Carriage Of Liquified Gas - P& I Club Ion

UK CLUB

FEBRUARY 2005 ISSUE 8

CAREFULLY TO CARRY The carriage of liquefied gases “The carrier shall properly and carefully load, handle, stow, carry, keep, care for and discharge the goods carried.” Hague Rules, Articles iii, Rule 2

Introduction The renewed interest in gas, which started in the

The introduction of a tanker designed to carry

1990s due to its excellent environmental

compressed natural gas (CNG) is anticipated in

credentials, has seen an increase in the order

the near future. A number of designs have been

book for LNG carriers – LNG carriers being the

produced but, due to the relatively low

leviathans of the gas carrier fleet. Yet, while

deadweight and high cost of these ships, the first

attracting great interest, the gas trade still

commercial application of this technology cannot

employs relatively few ships in comparison to oil

be predicted. The gas carrier is often portrayed in the media

tankers, and hence its inner workings are little known except to a specialist group of companies

as a potential floating bomb, but accident

and mariners.

statistics do not bear this out. Indeed, the sealed nature of liquefied gas cargoes, in tanks

Considering the fleet of gas carriers of over 3

1,000 m capacity, the total of nearly 1,000 ships

completely segregated from oxygen or air,

can be divided into 5 major types according to the

virtually excludes any possibility of a tank

following table:

explosion. However, the image of the unsafe ship

The gas carrier fleet (end 2004)

Ship numbers 3

Total capacity (m )

Pressurised LPG carriers

Semi-pressurised LPG carriers

Ethylene carriers

Fully refrigerated LPG carriers

LNG carriers

336

189

103

185

175

1,045,970

1,378,690

755,620

11,171,705

20,683,798

Source: Braemar Seascope Gas (all information given in good faith but without guarantee).

By contrast, the world oil tanker fleet for a similar size range is over 16,000 ships! IN THIS ISSUE

PAGE

Given the relative paucity of knowledge on gas

lingers, with some administrations and port state control organisations tending to target such ships for special inspection whenever they enter

tankers in comparison to oil tankers, the purpose

harbour. The truth is that serious accidents

The carriage of liquefied gases

1

of this article is to describe the gas carrier genre,

related to gas carrier cargoes have been few,

Liquefied natural gas

9

its particularities within each type and its

and the gas carrier’s safety record is

comparison with other tankers. The aim is to

acknowledged as an industry leader. As an

provide basic knowledge about gas carriers and

illustration of the robustness of gas carriers,

an overview of their strengths and weaknesses,

when the Gaz Fountain was hit by rockets in the

both from design and operational viewpoints.

first Gulf War, despite penetration of the

Bulk liquid cargoes – sampling

13

Carriage of potatoes 15 Fumigation of ships and their cargoes

19

Scrap metal

24

Hold cleaning – bulk cargoes

26

Direct reduced iron

35

A second article, on page 8, describes the

containment system with huge jet fires, the fires

liquefied natural gas (LNG) carrier in more detail

were successfully extinguished and the ship,

and a third article, to be published later, will

together with most cargo, salved.

describe the liquefied petroleum gas (LPG) carrier.

> continued over

1

Carriage of liquefied gases continued

Ammonia is one of the most common

non-liquefied form would be normally far too costly. The principal gas cargoes are

chemical gases and is carried worldwide in

LNG, LPG and a variety of petrochemical

large volumes, mainly for agricultural

due to a number of features. One such,

gases. All have their specific hazards.

purposes. It does however have particularly

almost unique to the class, is that cargo

LNG is liquefied natural gas and is

toxic qualities and requires great care

tanks are always kept under positive

methane naturally occurring within the

during handling and carriage. By

pressure (sometimes just a small

earth, or in association with oil fields. It is

regulation, all liquefied gases when carried

overpressure) and this prevents air

carried in its liquefied form at its boiling

in bulk must be carried on a gas carrier, as

entering the cargo system. (Of course

point of -162°C. Depending on the

defined by the IMO. IMO’s Gas Codes (see

special procedures apply when stemmed

standard of production at the loading

next section – Design of gas carriers)

for drydock). This means that only liquid

port, the quality of LNG can vary but it

provide a list of safety precautions and

cargo or vapour can be present and,

usually contains fractions of some

design features required for each product.

accordingly, a flammable atmosphere

heavier ends such as ethane (up to 5%)

cannot exist in the cargo system.

and traces of propane.

The relative safety of the gas carrier is

Moreover all large gas carriers utilise a

A specialist sector within the trade is the ethylene market, moving about one

The second main cargo type is LPG

million tonnes by sea annually, and very

closed loading system with no venting to

(liquefied petroleum gas). This grade

sophisticated ships are available for this

atmosphere, and a vapour return pipeline

covers both butane and propane, or a

carriage. Temperatures here are down to

to the shore is often fitted and used

mix of the two. The main use for these

-104°C and onboard systems require

where required. The oxygen-free nature

products varies from country to country

perhaps the highest degree of expertise

of the cargo system and the very serious

but sizeable volumes go as power station

within what is already a highly specialised

limitation of cargo escape to atmosphere

or refinery fuels. However LPG is also

and automated industry. Within this group

combine to make for a very safe design

sought after as a bottled cooking gas and

a sub-set of highly specialised ships is able

concept.

it can form a feedstock at chemical

to carry multi-grades simultaneously. Significant in the design and operation

plants. It is also used as an aerosol

The liquefied gases

propellant (with the demise of CFCs) and

of gas carriers is that methane vapour is

First let us consider some definitions in

is added to gasoline as a vapour pressure

lighter than air while LPG vapours are

the gas trade. According to the IMO, a

enhancer. Whereas methane is always

heavier than air. For this reason the gas

liquefied gas is a gaseous substance at

carried cold, both types of LPG may be

carrier regulations allow only methane to

ambient temperature and pressure, but

carried in either the pressurised or

be used as a propulsion fuel – any minor

liquefied by pressurisation or

refrigerated state. Occasionally they may

gas seepage in engine spaces being

refrigeration – sometimes a combination

be carried in a special type of carrier

naturally ventilated. The principal

of both. Virtually all liquefied gases are

known as the semi-pressurised ship.

hydrocarbon gases such as butane,

hydrocarbons and flammable in nature.

When fully refrigerated, butane is carried

propane and methane are non-toxic in

Liquefaction itself packages the gas into

at -5°C, with propane at -42°C, this latter

nature and a comparison of the relative

volumes well suited to international

temperature already introducing the

hazards from oils and gases is provided in

carriage – freight rates for a gas in its

need for special steels.

the table below:

Comparative hazards of some liquefied gases and oils GASES HAZARD

LNG

OILS 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 temperature

Eye irritant, narcotic, nausea

Eye irritant, narcotic, nausea

Flammability limits in air (%)

5-15

2-10

1-6

Not applicable

Storage pressure

Atmospheric

Often pressurised

Atmospheric

Atmospheric

Behaviour if spilt

Evaporates forming a visible ‘cloud’ that disperses readily and is non-explosive, unless contained

Evaporates forming an explosive vapour cloud

Forms a flammable pool which if ignited would burn with explosive force, environmental clean-up may be required

Forms a flammable pool, environmental clean-up is required

2

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

3,200 m3 coastal LPG carrier with cylindrical tanks.

(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.

16,650 m3 semi pressurised LPG carrier

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

78,000 m 3 LPG carrier with Type-A tanks

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

135,000 m3 LNG carrier with membrane tanks

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

137,000 m3 LNG carrier with Type-B tanks (Kvaerner Moss system)

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

distance of the inner hull from the outer

consequences of a ruptured containment

is defined in the gas codes. This spacing

system.

in existence before IMO codification and

introduces a vital safety feature to

ships built before 1977 are defined as

mitigate the consequences of collision

design is double containment and an

‘existing ships’ within the meaning of the

and grounding. Investigation of a

internal hold. The cargo tanks, more

rules. To cover these ships a voluntary

number of actual collisions at the time

generally referred to as the ‘cargo

code was devised, again by the IMO – the

the gas codes were developed drew

containment system’, are installed in the

Code for Existing Ships Carrying Liquefied

conclusions on appropriate hull

hold, often as a completely separate

Gases in Bulk (the Existing Ship Code).

separations which were then

entity from the ship; i.e. not part of the

Despite its voluntary status, virtually all

incorporated in the codes. Collisions do

ship’s structure or its strength members.

ships remaining in the fleet of this age –

occur within the class and, to date, the

Herein lies a distinctive difference

and because of longevity programmes

codes’ recommendations have stood the

between gas carriers and their sisters, the

there are still quite a number – have

test of time, with no penetrations of

oil tankers and chemical carriers.

certification in accordance with the

cargo containment having been reported

Existing Ship Code as otherwise

from this cause. The double hull concept

independent self-supporting type or of a

international chartering opportunities

includes the bottom areas as a protection

membrane design. The self-supporting

would be severely restricted.

against grounding and, again, the

tanks are defined in the IGC Code as

Cargo carriage in the pressurised fleet

So a principal feature of gas carrier

Cargo tanks may be of the

designer’s foresight has proven of great

being of Type-A, Type-B or Type-C.

comprises double cargo containment –

value in several serious grounding

Type-A containment comprises box-

hull and tank. All other gas carriers are

incidents, saving the crew and

shaped or prismatic tanks (i.e. shaped to

built with a double hull structure and the

surrounding populations from the

> continued over

3

Carriage of liquefied gases continued

ballast tanks and if problems are to

pressure vessels usually bi-lobe in cross-

develop with age then the ballast tanks are

section, designed for operating pressures

fit the hold). Type-B comprises tanks

prime candidates. These ships are the most

of up to 7 bars. The tanks are

where fatigue life and crack propagation

numerous class, comprising approximately

constructed of special grade steel

analyses have shown improved

40% of the fleet. They are nevertheless

suitable for the cargo carriage

characteristics. Such tanks are usually

relatively simple in design yet strong of

temperature. The tanks are insulated to

spherical but occasionally may be of

construction.

minimise heat input to the cargo. The

prismatic types. Type-C tanks are the

Cargo operations that accompany such

cargo boils off causing generation of

pure pressure vessels, often spherical or

ships include cargo transfer by flexible

vapour, which is reliquefied by

cylindrical, but sometimes bi-lobe in

hose and in certain areas, such as China,

refrigeration and returned to the cargo

shape to minimise broken stowage.

ship-to-ship transfer operations from

tanks. The required cargo temperature

larger refrigerated ships operating

and pressure is maintained by the

internationally are commonplace.

reliquefaction plant.

The fitting of one system in preference to another tends towards particular trades. For example, Type-C

Records show that several ships in this

These ships are usually larger than the

tanks are suited to small volume carriage.

class have been lost at sea because of

fully pressurised types and have cargo

They are therefore found most often on

collision or grounding, but penetration of

capacities up to about 20,000 m3. As

coastal or regional craft. The large

the cargo system has never been proven.

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 Pressurised LPG carrier with cylindrical tanks.

as a fully refrigerated liquid at -104°C.

international LPG carrier will normally be

In one case, a ship sank off Italy and

fitted with Type-A Tanks. Type-B tanks

several years later refloated naturally, to

and tanks following membrane principles

the surprise of all, as the cargo had

are found mainly within the LNG fleet.

slowly vaporised adding back lost

The pressurised fleet

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

buoyancy.

they have the ability to carry several

The first diagram, on the previous page,

The semi-pressurised fleet

grades. Typically this range can extend to

and the photograph above show a small

In these ships, sometimes referred to as

ethane, LPG, ammonia, propylene

fully pressurised carrier. Regional and

‘semi-refrigerated’, the cargo is carried in

butadiene and vinyl chloride monomer (VCM), all featuring on their certificate of

coastal cargoes are often carried in such craft with the cargo fully pressurised at

Semi-pressurised LPG carrier.

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

4

fitness. To aid in this process several

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

Fully refrigerated LPG carrier.

independent cargo systems co-exist

substantial reserve plant capacity

onboard to avoid cross contamination of

provided. The cargo tanks do not have to

the cargoes, especially for the

withstand high pressures and are

reliquefaction process.

therefore generally of the free standing

The ships range in size from about

prismatic type. The tanks are robustly

2,000 m3 to 15,000 m3 although several

stiffened internally and constructed of

larger ships now trade in ethylene. Ship

special low temperature resistant steel.

design usually includes independent cargo tanks (Type-C), and these may be

All ships have substantial double bottom spaces and some have side

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 > continued over

cylindrical or bi-lobe in shape constructed from stainless steel. An inert gas

LNG carrier with Type-B tanks (Kvaerner Moss system).

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 interbarrier 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.

LNG carrier with membrane tanks.

