment
Direct reduced iron – Minton, Treharne &Davies Limited
Whilst the information given in this newsletter is believedto be correct, the publishers do not guarantee itscompleteness or accuracy.
a long period of time a solid lump of DRI,
possibly 5,000 tonnes – difficult to
remove.
The International Group of P&I Clubs
circulated a document to their members in
August 1981 relating to the problem in
the carriage of DRI. Following a meeting
of IMO in January 1982 the Group
circulated a further document relating to
the safe carriage of DRI. The first item to
be stressed in this latter circular quoting
the IMO amendments was to the effect
that throughout the voyage an inert
atmosphere should be maintained with an
oxygen content less than 5%.
In May 2001 the UK P&I Club published
a circular which indicated the following:
a) The undersigned Association continues
to believe that the only proven method
of carrying this cargo safely is by
maintaining the cargo holds in an inert
atmosphere and believe the most
effective method of providing an inert
atmosphere is by injecting inert gas at
the bottom of the stow in order to
force out the air within the stow (see
photos below).
b) On present information, it is not
thought that the length or nature of
the voyage contemplated (IMO
Paragraph B) can ever justify the waiver
of the requirement of maintaining the
cargo in an inert atmosphere.
Under the ideal conditions of carriage,
perfectly sealed hold spaces for all types of
ships under all weather conditions it may
be possible to complete the voyage
maintaining an inert atmosphere
throughout the stowed cargo following
injection of inert gas at the
commencement of loading. It may also be
possible to prevent the ingress of sea
water into the hold spaces. However,
under certain conditions the hatchcovers
may 'work' and not remain 'airtight', thus
Ramnek tape could assist in this respect.
If hatch coaming drains are not sealed
leakage may also take place from diurnal
breathing and dynamic wind effects. Loss
of gas can also take place through
sampling via access hatches rather than
hatch sampling valves. It may therefore
be necessary to 'top up' the inert gas for
safe carriage to destination.
Hot moulded briquettes
Hot moulded briquettes of DRI are a
different proposition. The mined ore
passes through a densification process
but is then moulded at a temperature in
excess of 650o C. The briquettes may be
stored in open storage conditions. Prior to
shipment the shipper or competent
authority should provide the master with
a certificate to the effect that the material
is suitable for shipment and conforms
with the requirements of the IMO Code.
Loading during rain is not acceptable
but briquettes can be discharged under
all weather conditions. Water spray to
assist dust control is also permitted during
discharge. Hold spaces should be clean
and dry, and all combustible materials
removed before loading. Briquettes with
a temperature in excess of 60o C should
not be loaded.
Hydrogen may be slowly evolved if the
briquettes had been in contact with water
thus adequate ventilation should be
provided. There are no requirements to
monitor hydrogen and oxygen levels nor
to record temperature effects in the
cargo. Normal precautions of entering the
hold spaces should be observed in case of
oxygen depletion ■
Direct reduced iron continued
An inert atmosphere is maintained within the stow by injecting an inert gas from the bottom.
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