1

Introduction

The renewed interest in gas, which started in the

1990s due to its excellent environmental

credentials, has seen an increase in the order

book for LNG carriers – LNG carriers being the

leviathans of the gas carrier fleet. Yet, while

attracting great interest, the gas trade still

employs relatively few ships in comparison to oil

tankers, and hence its inner workings are little

known except to a specialist group of companies

and mariners.

Considering the fleet of gas carriers of over

1,000 m3 capacity, the total of nearly 1,000 ships

can be divided into 5 major types according to the

following table:

By contrast, the world oil tanker fleet for a

similar size range is over 16,000 ships!

Given the relative paucity of knowledge on gas

tankers in comparison to oil tankers, the purpose

of this article is to describe the gas carrier genre,

its particularities within each type and its

comparison with other tankers. The aim is to

provide basic knowledge about gas carriers and

an overview of their strengths and weaknesses,

both from design and operational viewpoints.

A second article, on page 8, describes the

liquefied natural gas (LNG) carrier in more detail

and a third article, to be published later, will

describe the liquefied petroleum gas (LPG) carrier.

“The carrier shall properlyand carefully load, handle,stow, carry, keep, care forand discharge the goods

carried.”

Hague Rules, Articles iii, Rule 2

CAREFULLY TO CARRY

> continued over

UK CLUB FEBRUARY 2005 ISSUE 8

The carriageof liquefied gases

IN THIS ISSUE PAGE

The carriage ofliquefied gases 1

Liquefied natural gas 9

Bulk liquid cargoes– sampling 13

Carriage of potatoes 15

Fumigation of shipsand their cargoes 19

Scrap metal 24

Hold cleaning– bulk cargoes 26

Direct reduced iron 35

The introduction of a tanker designed to carry

compressed natural gas (CNG) is anticipated in

the near future. A number of designs have been

produced but, due to the relatively low

deadweight and high cost of these ships, the first

commercial application of this technology cannot

be predicted.

The gas carrier is often portrayed in the media

as a potential floating bomb, but accident

statistics do not bear this out. Indeed, the sealed

nature of liquefied gas cargoes, in tanks

completely segregated from oxygen or air,

virtually excludes any possibility of a tank

explosion. However, the image of the unsafe ship

lingers, with some administrations and port state

control organisations tending to target such

ships for special inspection whenever they enter

harbour. The truth is that serious accidents

related to gas carrier cargoes have been few,

and the gas carrier’s safety record is

acknowledged as an industry leader. As an

illustration of the robustness of gas carriers,

when the Gaz Fountain was hit by rockets in the

first Gulf War, despite penetration of the

containment system with huge jet fires, the fires

were successfully extinguished and the ship,

together with most cargo, salved.

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

The gas carrier fleet (end 2004)

Pressurised Semi-pressurised Ethylene Fully refrigerated LNG carriersLPG carriers LPG carriers carriers LPG carriers

Ship numbers 336 189 103 185 175

Total capacity (m3) 1,045,970 1,378,690 755,620 11,171,705 20,683,798

2

Carriage of liquefied gases continued

The relative safety of the gas carrier is

due to a number of features. One such,

almost unique to the class, is that cargo

tanks are always kept under positive

pressure (sometimes just a small

overpressure) and this prevents air

entering the cargo system. (Of course

special procedures apply when stemmed

for drydock). This means that only liquid

cargo or vapour can be present and,

accordingly, a flammable atmosphere

cannot exist in the cargo system.

Moreover all large gas carriers utilise a

closed loading system with no venting to

atmosphere, and a vapour return pipeline

to the shore is often fitted and used

where required. The oxygen-free nature

of the cargo system and the very serious

limitation of cargo escape to atmosphere

combine to make for a very safe design

concept.

The liquefied gases

First let us consider some definitions in

the gas trade. According to the IMO, a

liquefied gas is a gaseous substance at

ambient temperature and pressure, but

liquefied by pressurisation or

refrigeration – sometimes a combination

of both. Virtually all liquefied gases are

hydrocarbons and flammable in nature.

Liquefaction itself packages the gas into

volumes well suited to international

carriage – freight rates for a gas in its

non-liquefied form would be normally far

too costly. The principal gas cargoes are

LNG, LPG and a variety of petrochemical

gases. All have their specific hazards.

LNG is liquefied natural gas and is

methane naturally occurring within the

earth, or in association with oil fields. It is

carried in its liquefied form at its boiling

point of -162°C. Depending on the

standard of production at the loading

port, the quality of LNG can vary but it

usually contains fractions of some

heavier ends such as ethane (up to 5%)

and traces of propane.

The second main cargo type is LPG

(liquefied petroleum gas). This grade

covers both butane and propane, or a

mix of the two. The main use for these

products varies from country to country

but sizeable volumes go as power station

or refinery fuels. However LPG is also

sought after as a bottled cooking gas and

it can form a feedstock at chemical

plants. It is also used as an aerosol

propellant (with the demise of CFCs) and

is added to gasoline as a vapour pressure

enhancer. Whereas methane is always

carried cold, both types of LPG may be

carried in either the pressurised or

refrigerated state. Occasionally they may

be carried in a special type of carrier

known as the semi-pressurised ship.

When fully refrigerated, butane is carried

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

temperature already introducing the

need for special steels.

Ammonia is one of the most common

chemical gases and is carried worldwide in

large volumes, mainly for agricultural

purposes. It does however have particularly

toxic qualities and requires great care

during handling and carriage. By

regulation, all liquefied gases when carried

in bulk must be carried on a gas carrier, as

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

next section – Design of gas carriers)

provide a list of safety precautions and

design features required for each product.

A specialist sector within the trade is

the ethylene market, moving about one

million tonnes by sea annually, and very

sophisticated ships are available for this

carriage. Temperatures here are down to

-104°C and onboard systems require

perhaps the highest degree of expertise

within what is already a highly specialised

and automated industry. Within this group

a sub-set of highly specialised ships is able

to carry multi-grades simultaneously.

Significant in the design and operation

of gas carriers is that methane vapour is

lighter than air while LPG vapours are

heavier than air. For this reason the gas

carrier regulations allow only methane to

be used as a propulsion fuel – any minor

gas seepage in engine spaces being

naturally ventilated. The principal

hydrocarbon gases such as butane,

propane and methane are non-toxic in

nature and a comparison of the relative

hazards from oils and gases is provided in

the table below:

Comparative hazards of some liquefied gases and oils

GASES OILS

HAZARD LNG LPG GASOLINE FUEL OIL

Toxic No No Yes Yes

Carcinogenic No No Yes Yes

Asphyxiant Yes (in confined spaces) Yes (in confined spaces) No No

Others Low temperature Moderately low Eye irritant, narcotic, Eye irritant, narcotic,temperature nausea nausea

Flammability limits 5-15 2-10 1-6 Not applicablein air (%)

Storage pressure Atmospheric Often pressurised Atmospheric Atmospheric

Behaviour if spilt Evaporates forming a Evaporates forming an Forms a flammable Forms a flammablevisible ‘cloud’ that explosive vapour cloud pool which if ignited pool, environmentaldisperses readily and is would burn with clean-up is requirednon-explosive, unless explosive force,contained environmental clean-up

may be required

3

3,200 m3 coastal LPG carrier with cylindrical tanks.

78,000 m3 LPG carrier with Type-A tanks

16,650 m3 semi pressurised LPG carrier

135,000 m3 LNG carrier with membrane tanks

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

> continued over

Design of gas carriers

The regulations for the design and

construction of gas carriers stem from

practical ship designs codified by the

International Maritime Organization

(IMO). This was a seminal piece of work

and drew upon the knowledge of many

experts in the field – people who had

already been designing and building such

ships. This work resulted in several rules

and a number of recommendations.

However all new ships (from June 1986)

are built to the International Code for the

Construction and Equipment of Ships

Carrying Liquefied Gases in Bulk (the IGC

Code). This code also defines cargo

properties and documentation, provided

to the ship (the Certificate of Fitness for

the Carriage of Liquefied Gases in Bulk),

shows the cargo grades the ship can carry.

In particular this takes into account

temperature limitations imposed by the

metallurgical properties of the materials

making up the containment and piping

systems. It also takes into account the

reactions between various gases and the

elements of construction not only on

tanks but also related to pipeline and

valve fittings.

When the IGC Code was produced an

intermediate code was also developed by

the IMO – the Code for the Construction

and Equipment of Ships Carrying

Liquefied Gases in Bulk (the GC Code).

This covers ships built between 1977 and

1986.

As alluded to above, gas carriers were

in existence before IMO codification and

ships built before 1977 are defined as

‘existing ships’ within the meaning of the

rules. To cover these ships a voluntary

code was devised, again by the IMO – the

Code for Existing Ships Carrying Liquefied

Gases in Bulk (the Existing Ship Code).

Despite its voluntary status, virtually all

ships remaining in the fleet of this age –

and because of longevity programmes

there are still quite a number – have

certification in accordance with the

Existing Ship Code as otherwise

international chartering opportunities

would be severely restricted.

Cargo carriage in the pressurised fleet

comprises double cargo containment –

hull and tank. All other gas carriers are

built with a double hull structure and the

distance of the inner hull from the outer

is defined in the gas codes. This spacing

introduces a vital safety feature to

mitigate the consequences of collision

and grounding. Investigation of a

number of actual collisions at the time

the gas codes were developed drew

conclusions on appropriate hull

separations which were then

incorporated in the codes. Collisions do

occur within the class and, to date, the

codes’ recommendations have stood the

test of time, with no penetrations of

cargo containment having been reported

from this cause. The double hull concept

includes the bottom areas as a protection

against grounding and, again, the

designer’s foresight has proven of great

value in several serious grounding

incidents, saving the crew and

surrounding populations from the

consequences of a ruptured containment

system.

So a principal feature of gas carrier

design is double containment and an

internal hold. The cargo tanks, more

generally referred to as the ‘cargo

containment system’, are installed in the

hold, often as a completely separate

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

ship’s structure or its strength members.

Herein lies a distinctive difference

between gas carriers and their sisters, the

oil tankers and chemical carriers.

Cargo tanks may be of the

independent self-supporting type or of a

membrane design. The self-supporting

tanks are defined in the IGC Code as

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

Type-A containment comprises box-

shaped or prismatic tanks (i.e. shaped to

4

Carriage of liquefied gases continued

fit the hold). Type-B comprises tanks

where fatigue life and crack propagation

analyses have shown improved

characteristics. Such tanks are usually

spherical but occasionally may be of

prismatic types. Type-C tanks are the

pure pressure vessels, often spherical or

cylindrical, but sometimes bi-lobe in

shape to minimise broken stowage.

The fitting of one system in

preference to another tends towards

particular trades. For example, Type-C

tanks are suited to small volume carriage.

They are therefore found most often on

coastal or regional craft. The large

ballast tanks and if problems are to

develop with age then the ballast tanks are

prime candidates. These ships are the most

numerous class, comprising approximately

40% of the fleet. They are nevertheless

relatively simple in design yet strong of

construction.

Cargo operations that accompany such

ships include cargo transfer by flexible

hose and in certain areas, such as China,

ship-to-ship transfer operations from

larger refrigerated ships operating

internationally are commonplace.