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

5

Carriage of liquefied gases continued

training standards for gas carrier crews

environment the continued growth in the

which come in addition to normal

fleet currently strains manpower

membrane type, or alternatively, prismatic

certification. These dangerous cargo

resources and training schedules and it is

in design. In the case of membrane tanks,

endorsements are spelt out in the STCW

possible that short cuts may be taken.

the cargo is contained within thin walled

Convention. Courses are divided into the

tanks of invar or stainless steel. The tanks

basic course for junior officers and the

operate at minimum crew levels, on the

are anchored in appropriate locations to

advanced course for senior officers. IMO

larger carriers it is normal to find

the inner hull and the cargo load is

rules require a certain amount of

increased crewing levels over and above

transmitted to the inner hull through the

onboard gas experience, especially at

the minimum required by the ship’s

intervening thermal insulation.

senior ranks, before taking on the

manning certificate. For example, it is

All LNG carriers have a watertight

responsible role or before progressing to

almost universal to carry a cargo

inner hull and most tank designs are

the next rank. This can introduce checks

engineer onboard a large gas carrier. An

required to have a secondary containment

and balances (say) in the case of a master

electrician is a usual addition and the

capable of safely holding any leakage for

from the bulk ore trades wanting to

deck officer complement may well be

a period of 15 days. Because of the

convert to the gas trade. The only way,

increased.

simplicity and reliability of stress analysis

without previous gas experience, to

of the spherical containment designs, a

achieve this switch is to have the

full secondary barrier is not required but

candidate complete the requisite course

Gas carriers and port operations

splash barriers and insulated drip trays

and sail as a supernumerary,

As gas carriers have grown in size, so too

protect the inner hull from any leakage

understudying the rank for a specified

has a concern over in-port safety.

that might occur in operation. Existing

period on a gas carrier. This can be costly

Indeed, the same concerns applied with

LNG carriers do not reliquefy boil-off

for seafarer and company alike.

the growth in tanker sizes when the

gases, they are steam ships and the gas is

Accordingly, as the switch can be difficult

VLCC came to the drawing board. The

used as fuel for the ship’s boilers. The first

to manage, especially at senior ranks,

solutions are similar; however, in the case

ships to burn this gas in medium speed

current requirements tend to maintain a

of the gas carrier, a higher degree of

diesel engines will be delivered in 2005/6,

close-knit cadre of ‘gas men or women’

automation and instrumentation is often

and ships with reliquefaction plant and

well experienced in the trade.

apparent controlling the interface

conventional slow speed diesel engines

In addition to the official certification

While the small gas carriers normally

between ship and shore. Terminals are also protected by careful

will enter service late in 2007. It is likely

for hazardous cargo endorsements, a

that gas turbine propelled ships may

number of colleges operate special

risk analysis at the time of construction

appear soon after this.

courses for gas cargo handling. In the UK

so helping to ensure that the location

a leader in the field is the Warsash

and size of maximum credible spill

Maritime Centre.

scenarios are identified, and that suitable

Crew training and numbers As they did for oil tankers and chemical carriers, the IMO has laid down a series of

While this situation provides for a well-trained and highly knowledgeable

precautions including appropriate safety distances are established between operational areas and local populations.

Hard arms at cargo manifold, including

Hard arm connection to manifold, showing

vapour return line (below, centre arm).

double ball valve safety release.

Regarding shipping operations, risk analysis often identifies the cargo manifold as the area likely to produce the

Hard arm quick connect/disconnect coupler (QCDC).

6

maximum credible spill. This should be

jetty was out of action for approximately

controlled by a number of measures.

six months. Fortunately the berth was in

Primarily, as for all large oil tankers, gas

an industrial area and collateral damage

carriers should be held firmly in position

to areas outside the refinery was limited.

whilst handling cargo, and mooring

As ships have grown in size the

management should be of a high calibre.

installation of vapour return lines

Mooring ropes should be well managed

interconnecting ship and shore vapour

throughout loading and discharging. Safe

systems has become more common.

mooring is often the subject of

Indeed, in the LNG industry it is required,

computerised mooring analysis, especially

with the vapour return being an integral

for new ships arriving at new ports, thus

part of the loading or discharging

helping to ensure a sensible mooring array

system. In the LPG trades, vapour returns

suited to the harshest conditions. An

are also common, but are only opened in

accident in the UK highlighted the

critical situations such as where onboard

consequences of a lack of such procedures

reliquefaction equipment is unable to

3

when, in 1993, a 60,000 m LPG carrier broke out from her berth in storm

cope with the loading rate and boil-off.

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?

●

A feature common to both ship and

Is the cargo containment system intact?

conditions. This was the subject of an

shore is that both have emergency

official MCA/HSE inquiry concluding

shutdown systems. It is now common to

that prior mooring analysis was vital to

interconnect such systems so that, for

safe operations. The safe mooring

example, an emergency on the ship will

principles attached to gas carriers are

stop shore-based loading pumps. One

similar to those recommended for oil

such problem may be the automatic

and what are its dispersal

tankers (they are itemised in Mooring

detection of the ship moving beyond the

characteristics?

Equipment Guidelines, see References ,

safe working envelope for the loading

page 13).

arms. A further refinement at some

The need for such ships to be held

●

Is the ship venting gas?

●

Is the ship likely to vent gas?

●

What will be the vented gas

●

tool available?

larger terminals is to have the loading

firmly in position during cargo handling is

arms fitted with emergency release

due in part to the use of loading arms

devices, so saving the loading arms from

(hard arms – see photos opposite) for

fracture (see centre photo opposite).

cargo transfer. Such equipment is of

Given good moorings and well-

Is a gas dispersion modelling

●

Is the ship damaged?

●

Does damage compromise the ship’s manoeuvring ability? What activities and services are

limited reach in comparison to hoses, yet it

designed loading arms, the most likely

provides the ultimate in robustness. It also

sources of leakage are identified and

planned to restore a seaworthy

provides simplicity in the connection at the

controlled.

condition?

cargo manifold.

●

●

Is ship-to-ship transfer

gas carrier is now quite common and, if

Hazards to shore workers and crewmembers at refit

not a national requirement, is certainly an

While the gas carrier accident record is

industry recommendation. The alternative

very good for normal operations, and

use of hoses is fraught with concerns over

exemplary with respect to cargo

hose care and maintenance, and their

operations and containment, the same

proper layout and support during

cannot be said for the risks it faces in

operations to prevent kinking and

drydock. Statistics show that the gas

abrasion. Further, accident statistics show

carrier in drydock presents a serious risk

that hoses have inferior qualities in

to personnel, particularly with respect to

comparison to the hard arms. Perhaps the

adequate ventilation through proper

worst case of hose failure occurred in

inerting and gas-freeing before repairs

1985 when a large LPG carrier was loading

begin. Most often the risk relates to

at Pajaritos, Mexico. Here, the hose burst

minor leakage from a cargo tank into the

and, in a short time, the resulting gas

insulation surrounding refrigerated LPG

port or public authorities

cloud ignited. The consequent fire and

tanks. A massive explosion occurred on

co-operate?

explosion impinged directly on three other

the Nyhammer at a Korean shipyard in

ships in harbour and resulted in four

1993 for this very reason, where

deaths. It was one of those accidents

considerable loss of life occurred.

which has led directly to a much increased

Although the ship was repaired, it was a

use of loading arms internationally. The

massive job ■

The use of loading arms for the large

7

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

●

Will customs and immigration procedures need facilitation for equipment and advisers?

Liquefied natural gas Background

consolidated rather than expanded.

the very earliest days, and with the

It was as far back as 1959 that the

Indeed, the American pricing problems,

appropriate safety equipment in place

Methane Pioneer carried the first

and the failure of an early US-built

the regulations allow methane to be

experimental LNG cargo, and 40 years

shipboard Conch containment system on

burnt in ship’s boilers. This is not the case

ago, in 1964, British Gas at Canvey Island

newbuildings, blanketed any spectacular

for LPG, where reliquefaction equipment

received the inaugural cargo from Arzew

progress in the Atlantic basin until the

is a fitment, but specifically because the

on the Methane Princess. Together with

regeneration of interest initiated by the

LPGs are heavier than air gases and use

the Methane Progress these two ships

Trinidad project in 1999.

in engine rooms is thereby disallowed.

formed the core of the Algeria to UK

At that time, the stifling of European

LNG quality

project. And the project-based nature of

interest was also due to the discovery of

LNG shipping was set to continue until

natural gas in the North Sea, so quantities

LNG is liquefied natural gas. It is sharply

the end of the 20th century. LNG carriers

to replace town gas were available in

clear and colourless. It comprises mainly

only existed where there were projects,

sufficient volume on the doorstep

methane but has a percentage of

with ships built specifically for

without the need for imports. This being

constituents such as ethane, butane and

employment within the projects. The

so, the first LNG project from Algeria to

propane together with nitrogen. It is

projects were based on huge joint

UK eventually faltered, with the receiving

produced from either gas wells or oil

ventures between cargo buyers, cargo

terminal at Canvey Island switching to

wells. In the case of the latter it is known

sellers and shippers, all in themselves

other interests. The stagnation of LNG in

as associated gas. At the point of

large companies prepared to do long-

the 70s and 80s applied the world over,

production the gas is processed to

term business together.

with the singular exception of imports to

remove impurities and the degree to

The projects were self-contained and

Japan and Korea. Here interest in LNG’s

which this is achieved depends on the

operated without much need for outside

potential as an environmentally-friendly

facilities available. Typically this results in

help. They supplied gas using a purpose-

fuel stayed vibrant; as it does today.

LNG with between 80% and 95%

built fleet operating like clockwork on a

LNG projects are massive multi-billion

methane content. The resulting LNG can

CIF basis. Due to commercial constraints,

dollar investments. Major projects in the

therefore vary in quality from loading

the need for precisely scheduled

Far East included Brunei to Japan,

terminal to loading terminal or from

deliveries and limited shore tank

Indonesia to Japan, Malaysia to Japan and

day-to-day.

capacities, spot loadings were not

Australia to Japan, comprising some 90%

feasible and it is only in recent years that

of the LNG trade of the day.

change significantly are the specific

some projects now accept LNG carriers as

Consequently, the Japanese defined

gravity and the calorific value of the

cross-traders, operating more like their

much of what is seen best today in way of

LNG, which depend on the

tramping cousins – the oil tankers.

safety standards and procedures. It is

characteristics of the gas field. The

Doubtless the trend to spot trading will

worthy of note, however, that some early

specific gravity affects the deadweight

continue. However, the co-operative

safety standards and practices are being

of cargo that can be carried in a given

nature of LNG’s beginnings has led to

questioned today in the light of

volume, and the calorific value affects

several operational features unique to

experience in a more mature industry.

both the monetary value of the cargo

the ships. In particular there is the acceptance that LNG carriers burn LNG

Other physical qualities that can

and the energy obtained from the boil-

LNG as a fuel

off gas fuel. These factors have significance in

cargo as a propulsive fuel. They also

Because the ships, terminals and

retain cargo onboard after discharge (the

commercial entities were all bound

commercial arrangements and gas

‘heel’) as an aid to keeping the ship

together in the same chain, advantages

quality is checked for each cargo, usually

cooled down and ready to load on arrival

could be seen in limiting ‘unnecessary’

in a shore-based laboratory by means of

at the load port. Thus matters that would

shipboard equipment, such as

gas chromatography. LNG vapour is

be anathema to normal international

reliquefaction plant, and allowing the

flammable in air and, in case of leakage,

trades are accepted as normal practice

boil-off to be burnt as fuel. One way or

codes require an exclusion zone to allow

for LNG.

another the ship would need fuel, be it oil

natural dispersion and to limit the risk of

or gas and, if gas, it was only then a

ignition of a vapour cloud. Fire hazards

there was also great interest in this new

matter to quantify usage and to direct the

are further limited by always handling

fuel in the USA and France. Receiving

appropriate cost to the appropriate

the product within oxygen-free systems.

terminals sprouted. However, gas pricing

project partner.

Unlike oil tankers under inert gas, or in

Again, looking back to the early days,

difficulties in the USA saw an end to early American interest while Gaz de France

Interestingly, this concept was recognised in the IMO’s Gas Codes from

8

some cases air, LNG carriers operate with the vapour space at 100%

methane. LNG vapour is non-toxic,

handle cargo and is reminiscent of old

specify the efficiency required. Usually

although in sufficient concentration it

tales of derring-do from the 19th century

this is stated in terms of a volume boil-off

can act as an asphyxiant.

when a cargo might have been burnt for

per day under set ambient conditions for

emergency purposes. It is nevertheless

sea and air temperature. The guaranteed

shipboard perspective. LNGs high in

the way in which the LNG trade operates.

maximum figure for boil-off would

nitrogen, with an atmospheric boiling

Boil-off is burnt in the ship’s boilers to the

normally be about 0.15% of cargo

point of -196°C, naturally allow nitrogen

extent that it evaporates from its mother

volume per day.

to boil-off preferentially at voyage start

liquid. Clearly cargo volumes at the

thus lowering the calorific value of the

discharge port do not match those

boilers must be boosted to the engine

gas as a fuel. Towards the end of a

loaded.

room by a low-duty compressor via a

Gas quality is also significant from a

ballast passage, when remaining ‘heel’

Accounting however is not

While at sea, vapours bound for the

vapour heater. The heater raises the

has all but been consumed, the

overlooked and LNG carriers are outfitted

temperature of the boil-off to a level

remaining liquids tend to be high on the

with sophisticated means of cargo

suited for combustion and to a point

heavier components such as the LPGs.

measurement. This equipment is

where cryogenic materials are no longer

This raises the boiling point of the

commonly referred to as the ‘custody

required in construction. The boil-off

remaining cargo and has a detrimental

transfer system’ and is used in preference

then enters the engine room suitably

effect on tank cooling capabilities in

to shore tank measurements. These

warmed but first passes an automatically

readiness for the next cargo.

systems normally have precise radar

controlled master gas valve before

measurement of tank ullage while the

reaching an array of control and shutoff

attributed to methane make it a great

tanks themselves are specially calibrated

valves for direction to each burner. As a

attraction today as a fuel at electric

by a classification society to a fine degree

safety feature, the gas pipeline through

power stations. It is a ‘clean’ fuel. It

of accuracy. The system automatically

the engine room is of annular

burns producing little or no smoke and

applies corrections for trim and list using

construction, with the outer pipe purged

nitrous oxide and sulphur oxide

equipment self-levelled in drydock. The

and constantly checked for methane

emissions produce figures far better than

resulting cargo volumes, corrected for

ingress. In this area, operational safety is

can be achieved when burning normal

the expansion and contraction of the

paramount and sensors cause shutdown

liquids such as low sulphur fuel oil.

tanks, are normally computed

of the master gas valve in alarm

Natural gas has thus become attractive

automatically by the system.

conditions. A vital procedure in the case

The good combustion qualities

to industry and governments striving to

Cargo tank design requires carriage at

of a boiler flameout is to purge all gas

meet environmental targets set under

atmospheric pressure and there is little to

from the boilers before attempting

various international protocols such as

spare in tank design for over or under

re-ignition. Without such care boiler

the Rio Convention and the Kyoto

pressures. Indeed, the extent to which

explosions are possible and occasional

Protocol. The practice of firing marine

pressure build-up can be contained in a

accidents of this type have occurred.

boilers on methane provides the further

ship’s tanks is very limited in the case of

environmental advantage of lesser soot-

membrane cargo tanks, although less so

Cargo care

blowing operations and much fewer

for Type-B tanks. Normally this is not a

The majority of LNG shippers and

carbon deposits.

problem, as at sea the ship is burning

receivers have a legitimate concern over

boil-off as fuel or in port has its vapour

foreign bodies getting into tanks and

Cargo handling

header connected to the terminal vapour

pipelines. The main concern is the risk of

The process of liquefaction is one of

return system. Clearly, however, there are

valve blockage if (say) an old welding rod

refrigeration and, once liquefied, the gas

short periods between these operations

becomes lodged in a valve seat. Such

is stored at atmospheric pressure at its

when pressure containment is necessary.

occurrences are not unknown with a ship

boiling point of -162°C. At loading

This can be managed. So taken together,

discharging first cargoes after

terminals any boil-off from shore tanks

shipboard operations efficiently carried

newbuilding or recently having come

can be reliquefied and returned to

out succeed in averting all possible

from drydock. Accordingly, and despite

storage. However, on ships this is almost

discharges to atmosphere, apart that is

discharge time diseconomies, it is

certainly not the case. According to

from minor escapes at pipe flanges, etc.

common practice to fit filters at the ship’s

design, it is onboard practice to burn

Certainly this is part of the design criteria

liquid manifold connections to stop any

boil-off gas (often together with fuel oil)

for the class as it is recognised that

such material from entering the shore

in the ship’s boilers to provide

methane is a greenhouse gas.

system. The ship normally supplies filters

propulsion. In the general terms of seaborne trade this is an odd way to

Boil-off gas (BOG) is limited by tank insulation and newbuilding contracts

9

fitting neatly into the manifold piping. > continued over

Liquefied natural gas continued

In a similar vein, even small particulate matter can cause concerns. The carryover 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.

LNG carrier with Type-B tanks (Kvaerner Moss system).

Ship care A temperature of -162°C is astonishingly

these materials do not commonly feature

when, resulting from a misoperation,

cold. Most standard materials brought

over the ship’s weatherdecks, tank

steam was accidentally applied to the

into contact with LNG become highly

weather covers or hull. These areas are

main turbine with the ship secured

brittle and fracture. For this reason

constructed from traditional carbon

alongside the berth. The ship broke out

pipelines and containment systems are

steel. Accordingly, every care is taken to

from the berth, but fortunately the

built from specially chosen material that

ensure that LNG is not spilt. A spill of LNG

loading arms had not been connected.

do not have these drawbacks. The

will cause irrevocable damage to the

This action was sufficient however for

preferred materials of construction are

decks or hull normally necessitating

cargo receivers to reject the ship, and the

aluminium and stainless steel. However

emergency drydocking. Accidents of this

cargo could only be delivered after a

Moss design (courtesy of Moss Maritime).

A cargo was once rejected in Japan

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’.

10

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 ‘brokenstowage’ 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

LNG carrier with membrane tanks.

also have its navigating bridge set at a

Membrane design (GTT).

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,

nature have occurred, fortunately none

six centreline tanks. Only a few have

resulting in ship sizes now of about

reporting serious personal injury, but

certification and equipment for cross

145,000 m3. That said, one of the newest

resulting, nevertheless, in extended

trading in LPG. The cargo boils on

in class is the Pioneer Knudsen, trading at

periods off-hire.

passage and is not re-liquefied onboard

only 1,100 m3 capacity from a facility

– it is carried at atmospheric pressure.

near Bergen to customers on the

specially designed and insulated to

Although there are four current methods

Norwegian west coast. At the end of

prevent leakage and rupture in the event

to construct seaborne LNG tanks, only

2004 the first orders were placed for LNG

of accident such as grounding or

two are in majority usage. There are the

carriers of more than 200,000m3 and

collision. That aside, though

spherical tanks of Moss design and the

ships to carry over 250,000m3 are

sophisticated in control and expensive in

membrane tanks from Gaz Transport or

expected to be delivered by the end of

materials, they are simple in concept.

Technigaz (two French companies, now

2008.

Mostly they carry LNG in just four, five or

amalgamated as GTT). Each is contained

> continued over

LNG carriers are double-hulled ships

11

Liquefied natural gas continued

Large modern LNG carriers have dimensions approximately as follows: Capacity (m3) Length Beam Loaded draft

recognise this and, together with

considered by many as a cut-off date. On

inspection regimes, the overall quality of

termination of their original projects we

LNG tonnage is kept to a high standard.

are now seeing many of the older ships

Age for age, they are probably the best

as surplus to requirements. Sometimes

maintained ships in the world. Of course

the project wishes to continue but only

145,000

215,000

some of these ships are now old and only

with new ships. So the older ships are

295m

315m

a few have ever been scrapped; some are

laid-off. In the past this would have been

48m

50m

over 30 years old. This is very old for a

their death knell but today this is not

large tanker trading all its life in salt

necessarily the case. The slow

water, when 25 years is already

development of a spot market has

12m

12m

LNG having a typical density of only 420 kg/m3 allows the ships, even when fully laden, to ride with a high freeboard.

Glossary

They never appear very low in the water as a fully laden oil tanker may do. Ballast

Administration

The Administration is the national authority responsible for shipping safety in the country concerned

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

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

manoeuvring in port in windy conditions the ships are always susceptible to being blown to one side of the channel, and

DCE

Dangerous Cargo Endorsement

Heel

The amount of liquid cargo remaining in a ship’s cargo tank

restrictions on port manoeuvring usually apply with extra tug power commonly

at the end of discharge. It is used to maintain the cargo

specified.

tanks cooled down during the ballast voyage by

Another salient feature of the LNG class is the propensity to fit steam

recirculating through the sprayers. On LPG ships such

turbine propulsion. This is an

cooling is carried out via the reliquefaction plant and on

anachronism brought about by a

LNG ships by using the in-tank spray pumps.

reluctance to change over the years, together with a fear that a system as yet

IGC Code

International Code for the Construction and Equipment of

untried on LNG carriers may not find

Ships Carrying Liquefied Gases in Bulk

favour with the principal charterers – the Japanese. Most other ship types of this

IMO

International Maritime Organization (a United Nations

size have diesel engines and the

agency)

engineers to run diesel equipment are plentiful and suitably trained. On the other hand, engineers knowledgeable in

LNG

Liquefied Natural Gas (methane with traces of heavier gases)

steam matters are few and their training base is the ship itself. This situation is changing though, with both diesel

LPG

Liquefied Petroleum Gas (typically butane and propane)

SIGTTO

Society of International Gas Tanker and Terminal

electric dual fuel systems and slow speed diesels now finding favour. With slow

Operators Ltd

speed diesel propulsion, reliquefaction plants will be required onboard to handle boil-off gas, and all diesel

SMS

Safety Management System – a company-wide SMS as required under the ISM Code

systems will require back-up gas disposal facilities – also known as ‘gas combustion units’ (GCUs) – for when

STCW Convention

International Convention on Standards of Training, Certification and Watchkeeping for Seafarers

either the reliquefaction plants or the duel fuel diesel engines are not available to process boil-off gas.

STCW Code

Seafarers’ Training, Certification and Watchkeeping Code

USCG

United States Coast Guard

LNG ships are expensive to build. They comprise very valuable assets: generally far too good to let rust away. Shipowners and ship managers alike

12

allowed the shipowner to consider life

The Society’s stated aim is to

extension programmes of considerable

encourage the safe and responsible

cost; all this set against the value of a

operation of liquefied gas tankers and

very expensive newbuilding. Today life

marine terminals handling liquefied gas;

extension programmes are common with

to develop advice and guidance for best

old ships making handsome profits in the

industry practice among its members and

Ship-to-Ship Transfer Guide (Liquefied

spot market ■

to promote criteria for best practice to all

Gases) – 1995, SIGTTO

who have responsibilities for, or an

The International Code for the

interest in, the continuing safety of gas

Construction and Equipment of Ships

tankers and terminals.

Carrying Liquefied Gases in Bulk,

SIGTTO Valuable assistance in the preparation of

The Society operates from its London

Safe Havens for Disabled Gas Carriers – 2003, SIGTTO Mooring Equipment Guidelines – 2001, OCIMF

(IGC Code) – IMO

these articles has come from the Society

office at 17 St. Helens Place EC3.

of International Gas Tanker and Terminal

Further details on activities and

A Contingency Planning and Crew

Operators (SIGTTO).

membership is available at

Response Guide for Gas Carrier Damage

www.sigtto.org

at Sea and in Port Approaches – 1999,

SIGTTO is the leading trade body in

SIGTTO

this field and has over 120 members covering nearly 95% of the world’s LNG fleet and 60% of the LPG fleet. SIGTTO

References

The aforementioned publications are

members also control most of the

Liquefied Gas Handling Principles on Ships

available from Witherby & Company Ltd,

terminals that handle these products.

and in Terminals – SIGTTO

London.

.............................................................................................................................................................................................

Bulk liquid cargoes – sampling Introduction

Retention and sealing

ship’s crew should be clearly labelled with

Sampling is a vitally important factor in

Due to the inability of the ship’s officers

the following:

the custody transfer of bulk liquid

to undertake analysis of samples, only

●

Ship’s name.

cargoes. Acquisition and subsequent care

the most obvious contamination

and retention of representative samples

problems will be apparent at the outset,

●

Operational status

can provide an important means of

such as:

rebutting unfounded allegations of cargo

before discharge. ●

Change in colour.

●

The presence of water (if water is not

contamination. This applies equally to chemical, petrochemical, petroleum

soluble in the cargo).

product and crude oil shipments. Cargo surveyors attending the loading

i.e. before loading, after Ioading,

Foreign particulate matter.

working on behalf of shippers or

●

Odour taint.*

consignees (or both, on a joint basis) and

Samples taken at the initial stages of

are not obliged to provide samples to the

cargo operations showing such obvious

ship, albeit that it is common practice to

cargo quality deviations should give

place samples in the custody of the

cause to halt cargo operations in order to

master at the loadport for delivery to the

carry out further investigations** and to

disport receivers. However, these samples

note protest.

or discharge of any given cargo are often

Sample type bottom, running, composite.

●

Wherever possible, samples drawn by the

Whether samples are provided by the

Identity of sampler i.e. surveyor, crewmember.

●

Date and time.

●

Location

All samples drawn should be sealed,

custody transfer samples provided.

draw samples for the ship’s protection.

Sample source

i.e. top, middle, bottom, dead

labelled, retained and recorded.

recommended that the vessel’s crew

●

●

on rare occasions are official-sealed

cargo interests to the ship or not, it is

Product.

i.e. tank number, manifold number. ●

are not the property of the ship and only

●

i.e. port, berth, anchorage. ●

Seal number.

Seals are customarily applied to samples * 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.

13

by an independent surveyor in order to > continued over

Sampling bulk liquid cargoes continued

capacity, balanced against the need to

sampling procedure is prescribed by the

retain sufficient sample volume to allow

specialist equipment in use. Appropriate

analysis in the event of a dispute arising.

safety procedures must be observed and

preserve sample provenance in the event

Generally, 500ml is a realistic

the sampler protected from exposure to

of dispute. Nowadays, seals are widely

compromise.

the cargo during sampling.

is increasingly common for ships to be

Where to take samples

Conclusion

equipped with their own seals.

During the custody transfer of a bulk

It is unquestionably the case that a

Alternatively, some owners use self-

liquid cargo, the principal sampling

vessel’s adherence to the above sampling

sealing tamper-evident bottle closures

points where cargo quality can be

procedure can provide the necessary

which may not be individually numbered

adequately monitored are:

evidence to rebut cargo quality claims in

but, nonetheless, preserve sample

1 Loadport shore tank(s).

available and relatively inexpensive and it

circumstances where unfounded

provenance. Marked samples should be retained in a dedicated locker, ideally for at least 12

2 Shoreline sample following any ‘packing’ or flushing operation.

months. Space considerations may make

3 Vessel’s manifold at commencement

this impractical in which case the samples

of loading and spot checks during

should be retained for as long as

loading.

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

A rigorous sampling system should form an essential part of a vessel’s ISM operational procedures ■

References

4 Vessel’s cargo tanks first foots.

ASTM D 4057

5 Vessel’s cargo tanks post-loading.

Standard Practice for Manual Sampling

6 Vessel’s cargo tanks pre-discharge. 7 Vessel’s manifold at commencement of discharge.

of Petroleum and Petroleum Products. ASTM E 300 Standard Practice for Sampling Industrial

8 Disport shore tank(s) pre- and post-

Chemicals.

discharge.

cargo surveyors who invariably have disposal methods already in place.

allegations are made against shipowners.

Ideally, all of these samples should be

BS 3195

taken on each cargo carrying voyage, but

Methods for Sampling Petroleum

Sample bottles

in any event, onboard ship samples 3 to 7

Products.

Sample bottles vary in size and in the

should always be taken by the crew for

materials from which they are made.

protection of the owner’s interests.