Records show that several ships in this

class have been lost at sea because of

collision or grounding, but penetration of

the cargo system has never been proven.

international LPG carrier will normally be

fitted with Type-A Tanks. Type-B tanks

and tanks following membrane principles

are found mainly within the LNG fleet.

The pressurised fleet

The first diagram, on the previous page,

and the photograph above show a small

fully pressurised carrier. Regional and

coastal cargoes are often carried in such

craft with the cargo fully pressurised at

ambient temperature. Accordingly, the

tanks are built as pure pressure vessels

without the need for any extra

metallurgical consideration appropriate

to colder temperatures. Design pressures

are usually for propane (about 20 bar) as

this form of LPG gives the highest vapour

pressure at ambient temperature. As

described above, ship design comprises

outer hull and an inner hold containing

the pressure vessels. These rest in saddles

built into the ship’s structure. Double

bottoms and other spaces act as water

Pressurised LPG carrier with cylindrical tanks.

In one case, a ship sank off Italy and

several years later refloated naturally, to

the surprise of all, as the cargo had

slowly vaporised adding back lost

buoyancy.

The semi-pressurised fleet

In these ships, sometimes referred to as

‘semi-refrigerated’, the cargo is carried in

Semi-pressurised LPG carrier.

pressure vessels usually bi-lobe in cross-

section, designed for operating pressures

of up to 7 bars. The tanks are

constructed of special grade steel

suitable for the cargo carriage

temperature. The tanks are insulated to

minimise heat input to the cargo. The

cargo boils off causing generation of

vapour, which is reliquefied by

refrigeration and returned to the cargo

tanks. The required cargo temperature

and pressure is maintained by the

reliquefaction plant.

These ships are usually larger than the

fully pressurised types and have cargo

capacities up to about 20,000 m3. As

with the fully pressurised ship, the cargo

tanks are of pressure vessel construction

and similarly located well inboard of the

ship’s side and also protected by double

bottom ballast tanks. This arrangement

again results in a very robust and

inherently buoyant ship.

The ethylene fleet

Ethylene, one of the chemical gases, is

the premier building block of the

petrochemicals industry. It is used in the

production of polyethylene, ethylene

dichloride, ethanol, styrene, glycols and

many other products. Storage is usually

as a fully refrigerated liquid at -104°C.

Ships designed for ethylene carriage

also fall into the semi-pressurised class.

They are relatively few in number but are

among the most sophisticated ships

afloat. In the more advanced designs

they have the ability to carry several

grades. Typically this range can extend to

ethane, LPG, ammonia, propylene

butadiene and vinyl chloride monomer

(VCM), all featuring on their certificate of

fitness. To aid in this process several

5

independent cargo systems co-exist

onboard to avoid cross contamination of

the cargoes, especially for the

reliquefaction process.

The ships range in size from about

2,000 m3 to 15,000 m3 although several

larger ships now trade in ethylene. Ship

design usually includes independent

cargo tanks (Type-C), and these may be

cylindrical or bi-lobe in shape constructed

from stainless steel. An inert gas

generator is provided to produce dry

inert gas or dry air. The generator is used

for inerting and for the dehydration of

the cargo system as well as the inter-

barrier spaces during voyage. For these

condensation occurs on cold surfaces

with unwanted build-ups of ice. Deck

tanks are normally provided for

changeover of cargoes.

The hazards associated with the

cargoes involved are obvious from

temperature, toxic and flammable

concerns. Accordingly, the safety of all

such craft is critical with good

management and serious personnel

training remaining paramount.

The fully refrigerated fleet

These are generally large ships, up to

about 100,000 m3 cargo capacity, those

above 70,000 m3 being designated as

VLGCs. Many in the intermediate range

(say 30,000 m3 to 60,000 m3) are suitable

for carrying the full range of hydrocarbon

liquid gas from butane to propylene and

may be equipped to carry chemical liquid

gases such as ammonia. Cargoes are

carried at near ambient pressure and at

temperatures down to -48ºC.

Reliquefaction plants are fitted, with

> continued over

substantial reserve plant capacity

provided. The cargo tanks do not have to

withstand high pressures and are

therefore generally of the free standing

prismatic type. The tanks are robustly

stiffened internally and constructed of

special low temperature resistant steel.

All ships have substantial double

bottom spaces and some have side

Fully refrigerated LPG carrier.

ballast tanks. In all cases the tanks are

protectively located inboard. The ship’s

structure surrounding or adjacent to the

cargo tanks is also of special grade steel,

in order to form a secondary barrier to

safely contain any cold cargo should it

leak from the cargo tanks.

All cargo tanks, whether they be of the

pressure vessel type or rectangular, are

provided with safety relief valves amply

sized to relieve boil-off in the absence of

reliquefaction and even in conditions of

surrounding fire.

The LNG fleet

Although there are a few exceptions, the

principal ships in the LNG fleet range from

75,000m3 to 150,000m3 capacity, with

ships of up to 265,000 m3 expected by the

end of the decade. The cargo tanks are

thermally insulated and the cargo carried

at atmospheric pressure. Cargo tanks may

be free standing spherical, of the

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

LNG carrier with membrane tanks.

6

membrane type, or alternatively, prismatic

in design. In the case of membrane tanks,

the cargo is contained within thin walled

tanks of invar or stainless steel. The tanks

are anchored in appropriate locations to

the inner hull and the cargo load is

transmitted to the inner hull through the

intervening thermal insulation.

All LNG carriers have a watertight

inner hull and most tank designs are

required to have a secondary containment

capable of safely holding any leakage for

a period of 15 days. Because of the

simplicity and reliability of stress analysis

of the spherical containment designs, a

full secondary barrier is not required but

splash barriers and insulated drip trays

protect the inner hull from any leakage

that might occur in operation. Existing

LNG carriers do not reliquefy boil-off

gases, they are steam ships and the gas is

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

ships to burn this gas in medium speed

diesel engines will be delivered in 2005/6,

and ships with reliquefaction plant and

conventional slow speed diesel engines

will enter service late in 2007. It is likely

that gas turbine propelled ships may

appear soon after this.

Crew training and numbers

As they did for oil tankers and chemical

carriers, the IMO has laid down a series of

training standards for gas carrier crews

which come in addition to normal

certification. These dangerous cargo

endorsements are spelt out in the STCW

Convention. Courses are divided into the

basic course for junior officers and the

advanced course for senior officers. IMO

rules require a certain amount of

onboard gas experience, especially at

senior ranks, before taking on the

responsible role or before progressing to

the next rank. This can introduce checks

and balances (say) in the case of a master

from the bulk ore trades wanting to

convert to the gas trade. The only way,

without previous gas experience, to

achieve this switch is to have the

candidate complete the requisite course

and sail as a supernumerary,

understudying the rank for a specified

period on a gas carrier. This can be costly

for seafarer and company alike.

Accordingly, as the switch can be difficult

to manage, especially at senior ranks,

current requirements tend to maintain a

close-knit cadre of ‘gas men or women’

well experienced in the trade.

In addition to the official certification

for hazardous cargo endorsements, a

number of colleges operate special

courses for gas cargo handling. In the UK

a leader in the field is the Warsash

Maritime Centre.

While this situation provides for a

well-trained and highly knowledgeable

environment the continued growth in the

fleet currently strains manpower

resources and training schedules and it is

possible that short cuts may be taken.

While the small gas carriers normally

operate at minimum crew levels, on the

larger carriers it is normal to find

increased crewing levels over and above

the minimum required by the ship’s

manning certificate. For example, it is

almost universal to carry a cargo

engineer onboard a large gas carrier. An

electrician is a usual addition and the

deck officer complement may well be

increased.

Gas carriers and portoperations

As gas carriers have grown in size, so too

has a concern over in-port safety.

Indeed, the same concerns applied with

the growth in tanker sizes when the

VLCC came to the drawing board. The

solutions are similar; however, in the case

of the gas carrier, a higher degree of

automation and instrumentation is often

apparent controlling the interface

between ship and shore.

Terminals are also protected by careful

risk analysis at the time of construction

so helping to ensure that the location

and size of maximum credible spill

scenarios are identified, and that suitable

precautions including appropriate safety

distances are established between

operational areas and local populations.

Regarding shipping operations, risk

analysis often identifies the cargo

manifold as the area likely to produce the

Hard arm quick connect/disconnect coupler

(QCDC).

Hard arms at cargo manifold, including

vapour return line (below, centre arm).

Hard arm connection to manifold, showing

double ball valve safety release.

Carriage of liquefied gases continued

7

maximum credible spill. This should be

controlled by a number of measures.

Primarily, as for all large oil tankers, gas

carriers should be held firmly in position

whilst handling cargo, and mooring

management should be of a high calibre.

Mooring ropes should be well managed

throughout loading and discharging. Safe

mooring is often the subject of

computerised mooring analysis, especially

for new ships arriving at new ports, thus

helping to ensure a sensible mooring array

suited to the harshest conditions. An

accident in the UK highlighted the

consequences of a lack of such procedures

when, in 1993, a 60,000 m3 LPG carrier

broke out from her berth in storm

conditions. This was the subject of an

official MCA/HSE inquiry concluding

that prior mooring analysis was vital to

safe operations. The safe mooring

principles attached to gas carriers are

similar to those recommended for oil

tankers (they are itemised in Mooring

Equipment Guidelines, see References ,

page 13).

The need for such ships to be held

firmly in position during cargo handling is

due in part to the use of loading arms

(hard arms – see photos opposite) for

cargo transfer. Such equipment is of

limited reach in comparison to hoses, yet it

provides the ultimate in robustness. It also

provides simplicity in the connection at the

cargo manifold.

The use of loading arms for the large

gas carrier is now quite common and, if

not a national requirement, is certainly an

industry recommendation. The alternative

use of hoses is fraught with concerns over

hose care and maintenance, and their

proper layout and support during

operations to prevent kinking and

abrasion. Further, accident statistics show

that hoses have inferior qualities in

comparison to the hard arms. Perhaps the

worst case of hose failure occurred in

1985 when a large LPG carrier was loading

at Pajaritos, Mexico. Here, the hose burst

and, in a short time, the resulting gas

cloud ignited. The consequent fire and

explosion impinged directly on three other

ships in harbour and resulted in four

deaths. It was one of those accidents

which has led directly to a much increased

use of loading arms internationally. The

jetty was out of action for approximately

six months. Fortunately the berth was in

an industrial area and collateral damage

to areas outside the refinery was limited.

As ships have grown in size the

installation of vapour return lines

interconnecting ship and shore vapour

systems has become more common.

Indeed, in the LNG industry it is required,

with the vapour return being an integral

part of the loading or discharging

system. In the LPG trades, vapour returns

are also common, but are only opened in

critical situations such as where onboard

reliquefaction equipment is unable to

cope with the loading rate and boil-off.

A feature common to both ship and

shore is that both have emergency

shutdown systems. It is now common to

interconnect such systems so that, for

example, an emergency on the ship will

stop shore-based loading pumps. One

such problem may be the automatic

detection of the ship moving beyond the

safe working envelope for the loading

arms. A further refinement at some

larger terminals is to have the loading

arms fitted with emergency release

devices, so saving the loading arms from

fracture (see centre photo opposite).