Glass and plastic bottles can be dark or

Further samples might be considered,

clear. Most samples can generally be

such as 3, following changeover of

stored in clear glass bottles. Light

shoretanks at a mid-loading stage.

sensitive samples, however, should be

BS 5309 Methods for Sampling Chemical Products.

stored in brown bottles*. Certain

Method of drawing samples

IP

samples, such as caustic soda or potash

Samples should be drawn in compliance

Petroleum Measurements Manual Part IV

require plastic containers. Petroleum

with industry practice as set out in

Sampling – Section I Manual Methods.

products/crude oil samples are often

publications such as those issued by

retained in lacquer-lined tinplate

ASTM, API and BS (see References). In

containers. These types of containers are,

general, a ‘running’ sample taken by use

in general, unsuitable for retention of

of a bottle and sample cage is the

chemical cargo samples. Where possible,

preferred method of obtaining a

a range of containers should be available.

representative sample in a homogeneous

Sample bottle closures vary in the

bulk cargo. Where the cargo may not be

chemical resistance of the sealing insert.

homogenous, careful zone sampling is

Waxed cardboard disc type should only

required to produce a representative

be used for petroleum products/crude

composite sample. The properties of

oils. Aluminium foil-faced cardboard

some chemical cargoes require that

discs are unsuitable for acid or alkaline

special sampling procedures are adopted

samples. Preferred inserts are

such as excluding air, using specialist

polypropylene or PTFE.

sample valves or indeed ‘closed’

Sample bottle size may be determined, to some extent, by storage

sampling methods due to the toxicity or flammability of the cargo. Here, the

14

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.

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.

which produce new growth).

Seed potatoes for shipment comprise

Potato tuber diseases may be the

small whole tubers each with at least one

result of micro-organisms or adverse

eye to produce the new growth. Seed

preshipment storage conditions.They

potatoes are grown under a regulated

may also be the result of improper

Tuber shape – round, oblate, oval, or

certification programme to ensure that

stowage and conditions of carriage.

kidney shaped.

they are as disease-free as possible.

Flesh colours – white, cream, yellow, blue/purple/red or striated.

●

Three basic types of potato, left to right: early/new; late/mature and; seed (notice fragile ‘eyes’

Potatoes are grown under the soil and, as such, when harvested will always

●

Usage – table, processing or seed.

●

Harvest time – early/new or immature,

Once potatoes have been harvested they

invading micro-organisms, which will

or late/mature.

must be stored under optimal conditions

attack the tubers if the natural defence

Potatoes are grown throughout the

until released for shipment. However no

mechanism is ruptured. This can result

world, except in humid tropical lowland

storage is able to improve the product

from mechanical damage, either during

areas. They are one of the worlds most

placed therein, but much can be

harvesting or subsequent handling or,

important food crops, and thus are an

achieved to minimise losses.

alternatively, can result from other forms

important commodity of trade.

Pre-shipment considerations

High temperatures cause the tuber

contain on their surfaces spores of

of deterioration such as sun-scald. It may

For the purposes of this article we

respiration rate to increase, whereby

also result if the tuber is subjected to

shall refer to three basic types of potato,

oxygen and food reserves are used,

wetting such that a film of water is

which are:

potentially resulting in excessive

present over its surface.

shrinkage. Freezing or chilling ●

Early/new or immature.

Some of the principal diseases found

temperatures can damage and kill tuber

at the time of harvesting may include

cells. If the air surrounding the tubers has

Phytophthora infestans (potato blight); a

a low humidity then water will move

dry mealy rot due to species of Fusarium

from the tubers to the air, resulting in

(dry rot); a bacterial soft rot caused by

All of which require special

weight loss. Should the oxygen content

Erwinia ssp. (black leg); or brown rot

considerations for stowage and carriage.

of the air fall to a low level, cells within

caused by the bacterium Ralstonia

the tubers die and ‘blackheart’ forms.

solanacearum and ring rot caused by the

● ●

Late/mature. Seed.

Early or new potatoes have thin, relatively loose, skins that are easily

Sprouting is a natural function of the

removed and are thus readily liable to

tuber, however, during shipment it is not

damage. Over more recent years,

desirable as, in the event, quality and

demand for this type of potato has

condition will suffer. Sprout suppressant

increased and large quantities are

chemicals or other methods

shipped from Cyprus, Greece, Israel,

may be used prior to

Turkey and the Canary Islands during the

shipment to preclude

northern winter and spring seasons.

sprouting but control in

Late/mature potatoes have firm skins

stowage can only be

and are therefore more resistant to

maintained by application

damage and much easier to carry than

of the correct

immature potatoes.

temperature(s).

15

bacterium Clavibacter michiganensis subsp. sepedonicus, both of which are > continued over

Left: Bacterial soft rot in potatoes can,

handling to and from the vessel,

through contact, infect adjacent tubers.

especially when immature/new potatoes

port, or alternatively rejection of a cargo

are being shipped. Bags of potatoes

of potatoes as a result of infestation or

should not be walked over or handled

infection by serious bacterial diseases,

roughly, with special care taken if

not only may cause massive delays to a

palletised units of bags are over-stowed

vessel but also considerable additional

by a second tier of pallets. In light rain,

problems for the shipowners.

snow, or damp weather cargo must be

Greening may occur in any part of a

protected from moisture to preclude the

tuber exposed to light. Exposure to bright

onset of premature spoilage by bacterial

light during post harvest handling, or

soft rot. Do not load or discharge

longer periods (7 to 14 days) of low light,

potatoes during heavy rain.

can result in the development of chlorophyll (greening) and bitter, toxic

Summary Subsequent to harvesting and prior to

Carriage of potatoes continued

glycoalkaloids, such as solanine. Experts

notifiable diseases in the UK and other

advise that whereas in cultivated varieties

countries.

green discolour of the flesh does not

Early or new potato tubers should

cause substantive harm to health, it

be graded and sorted:

Post-harvest deterioration i.e. storage/ stowage deterioration will normally result

undoubtedly will, depending upon

from the development of bacterial soft

extent, result in a loss of value of

rot, usually the result of infection by

consignments. Green flesh of potatoes

Erwinia ssp. which causes collapse of the

tastes bitter and must be cut away before

cells of the infected potatoes exuding

cooking.

heavily infected fluid and gives rise, by

When presented for shipment,

contact, to soft rot developing in adjacent

consignments should be inspected for

tubers. Hence over a period of time the

external condition of the packaging.

contents of whole bags may collapse to a

Evidence of wet patch staining of the

malodorous slime.

bags, or any associated malodours,

packing for shipment:

●

without mechanical damage;

●

sound, without disease;

●

dry;

●

without greening;

●

free from adherent soil and stones;

●

and stored at optimum temperatures.

should alert crewmembers to likely

Late or mature potato tubers

infestation by insects, which has been a

problems and the vessel’s P&I association

should, in addition to the above:

problem since potatoes have been grown.

should be requested to appoint an expert

The two most serious infestants of potato

surveyor to investigate and ensure only

crops are the North American black and

healthy and undamaged potatoes are

yellow striped beetle (Colorado Beetle)

shipped. Since potatoes have been

and the Potato Tuber Moth (Phthorimaea

shipped in woven polypropylene bags of

operculella).

varying dark colours it has become

Another cause of deterioration is

It is necessary for shippers or charterers

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

extremely difficult to recognise wet

to provide phyto-sanitary certificates,

patches from superficial examinations;

attached to the bill(s) of lading or other

close inspections are thus recommended.

trade documents. These certificates are

●

Mechanical damage is one of the

addition to those points noted under ‘early potatoes’: ●

consist of unwashed tubers and may

produced by the Authority of the country

most important factors affecting potato

contain loose soil and foreign material

of origin indicating that the specified

condition, since it is largely preventable.

but should generally be free of caked

consignment(s) have been inspected or

Special care is therefore essential during

soil.

treated according to the importing country’s requirements. Recent legislation

Potato tubers infested with Colorado Beetle.

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

16

Signs of infestation by the Potato Tuber Moth.

Packaging

1000 kg than late / mature potatoes and

Potatoes may be packed in hessian bags,

are commensurately more difficult to

woven polypropylene bags, sacks lined

carry. When potatoes are presented for

with an internal perforated polyethylene bag and sometimes cartons or crates.

loading in bags, stow heights of up to

Various sizes of bags are utilised,

eight tiers are preferable. To ensure

however the bags will usually contain

adequate ventilation of cargo blocks,

about 25 kg of tubers.

maximum stow heights of twelve to thirteen bags should never be exceeded.

A more recent innovation is to pack potatoes in large open-top lift bags

The stowage must be so arranged to

weighing some two to three tonnes.

ensure a free flow of air throughout the

New potatoes are frequently packed in

compartments.

moist or dry peat moss. The main

Bags shipped on pallets are usually

purpose for including moist peat moss

stacked to a height of eight/nine bags

within the bags is to protect the ‘new’

and are often secured to the pallet base-

tubers and to preclude skin-set and thus

boards by means of nylon netting. Care

maintaining their value. However, excess

must be taken, (especially when the

temperature for the carriage of potatoes

free water or release of water from the

bags are constructed of woven

is plus 4o Celsius (39o Fahrenheit) and

peat moss during carriage can cause

polyethylene) to ensure that the

carriage is usually recommended at plus 4o

problems leading to bacterial soft rot of

contents of pallets are fully and properly

to 5o Celsius (39o to 41o Fahrenheit) at a

the tubers.

secured.

relative humidity of between 90 and 95%.

The frictionless nature of this type of

Potatoes packed in large open-top lift bags.

The approximate lowest safe

However potatoes destined for processing

Stowage

outer bag frequently results in the pallet

will require to be carried at temperatures

As for any product which may enter the

loads becoming deformed and, in some

depending upon their cultivar. In these

human food chain, preparation of

cases, detached from the base-boards.

cases, it is thus essential for shippers to

stowages will include ensuring that the

This slippage can result in additional

provide detailed instructions and for those

cargo spaces are clean and dry. Potatoes

stevedoring costs for re-making the

instructions to be rigorously followed.

are highly sensitive to odours and readily

pallets. Slippage of woven polyethylene

absorb foreign smells from chemicals,

bags from pallets, and also when loose

for potatoes will depend upon the

mineral oils, and some fruits, etc. All

stowed, into ventilation channels will

permanent air circulation systems

compartments destined for stowage of

cause restrictions of air flow and must be

incorporated in a vessel. Strict supervision

potatoes must be free from malodours

prevented by the use of timber dunnage

of cargo stowage must ensure that airflow

and volatile substances.

or dunnage nets.

will be evenly distributed throughout the

Potato tubers are living organisms

The exact stowage patterns adopted

compartments for maintenance of

that consume oxygen and evolve carbon

Stowages in refrigerated cargo

dioxide, water and heat. The principal

vessels

problem as far as stowage and carriage

As previously noted, not only do growing

compartment / flesh temperatures should

is concerned is the heat produced, and

and harvesting conditions influence the

be maintained throughout the transit

therefore good climate control is

post harvest/pre-shipment behaviour of

period.

required to maintain the condition of

potatoes but, additionally, post-harvest

tubers. Condensation in the form of ship

storage conditions are also critical to the

refrigerated stowages, the cargo should

or cargo sweat should not be allowed to

optimum temperature requirements for

ideally be landed to stores at similar

develop during a voyage. Long voyages

their carriage. Therefore written

temperatures to that of carriage. If cold

therefore demand more critical control

instructions for the carriage temperature

cargoes are discharged into ambient

than short-term voyages.

regime should always be obtained from

warm humid conditions then a risk of

the shippers and should be complied

condensation forming on the tubers may

cargoes of potatoes is noted in the table

with throughout the voyage. Transport

exist and bacterial soft rot will ensue.

below.

temperatures must be such that

Some shippers/consignees will request the

respiration and weight losses due to

vessel to undertake a dual temperature

new / immature potatoes

evaporation are maintained to a

regime during transit and require the

produce considerably more heat per

minimum.

vessel to slowly raise the temperature of

An example of the heat produced by

From these figures it is evident that

Type of potatoes

optimal temperature control. Detailed records of cargo

the cargo, to above the anticipated

kcal per 1000 kg per 24 hours O

At C

O

O

At the time of discharge from

O

O

5

10

15

20

Immature

735

1070

1380

1930

Mature

370

520

550

735

17

ambient dew point at the discharge port, commencing some two to three days before discharge is due to commence. > continued over

Carriage of potatoes continued

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 Blackheart is formed when the oxygen

Greening occurs when tubers are exposed to

content of the air falls to a low level.

bright light or long periods of low light.

certain circumstances; however stability

voyages, to either run the fans on lesser

duration, closed cargo containers may be

of each block is critical and when loose

power (reduction of speed) or for lesser

used but doors should remain open

stowed, bags must be key-stacked to

times (ventilate intermittently) in order to

when ever possible to promote

construct a locking stow precluding

maintain humidity and preclude water

ventilation. Stowage on deck must

slippage or collapse of bags into the air

loss from the tubers (desiccation).

include provisions to protect the cargo

exceed 3 metres by 3 metres square. Smaller blocks may be preferred under

channels potentially causing a breakdown in the air circulation.

Details of ambient air wet and dry

from rain, sea-spray and sunlight.

bulb temperatures, hold wet and dry bulb

Flat racks are also used for below-

air temperatures / flesh temperatures and

deck stowages in well-ventilated compar,

compression damage/bruising to the

the ventilation regime undertaken

provisions should be made to afford

potatoes (especially new/immature

according to the acquired data regularly

exposed bags protection against rain and

tubers) but may also result in excessive

obtained must be recorded in a dedicated

sunlight prior to loading and subsequent

heating due to metabolic processes. Bags

ventilation logbook or alternatively the

to discharge.

should be stowed ideally to eight tiers in

deck log book.

High stows may not only cause

Seed potatoes

height, but never more than twelve to thirteen. The width of the air channels

Ro-Ro vessels

Seed potatoes are usually shipped

around the cargo blocks should be in the

Cargoes of new/immature potatoes have

around the world in smaller

order of 20 to 30 cms. constructed using

for some time been shipped from Eastern

consignments than those of new or

dunnage and/or the locking stow noted

Mediterranean ports in the holds of

mature potatoes. The value of seed

above. Cargo should be stowed clear of

Ro-Ro vessels. Packed in woven

potatoes is much greater than potatoes

transverse bulkheads and ship’s sides to

polypropylene bags, shipped on pallet

destined for consumption and special

promote air circulation with exposed steel

boards with bags secured by nylon nets,

care should be taken as any loss in

work protected by paper mats or other

losses and/or additional costs have been

quality or condition will potentially result

sheeting to preclude condensation

experienced due to the displacement of

in substantial claims. They may be carried

damage.

bags from the pallet boards.

in a mechanically ventilated stowage but

Potato cargoes should be kept well

Bearing in mind the practice of

for longer voyages involving any

clear of engine room bulkheads and any

keeping the Ro-Ro deck lights illuminated

prolonged period in warm climatic

other local heat source situated on the

throughout the voyage the problem of

conditions, say in excess of 20o Celsius,

vessel.

tuber greening has been experienced.

they should be carried under

The stowage on any vessel should be

Attempts to prevent this have included

refrigeration at a temperature of 2o to 4o

designed to suit the type of permanent

covering stowages with polythene

Celsius.

ventilation system fitted. Potato cargoes

sheets, which unfortunately reduce the

make heavy demands on ships’ ventilation

effectiveness of the hold ventilation

Safety

systems and a capacity of at least fifteen

system. Hold lights should never remain

Inadequate, or failure of, ventilation in

air changes per hour in each empty hold is

continuously illuminated throughout a

spaces containing cargoes of potatoes

required. At these rates the ventilation

voyage, even of short duration.

can cause life threatening concentrations

when weather and climatic conditions

Transport of potatoes in ISO

depletion to arise. Thus under these or

prevent e.g. risk of shipping water

containers

suspected conditions the

through the weatherdeck ventilators or

Cargoes of potatoes may be carried in

compartment(s) must be fully ventilated

condensation forming on the cargo or

fan assisted ventilated containers, open

and a gas measurement conducted. The

internal ship’s structures. At higher rates

sided containers, insulated refrigerated

threshold limit value (TLV) for CO2

of air changes per hour consideration

containers and ‘port-hole’ insulated

concentrations is 0.49 % by volume ■

should be given, especially on longer

containers. For voyages of a short

of carbon dioxide (CO2) or oxygen (O2)

system should be run continuously except

18

Fumigation of ships and their cargoes Introduction

rodent, insect or beetle, and stage of

and ventilation completed before

Fumigation is a procedure that is used

its life cycle).

sailing.

throughout the world to eradicate pests

●

Type of fumigant applied.

or

●

Concentration and distribution of gas.

●

●

Temperature.

●

Length of time fumigant must be

that infest all types of goods, commodities, warehouses, processing factories and transport vehicles including ships and their cargoes.

1 What are fumigants and how do they work? Fumigants are gases, which are toxic to the target infestation. They can be

liquids or reaction products from solids,

voyage (intransit).

suffocants in the case of controlled or

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

In these situations the fumigation continues during the voyage and is not

●

Nature of commodity.

finished until the ventilation and removal

●

Nature of commodity packaging.

●

Monitoring system.

●

Ventilation system.

of residues is completed, which is

1.2 Aim of fumigation

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 deepseated 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

●

Nature of infestation (type of pest e.g;

3 Rules, regulations and guidelines that affect the fumigation process 3.1 The United Nations International

environment, which will contain an

Maritime Organization (IMO) Safety of

effective concentration of fumigant gas

Life at Sea (SOLAS) Convention places an

at a given temperature, for a sufficient

obligation on all governments to ensure

period of time to kill any live infestations.

all shipping activities are carried out

Both the time measured (hours or

safely.

days) of exposure and concentration of gas is critical to fumigation efficiency.

3.2 The Recommendations on the Safe

Dosages applied are usually expressed as

Use of Pesticides in Ships (IMO

grams per cubic metre, concentrations

Recommendations) published by the IMO

measured during the fumigation are

(revised 2002) are intended as a guide to

usually expressed in parts per million

all those involved in the use of pesticides

(PPM) or grams per cubic metre, and total

and fumigants on ships and are

concentrations actually achieved, as

recommended to governments in respect

concentration-time-products (CTPs).

of their legal obligations under the

The fumigation process is not completed until ventilation has been

SOLAS Convention. These recommendations are referred

effectively carried out, and removal of

to throughout this document as within

any residues is completed.

the IMO Recommendations.

2 When can ships’ cargoes be fumigated?

3.3 Individual countries (e.g. US and Canadian Coastguard) have their own requirements, but some governments

The ship’s cargo can be fumigated and

have chosen to make the IMO

ventilated:

Recommendations mandatory on all

In warehouse or storage silos before

vessels in their territorial waters (e.g. UK).

loading.

3.4 The IMO International Maritime

●

In freight containers before loading.

Dangerous Goods (IMDG) Code, which is

●

In the hold of the ship with fumigation

> continued over

●

considered for fumigants to be effective are:

normally at the first discharge port.

Fumigation aims to create an

air, or with mists, aerosols or fogs, which are liquid droplets, of various sizes, in air.

voyage (intransit).

Containment of fumigant.

modified atmospheres. On release, they mix with air at a molecular level. They are

In freight containers before loading

●

always act in the gaseous phase. They act either as respiratory poisons, or as

●

with fumigation continuing during the

Method by which fumigant is administered.

applied as gas, liquid or in solid formulations, but after vaporisation from

fumigation continued during the

applied. ●

In the hold prior to sailing with

19

Fumigation continued

mandatory in many parts of the world

provided data is provided to the master as

fumigation and fumigant application

6.4 and Annex 1A.

compliance.

under SOLAS, specifically relates to the fumigation of packaged goods only and will be referred to under section 8 on freight container fumigation.

5 Intransit fumigation of bulk and bagged cargoes with phosphine gas

The fumigation of packaged goods

5.1 Phosphine is only fully effective if a

and freight container recommendations,

lethal concentration is maintained for a

are referred to throughout this document

period of time that can be as little as 3

as within the IMDG Code.

days or as much as 3 weeks.

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.

✔ Statement of vessel suitability for

set out in IMO Recommendations 6.2 and

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

✔ 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

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.

ventilation. ✔ Precautions and procedures during discharge. ✔ Also to provide sufficient additional

4 Fumigants that can be used for intransit fumigation of bulk and bagged cargoes in ships’ holds

5.2 When the owners/charterers/master

respiratory protective equipment (RPE)

agree to fumigation being carried out

where necessary to the vessel, to

intransit with phosphine, the master

ensure the requirements of IMO in

should ensure he is familiar with the

respect of RPE are available for the

4.1 The most widely used fumigant for

requirements of IMO Recommendations

duration of the voyage. (Note; the RPE

intransit fumigation is phosphine (PH3).

3.4.3.1. – 3.4.3.20. This will enable the

may consist of SCBA or canister

The gas is normally generated from

master to be clear what the obligations of

respirators or a combination of both

aluminium phosphide or sometimes

both fumigator and master are.

but the minimum requirement is for 4

magnesium phosphide, but can also be

A checklist of these obligations is as

applied direct from cylinders.

follows:

4.2 Methyl bromide should never be used

5.2.1 Fumigator

for fumigation intransit (IMO

To provide written documentation in

5.2.2 Master

Recommendations, Annex 1D).

respect of the following:

✔ Appoint a competent crewmember to

4.3 Insecticides such as dichlorvos,

✔ Pre-fumigation inspection certificate.

pirimiphos-methyl, malathion, permethrin and others may be sprayed on to the grain during loading. These are not fumigants and should be allowed

sets of RPE). Refer also to IMO Recommendations Annex 4.

✔ Standard safety recommendations for vessels with fumigated grain cargoes. ✔ Gas tightness statement.

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

Probing aluminium phosphide in retrievable sleeves into a bulk cargo.

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

20

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

Ventilating the cargo prior to discharge.

Checking the gas concentrations in the cargo prior to discharge.

Recommendations 3.4.3.12). ✔ It must be clearly understood by the

removed have been removed, and

ashore until the ship is certified ‘gas free’

master that, even if no leakage of

that any other requirements of the

in writing by the fumigator in charge.

fumigant is detectable at the time of

discharge port have been met (IMO

The fumigator is responsible for the

sailing, this does not mean that

Recommendations 3.4.3.17).

safety and efficiency of the fumigation,

leakage will not occur at some time during the voyage due to the

Refer also to IMO Recommendations, Annex 4.

though crewmembers may remain in attendance to ensure the safety of the ship provided they adhere to safety

movement of the ship or other

6 Fumigation of bulk and bagged cargo with ventilation in port

instructions issued by the fumigator in

✔ During the voyage, the master should

This procedure can be used either after

from cargoes can be a very slow process

ensure that regular checks for gas

loading and prior to sailing (6.1) or on

if sufficient powered ventilation is not

leakage should be made throughout

arrival at the discharge port prior to

available and the master (or his

all occupied areas and the findings

discharging (6.2).

representative) should ensure that the

recorded in the ships log (IMO

6.1 After loading and prior to sailing

Recommendations 3.4.3.13). If any

gas are below the TLV (IMO

Phosphine fumigation is the only

leakage is detected appropriate

Recommendations, Annex 2) throughout

fumigant that should be accepted for this

precautions to avoid any crew being

all parts of the cargo and holds.

procedure, as methyl bromide

exposed to harmful concentrations

(though frequently used) is not

must be taken. If requested to do so

in port, prior to discharge, will normally

recommended (IMO Recommendations,

by the fumigator, the master may,

take from 1-2 weeks to complete and

Annex 1D).

therefore is only occasionally specified.

factors. This is why it is essential the master ensures regular checks are carried out during the voyage.

prior to arrival at the first discharge

charge. The ventilation of methyl bromide

fumigator has ensured that residues of

Phosphine fumigation and ventilation

Phosphine fumigation and ventilation

All procedures as for intransit fumigation

port, start the ventilation of the cargo

in port, prior to sailing, will normally take

spaces.

should be followed to ensure a safe and

from 1-2 weeks to complete and

effective fumigation.

✔ Prior to arrival at the first discharge

therefore is only occasionally specified.

port the master should inform the

All procedures as for intransit fumigation

authorities at the port that the cargo

should be followed to ensure a safe and

has been fumigated intransit. (IMO

effective fumigation.

Recommendations 3.4.3.16).

6.2 At discharge port prior to

7 Fumigation of empty cargo holds and/or accomodation to eradicate rodent or insect infestation

discharge

7.1 Methyl bromide is the most common

master should not allow discharge of

Methyl bromide is the most common

fumigant used for this purpose (although

the cargo to commence until he is

fumigant used for this purpose as it is

hydrogen cyanide (HCN) or sulfuryl

satisfied that the cargo has been

normally possible to achieve an effective

fluoride may be used in some countries)

correctly ventilated and aluminium

fumigation of the cargo in 24-48 hours.

phosphide residues that can be

The crew should be landed and remain

✔ On arrival at the discharge port the

21

> continued over

Fumigation continued

8.3.3 Obligations on the master

as it is normally possible to achieve an

✔ The master must ensure that he knows

effective fumigation of the empty spaces

where containers under fumigation

in 12-24 hours.

are stowed. ✔ The master must ensure he has

7.2 The crew should be landed and remain ashore until the ship is certified

suitable gas detection equipment

‘gas free’ in writing by the fumigator in

onboard for the types of fumigant

charge as for 6.2 above.

present, and that he has received instructions for the use of the

8 The intransit fumigation of freight containers

with no warning notices attached and

8.1 The reason for the fumigation of

no accompanying documentation

containers is normally to try to ensure

stating they have been fumigated.

discharge port the master should

that when the goods arrive at the

This process is in direct contravention

inform the authorities at the discharge

discharge port they are free of live pests/

of the IMDG Code. There may be

point that he is carrying containers

insects.

dangerous levels of fumigant gas

under fumigation.

equipment.

inside the container when it arrives at

✔ Prior to arrival of the vessel at the

✔ If the master (or his representative)

8.2 Containers are normally fumigated

its destination which is both illegal

and subsequently ventilated prior to

suspects that unmarked containers

and dangerous.

may have been fumigated and loaded

Containers that have been fumigated

8.3.1 Obligations on the fumigator

onboard they should take suitable

and subsequently ventilated and where a

✔ The fumigator must ensure that, as far

being loaded onboard the ship.

precautions and report their suspicions

‘certificate of freedom from harmful

as is practicable, the container is made

concentration of gas’ has been issued,

gas tight before the fumigant is

can be loaded onboard ships as if they

applied.

had not been fumigated (IMO Recommendations 3.5.2.1).

to the authorities prior to arrival at the discharge port. 8.3.4 Obligations on the receivers

✔ The fumigator must ensure that the

✔ The receiver (or his agent) must ensure

containers are clearly marked with

that any fumigant residues are

8.3 Frequently containers are fumigated

appropriate warning signs stating the

removed, and the container checked

but not ventilated prior to loading and

type of fumigant used and the date

and certificated as being free from

these containers are therefore fumigated

applied and all other details as

harmful concentrations of fumigant by

intransit, as the ventilation process will

required by the IMDG Code and IMO

a suitably qualified person before the

not take place until after they have been

Recommendations Annex 3.

cargo in the container is removed ■

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’.

✔ The fumigator must ensure the agreed formulation of fumigant is used at the correct dosage to comply with the contractual requirements.

For further information: International Maritime Organization

8.3.2 Obligations on the exporter

4 Albert Embankment, London, SE1 7SR

✔ The exporter must ensure that the

Tel: 0207 735 7611. Fax: 0207 587 3210

containers are clearly marked by the

www.imo.org

fumigator with appropriate warning

International Maritime Fumigation

WARNING – Containers are still

signs stating the type of fumigant used

Organisation

sometimes shipped under fumigation

and the date applied and all other

Friars Courtyard, 30 Princes Street,

details as required by the IMDG Code

Ipswich, Suffolk, IP1 1RJ or any member

and IMO Recommendations Annex 3.

worldwide. See – www.imfo.com.