Given good moorings and well-

designed loading arms, the most likely

sources of leakage are identified and

controlled.

Hazards to shore workers andcrewmembers at refit

While the gas carrier accident record is

very good for normal operations, and

exemplary with respect to cargo

operations and containment, the same

cannot be said for the risks it faces in

drydock. Statistics show that the gas

carrier in drydock presents a serious risk

to personnel, particularly with respect to

adequate ventilation through proper

inerting and gas-freeing before repairs

begin. Most often the risk relates to

minor leakage from a cargo tank into the

insulation surrounding refrigerated LPG

tanks. A massive explosion occurred on

the Nyhammer at a Korean shipyard in

1993 for this very reason, where

considerable loss of life occurred.

Although the ship was repaired, it was a

massive job ■

Checklist

The following checklist, made

available from SIGTTO, may be

used as guidance in a casualty

situation involving a disabled gas

carrier.

● What cargo is onboard?

● Is specialist advice available in

respect of the cargo and its

properties?

● Are all parties involved aware of

cargo properties?

● Is the cargo containment

system intact?

● Is the ship venting gas?

● Is the ship likely to vent gas?

● What will be the vented gas

and what are its dispersal

characteristics?

● Is a gas dispersion modelling

tool available?

● Is the ship damaged?

● Does damage compromise the

ship’s manoeuvring ability?

● What activities and services are

planned to restore a seaworthy

condition?

● Is ship-to-ship transfer

equipment available if

required?

● When is it expected the ship will

be seaworthy again?

● Is prevailing shelter (and other

dangers) suitable for the

intended repairs?

● What contingency plans are

required?

● Who will control the operation?

● How will the ship operator and

port or public authorities

co-operate?

● Will customs and immigration

procedures need facilitation for

equipment and advisers?

8

Liquefied natural gas

Background

It was as far back as 1959 that the

Methane Pioneer carried the first

experimental LNG cargo, and 40 years

ago, in 1964, British Gas at Canvey Island

received the inaugural cargo from Arzew

on the Methane Princess. Together with

the Methane Progress these two ships

formed the core of the Algeria to UK

project. And the project-based nature of

LNG shipping was set to continue until

the end of the 20th century. LNG carriers

only existed where there were projects,

with ships built specifically for

employment within the projects. The

projects were based on huge joint

ventures between cargo buyers, cargo

sellers and shippers, all in themselves

large companies prepared to do long-

term business together.

The projects were self-contained and

operated without much need for outside

help. They supplied gas using a purpose-

built fleet operating like clockwork on a

CIF basis. Due to commercial constraints,

the need for precisely scheduled

deliveries and limited shore tank

capacities, spot loadings were not

feasible and it is only in recent years that

some projects now accept LNG carriers as

cross-traders, operating more like their

tramping cousins – the oil tankers.

Doubtless the trend to spot trading will

continue. However, the co-operative

nature of LNG’s beginnings has led to

several operational features unique to

the ships. In particular there is the

acceptance that LNG carriers burn LNG

cargo as a propulsive fuel. They also

retain cargo onboard after discharge (the

‘heel’) as an aid to keeping the ship

cooled down and ready to load on arrival

at the load port. Thus matters that would

be anathema to normal international

trades are accepted as normal practice

for LNG.

Again, looking back to the early days,

there was also great interest in this new

fuel in the USA and France. Receiving

terminals sprouted. However, gas pricing

difficulties in the USA saw an end to early

American interest while Gaz de France

consolidated rather than expanded.

Indeed, the American pricing problems,

and the failure of an early US-built

shipboard Conch containment system on

newbuildings, blanketed any spectacular

progress in the Atlantic basin until the

regeneration of interest initiated by the

Trinidad project in 1999.

At that time, the stifling of European

interest was also due to the discovery of

natural gas in the North Sea, so quantities

to replace town gas were available in

sufficient volume on the doorstep

without the need for imports. This being

so, the first LNG project from Algeria to

UK eventually faltered, with the receiving

terminal at Canvey Island switching to

other interests. The stagnation of LNG in

the 70s and 80s applied the world over,

with the singular exception of imports to

Japan and Korea. Here interest in LNG’s

potential as an environmentally-friendly

fuel stayed vibrant; as it does today.

LNG projects are massive multi-billion

dollar investments. Major projects in the

Far East included Brunei to Japan,

Indonesia to Japan, Malaysia to Japan and

Australia to Japan, comprising some 90%

of the LNG trade of the day.

Consequently, the Japanese defined

much of what is seen best today in way of

safety standards and procedures. It is

worthy of note, however, that some early

safety standards and practices are being

questioned today in the light of

experience in a more mature industry.

LNG as a fuel

Because the ships, terminals and

commercial entities were all bound

together in the same chain, advantages

could be seen in limiting ‘unnecessary’

shipboard equipment, such as

reliquefaction plant, and allowing the

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

another the ship would need fuel, be it oil

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

matter to quantify usage and to direct the

appropriate cost to the appropriate

project partner.

Interestingly, this concept was

recognised in the IMO’s Gas Codes from

the very earliest days, and with the

appropriate safety equipment in place

the regulations allow methane to be

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

for LPG, where reliquefaction equipment

is a fitment, but specifically because the

LPGs are heavier than air gases and use

in engine rooms is thereby disallowed.

LNG quality

LNG is liquefied natural gas. It is sharply

clear and colourless. It comprises mainly

methane but has a percentage of

constituents such as ethane, butane and

propane together with nitrogen. It is

produced from either gas wells or oil

wells. In the case of the latter it is known

as associated gas. At the point of

production the gas is processed to

remove impurities and the degree to

which this is achieved depends on the

facilities available. Typically this results in

LNG with between 80% and 95%

methane content. The resulting LNG can

therefore vary in quality from loading

terminal to loading terminal or from

day-to-day.

Other physical qualities that can

change significantly are the specific

gravity and the calorific value of the

LNG, which depend on the

characteristics of the gas field. The

specific gravity affects the deadweight

of cargo that can be carried in a given

volume, and the calorific value affects

both the monetary value of the cargo

and the energy obtained from the boil-

off gas fuel.

These factors have significance in

commercial arrangements and gas

quality is checked for each cargo, usually

in a shore-based laboratory by means of

gas chromatography. LNG vapour is

flammable in air and, in case of leakage,

codes require an exclusion zone to allow

natural dispersion and to limit the risk of

ignition of a vapour cloud. Fire hazards

are further limited by always handling

the product within oxygen-free systems.

Unlike oil tankers under inert gas, or in

some cases air, LNG carriers operate

with the vapour space at 100%

9

methane. LNG vapour is non-toxic,

although in sufficient concentration it

can act as an asphyxiant.

Gas quality is also significant from a

shipboard perspective. LNGs high in

nitrogen, with an atmospheric boiling

point of -196°C, naturally allow nitrogen

to boil-off preferentially at voyage start

thus lowering the calorific value of the

gas as a fuel. Towards the end of a

ballast passage, when remaining ‘heel’

has all but been consumed, the

remaining liquids tend to be high on the

heavier components such as the LPGs.

This raises the boiling point of the

remaining cargo and has a detrimental

effect on tank cooling capabilities in

readiness for the next cargo.

The good combustion qualities

attributed to methane make it a great

attraction today as a fuel at electric

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

burns producing little or no smoke and

nitrous oxide and sulphur oxide

emissions produce figures far better than

can be achieved when burning normal

liquids such as low sulphur fuel oil.

Natural gas has thus become attractive

to industry and governments striving to

meet environmental targets set under

various international protocols such as

the Rio Convention and the Kyoto

Protocol. The practice of firing marine

boilers on methane provides the further

environmental advantage of lesser soot-

blowing operations and much fewer

carbon deposits.

Cargo handling

The process of liquefaction is one of

refrigeration and, once liquefied, the gas

is stored at atmospheric pressure at its

boiling point of -162°C. At loading

terminals any boil-off from shore tanks

can be reliquefied and returned to

storage. However, on ships this is almost

certainly not the case. According to

design, it is onboard practice to burn

boil-off gas (often together with fuel oil)

in the ship’s boilers to provide

propulsion. In the general terms of

seaborne trade this is an odd way to

handle cargo and is reminiscent of old

tales of derring-do from the 19th century

when a cargo might have been burnt for

emergency purposes. It is nevertheless

the way in which the LNG trade operates.

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

extent that it evaporates from its mother

liquid. Clearly cargo volumes at the

discharge port do not match those

loaded.

Accounting however is not

overlooked and LNG carriers are outfitted

with sophisticated means of cargo

measurement. This equipment is

commonly referred to as the ‘custody

transfer system’ and is used in preference

to shore tank measurements. These

systems normally have precise radar

measurement of tank ullage while the

tanks themselves are specially calibrated

by a classification society to a fine degree

of accuracy. The system automatically

applies corrections for trim and list using

equipment self-levelled in drydock. The

resulting cargo volumes, corrected for

the expansion and contraction of the

tanks, are normally computed

automatically by the system.

Cargo tank design requires carriage at

atmospheric pressure and there is little to

spare in tank design for over or under

pressures. Indeed, the extent to which

pressure build-up can be contained in a

ship’s tanks is very limited in the case of

membrane cargo tanks, although less so

for Type-B tanks. Normally this is not a

problem, as at sea the ship is burning

boil-off as fuel or in port has its vapour

header connected to the terminal vapour

return system. Clearly, however, there are

short periods between these operations

when pressure containment is necessary.

This can be managed. So taken together,

shipboard operations efficiently carried

out succeed in averting all possible

discharges to atmosphere, apart that is

from minor escapes at pipe flanges, etc.

Certainly this is part of the design criteria

for the class as it is recognised that

methane is a greenhouse gas.

Boil-off gas (BOG) is limited by tank

insulation and newbuilding contracts

specify the efficiency required. Usually

this is stated in terms of a volume boil-off

per day under set ambient conditions for

sea and air temperature. The guaranteed

maximum figure for boil-off would

normally be about 0.15% of cargo

volume per day.

While at sea, vapours bound for the

boilers must be boosted to the engine

room by a low-duty compressor via a

vapour heater. The heater raises the

temperature of the boil-off to a level

suited for combustion and to a point

where cryogenic materials are no longer

required in construction. The boil-off

then enters the engine room suitably

warmed but first passes an automatically

controlled master gas valve before

reaching an array of control and shutoff

valves for direction to each burner. As a

safety feature, the gas pipeline through

the engine room is of annular

construction, with the outer pipe purged

and constantly checked for methane

ingress. In this area, operational safety is

paramount and sensors cause shutdown

of the master gas valve in alarm

conditions. A vital procedure in the case

of a boiler flameout is to purge all gas

from the boilers before attempting

re-ignition. Without such care boiler

explosions are possible and occasional

accidents of this type have occurred.

Cargo care

The majority of LNG shippers and

receivers have a legitimate concern over

foreign bodies getting into tanks and

pipelines. The main concern is the risk of

valve blockage if (say) an old welding rod

becomes lodged in a valve seat. Such

occurrences are not unknown with a ship

discharging first cargoes after

newbuilding or recently having come

from drydock. Accordingly, and despite

discharge time diseconomies, it is

common practice to fit filters at the ship’s

liquid manifold connections to stop any

such material from entering the shore

system. The ship normally supplies filters

fitting neatly into the manifold piping.