✔ The exporter must ensure that the master is informed prior to the loading of the containers. ✔ The exporter must ensure that

Annex 1

shipping documents show the date of

A summary of the various methods of

fumigation and the type of fumigant

phosphine application methodology

and the amount used all as required in

that can be considered for intransit

the IMDG Code, volume 1, page 35

fumigation of bulk or bagged cargoes

and specifically section 9.9.

in ships’ holds.

22

1 Application of tablets or pellets to

5 Application of tablets or pellets by

9 Use of powered re-circulation

cargo surface (or into the top half

probing into the cargo a few metres in

system with phosphine from

metre).

retrievable sleeves.

cylinders.

High concentrations of gas build up in

All points as for 2, except that with this

This is not yet available but could be in

the head space, potentially resulting in a

method powdery residues can be removed

the future and will enable phosphine

lot of leakage through the hatchcovers

prior to discharge.

fumigation to be carried out without

unless they are very well sealed. Very

6 Fitting of an enclosed powered

little penetration down into the cargo.

re-circulation system to the hold and

Powdery residues cannot be removed.

application of aluminium phosphide

Good kill of insects in top part of

tablets or pellets to the surface.

cargo but negligible effect on eggs or

This will ensure the gas is distributed

juvenile or even adults in lower part of

throughout the cargo evenly and rapidly

cargo.

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.

making maximum use of the fumigant in 2 Application of tablets or pellets

the shortest possible time. Powdery

by probing into the cargo a few

residues cannot be removed.

metres. 7 Fitting of an enclosed powered

Less loss of gas through hatchcovers

re-circulation system to the hold and

than in 1. Better penetration of gas than when applied on surface only but unlikely to be fully effective unless holds are

application of aluminium phosphide in blankets, sachets or sleeves on the surface or probed into the top one or

relatively shallow and voyage time

two metres.

relatively long. Powdery residues cannot

powdery residues can be removed. Also 3 Application of tablets or pellets by

gaseous residues can be removed more

deep probing into the full depth of

easily than with other methods, as once

the cargo.

the powdery residues have been removed

This is difficult to achieve and currently

the re-circulation system can be used to

practically impossible if the cargo is more

assist this to happen rapidly.

than 10 metres deep. Ensures effective

References International Maritime Organization Recommendations on the Safe Use of Pesticides in Ships revised 2002.

As for 6, except that with this method,

be removed.

Annex 2

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

8 Deep probing into the full depth of

Recommendations on the Safe Use of

the cargo (however deep) with tablets

Pesticides in Ships referred to above).

or pellets (in retrievable sleeves when

Published by IMO London as above. Refer

required).

to Dangerous Goods List under entry UN

4 Application of aluminium

This is being developed in Canada but is

3359.

phosphide in blankets, sachets or

not yet available. Also deep probing using

sleeves, placed on the surface of the

pre-inserted pipes.

cargo (or into the top half metre).

Will enable good distribution of gas to be

All points the same as 1, except that with

achieved without the requirement for a

Code of Practice (COP)

this method powdery residues can be

powered re-circulation system, provided

Obtainable from the IMFO website

removed prior to discharge.

the voyage is long enough.

www.imfo.com ■

fumigation provided voyage time is relatively long to allow gas to distribute. Powdery residues cannot be removed.

Fumigation of cargo in ship’s hold using phosphine and the J. System.

The International Maritime Fumigation Organisation (IMFO)

Traditional fumigation of cargo in ship’s hold using phosphine. Phosphine applied to surface or probed a few metres into cargo

Phosphine applied to surface >

Fan Manhole

>

Gas moves down very slowly from surface

>

>

After 5-7 days some gas should reach 10-12 metres at effective concentrations

Phosphine drawn from the surface to bottom of hold

Gas unlikely to reach 15-20 metres in effective concentrations however long the voyage

Phosphine permeates through cargo as re-circulation continues

23

Scrap metal (borings,shavings,turnings,cuttings,dross) Ferrous materials in the form of iron

are frequently seen in cargoes of metal

by the safety equipment regulations,

swarf, steel swarf, borings, shavings or

turnings but these flames are usually the

should be provided.

cuttings are classified in the IMO Code of

result of ignition of the cutting oils, rags,

Safe Practice for Solid Bulk Materials as

timber and other combustible materials

materials liable to self heating and to

mixed with the turnings.

ignite spontaneously. Turnings are produced by the

Spontaneous heating of metal turnings has caused several major

If the surface temperature exceeds 90ºC during loading, further loading should cease and should not recommence until the temperature has fallen below 85ºC.

machining of steel, turning, milling,

casualties. In the incident mentioned

drilling, etc. When produced the turnings

above spontaneous heating was

The ship should not depart unless the

may be long and will form a tangled mass

detected, the vessel was moved from port

temperature is below 65ºC and has

but they may be passed through a

to port in attempts to agree discharge.

shown a steady or downward trend in

crusher or chip breaker to form shorter

After weeks of delay all the holds were

temperature for at least eight hours.

lengths. Both forms of turnings are

eventually flooded to reduce the heating

During loading and transport the bilge

shipped and shipments are frequently a

for safe discharge of cargo. Following

of each cargo space in which the

mixture of short and long chips. The

discharge of the turnings the vessel

material is stowed should be as dry as

density of the short chips is of the order

loaded a cargo of conventional scrap.

practicable.

of 60 pounds per cubic foot, twice the

During the subsequent voyage rough

density of the longer chips as they tend

weather was encountered, cracks

compacted in the cargo space as

to compact more readily.

developed in the shell plating, the holds

frequently as practicable with a

flooded and the vessel was lost with 29

bulldozer or other means. After

lives.

loading, the material should be

Borings are produced during the making of iron castings. Because of the

3 During loading, the material should be

nature of the parent metal, borings break

In another incident heated turnings

up more readily than turnings. They tend

formed a solid mass in the hold which had

to be finer and the bulk density is greater

to be mechanically broken into pieces

than turnings.

before discharge by grab. In a further

Whilst at sea any rise in surface

incident, following a normal passage it

temperature of the material indicates

contaminated with oils – cutting oils for

was not possible to discharge the cargo

a self-heating reaction problem. If the

instance – used in the manufacturing

by grabs. The surface of the stow had

temperature should rise to 80ºC, a

processes. Oily rags and other

crusted to a hard mass. Bulldozers were

potential fire is developing and the

combustible matter may also be found

used to loosen the surface of the cargo

ship should make for the nearest port.

among the loads.

and several hours later fire was observed

Water should not be used at sea. Early

in all of the holds.

application of an inert gas to a

Turnings and borings may be

Iron will oxidise, (rust) and iron in a finely divided form will oxidise rapidly.

The IMO Code of Safe Practice for

trimmed to eliminate peaks and should be compacted.

smouldering fire may be effective. In

This oxidation is an exothermic reaction,

Solid Bulk Cargoes has special

port, copious quantities of water may

heat is evolved. In a shallow level mass of

requirements for the loading of turnings

be used but due consideration should

turnings this heat will be lost to the

and borings which include:

be given to stability.

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

1 Prior to loading, the temperature of

4 Entry into cargo spaces containing this

the material should not exceed 55ºC.

material should be made only with the

Wooden battens, dunnage and debris

main hatches open and after adequate

should be removed from the cargo

ventilation and when using breathing

space before the material is loaded.

apparatus.

2 The surface temperature of the

It will be noted that compacting the cargo

oils, oily rags or combustible matter.

material should be taken prior to,

as loaded with a bulldozer is

The turnings may heat to high

during and after loading and daily

recommended. This will tend to form a

temperatures but will not necessarily

during the voyage. Temperature

dense mass, pushing the short turnings

exhibit flames. In one incident

readings during the voyage should be

into the bundles of long turnings, tending

temperatures in excess of 500ºC were

taken in such a way that entry into the

to exclude air from the stow. However

observed six feet below the surface of

cargo space is not required, or

some authorities argue that compacting

the cargo. Temperatures of this order

alternatively, if entry is required for this

the stow tends to break up the long

may cause structural damage to the

purpose, sufficient breathing

turnings, creating greater surface areas

steelwork of the carrying vessel. Flames

apparatus, additional to that required

for the oxidation process. However

24

shorter turnings should compact more

batteries, car components, galvanising

readily than the longer forms and thus

processes, etc. Zinc ashes are formed on

reduce the area exposed to oxidation.

the surface of molten zinc baths, and

The reference to trimming level

whilst primarily zinc oxide, particles of

ensures that there is less cargo surface

finely divided zinc will also adhere to the

exposed to the air than cargo in a peaked

oxide. The various types of zinc are

condition. Furthermore, theoretically air

treated by processes to produce pure zinc

will pass across the top of a level trim, but

metal. The ashes, dross, skimmings and

can pass through the stow if loaded in a peaked condition creating a ‘chimney’

residues are all reactive in the presence of

effect, thus accelerating the heating

moisture liberating the flammable gas

process.

hydrogen and various toxic gases.

The requirements for entry into cargo

Surface temperature reading.

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.

IMO Code for Solid Bulk Cargoes which 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 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

Metal dross and residues

to be shipped for not less than three days.

Aluminium dross

The material should only be loaded under

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

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

Aluminium dross, aluminium salt slags,

weather in the particle size in which it is

Aluminium dross is formed during the

The materials are also listed in the

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.

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

painted or litter scrap is recovered. The

Zinc dross

later spread on the quayside in a thin

main components of dross are aluminium

Zinc dross, zinc skimmings, zinc ash and

layer to dry. Seven days later hydrogen

oxide and entrained aluminium. Small

zinc residues are all materials obtained

was still being evolved to the

amounts of magnesium oxide, aluminium

from the recovery of zinc. The zinc types

atmosphere, as proved by tests with a

carbide and nitride are also present.

may be recovered from galvanised sheets,

hydrogen gas detector ■

25

Hold cleaning: bulk cargoes – preparing a ship for grain Surveyors inspection/ requirements Prior to loading grain, all ships are usually

ledges, pipe guards, or other fittings in

on the bulkheads will require a

the holds.

‘degreasing chemical wash’ and a fresh

If the ship has been carrying DRI

water rinse in order to pass a grain

subject to a survey by an approved

(direct reduced iron), the dust created by

inspection. The degreasing chemical used

independent surveyor. The surveyor will

this particular cargo during loading or

should be environmentally acceptable for

require the vessels particulars and details

discharging, will be carried to all areas of

marine use, and safe to apply by ships

of at least the last three cargoes carried.

the ships structure and the reaction

staff, who have had no special training

He will then inspect the holds for

between iron, oxygen and salt will create

and do not require any specialised

cleanliness and infestation, or the

an aggressive effect wherever the dust

protective equipment. Product safety

presence of any material which could

may settle. This is particularly noticeable

data sheets of the chemical should be

lead to infestation.

on painted superstructures. (The IMO

read, understood and followed by all

Bulk Cargo Code contains guidelines).

persons involved with the

When the surveyor is satisfied with the condition of the hold, he will issue

Whenever salt water washing is used

the ship with a certificate stating which

to clean hatches, the relevant holds

holds are fit to load grain.

should always be rinsed with fresh water

environmentally friendly degreasing chemical. To avoid taint problems, fresh paint

to minimise the effects of corrosion and

should not to be used in the holds or

Purpose:

to prevent salt contamination of future

under the hatch lids at anytime during

To ensure cargo holds are prepared to

cargoes. In this respect, arrangements

the hold preparation, unless there is

receive the next cargo.

should be made in good time to ensure

sufficient time for the paint to cure and

Large claims have arisen when cargo

sufficient fresh water is available for this

be free of odour as per the

holds have not been cleaned sufficiently

operation.

manufacturer’s instructions. Most marine

to prevent cargo contamination.

Before undertaking a fresh water

coatings require at least seven days for

rinse, the supply line (normally the deck

the paint to be fully cured and odour

holds are dependent upon the previous

fire main or similar) will need to be

free. All paint used in the holds and

cargo carried, the next cargo to be

flushed through to remove any residual

underside of the hatchcovers should be

carried, charterers’ requirements, the

salt water. Accordingly, it is suggested

certified grain compatible and a

requirements of shippers and/or the

that fresh water rinsing of the holds is

certificate confirming this should be

authorities at the port of loading and the

left until the end of hold cleaning

available onboard. Freshly painted

receivers.

operations to minimise the amount of

hatches or hatchcovers will normally

fresh water required.

result in instant failure during the grain

The requirements for cleaning the

It is becoming common practice for receivers to have an inspector at the load port.

Grain preparation and safe carriage

inspection, unless the paint has had time to cure. Processed grains or grain cargoes that

General

One of the most difficult hold cleaning

are highly susceptible to discolouration

Regardless of the previous cargo, all

tasks is to prepare a ship for a grain

and taint should only be stowed in holds

holds should be thoroughly cleaned by

cargo after discharging a dirty or dusty

that have the paint covering intact. It is

sweeping, scraping and high-pressure

cargo such as coal or iron ore,

important that there is no bare steel,

sea water washing to remove all previous

particularly if the last cargo has left ‘oily’

rust, scale, or any rust staining in the

cargo residues and any loose scale or

stains on the paintwork or other

hold.

paint, paying particular attention to any

deposits stubbornly adhering to the steel

that may be trapped behind beams,

surfaces. Greasy deposits which remain

Cargo hold, coal sticking and discharging salt.

26

Dependent upon the quality of the grain to be carried, the charter may

require the holds to be fumigated. This may be accomplished on passage with fumigant tablets introduced into the

The hatch rubber seals should also be washed to remove cargo grime. However, caution is required to ensure

cargo on completion of loading.

that the hatch rubber seals are not

Fumigation can also be undertaken at the

damaged by the high pressure from the

port of loading (or occasionally

fresh water gun.

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. Gasdetectors and proper personal protective equipment should be available and

Shore bulldozer/cocoa beans and shore

relevant ship’s officers should receive

personnel cleaning holds.

appropriate training in their use. After introduction of the fumigant, an

probably assist the removal of cargo

appropriate period should be allowed

remains from all of the holds using the

(normally 12 hours) for the gas to build

shore crane or other cargo-handling

up sufficient pressure so that any leaks can be detected: the vessel must not depart from port before this period has

Hatchcover underside and clean hatch rubber.

After washing, depending on weather

facilities, which will avoid lengthy difficulties for ships staff during the ballast voyage.

expired. The entire process should be

conditions, cargo dust may lightly

certified by a qualified fumigator. The

Discharging soya meal; tapioca cargo sticking

contaminate the underside of the hatch

holds must not be ventilated until the

and; cargo hold after discharging minerals.

lids; however, the dust particles can easily

minimum fumigation period has expired,

be removed at a later date using a high-

and care must be taken to ensure that

pressure portable fresh water gun.

subsequent ventilation does not endanger the crew.

Alongside the discharge port 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

Hatch undersides and rubber packing.

of the hatchcovers using liquid soap (such as teepol), followed by a fresh

Ballast hold

water rinse with a high-pressure water

If the ship has a ballast hold, this should

gun.

be discharged as soon as possible during

Example: Portable high-pressure fresh water guns from Stromme.

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

27

> continued over

Hold cleaning continued

Hatch drain with cap attached by small chain.

accepted by the port authority. The washing of cargo debris into the dock is not acceptable.

The bilges and strums of the ballast

In some loading ports, where

hold should be thoroughly cleaned and all traces of previous cargo removed. The

helicopter operations are used for

bilge suctions should be tested and

embarking and disembarking the pilot, it

confirmed as clear prior to any washing

is a normal requirement of the port to

out of the cargo holds and the bilge

wash down the helicopter area and at

spaces pumped out and secured with the

least one hatch length either side of the

bilge blanks.

helicopter area, ensuring that cargo

To prevent ballast water ingress into

tightness should be attached by a chain

debris is not washed into the dock.

the bilge area, it is essential that the

to the drain. These blanking caps or plugs

rubber joint/gasket is in good condition

are provided if the drains do not have an

and all the bilge-blank securing bolts are

approved automatic means of preventing

To prevent cargo debris from the main

fitted tightly. The un-seamanlike practice

water ingress into the hold.

deck being walked into the

of securing the bilge blank with four

If time permits, when the cargo has

Preparation at sea

accommodation and tramped into freshly

bolts is unacceptable and may result in

been discharged from respective hatches,

washed cargo holds, wash down the

pressurising the bilge line. This must be

all inner hatch coamings’ should be

main decks and accommodation block as

avoided.

teepol washed and fresh water rinsed

soon as possible after clearing the port of

with the fresh water high-pressure gun

discharge, mindful of pollution from the

because it is more convenient to wash

cargo remains.

this area in port rather than at sea.

Ship’s main deck covered by previous cargo.

Hold suction arrangement and filter.

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. Prior to the commencement of the

Scupper plug fitted.

hold-cleaning, a quick safety pre-brief meeting should take place, which should include all the personnel who will be

Hatchcovers

involved in the hold cleaning. During the

Prior to closing the hatchcovers, all the

pre-brief the hold-cleaning schedule

hatch track-ways should be swept clean,

should be discussed and the equipment

then carefully hosed down. If a

and chemicals to be used must be fully

compressed air gun is used, it should be

explained and the safety data sheets

used with caution and suitable safety

understood by all involved. Basic safety

equipment should be worn to ensure both face and body protection. Coaming/trackway covered in fertiliser.

Under normal circumstances, when it

routines should be established and the

rains during cargo operations,

wearing of suitable attire throughout the

discoloured water from the decks will

hold cleaning must be of paramount

flow into the dock and this is normally

importance. The wearing of oilskins, safety shoes/

Cement staining on decks and hatchcovers.

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

All hatch corner drains, including the

waistcoats will help to improve safety in

non return valves, should be proved clean

the hold. The ‘permit to work’ should be

and clear. The blanking caps on the hatch

completed on a daily basis, as this will

corner drains, used to ensure hold air-

help reduce the risk of accidents.

28

Hold cleaning

Some ships are fitted with fixed hold

All cargo residues washed down must

Prior to high pressure hold washing,

cleaning equipment, normally fitted

be removed via the hold eductors or

excess cargo residue on the tank top

under the hatchcovers. This method of

mucking winch. Special attention should

should be removed by hand sweeping

hold cleaning is less labour intensive.

be given to cargo residues wedged

and lifted out of the holds via the use of a

A flexible high-pressure hose is

behind pipe brackets, hold ladders, and

portable mucking winch. As explained

connected between a flange on the

on the under-deck girders and

earlier, a good working relationship with

hatchcover and the deck high-pressure

transversals. Special attention should be

the stevedores at the discharge port may

hold washing line.

paid to ventilators to ensure that

help to expedite this operation.

Fixed hold cleaning gun under hatch lids and

After all excessive cargo residue has

fixed hold cleaning connection on deck.

remnants of previous cargo have been removed and the area is grain clean.

been removed then the holds can be

Binoculars are quite useful for spotting

washed with salt water using a high-

cargo remains in high places. Hold bilges

pressure hold cleaning gun,

and recessed hatboxes should be cleaned

supplemented by the deck air line to

out and all cargo remains removed. Bilge

provide increased pressure. This is the

suctions must be tested both before and

most commonly used method of hold

after washing and the results entered in

cleaning, however the hold cleaning gun

the cargo notebook and/or deck log

normally requires two seamen to safely

book.

control the increased water pressure. Typical hold cleaning equipment: crew

Salt water chemical wash and hand scraping

operating a Toby gun and a Toby gun from

To remove any greasy deposits from the

Stromme.

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 Other ships have permanent highpressure hold cleaning equipment that

equipment. Numerous degreasing chemicals are

can be lowered through a flange on the

available (eg. Sea Shield detergent) and

main deck, turned ninety degrees and

work quite effectively, if they are directly

bolted to the high-pressure deck wash

injected into the firemain via the general

service line.

service pump strainer cover. Manufacturer’s instructions must always

Hold cleaning equipment in the stowed position above the deck. Note the flange on the deck wash line.

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 > continued over

29

and jet washed with fresh water using the

discharge nozzle. The quantity of

Fresh water rinse and hold preparation

chemical introduced is controlled by the

The final stage of hold washing is the

With the hatch lids open, binoculars

operator or an assistant, lifting the

fresh water rinse. A ship preparing for a

should be used to sight the holds for any

nozzle clear of the drum. However, this

grain cargo would be advised to carry

cargo remains.

method of educting the chemical from

additional fresh water in a convenient

Hold cleaning continued

high-pressure fresh water gun.

To prevent possible condensation in

the drum into the discharge nozzle is

tank. This is often the after peak, which

the hold, all the recessed hold eductors (if

time consuming and more awkward for

can be pumped into the fire main via a GS

fitted) must be drained of any water

the operator and restricts his movement

pump. A typical 110,000 dwt bulk carrier

residue, be clean dry and odourless. There

around the hold. In addition it carries a

will require around 30 tonnes of fresh

is usually a small stainless steel drain plug

greater risk of an accident or spillage of

water per hatch. Prior to commencing

on the underside of the eductor which

degreasing chemical because the

the fresh water rinse, the fire line is

can be temporarily removed to allow the

chemical drums have to be lowered into

flushed through with the after peak fresh

eductor water to drain into the bilge area.

each and every hold, whereas the first

water to remove all traces of salt water. If

When the eductor is empty the drain plug

method allows all the degreasing

a GS pump is used, the flushing through

must be replaced and secured. The

chemical to be situated at one place i.e.

takes a few minutes and only uses a few

eductor hold plate must be secured with

by the GS pump.

tonnes of fresh water. Once the fire main

all the securing bolts and duct tape

is clear of salt, all deck fire hydrants and

should be used to cover both the securing

station used successfully aboard a vessel

anchor washers should be sighted and

bolts and recessed lid handles.

consisted of: a transparent container of

confirmed that they are closed.

One degreasing chemical injection

120-litre capacity, graduated in 10 litre

If a GS pump is to be used for the hold

Hold bilges should be completely dried out, odourless and in a fully operating

units; a 5 metre transparent length of

rinse, to prevent possible pump damage,

condition. The surveyor will usually

reinforced hose with one end fitted with

a return line into the after peak should be

require to sight one bilge in each hold to

a 40cm long steel uptake branch pipe

set up using a hose connected from the

ensure that they have been cleaned out

and the other end open. The branch pipe

fire main into the after peak vent.

correctly.

was inserted into the chemical container

On completion of the hold fresh water

The tank top must be completely dry

and the open end of the transparent

rinse, all hatch entrances, hatch

and any indentations on the tank top

reinforced pipe was connected to the

trunkings and hand ladders should be

must be wiped dry. The hold should be

hand valve on the pump strainer cover

hand washed and fresh water rinsed

made completely odourless, by

using two jubilee clips. The small hand

using the fresh water high-pressure gun.

maximising hold ventilation. Two layers of

valve on the strainer cover was used to

It is not advisable to rinse and clean the

clean hessian cloth should be fitted to the

control the flow of chemical into the fire

access ladders and hatches before

bilge strainer plate to further restrict

pump.

washing the main hold, because

cargo particles entering the bilge area.

splashings from the hold bulkheads will

Duct tape is used to cover the small gap

water chemical wash, all fire hydrants

often contaminate the freshly washed

between the bilge strainer and tank top.

and anchor wash hydrants on deck

ladders. Bulkheads either side of all the

The hold hydrant area, if fitted, should be

should be checked and confirmed as fully

hand ladders should be hand cleaned and

cleaned and dried out. The steel cover

closed.

jet washed as far as one can safely reach,

refitted and secured in place with all its

using long handled turks heads. Safety

bolts/screws.

gun should be opened and the fire and

body harnesses and (if required) a bosun’s chair should be used when undertaking

Hatch undersides

GS pump started.

Prior to starting the high-pressure sea

The hydrant serving the hold cleaning

To avoid unnecessary chemical waste, predetermined times of injecting the

When it is safe to open the hatches all the

this task. When it is safe to open the hatches, all

chemical into the fire main should be

the hatch coamings should be hand

agreed between the hold cleaning party

washed using long handled turks heads

and the person controlling the rate of chemical injection. On a 110,000 dwt

Holds drying after washing.

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.

30

hatchcover undersides should be hand washed and fresh water jet washed using > continued over

the high-pressure fresh water gun. If all

Faulty or suspect sections of hatch

The first team to enter the open hold

the hatchcover undersides were hand

rubber should be replaced in their

should comprise the grain inspector, a

cleaned at the discharge port, this

entirety; localised replacement or

deck officer and a seaman. Under no

operation will be completed very quickly

‘building up’ of hatch rubbers using

circumstances should grain inspectors be

and a high-pressure jet wash may suffice.

sealing tape is discouraged.

allowed to inspect the hatches unescorted

All loose scale and any flaking paint from the hatchcover undersides must be

Poor practice: hatch tape used to build up cross joints. This is discouraged.

by a deck officer. A second team consisting of a deck

removed. All ledges on the hatch

officer and some crewmembers should be

undersides must be checked to see that

standing by at the top of the hatch being

they are clean. All hatch rubbers and

inspected. The second team should have

centre line drain channels should be

available additional clean brooms, clean

clean and clear of any cargo remains or

mops, scrapers, buckets, clean heaving

other debris.

lines and clean white rags.

Hatch watertight integrity

test the bilges (dry sucking only).

The engineers should be on standby to

To prevent cargo claims due to water

Radio contact is essential between all

ingress, all hatch seals (both longitudinal

three teams to prevent lengthy delays.

and transverse), hold access lids and

Any personnel entering the holds

seals around the hatch sides should be

should have clean safety shoes or clean

chalk marked and water tested using

safety sea boots. It is essential that any

deck wash hoses.

debris on the main deck is not walked into

Hose testing and a typical hose test.

the clean holds. Some ships issue

Grain inspection

overshoes to personnel entering the hold.

Prior to the grain inspection all hatches

If the inspector finds a fault with a

and access lids must be open and safely

hold, if at all possible, the fault should be

secured with all locking pins/bars.

identified and recorded, and remedial

All hatches should be checked for

action agreed with the inspector. If

loose scale or flaking paint. Invariably

possible the fault should be rectified

there will be a little scale on the tank top,

immediately and preferably before the

which can quickly be removed. If weather

inspector leaves the ship. If this is not

conditions permit during the day, the

possible a time should be agreed for his

holds should be opened to allow fresh air

re-inspection.

to assist the hold drying process. All small

Ballast hold

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.

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

Hold ready to load wheat.

ballast hold preparation will be quickly completed.

A more accurate method of testing a

Loading grain

hatch for leakage is to use ultrasonic

Hatches not being loaded should be kept

equipment. However this is usually

closed. All hatches after passing the grain

completed by shore personnel who are

inspection and prior to loading, must be

trained in the use of this equipment.

inspected on a daily basis to ensure that Ultrasonic hatch testing for leaks.

they are still completely dry. Hatches containing grain cargo must not be 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.

31

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 > continued over

Hold cleaning continued

Grain settling in the cargo hold.

are applied. Foam compound should not

the grain being loaded is not in a wet

be used to ensure hatch watertight

condition. These inspections should be

integrity.

recorded in the deck log book.

Do not use foam to seal hatches.

Loading grain; other hatches closed.

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 To prevent unauthorised access to the

corners).

oxygen depleted grain holds, and where Loading grain to all corners.

fumigation in transit is to be undertaken, all the hold access lids should either be

During the loading of grain, dust

padlocked or have steel security seals

clouds often develop. These are a health

fitted.

hazard and additional safety requirements, such as the wearing of eye

Security seal in place.

protection goggles and dust masks should be observed by all personnel in the vicinity of the dust cloud. Grain dust cloud presents a health hazard. Loading barley (bottom).