> continued over

10

In a similar vein, even small particulate

matter can cause concerns. The carry-

over of silica gel dust from inert gas driers

is one such example. Another possible

cause of contamination is poor

combustion at inert gas plants and ships

tanks becoming coated with soot and

carbon deposits during gas freeing and

gassing up operations. Subsequently, the

contaminants may be washed into gas

mains and, accordingly, cargoes may be

rejected if unfit. Tank cleanliness is vital

and, especially after drydock, tanks must

be thoroughly vacuumed and dusted.

A cargo was once rejected in Japan

when, resulting from a misoperation,

steam was accidentally applied to the

main turbine with the ship secured

alongside the berth. The ship broke out

from the berth, but fortunately the

loading arms had not been connected.

This action was sufficient however for

cargo receivers to reject the ship, and the

cargo could only be delivered after a

specialised ship-to-ship transfer operation

had been accomplished. The ship-to-ship

transfer of LNG has only ever been

carried out on a few occasions and is an

operation requiring perfect weather,

great care and specialist equipment.

Another case of cargo rejection, this

time resulting in a distressed sale,

involved a shipment to Cove Point in the

USA, where the strict requirements which

prevail on in-tank pressures on arrival at

the berth were not adhered to. The ship

had previously been ordered to reduce

pressure for arrival. This is a difficult job

to perform satisfactorily and, if it is to be

successful, the pressure reduction

operation must progress with diligence

throughout the loaded voyage by forcing

additional cargo evaporation to the

boilers. This cools the cargo and hence

reduces vapour space pressure. The

process of drawing vapour from the

vapour space at the last moment is

ineffective, because the cargo itself is not

in balance with that pressure and once

gas burning stops the vapour space will

return to its high equilibrium pressure.

This process is known in the trade as

‘cargo conditioning’.

Ship care

A temperature of -162°C is astonishingly

cold. Most standard materials brought

into contact with LNG become highly

brittle and fracture. For this reason

pipelines and containment systems are

built from specially chosen material that

do not have these drawbacks. The

preferred materials of construction are

aluminium and stainless steel. However

these materials do not commonly feature

over the ship’s weatherdecks, tank

weather covers or hull. These areas are

constructed from traditional carbon

steel. Accordingly, every care is taken to

ensure that LNG is not spilt. A spill of LNG

will cause irrevocable damage to the

decks or hull normally necessitating

emergency drydocking. Accidents of this

Moss design (courtesy of Moss Maritime).

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

Liquefied natural gas continued

11

nature have occurred, fortunately none

reporting serious personal injury, but

resulting, nevertheless, in extended

periods off-hire.

LNG carriers are double-hulled ships

specially designed and insulated to

prevent leakage and rupture in the event

of accident such as grounding or

collision. That aside, though

sophisticated in control and expensive in

materials, they are simple in concept.

Mostly they carry LNG in just four, five or

Membrane design (GTT).

within the double hull where the water

ballast tanks reside. The world fleet

divides approximately 50/50 between the

two systems.

Regarding spherical tanks, a very

limited number were constructed from

9% nickel steel, the majority are

constructed from aluminium. A

disadvantage of the spherical system is

that the tanks do not fit the contours of a

ship’s hull and the consequent ‘broken-

stowage’ is a serious diseconomy. In

general terms, for two LNG ships of the

same carrying capacity, a ship of Moss

design will be about 10% longer. It will

also have its navigating bridge set at a

higher level to allow good viewing for

safe navigation. On the other hand the

spherical tanks are simple in design and

simple to install in comparison to the

membrane system, with its complication

of twin barriers and laminated-type

construction.

Tank designs are often a controlling

factor in building an LNG carrier.

Shipyards usually specialise in one type or

the other. Where a yard specialises in the

Moss system, giant cranes are required to

lift the tanks into the ships and limits on

crane outreach and construction tooling

facilities currently restrict such tanks to a

diameter of about 40 metres.

Early LNG carriers had carrying

capacities of about 25,000 m3. This

swiftly rose to about 75,000 m3 for the

Brunei project and later ships settled on

125,000 m3. For some years this

remained the norm, giving a loaded

draught of about 11.5 metres, thus

stretching the port facilities of most

discharge terminals to their limits. Since

then, however, there have been some

incremental increases in size, usually

maintaining draft but increasing beam,

resulting in ship sizes now of about

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

in class is the Pioneer Knudsen, trading at

only 1,100 m3 capacity from a facility

near Bergen to customers on the

Norwegian west coast. At the end of

2004 the first orders were placed for LNG

carriers of more than 200,000m3 and

ships to carry over 250,000m3 are

expected to be delivered by the end of

2008.

six centreline tanks. Only a few have

certification and equipment for cross

trading in LPG. The cargo boils on

passage and is not re-liquefied onboard

– it is carried at atmospheric pressure.

Although there are four current methods

to construct seaborne LNG tanks, only

two are in majority usage. There are the

spherical tanks of Moss design and the

membrane tanks from Gaz Transport or

Technigaz (two French companies, now

amalgamated as GTT). Each is contained

LNG carrier with membrane tanks.

> continued over

12

Large modern LNG carriers have

dimensions approximately as follows:

recognise this and, together with

inspection regimes, the overall quality of

LNG tonnage is kept to a high standard.

Age for age, they are probably the best

maintained ships in the world. Of course

some of these ships are now old and only

a few have ever been scrapped; some are

over 30 years old. This is very old for a

large tanker trading all its life in salt

water, when 25 years is already

Glossary

Administration The Administration is the national authority responsible for

shipping safety in the country concerned

Certificate of Certificate of Fitness for the Carriage of Liquefied Gases in

Fitness Bulk, an essential gas carrier certificate required by, and

defined in, the IGC Code

DCE Dangerous Cargo Endorsement

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

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

tanks cooled down during the ballast voyage by

recirculating through the sprayers. On LPG ships such

cooling is carried out via the reliquefaction plant and on

LNG ships by using the in-tank spray pumps.

IGC Code International Code for the Construction and Equipment of

Ships Carrying Liquefied Gases in Bulk

IMO International Maritime Organization (a United Nations

agency)

LNG Liquefied Natural Gas (methane with traces of heavier

gases)

LPG Liquefied Petroleum Gas (typically butane and propane)

SIGTTO Society of International Gas Tanker and Terminal

Operators Ltd

SMS Safety Management System – a company-wide SMS as

required under the ISM Code

STCW Convention International Convention on Standards of Training,

Certification and Watchkeeping for Seafarers

STCW Code Seafarers’ Training, Certification and Watchkeeping Code

USCG United States Coast Guard

Capacity (m3) 145,000 215,000

Length 295m 315m

Beam 48m 50m

Loaded draft 12m 12m

Liquefied natural gas continued considered by many as a cut-off date. On

termination of their original projects we

are now seeing many of the older ships

as surplus to requirements. Sometimes

the project wishes to continue but only

with new ships. So the older ships are

laid-off. In the past this would have been

their death knell but today this is not

necessarily the case. The slow

development of a spot market has

LNG having a typical density of only

420 kg/m3 allows the ships, even when

fully laden, to ride with a high freeboard.

They never appear very low in the water

as a fully laden oil tanker may do. Ballast

drafts are maintained close to laden

drafts and, for a ship having a laden

draft of 12 metres, a ballast draft of 11

metres is likely. This means that for

manoeuvring in port in windy conditions

the ships are always susceptible to being

blown to one side of the channel, and

restrictions on port manoeuvring usually

apply with extra tug power commonly

specified.

Another salient feature of the LNG

class is the propensity to fit steam

turbine propulsion. This is an

anachronism brought about by a

reluctance to change over the years,

together with a fear that a system as yet

untried on LNG carriers may not find

favour with the principal charterers – the

Japanese. Most other ship types of this

size have diesel engines and the

engineers to run diesel equipment are

plentiful and suitably trained. On the

other hand, engineers knowledgeable in

steam matters are few and their training

base is the ship itself. This situation is

changing though, with both diesel

electric dual fuel systems and slow speed

diesels now finding favour. With slow

speed diesel propulsion, reliquefaction

plants will be required onboard to

handle boil-off gas, and all diesel

systems will require back-up gas disposal

facilities – also known as ‘gas

combustion units’ (GCUs) – for when

either the reliquefaction plants or the

duel fuel diesel engines are not available

to process boil-off gas.

LNG ships are expensive to build.

They comprise very valuable assets:

generally far too good to let rust away.

Shipowners and ship managers alike

13

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

Introduction

Sampling is a vitally important factor in

the custody transfer of bulk liquid

cargoes. Acquisition and subsequent care

and retention of representative samples

can provide an important means of

rebutting unfounded allegations of cargo

contamination. This applies equally to

chemical, petrochemical, petroleum

product and crude oil shipments.

Cargo surveyors attending the loading

or discharge of any given cargo are often

working on behalf of shippers or

consignees (or both, on a joint basis) and

are not obliged to provide samples to the

ship, albeit that it is common practice to

place samples in the custody of the

master at the loadport for delivery to the

disport receivers. However, these samples

are not the property of the ship and only

on rare occasions are official-sealed

custody transfer samples provided.

Whether samples are provided by the

cargo interests to the ship or not, it is

recommended that the vessel’s crew

draw samples for the ship’s protection.

Retention and sealing

Due to the inability of the ship’s officers

to undertake analysis of samples, only

the most obvious contamination

problems will be apparent at the outset,

such as:

● Change in colour.

● The presence of water (if water is not

soluble in the cargo).

● Foreign particulate matter.

● Odour taint.*

Samples taken at the initial stages of

cargo operations showing such obvious

cargo quality deviations should give

cause to halt cargo operations in order to

carry out further investigations** and to

note protest.

All samples drawn should be sealed,

labelled, retained and recorded.

Wherever possible, samples drawn by the

* Safety: Odour is not an issue on all cargoes. Toxic and

highly odiforous cargoes should not be tested for

odour.

** A P&I surveyor should be summoned.

Bulk liquid cargoes– sampling

ship’s crew should be clearly labelled with

the following:

● Ship’s name.

● Operational status

i.e. before loading, after Ioading,

before discharge.

● Product.

● Sample source

i.e. tank number, manifold number.

● Sample type

i.e. top, middle, bottom, dead

bottom, running, composite.

● Identity of sampler

i.e. surveyor, crewmember.

● Date and time.

● Location

i.e. port, berth, anchorage.

● Seal number.

Seals are customarily applied to samples

by an independent surveyor in order to

> continued over

SIGTTO

Valuable assistance in the preparation of

these articles has come from the Society

of International Gas Tanker and Terminal

Operators (SIGTTO).

SIGTTO is the leading trade body in

this field and has over 120 members

covering nearly 95% of the world’s LNG

fleet and 60% of the LPG fleet. SIGTTO

members also control most of the

terminals that handle these products.

The Society’s stated aim is to

encourage the safe and responsible

operation of liquefied gas tankers and

marine terminals handling liquefied gas;

to develop advice and guidance for best

industry practice among its members and

to promote criteria for best practice to all

who have responsibilities for, or an

interest in, the continuing safety of gas

tankers and terminals.

The Society operates from its London

office at 17 St. Helens Place EC3.

Further details on activities and

membership is available at

www.sigtto.org

References

Liquefied Gas Handling Principles on Ships

and in Terminals – SIGTTO

Safe Havens for Disabled Gas Carriers –

2003, SIGTTO

Mooring Equipment Guidelines – 2001,

OCIMF

Ship-to-Ship Transfer Guide (Liquefied

Gases) – 1995, SIGTTO

The International Code for the

Construction and Equipment of Ships

Carrying Liquefied Gases in Bulk,

(IGC Code) – IMO

A Contingency Planning and Crew

Response Guide for Gas Carrier Damage

at Sea and in Port Approaches – 1999,

SIGTTO

The aforementioned publications are

available from Witherby & Company Ltd,

London.

allowed the shipowner to consider life

extension programmes of considerable

cost; all this set against the value of a

very expensive newbuilding. Today life

extension programmes are common with

old ships making handsome profits in the

spot market ■

14

preserve sample provenance in the event

of dispute. Nowadays, seals are widely

available and relatively inexpensive and it

is increasingly common for ships to be

equipped with their own seals.

Alternatively, some owners use self-

sealing tamper-evident bottle closures

which may not be individually numbered

but, nonetheless, preserve sample

provenance.

Marked samples should be retained in

a dedicated locker, ideally for at least 12

months. Space considerations may make

this impractical in which case the samples

should be retained for as long as

possible. However, where the cargo is

known or expected to be the subject of

dispute, samples should be retained for

at least 12 months in any event. Samples

should not be exposed to extremes of

temperature and should be kept in

darkness. When no longer required,

disposal should be by appropriate means;

many owners use the services of local

cargo surveyors who invariably have

disposal methods already in place.

Sample bottles

Sample bottles vary in size and in the

materials from which they are made.

Glass and plastic bottles can be dark or

clear. Most samples can generally be

stored in clear glass bottles. Light

sensitive samples, however, should be

stored in brown bottles*. Certain

samples, such as caustic soda or potash

require plastic containers. Petroleum

products/crude oil samples are often

retained in lacquer-lined tinplate

containers. These types of containers are,

in general, unsuitable for retention of

chemical cargo samples. Where possible,

a range of containers should be available.

Sample bottle closures vary in the

chemical resistance of the sealing insert.

Waxed cardboard disc type should only

be used for petroleum products/crude

oils. Aluminium foil-faced cardboard

discs are unsuitable for acid or alkaline

samples. Preferred inserts are

polypropylene or PTFE.

Sample bottle size may be

determined, to some extent, by storage

capacity, balanced against the need to

retain sufficient sample volume to allow

analysis in the event of a dispute arising.

Generally, 500ml is a realistic

compromise.

Where to take samples

During the custody transfer of a bulk

liquid cargo, the principal sampling

points where cargo quality can be

adequately monitored are:

1 Loadport shore tank(s).

2 Shoreline sample following any

‘packing’ or flushing operation.

3 Vessel’s manifold at commencement

of loading and spot checks during

loading.

4 Vessel’s cargo tanks first foots.

5 Vessel’s cargo tanks post-loading.

6 Vessel’s cargo tanks pre-discharge.

7 Vessel’s manifold at commencement

of discharge.

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

discharge.

Ideally, all of these samples should be

taken on each cargo carrying voyage, but

in any event, onboard ship samples 3 to 7

should always be taken by the crew for

protection of the owner’s interests.

Further samples might be considered,

such as 3, following changeover of

shoretanks at a mid-loading stage.

Method of drawing samples

Samples should be drawn in compliance

with industry practice as set out in

publications such as those issued by

ASTM, API and BS (see References). In

general, a ‘running’ sample taken by use

of a bottle and sample cage is the

preferred method of obtaining a

representative sample in a homogeneous

bulk cargo. Where the cargo may not be

homogenous, careful zone sampling is

required to produce a representative

composite sample. The properties of

some chemical cargoes require that

special sampling procedures are adopted

such as excluding air, using specialist

sample valves or indeed ‘closed’

sampling methods due to the toxicity or

flammability of the cargo. Here, the

sampling procedure is prescribed by the

specialist equipment in use. Appropriate

safety procedures must be observed and

the sampler protected from exposure to

the cargo during sampling.

Conclusion

It is unquestionably the case that a

vessel’s adherence to the above sampling

procedure can provide the necessary

evidence to rebut cargo quality claims in

circumstances where unfounded

allegations are made against shipowners.

A rigorous sampling system should form

an essential part of a vessel’s ISM

operational procedures ■

References

ASTM D 4057

Standard Practice for Manual Sampling

of Petroleum and Petroleum Products.

ASTM E 300

Standard Practice for Sampling Industrial

Chemicals.

BS 3195

Methods for Sampling Petroleum

Products.

BS 5309

Methods for Sampling Chemical

Products.

IP

Petroleum Measurements Manual Part IV

Sampling – Section I Manual Methods.

API

Manual of Petroleum Measurement

Standards Ch 8, Standard Methods of

Sampling Petroleum and Petroleum

Products.

* Brown bottles impede inspection of the sample for

colour/water/particulates. It is suggested that clear

glass bottles are used initially and, after inspection,

the sample transferred to a dark brown bottle for

storage.

Sampling bulk liquid cargoes continued

15

> continued over

Carriage of potatoes

Introduction

The potato tuber, Solanum tuberosum L.,

is an annual of the Solanaceae family and

originally native to South America.

The edible tuber forms at the end of

the underground stems or stolons of the

plants and within which the starch-rich

nutrients are stored. Colour together

with other criteria form important

characteristics for identifying the

numerous varieties of potatoes:

● Skin colours – brown, russet, white,

yellow, pink or red.

● Skin textures – rough or smooth.

● Flesh colours – white, cream, yellow,

blue/purple/red or striated.

● Tuber shape – round, oblate, oval, or

kidney shaped.

● Usage – table, processing or seed.

● Harvest time – early/new or immature,

or late/mature.

Potatoes are grown throughout the

world, except in humid tropical lowland

areas. They are one of the worlds most

important food crops, and thus are an

important commodity of trade.

For the purposes of this article we

shall refer to three basic types of potato,

which are:

● Early/new or immature.

● Late/mature.

● Seed.

All of which require special

considerations for stowage and carriage.

Early or new potatoes have thin,

relatively loose, skins that are easily

removed and are thus readily liable to

damage. Over more recent years,

demand for this type of potato has

increased and large quantities are

shipped from Cyprus, Greece, Israel,

Turkey and the Canary Islands during the

northern winter and spring seasons.

Late/mature potatoes have firm skins

and are therefore more resistant to

damage and much easier to carry than

immature potatoes.

Seed potatoes for shipment comprise

small whole tubers each with at least one

eye to produce the new growth. Seed

potatoes are grown under a regulated

certification programme to ensure that

they are as disease-free as possible.

Pre-shipment considerations

Once potatoes have been harvested they

must be stored under optimal conditions

until released for shipment. However no

storage is able to improve the product

placed therein, but much can be

achieved to minimise losses.

High temperatures cause the tuber

respiration rate to increase, whereby

oxygen and food reserves are used,

potentially resulting in excessive

shrinkage. Freezing or chilling

temperatures can damage and kill tuber

cells. If the air surrounding the tubers has

a low humidity then water will move

from the tubers to the air, resulting in

weight loss. Should the oxygen content

of the air fall to a low level, cells within

the tubers die and ‘blackheart’ forms.

Sprouting is a natural function of the

tuber, however, during shipment it is not

desirable as, in the event, quality and

condition will suffer. Sprout suppressant

chemicals or other methods

may be used prior to

shipment to preclude

sprouting but control in

stowage can only be

maintained by application

of the correct

temperature(s).

Potato tuber diseases may be the

result of micro-organisms or adverse

preshipment storage conditions.They

may also be the result of improper

stowage and conditions of carriage.

Potatoes are grown under the soil

and, as such, when harvested will always

contain on their surfaces spores of

invading micro-organisms, which will

attack the tubers if the natural defence

mechanism is ruptured. This can result

from mechanical damage, either during

harvesting or subsequent handling or,

alternatively, can result from other forms

of deterioration such as sun-scald. It may

also result if the tuber is subjected to

wetting such that a film of water is

present over its surface.

Some of the principal diseases found

at the time of harvesting may include

Phytophthora infestans (potato blight); a

dry mealy rot due to species of Fusarium

(dry rot); a bacterial soft rot caused by

Erwinia ssp. (black leg); or brown rot

caused by the bacterium Ralstonia

solanacearum and ring rot caused by the

bacterium Clavibacter michiganensis

subsp. sepedonicus, both of which are

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

which produce new growth).

15

16

Carriage of potatoes continued

notifiable diseases in the UK and other

countries.

Post-harvest deterioration i.e. storage/

stowage deterioration will normally result

from the development of bacterial soft

rot, usually the result of infection by

Erwinia ssp. which causes collapse of the

cells of the infected potatoes exuding

heavily infected fluid and gives rise, by

contact, to soft rot developing in adjacent

tubers. Hence over a period of time the

contents of whole bags may collapse to a

malodorous slime.

Another cause of deterioration is

infestation by insects, which has been a

problem since potatoes have been grown.

The two most serious infestants of potato

crops are the North American black and

yellow striped beetle (Colorado Beetle)

and the Potato Tuber Moth (Phthorimaea

operculella).

It is necessary for shippers or charterers

to provide phyto-sanitary certificates,

attached to the bill(s) of lading or other

trade documents. These certificates are

produced by the Authority of the country

of origin indicating that the specified

consignment(s) have been inspected or

treated according to the importing

country’s requirements. Recent legislation

The Potatoes Originating in Egypt

(England) Regulations 2004 came into

force on 15 May 2004.

Whereas the master should be able to

rely upon a valid phyto-sanitary certificate

he does have a continuing duty in relation

to cargo in his charge. For example, if

infestation is noticed during the voyage,

the master/owners must take reasonable

steps to deal with the situation.

Fumigation prior to berthing at an arrived

port, or alternatively rejection of a cargo

of potatoes as a result of infestation or

infection by serious bacterial diseases,

not only may cause massive delays to a

vessel but also considerable additional

problems for the shipowners.

Greening may occur in any part of a

tuber exposed to light. Exposure to bright

light during post harvest handling, or

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

can result in the development of

chlorophyll (greening) and bitter, toxic

glycoalkaloids, such as solanine. Experts

advise that whereas in cultivated varieties

green discolour of the flesh does not

cause substantive harm to health, it

undoubtedly will, depending upon

extent, result in a loss of value of

consignments. Green flesh of potatoes

tastes bitter and must be cut away before

cooking.

When presented for shipment,

consignments should be inspected for

external condition of the packaging.

Evidence of wet patch staining of the

bags, or any associated malodours,

should alert crewmembers to likely

problems and the vessel’s P&I association

should be requested to appoint an expert

surveyor to investigate and ensure only

healthy and undamaged potatoes are

shipped. Since potatoes have been

shipped in woven polypropylene bags of

varying dark colours it has become

extremely difficult to recognise wet

patches from superficial examinations;

close inspections are thus recommended.