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.

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.

Hatch vent to secure.

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.

If the master is in any doubt about the condition of the grain during the load, he

If the voyage instructions require

Guidance can be obtained from Bulk

must issue a note of protest and seek

hatch sealing tape to be used, as an

Carrier Practice: A Practical Guide (ISBN

advice from his operators and/or the UK

additional precaution to prevent water

928 0114 581).

P&I Club.

ingress, then the hatch surfaces must be

If the vessel has any oil tanks adjacent

scrupulously clean before the sealing

to or under the cargo holds, any steam

Completion of a hatch

tape is applied. In cold climates, some

heating to these tanks should be

All holds to be filled must be absolutely

brands of tape will adhere better if

minimised, but in any case carefully

full. It is essential that the loading spout,

warmed in the engine room before they

monitored and full records maintained to

32

prevent cargo heating and possible cargo

✔ All hatch corner drains and non-return

damage. This is a point that is often

valves are working correctly and are

overlooked by ships staff.

complete in all respects.

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

This figure of one day per hold is

✔ 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

iron ore. If the vessel’s previous cargo was

✔ All hold bilge plates have all the

grain, then the chemical wash may not be

securing bolts fitted and the ships

required, but the holds should still be

approved ballast holds have the

hand scraped to remove any loose scale

blanks. This is often a spectacle piece

and paint.

which can be rotated on deck.

Grain cleaning ‘equipment’ checklist

✔ All ballast line hold cover plates have good condition.

operator.

the vessel’s previous cargo was coal or

allow safe access for all personnel.

materials can be planned. A lack of

the ship and costly off hire for the

The ‘simplified’ schedule assumes that

bulkheads are in good condition to

all the bolts fitted and they are all in

shore may result in difficulties for

usually acceptable to charterers.

✔ All hatch ladders on fwd and aft

cleaning time, manpower and communication between ship and

Under normal circumstances It often takes one day to clean a hold.

✔ A fully working high-pressure hold cleaning gun (Toby gun or Semjet or

✔ All hatch access lids can have a hatch

similar) – complete with sufficient deck

seal or padlock fitted after loading, to

wash down hoses and air-lines all in

prevent unauthorised entry into

good condition.

oxygen depleted area.

Fire hoses must not be used as wash

✔ No infestation is onboard. This

down hoses as they are part of the

includes all the storerooms, as these

ships safety equipment.

areas are also liable to be inspected by

✔ Ship has a fully operational salvage

grain inspectors.

pump (Wilden pump) and approved

✔ Approved grain stability books

spares.

carriage of additional fresh water –

onboard and the pre-calculated load

confirmation that the after-peak tank

conditions (using appropriate grain

can be discharged via the deck service

shift moments) have been completed.

high-pressure fresh water rinse of all

line and, if after-peak is ‘filled’ with

In some ports, these calculations have

the holds. It will be more cost effective

fresh water, the ship can still maintain

to be approved by the local authorities.

to over-supply fresh water for hold

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

✔ Sufficient fresh water to complete a

cleaning than the ship to run out

✔ A hold-cleaning schedule using

during the hold cleaning. (A typical

realistic times has been prepared.

100,000dwt bulker requires around

The ‘simplified’ example, below, is not an

30 tonnes per hatch).

actual working schedule.

> continued over

Simplified schedule. Order of events (In port) Hatch undersides

Day 1

Day 2

x

x

Wash down decks

x

HP saltwater wash holds

x

Day 3

Day 4

Day 5

Day 6

x

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).

Chemical wash holds – scrape – and SW rinse

x

FW rinse and hold preparation

x

Clean hatch lids undersides

x

Check holds and hatch watertightness

x

33

x

Day7

Hold cleaning continued

during cleaning. Each lamp to be complete with 50 metres of cable and

✔ 1 x portable pressurised fresh water gun, complete with extended handle and 30 metres of pressurised hose. ✔ 6 x long handle steel scrapers

have a waterproof plug fitted. ✔ 10 x spare halogen bulbs for above. ✔ 2 x 50 metre extension cables each complete with three waterproof

complete with handles. ✔ 3 x lightweight, strong, aluminium extension poles with capability to

outlet sockets and a waterproof plug. ✔ 5 x 20 litre drums concentrated teepol.

extend to approx 5 metres. ✔ 6 x long handled rubber squeegee

✔ Sufficient drums of de-greasing chemical wash suitable for use with

complete with 1 metre rubber blades.

sea water (e.g. Sea Shield detergent

✔ 10 x heavy-duty bass brooms, c/w

cleaner or equivalent).

handles, suitable for hold cleaning. ✔ 6 x corn brooms c/w with handles. ✔ 6 x heavy-duty mops, c/w handles.

Typical examples of hold failures The following images from a vessel which

✔ 6 x spare mop heads suitable for above.

failed a grain survey, would suggest that:

✔ 4 x galvanized, roller wringer, mop

●

buckets. ✔ 6 x turks heads, round head 4 inch, c/w handles.

water wash. ●

No chemical wash was undertaken.

●

No hard scraping of the bulkheads

✔ 6 x small 6 inch wide, hand shovels,

was completed.

steel, suitable for digging out hold bilges.

Ships crew completed a very quick salt

●

Previous hold cleaning had not been supervised (history of the ships

✔ 3 x 25 metre length, lint free soogee

cargoes on the stiffeners).

cloth, width approx 30cm. ✔ 1 x 50 metre length burlap, 1 metre wide.

Showing: ●

(coal).

✔ 10 x rolls of 50 metre length, 10cm wide, grey, industrial strength duct tape.

●

Cargo dust residues.

●

Deposits of previous cargoes in hard to reach places.

✔ 6 x 20 metre length, ‘yellow’ wash down hoses, duraline, 45mm dia

Staining from the previous cargo

●

Flaking paint and scale ■

complete with couplings suitable for ship’s fire main. ✔ 4 x plastic jet nozzles, suitable for above hoses. ✔ 4 x 50 metre lengths, transparent

References

plastic, reinforced garden hose,

Bulk Carrier Practice – A Practical Guide.

complete with male and female plastic

(ISBN 928 0114 581)

couplings to join each section.(for use

Recommendation on the Safe Use of

with Kew gun).

Pesticides on Ships. (ISBN 9280111205)

✔ 2 x universal tap connectors for above reinforced transparent plastic garden

Product Safety Data Sheets – for

hose.

degreasing chemical used. Bulk Cargo Code – IMO Publication. (ISBN

✔ Sufficient hatch sealing tape to comply

9280110616)

with operators instructions.

MARPOL. (ISBN 9280114174)

✔ 4 x 500 watt, portable lightweight

www.stromme.com

halogen lights to illuminate hatches

34

Direct reduced iron including DRI fines

For a long period of time iron has been

During a period of six months in

Shippers should certify that the material

produced in blast furnaces by reduction

2003/2004 there were three serious

conforms with the requirements of this

of iron ore, that is removing the oxides of

casualties related to the carriage of DRI

Code.”

the ore. High shipping costs are paid for

and DRI fines including loss of life and

shipping the iron oxides from the ore

sinking of two of the ships.

producing areas to the iron producing

The most positive method of carrying

The Code continues with a section ‘Shipper’s Requirements’. This states that prior to shipment the DRI should be aged

furnaces. Reduction of the ore in blast

DRI safely, free from the effects of

for at least 72 hours or treated with an air

furnaces is then a high energy demand

oxygen and sea water is to ensure that

passivation technique, or some other

process. Research in the steel making

the cargo compartments are effectively

equivalent method that reduces the

industry has produced a method to

sealed and inerted. The compartments

reactivity of the material to at least the

directly reduce the ores to metal, the

should be inerted to the extent that the

same level as the aged product.

product known as direct reduced iron,

oxygen content of the atmosphere is less

DRI. Iron ore is crushed and formed into

than 5%.

pellets. The pellets are then heated in a

It states under Paragraph A that the shipper should provide the necessary

Direct reduced iron such as lumps,

specific instructions for carriage either:

furnace, at a temperature below the

pellets and cold moulded briquettes are

melting point of any of the metal in the

included in the IMO Code of Safe

ore, in the presence of reducing gases.

Practice for Solid Bulk Cargoes under BC

The ore is reduced to metal by the

No.015. Direct reduced iron, briquettes,

removal of oxygen, leaving the metal in a

hot moulded are included in the Code

rigid but sponge-like structure. This

under BC No.016. It is important to note

sponge-like structure has an extremely

that the entries in the Code relate to:

high surface area to mass ratio, possibly a

“Direct Reduced Iron DRI” and “Direct

that the DRI has been treated with an

thousand times greater than the surface

Reduced Iron”

oxidation and corrosion inhibiting

area of a piece of iron of the same mass.

Examples are indicated “such as

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

process which has been proved to the

It is well known that iron will readily

lumps, pellets, briquettes etc”. However

satisfaction of the competent authority

oxidise or ‘rust’. This ‘rusting’ process is

this does not exclude fines. Fines are fine

to provide effective protection against

obviously increased with an increase in

particles of direct reduced iron created

dangerous reaction with sea water or

surface area as exhibited by DRI pellets.

during the manufacturing, handling and

air under shipping conditions.

The rusting process is an exothermic

storage of the material. Fines as

The provision of Paragraph A may be

reaction, that is to say heat is evolved

marketed normally have specifications

waived or varied if agreed by the

during the process. Furthermore this

relating to total iron and metallic iron.

competent authorities taking into account

reaction is accelerated in the presence of

The fines may thus evolve hydrogen if in

the sheltered nature, length, duration, or

water or moisture and further

contact with water, which is also stated

any other applicable conditions of any

accelerated by the presence of an

in the Code.

specific voyage.

Apparently one shipper and one

The Code then continues to describe

between DRI and water results in the

author considers that DRI fines and HBI

the relevant precautions, loading carriage

production of the highly flammable gas

fines are not included in the IMO Code.

etc.

hydrogen.

However this is not the case, the IMO

electrolyte as in sea water. The reaction

Despite all these problems, DRI cargoes

entry clearly states, direct reduced iron,

are safely carried to destination. However

relies upon excluding oxygen and water,

which would include fines derived from

if the precautions are not observed there

particularly sea water, from the stow.

direct reduced iron.

can be severe problems during discharge

Thus the safe carriage of DRI pellets

Certain manufacturers have developed

The IMO Code of Safe Practice for

of heated cargo. Expensive fire fighting

passivation techniques for the DRI pellets,

Solid Bulk Cargoes under the title ‘Special

procedures involving the use of vast

which supposedly prevent the effect of

Requirements’ states:

quantities of solid inert materials, inert gas

moisture and oxygen reacting with the

“Certification: A competent person

etc, long delays to the discharge. Even

pellets. However following a serious fire

recognised by the National

when removed from the ship’s hold a

in a ship carrying passivated pellets, there

Administration of the country of

heated cargo can cause problems on the

are doubts whether the passivation

shipment should certify to the ship’s

quayside. At one port there remained for

technique is satisfactory for the safe

Master that the DRI at the time of

carriage of the pellets.

loading, is suitable for shipment.

35

> continued over

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

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.

that throughout the voyage an inert

Hot moulded briquettes

atmosphere should be maintained with an

Hot moulded briquettes of DRI are a

oxygen content less than 5%.

different proposition. The mined ore

In May 2001 the UK P&I Club published

passes through a densification process

a circular which indicated the following:

but is then moulded at a temperature in

a) The undersigned Association continues

excess of 650o C. The briquettes may be

to believe that the only proven method

stored in open storage conditions. Prior to

of carrying this cargo safely is by

shipment the shipper or competent

maintaining the cargo holds in an inert

authority should provide the master with

atmosphere and believe the most

a certificate to the effect that the material

effective method of providing an inert

is suitable for shipment and conforms

atmosphere is by injecting inert gas at

with the requirements of the IMO Code.

the bottom of the stow in order to

Loading during rain is not acceptable

force out the air within the stow (see

but briquettes can be discharged under

photos below).

all weather conditions. Water spray to

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.

assist dust control is also permitted during discharge. Hold spaces should be clean and dry, and all combustible materials removed before loading. Briquettes with o

a temperature in excess of 60 C should not be loaded. Hydrogen may be slowly evolved if the

Under the ideal conditions of carriage,

briquettes had been in contact with water

perfectly sealed hold spaces for all types of

thus adequate ventilation should be

ships under all weather conditions it may

provided. There are no requirements to

be possible to complete the voyage

monitor hydrogen and oxygen levels nor

maintaining an inert atmosphere

to record temperature effects in the

throughout the stowed cargo following

cargo. Normal precautions of entering the

injection of inert gas at the

hold spaces should be observed in case of

commencement of loading. It may also be

oxygen depletion ■

An inert atmosphere is maintained within the stow by injecting an inert gas from the bottom.

36

.............................................................................................................................................................................................................................................................................................

Direct reduced iron continued

Acknowledgements The UK P&I Club would like to thank the Carefully to Carry Advisory Committee for the following articles: The carriage of liquefied gases / Liquefied natural gas – Wavespec Limited Bulk liquid cargoes – sampling – CWA International Limited Carriage of potatoes – John Banister Limited Fumigation of ships and their cargoes – Igrox Limited Scrap metal – Minton, Treharne & Davies Limited Hold cleaning – UK Club Loss Prevention Department Direct reduced iron – Minton, Treharne & Davies Limited

Whilst the information given in this newsletter is believed to be correct, the publishers do not guarantee its completeness or accuracy.

Carefully to Carry Edited by: Karl Lumbers Tel: +44 (0)20 7204 2307 e-mail: [email protected] Colin Legget

Tel: +44 (0)20 7204 2217

e-mail: [email protected] 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 Ship Assurance Association (Bermuda) Limited The United Kingdom Freight Demurrage and Defence Association Limited

Carefully to Carry on-line This newsletter and earlier editions can be viewed on the Club’s website: http://www.ukpandi.com