Mechanical damage is one of the

most important factors affecting potato

condition, since it is largely preventable.

Special care is therefore essential during

handling to and from the vessel,

especially when immature/new potatoes

are being shipped. Bags of potatoes

should not be walked over or handled

roughly, with special care taken if

palletised units of bags are over-stowed

by a second tier of pallets. In light rain,

snow, or damp weather cargo must be

protected from moisture to preclude the

onset of premature spoilage by bacterial

soft rot. Do not load or discharge

potatoes during heavy rain.

Summary

Subsequent to harvesting and prior to

packing for shipment:

Early or new potato tubers should

be graded and sorted:

● without mechanical damage;

● sound, without disease;

● dry;

● without greening;

● free from adherent soil and stones;

● and stored at optimum temperatures.

Late or mature potato tubers

should, in addition to the above:

● be fully mature and firm skinned;

● have been stored for a specific post

harvest period of 10 to 14 days

(wound healing and curing).

Seed potato tubers may, in

addition to those points noted

under ‘early potatoes’:

● consist of unwashed tubers and may

contain loose soil and foreign material

but should generally be free of caked

soil.

Left: Bacterial soft rot in potatoes can,

through contact, infect adjacent tubers.

Potato tubers infested with Colorado Beetle. Signs of infestation by the Potato Tuber Moth.

17

> continued over

Packaging

Potatoes may be packed in hessian bags,

woven polypropylene bags, sacks lined

with an internal perforated polyethylene

bag and sometimes cartons or crates.

Various sizes of bags are utilised,

however the bags will usually contain

about 25 kg of tubers.

A more recent innovation is to pack

potatoes in large open-top lift bags

weighing some two to three tonnes.

New potatoes are frequently packed in

moist or dry peat moss. The main

purpose for including moist peat moss

within the bags is to protect the ‘new’

tubers and to preclude skin-set and thus

maintaining their value. However, excess

free water or release of water from the

peat moss during carriage can cause

problems leading to bacterial soft rot of

the tubers.

Stowage

As for any product which may enter the

human food chain, preparation of

stowages will include ensuring that the

cargo spaces are clean and dry. Potatoes

are highly sensitive to odours and readily

absorb foreign smells from chemicals,

mineral oils, and some fruits, etc. All

compartments destined for stowage of

potatoes must be free from malodours

and volatile substances.

Potato tubers are living organisms

that consume oxygen and evolve carbon

dioxide, water and heat. The principal

problem as far as stowage and carriage

is concerned is the heat produced, and

therefore good climate control is

required to maintain the condition of

tubers. Condensation in the form of ship

or cargo sweat should not be allowed to

develop during a voyage. Long voyages

therefore demand more critical control

than short-term voyages.

An example of the heat produced by

cargoes of potatoes is noted in the table

below.

From these figures it is evident that

new / immature potatoes

produce considerably more heat per

1000 kg than late / mature potatoes and

are commensurately more difficult to

carry.

When potatoes are presented for

loading in bags, stow heights of up to

eight tiers are preferable. To ensure

adequate ventilation of cargo blocks,

maximum stow heights of twelve to

thirteen bags should never be exceeded.

The stowage must be so arranged to

ensure a free flow of air throughout the

compartments.

Bags shipped on pallets are usually

stacked to a height of eight/nine bags

and are often secured to the pallet base-

boards by means of nylon netting. Care

must be taken, (especially when the

bags are constructed of woven

polyethylene) to ensure that the

contents of pallets are fully and properly

secured.

The frictionless nature of this type of

outer bag frequently results in the pallet

loads becoming deformed and, in some

cases, detached from the base-boards.

This slippage can result in additional

stevedoring costs for re-making the

pallets. Slippage of woven polyethylene

bags from pallets, and also when loose

stowed, into ventilation channels will

cause restrictions of air flow and must be

prevented by the use of timber dunnage

or dunnage nets.

Stowages in refrigerated cargo

vessels

As previously noted, not only do growing

and harvesting conditions influence the

post harvest/pre-shipment behaviour of

potatoes but, additionally, post-harvest

storage conditions are also critical to the

optimum temperature requirements for

their carriage. Therefore written

instructions for the carriage temperature

regime should always be obtained from

the shippers and should be complied

with throughout the voyage. Transport

temperatures must be such that

respiration and weight losses due to

evaporation are maintained to a

minimum.

The approximate lowest safe

temperature for the carriage of potatoes

is plus 4o Celsius (39o Fahrenheit) and

carriage is usually recommended at plus 4o

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

relative humidity of between 90 and 95%.

However potatoes destined for processing

will require to be carried at temperatures

depending upon their cultivar. In these

cases, it is thus essential for shippers to

provide detailed instructions and for those

instructions to be rigorously followed.

The exact stowage patterns adopted

for potatoes will depend upon the

permanent air circulation systems

incorporated in a vessel. Strict supervision

of cargo stowage must ensure that airflow

will be evenly distributed throughout the

compartments for maintenance of

optimal temperature control.

Detailed records of cargo

compartment / flesh temperatures should

be maintained throughout the transit

period.

At the time of discharge from

refrigerated stowages, the cargo should

ideally be landed to stores at similar

temperatures to that of carriage. If cold

cargoes are discharged into ambient

warm humid conditions then a risk of

condensation forming on the tubers may

exist and bacterial soft rot will ensue.

Some shippers/consignees will request the

vessel to undertake a dual temperature

regime during transit and require the

vessel to slowly raise the temperature of

the cargo, to above the anticipated

ambient dew point at the discharge port,

commencing some two to three days

before discharge is due to commence.

Type of potatoes kcal per 1000 kg per 24 hours

At OC 5O 10O 15O 20O

Immature 735 1070 1380 1930

Mature 370 520 550 735

Potatoes packed in large open-top lift bags.

18

Blackheart is formed when the oxygen

content of the air falls to a low level.

Stowages in mechanically ventilated

general cargo spaces

The usual system adopted is to use block

stowage with air channels around each

cargo block. This system relies on

convection cooling. The cargo is stowed

clear of the deck either by placing it on

double dunnage or alternatively on pallet

boards. Cargo blocks should normally not

exceed 3 metres by 3 metres square.

Smaller blocks may be preferred under

certain circumstances; however stability

of each block is critical and when loose

stowed, bags must be key-stacked to

construct a locking stow precluding

slippage or collapse of bags into the air

channels potentially causing a breakdown

in the air circulation.

High stows may not only cause

compression damage/bruising to the

potatoes (especially new/immature

tubers) but may also result in excessive

heating due to metabolic processes. Bags

should be stowed ideally to eight tiers in

height, but never more than twelve to

thirteen. The width of the air channels

around the cargo blocks should be in the

order of 20 to 30 cms. constructed using

dunnage and/or the locking stow noted

above. Cargo should be stowed clear of

transverse bulkheads and ship’s sides to

promote air circulation with exposed steel

work protected by paper mats or other

sheeting to preclude condensation

damage.

Potato cargoes should be kept well

clear of engine room bulkheads and any

other local heat source situated on the

vessel.

The stowage on any vessel should be

designed to suit the type of permanent

ventilation system fitted. Potato cargoes

make heavy demands on ships’ ventilation

systems and a capacity of at least fifteen

air changes per hour in each empty hold is

required. At these rates the ventilation

system should be run continuously except

when weather and climatic conditions

prevent e.g. risk of shipping water

through the weatherdeck ventilators or

condensation forming on the cargo or

internal ship’s structures. At higher rates

of air changes per hour consideration

should be given, especially on longer

voyages, to either run the fans on lesser

power (reduction of speed) or for lesser

times (ventilate intermittently) in order to

maintain humidity and preclude water

loss from the tubers (desiccation).

Details of ambient air wet and dry

bulb temperatures, hold wet and dry bulb

air temperatures / flesh temperatures and

the ventilation regime undertaken

according to the acquired data regularly

obtained must be recorded in a dedicated

ventilation logbook or alternatively the

deck log book.

Ro-Ro vessels

Cargoes of new/immature potatoes have

for some time been shipped from Eastern

Mediterranean ports in the holds of

Ro-Ro vessels. Packed in woven

polypropylene bags, shipped on pallet

boards with bags secured by nylon nets,

losses and/or additional costs have been

experienced due to the displacement of

bags from the pallet boards.

Bearing in mind the practice of

keeping the Ro-Ro deck lights illuminated

throughout the voyage the problem of

tuber greening has been experienced.

Attempts to prevent this have included

covering stowages with polythene

sheets, which unfortunately reduce the

effectiveness of the hold ventilation

system. Hold lights should never remain

continuously illuminated throughout a

voyage, even of short duration.

Transport of potatoes in ISO

containers

Cargoes of potatoes may be carried in

fan assisted ventilated containers, open

sided containers, insulated refrigerated

containers and ‘port-hole’ insulated

containers. For voyages of a short

Carriage of potatoes continued

duration, closed cargo containers may be

used but doors should remain open

when ever possible to promote

ventilation. Stowage on deck must

include provisions to protect the cargo

from rain, sea-spray and sunlight.

Flat racks are also used for below-

deck stowages in well-ventilated compar,

provisions should be made to afford

exposed bags protection against rain and

sunlight prior to loading and subsequent

to discharge.

Seed potatoes

Seed potatoes are usually shipped

around the world in smaller

consignments than those of new or

mature potatoes. The value of seed

potatoes is much greater than potatoes

destined for consumption and special

care should be taken as any loss in

quality or condition will potentially result

in substantial claims. They may be carried

in a mechanically ventilated stowage but

for longer voyages involving any

prolonged period in warm climatic

conditions, say in excess of 20o Celsius,

they should be carried under

refrigeration at a temperature of 2o to 4o

Celsius.

Safety

Inadequate, or failure of, ventilation in

spaces containing cargoes of potatoes

can cause life threatening concentrations

of carbon dioxide (CO2) or oxygen (O2)

depletion to arise. Thus under these or

suspected conditions the

compartment(s) must be fully ventilated

and a gas measurement conducted. The

threshold limit value (TLV) for CO2

concentrations is 0.49 % by volume ■

Greening occurs when tubers are exposed to

bright light or long periods of low light.

19

Fumigation of shipsand their cargoes

Introduction

Fumigation is a procedure that is used

throughout the world to eradicate pests

that infest all types of goods,

commodities, warehouses, processing

factories and transport vehicles including

ships and their cargoes.

1 What are fumigants andhow do they work?

Fumigants are gases, which are toxic to

the target infestation. They can be

applied as gas, liquid or in solid

formulations, but after vaporisation from

liquids or reaction products from solids,

always act in the gaseous phase. They act

either as respiratory poisons, or as

suffocants in the case of controlled or

modified atmospheres. On release, they

mix with air at a molecular level. They are

capable of rapidly diffusing from one

area to another and through

commodities and buildings.

Fumigants should not be confused

with smokes, which are solid particles in

air, or with mists, aerosols or fogs, which

are liquid droplets, of various sizes, in air.

Smokes, mists, aerosols or fogs are not

fumigants as they are unable to diffuse

(i.e. they do not mix with air at a

molecular level) and do not reach deep-

seated infestations in commodities or

structures.

The fumigant gases used to carry out

the fumigation process are numerous,

but the most commonly used currently

for the treatment of ships cargoes are

phosphine and methyl bromide. Others

used are carbon dioxide and more

recently sulfuryl fluoride, which is

starting to replace the use of methyl

bromide.

1.1 How does a fumigant gas work

effectively?

The critical parameters, which need to be

considered for fumigants to be effective

are:

● Nature of infestation (type of pest e.g;

rodent, insect or beetle, and stage of

its life cycle).

● Type of fumigant applied.

● Concentration and distribution of gas.

● Temperature.

● Length of time fumigant must be

applied.

● Method by which fumigant is

administered.

● Containment of fumigant.

● Nature of commodity.

● Nature of commodity packaging.

● Monitoring system.

● Ventilation system.

1.2 Aim of fumigation

Fumigation aims to create an

environment, which will contain an

effective concentration of fumigant gas

at a given temperature, for a sufficient

period of time to kill any live infestations.

Both the time measured (hours or

days) of exposure and concentration of

gas is critical to fumigation efficiency.

Dosages applied are usually expressed as

grams per cubic metre, concentrations

measured during the fumigation are

usually expressed in parts per million

(PPM) or grams per cubic metre, and total

concentrations actually achieved, as

concentration-time-products (CTPs).

The fumigation process is not

completed until ventilation has been

effectively carried out, and removal of

any residues is completed.

2 When can ships’ cargoes befumigated?

The ship’s cargo can be fumigated and

ventilated:

● In warehouse or storage silos before

loading.

● In freight containers before loading.

● In the hold of the ship with fumigation > continued over

and ventilation completed before

sailing.

or

● In the hold prior to sailing with

fumigation continued during the

voyage (intransit).

● In freight containers before loading

with fumigation continuing during the

voyage (intransit).

In these situations the fumigation

continues during the voyage and is not

finished until the ventilation and removal

of residues is completed, which is

normally at the first discharge port.

3 Rules, regulations andguidelines that affect thefumigation process

3.1 The United Nations International

Maritime Organization (IMO) Safety of

Life at Sea (SOLAS) Convention places an

obligation on all governments to ensure

all shipping activities are carried out

safely.

3.2 The Recommendations on the Safe

Use of Pesticides in Ships (IMO

Recommendations) published by the IMO

(revised 2002) are intended as a guide to

all those involved in the use of pesticides

and fumigants on ships and are

recommended to governments in respect

of their legal obligations under the

SOLAS Convention.

These recommendations are referred

to throughout this document as within

the IMO Recommendations.

3.3 Individual countries (e.g. US and

Canadian Coastguard) have their own

requirements, but some governments

have chosen to make the IMO

Recommendations mandatory on all

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

3.4 The IMO International Maritime

Dangerous Goods (IMDG) Code, which is

20

✔ Statement of vessel suitability for

fumigation and fumigant application

compliance.

✔ Manufacturers information or safety

data sheet.

✔ First aid and medical treatment

instructions.

✔ Fumigation certificate.

✔ Fumigation plan.

✔ Instructions for the use of the

phosphine gas detecting equipment.

✔ Precautions and procedures during

voyage.

✔ Instructions for aeration and

ventilation.

✔ Precautions and procedures during

discharge.

✔ Also to provide sufficient additional

respiratory protective equipment (RPE)

where necessary to the vessel, to

ensure the requirements of IMO in

respect of RPE are available for the

duration of the voyage. (Note; the RPE

may consist of SCBA or canister

respirators or a combination of both

but the minimum requirement is for 4

sets of RPE).

Refer also to IMO Recommendations

Annex 4.

5.2.2 Master

✔ Appoint a competent crewmember to

accompany the fumigator during the

inspections/testing of empty holds

prior to loading to determine whether

they are gas tight, or can be made gas

tight and, if necessary, what work is to

be carried out to ensure they are gas

tight.

✔ Ensure the crew is briefed on the

fumigation process before fumigation

takes place.

✔ Ensure the crew search the vessel

thoroughly to ensure there are no

stowaways or other unauthorised

personnel onboard before fumigation

takes place.

✔ Appoint at least two members of the

crew to be trained by the fumigator to

act as representatives of the master

during the voyage to ensure safe

Fumigation continued

mandatory in many parts of the world

under SOLAS, specifically relates to the

fumigation of packaged goods only and

will be referred to under section 8 on

freight container fumigation.

The fumigation of packaged goods

and freight container recommendations,

are referred to throughout this document

as within the IMDG Code.

3.5 The International Maritime

Fumigation Organisation (IMFO) Code of

Practice (COP) provides clear guidance to

fumigators and ships’ masters in respect

of bagged and bulk cargoes, in addition

to packaged goods.

IMFO is an organisation of

independent maritime fumigation

servicing companies with members in

many countries. See Annex 2.

4 Fumigants that can be usedfor intransit fumigation ofbulk and bagged cargoes inships’ holds

4.1 The most widely used fumigant for

intransit fumigation is phosphine (PH3).

The gas is normally generated from

aluminium phosphide or sometimes

magnesium phosphide, but can also be

applied direct from cylinders.

4.2 Methyl bromide should never be used

for fumigation intransit (IMO

Recommendations, Annex 1D).

4.3 Insecticides such as dichlorvos,

pirimiphos-methyl, malathion,

permethrin and others may be sprayed

on to the grain during loading. These are

not fumigants and should be allowed

provided data is provided to the master as

set out in IMO Recommendations 6.2 and

6.4 and Annex 1A.

5 Intransit fumigation of bulkand bagged cargoes withphosphine gas

5.1 Phosphine is only fully effective if a

lethal concentration is maintained for a

period of time that can be as little as 3

days or as much as 3 weeks.

The actual time needed will vary

according to the cargo temperatures,

insect species that may be present, and

the system of fumigation (refer to Annex

1 of this article for brief details of the

types of system).

This is the reason why fumigation with

phosphine is almost always carried out

during the voyage (intransit) so that the

voyage time can be used to ensure a fully

effective treatment.

5.2 When the owners/charterers/master

agree to fumigation being carried out

intransit with phosphine, the master

should ensure he is familiar with the

requirements of IMO Recommendations

3.4.3.1. – 3.4.3.20. This will enable the

master to be clear what the obligations of

both fumigator and master are.

A checklist of these obligations is as

follows:

5.2.1 Fumigator

To provide written documentation in

respect of the following:

✔ Pre-fumigation inspection certificate.

✔ Standard safety recommendations for

vessels with fumigated grain cargoes.

✔ Gas tightness statement.

Probing aluminium phosphide in retrievable sleeves into a bulk cargo.

21

conditions, in respect of the

fumigations, are maintained onboard

the ship during the voyage.

✔ After the fumigant has been applied

and appropriate tests have been

completed, the master should provide

his representative to accompany the

fumigator, to make a check that all

working spaces are free of harmful

concentration of gas (IMO

Recommendations 3.4.3.11).

✔ When the fumigator has discharged

his responsibilities, the fumigator

should formally hand over in writing

responsibility to the master for

maintaining safe conditions in all

occupied areas, which the master

should accept (IMO

Recommendations 3.4.3.12).

✔ It must be clearly understood by the

master that, even if no leakage of

fumigant is detectable at the time of

sailing, this does not mean that

leakage will not occur at some time

during the voyage due to the

movement of the ship or other

factors. This is why it is essential the

master ensures regular checks are

carried out during the voyage.

✔ During the voyage, the master should

ensure that regular checks for gas

leakage should be made throughout

all occupied areas and the findings

recorded in the ships log (IMO

Recommendations 3.4.3.13). If any

leakage is detected appropriate

precautions to avoid any crew being

exposed to harmful concentrations

must be taken. If requested to do so

by the fumigator, the master may,

prior to arrival at the first discharge

port, start the ventilation of the cargo

spaces.

✔ Prior to arrival at the first discharge

port the master should inform the

authorities at the port that the cargo

has been fumigated intransit. (IMO

Recommendations 3.4.3.16).

✔ On arrival at the discharge port the

master should not allow discharge of

the cargo to commence until he is

satisfied that the cargo has been

correctly ventilated and aluminium

phosphide residues that can be

removed have been removed, and

that any other requirements of the

discharge port have been met (IMO

Recommendations 3.4.3.17).

Refer also to IMO Recommendations,

Annex 4.

6 Fumigation of bulk andbagged cargo with ventilationin port

This procedure can be used either after

loading and prior to sailing (6.1) or on

arrival at the discharge port prior to

discharging (6.2).

6.1 After loading and prior to sailing

Phosphine fumigation is the only

fumigant that should be accepted for this

procedure, as methyl bromide

(though frequently used) is not

recommended (IMO Recommendations,

Annex 1D).

Phosphine fumigation and ventilation

in port, prior to sailing, will normally take

from 1-2 weeks to complete and

therefore is only occasionally specified.

All procedures as for intransit fumigation

should be followed to ensure a safe and

effective fumigation.

6.2 At discharge port prior to

discharge

Methyl bromide is the most common

fumigant used for this purpose as it is

normally possible to achieve an effective

fumigation of the cargo in 24-48 hours.

The crew should be landed and remain > continued over

Checking the gas concentrations in the cargo

prior to discharge.

Ventilating the cargo prior to discharge.

ashore until the ship is certified ‘gas free’

in writing by the fumigator in charge.

The fumigator is responsible for the

safety and efficiency of the fumigation,

though crewmembers may remain in

attendance to ensure the safety of the

ship provided they adhere to safety

instructions issued by the fumigator in

charge.

The ventilation of methyl bromide

from cargoes can be a very slow process

if sufficient powered ventilation is not

available and the master (or his

representative) should ensure that the

fumigator has ensured that residues of

gas are below the TLV (IMO

Recommendations, Annex 2) throughout

all parts of the cargo and holds.

Phosphine fumigation and ventilation

in port, prior to discharge, will normally

take from 1-2 weeks to complete and

therefore is only occasionally specified.

All procedures as for intransit fumigation

should be followed to ensure a safe and

effective fumigation.

7 Fumigation of empty cargoholds and/or accomodation toeradicate rodent or insectinfestation

7.1 Methyl bromide is the most common

fumigant used for this purpose (although

hydrogen cyanide (HCN) or sulfuryl

fluoride may be used in some countries)

22

Fumigation continued

as it is normally possible to achieve an

effective fumigation of the empty spaces

in 12-24 hours.

7.2 The crew should be landed and

remain ashore until the ship is certified

‘gas free’ in writing by the fumigator in

charge as for 6.2 above.

8 The intransit fumigation offreight containers

8.1 The reason for the fumigation of

containers is normally to try to ensure

that when the goods arrive at the

discharge port they are free of live pests/

insects.

8.2 Containers are normally fumigated

and subsequently ventilated prior to

being loaded onboard the ship.

Containers that have been fumigated

and subsequently ventilated and where a

‘certificate of freedom from harmful

concentration of gas’ has been issued,

can be loaded onboard ships as if they

had not been fumigated (IMO

Recommendations 3.5.2.1).

8.3 Frequently containers are fumigated

but not ventilated prior to loading and

these containers are therefore fumigated

intransit, as the ventilation process will

not take place until after they have been

discharged from the ship. The carriage of

containers intransit under fumigation is

covered by the IMDG Code whereby

these containers are classified in Section

3.2 Dangerous Goods List as ‘Fumigated

unit Class 9 UN 3359’. Also refer to the

IMDG Code Supplement Section 3.5.1

and 3.5.2 of chapter called ‘Safe use of

pesticides in ships’.

WARNING – Containers are still

sometimes shipped under fumigation

with no warning notices attached and

no accompanying documentation

stating they have been fumigated.

This process is in direct contravention

of the IMDG Code. There may be

dangerous levels of fumigant gas

inside the container when it arrives at

its destination which is both illegal

and dangerous.

8.3.1 Obligations on the fumigator

✔ The fumigator must ensure that, as far

as is practicable, the container is made

gas tight before the fumigant is

applied.

✔ The fumigator must ensure that the

containers are clearly marked with

appropriate warning signs stating the

type of fumigant used and the date

applied and all other details as

required by the IMDG Code and IMO

Recommendations Annex 3.

✔ The fumigator must ensure the agreed

formulation of fumigant is used at the

correct dosage to comply with the

contractual requirements.

8.3.2 Obligations on the exporter

✔ The exporter must ensure that the

containers are clearly marked by the

fumigator with appropriate warning

signs stating the type of fumigant used

and the date applied and all other

details as required by the IMDG Code

and IMO Recommendations Annex 3.

✔ The exporter must ensure that the

master is informed prior to the loading

of the containers.

✔ The exporter must ensure that

shipping documents show the date of

fumigation and the type of fumigant

and the amount used all as required in

the IMDG Code, volume 1, page 35

and specifically section 9.9.

8.3.3 Obligations on the master

✔ The master must ensure that he knows

where containers under fumigation

are stowed.

✔ The master must ensure he has

suitable gas detection equipment

onboard for the types of fumigant

present, and that he has received

instructions for the use of the

equipment.

✔ Prior to arrival of the vessel at the

discharge port the master should

inform the authorities at the discharge

point that he is carrying containers

under fumigation.

✔ If the master (or his representative)

suspects that unmarked containers

may have been fumigated and loaded

onboard they should take suitable

precautions and report their suspicions

to the authorities prior to arrival at the

discharge port.

8.3.4 Obligations on the receivers

✔ The receiver (or his agent) must ensure

that any fumigant residues are

removed, and the container checked

and certificated as being free from

harmful concentrations of fumigant by

a suitably qualified person before the

cargo in the container is removed ■

For further information:

International Maritime Organization

4 Albert Embankment, London, SE1 7SR

Tel: 0207 735 7611. Fax: 0207 587 3210

www.imo.org

International Maritime Fumigation

Organisation

Friars Courtyard, 30 Princes Street,

Ipswich, Suffolk, IP1 1RJ or any member

worldwide. See – www.imfo.com.

Annex 1

A summary of the various methods of

phosphine application methodology

that can be considered for intransit

fumigation of bulk or bagged cargoes

in ships’ holds.

23

1 Application of tablets or pellets to

cargo surface (or into the top half

metre).

High concentrations of gas build up in

the head space, potentially resulting in a

lot of leakage through the hatchcovers

unless they are very well sealed. Very

little penetration down into the cargo.

Powdery residues cannot be removed.

Good kill of insects in top part of

cargo but negligible effect on eggs or

juvenile or even adults in lower part of

cargo.

2 Application of tablets or pellets

by probing into the cargo a few

metres.

Less loss of gas through hatchcovers

than in 1. Better penetration of gas than

when applied on surface only but unlikely

to be fully effective unless holds are

relatively shallow and voyage time

relatively long. Powdery residues cannot

be removed.

3 Application of tablets or pellets by

deep probing into the full depth of

the cargo.

This is difficult to achieve and currently

practically impossible if the cargo is more

than 10 metres deep. Ensures effective

fumigation provided voyage time is

relatively long to allow gas to distribute.

Powdery residues cannot be removed.

4 Application of aluminium

phosphide in blankets, sachets or

sleeves, placed on the surface of the

cargo (or into the top half metre).

All points the same as 1, except that with

this method powdery residues can be

removed prior to discharge.

5 Application of tablets or pellets by

probing into the cargo a few metres in

retrievable sleeves.

All points as for 2, except that with this

method powdery residues can be removed

prior to discharge.

6 Fitting of an enclosed powered

re-circulation system to the hold and

application of aluminium phosphide

tablets or pellets to the surface.

This will ensure the gas is distributed

throughout the cargo evenly and rapidly

making maximum use of the fumigant in

the shortest possible time. Powdery

residues cannot be removed.

7 Fitting of an enclosed powered

re-circulation system to the hold and

application of aluminium phosphide in

blankets, sachets or sleeves on the

surface or probed into the top one or

two metres.

As for 6, except that with this method,

powdery residues can be removed. Also

gaseous residues can be removed more

easily than with other methods, as once

the powdery residues have been removed

the re-circulation system can be used to

assist this to happen rapidly.

8 Deep probing into the full depth of

the cargo (however deep) with tablets

or pellets (in retrievable sleeves when

required).

This is being developed in Canada but is

not yet available. Also deep probing using

pre-inserted pipes.

Will enable good distribution of gas to be

achieved without the requirement for a

powered re-circulation system, provided

the voyage is long enough.

9 Use of powered re-circulation

system with phosphine from

cylinders.

This is not yet available but could be in

the future and will enable phosphine

fumigation to be carried out without

using aluminium phosphide. This will

mean no powdery residues to deal with

and therefore residue and safety

problems at the discharge port will be

minimised. A powered re-circulation

system will be needed to enable this

system to work with maximum efficacy.

Annex 2

References

International Maritime Organization

Recommendations on the Safe Use of

Pesticides in Ships revised 2002.

Published by IMO, 4 Albert Embankment,

London, SE1 76R

International Maritime Organization

The International Maritime Dangerous

Goods Code (IMDG Code) Volumes 1, 2

and Supplement (which includes the

Recommendations on the Safe Use of

Pesticides in Ships referred to above).

Published by IMO London as above. Refer

to Dangerous Goods List under entry UN

3359.

The International Maritime Fumigation

Organisation (IMFO)

Code of Practice (COP)

Obtainable from the IMFO website

www.imfo.com ■

Manhole

Phosphine drawn from thesurface to bottom of hold

Phosphine permeatesthrough cargo asre-circulation continues

Fan

Phosphine applied to surface

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

Traditional fumigation of cargo in ship’s holdusing phosphine.

Phosphine applied to surface or probeda few metres into cargo

Gas moves down veryslowly from surface

After 5-7 days some gasshould reach 10-12 metresat effective concentrations

Gas unlikely to reach 15-20metres in effectiveconcentrations howeverlong the voyage

>

>

>

>

24

Ferrous materials in the form of iron

swarf, steel swarf, borings, shavings or

cuttings are classified in the IMO Code of

Safe Practice for Solid Bulk Materials as

materials liable to self heating and to

ignite spontaneously.

Turnings are produced by the

machining of steel, turning, milling,

drilling, etc. When produced the turnings

may be long and will form a tangled mass

but they may be passed through a

crusher or chip breaker to form shorter

lengths. Both forms of turnings are

shipped and shipments are frequently a

mixture of short and long chips. The

density of the short chips is of the order

of 60 pounds per cubic foot, twice the

density of the longer chips as they tend

to compact more readily.

Borings are produced during the

making of iron castings. Because of the

nature of the parent metal, borings break

up more readily than turnings. They tend

to be finer and the bulk density is greater

than turnings.

Turnings and borings may be

contaminated with oils – cutting oils for

instance – used in the manufacturing

processes. Oily rags and other

combustible matter may also be found

among the loads.

Iron will oxidise, (rust) and iron in a

finely divided form will oxidise rapidly.

This oxidation is an exothermic reaction,

heat is evolved. In a shallow level mass of

turnings this heat will be lost to the

surrounding atmosphere. However in

large compact quantities as in a cargo

hold this heat will be largely retained and

as a result the temperature of the mass

will increase. This oxidation process is

accelerated if the material is wetted or

damp, contaminated with certain cutting

oils, oily rags or combustible matter.

The turnings may heat to high

temperatures but will not necessarily

exhibit flames. In one incident

temperatures in excess of 500ºC were

observed six feet below the surface of

the cargo. Temperatures of this order

may cause structural damage to the

steelwork of the carrying vessel. Flames

Scrap metal(borings,shavings,turnings,cuttings,dross)

are frequently seen in cargoes of metal

turnings but these flames are usually the

result of ignition of the cutting oils, rags,

timber and other combustible materials

mixed with the turnings.

Spontaneous heating of metal

turnings has caused several major

casualties. In the incident mentioned

above spontaneous heating was

detected, the vessel was moved from port

to port in attempts to agree discharge.

After weeks of delay all the holds were

eventually flooded to reduce the heating

for safe discharge of cargo. Following

discharge of the turnings the vessel

loaded a cargo of conventional scrap.

During the subsequent voyage rough

weather was encountered, cracks

developed in the shell plating, the holds

flooded and the vessel was lost with 29

lives.

In another incident heated turnings

formed a solid mass in the hold which had

to be mechanically broken into pieces

before discharge by grab. In a further

incident, following a normal passage it

was not possible to discharge the cargo

by grabs. The surface of the stow had

crusted to a hard mass. Bulldozers were

used to loosen the surface of the cargo

and several hours later fire was observed

in all of the holds.

The IMO Code of Safe Practice for

Solid Bulk Cargoes has special

requirements for the loading of turnings

and borings which include:

1 Prior to loading, the temperature of

the material should not exceed 55ºC.

Wooden battens, dunnage and debris

should be removed from the cargo

space before the material is loaded.

2 The surface temperature of the

material should be taken prior to,

during and after loading and daily

during the voyage. Temperature

readings during the voyage should be

taken in such a way that entry into the

cargo space is not required, or

alternatively, if entry is required for this

purpose, sufficient breathing

apparatus, additional to that required

by the safety equipment regulations,

should be provided.

If the surface temperature exceeds

90ºC during loading, further loading

should cease and should not

recommence until the temperature

has fallen below 85ºC.

The ship should not depart unless the

temperature is below 65ºC and has

shown a steady or downward trend in

temperature for at least eight hours.

During loading and transport the bilge

of each cargo space in which the

material is stowed should be as dry as

practicable.

3 During loading, the material should be

compacted in the cargo space as

frequently as practicable with a

bulldozer or other means. After

loading, the material should be

trimmed to eliminate peaks and

should be compacted.

Whilst at sea any rise in surface

temperature of the material indicates

a self-heating reaction problem. If the

temperature should rise to 80ºC, a

potential fire is developing and the

ship should make for the nearest port.

Water should not be used at sea. Early

application of an inert gas to a

smouldering fire may be effective. In

port, copious quantities of water may

be used but due consideration should

be given to stability.

4 Entry into cargo spaces containing this

material should be made only with the

main hatches open and after adequate

ventilation and when using breathing

apparatus.

It will be noted that compacting the cargo

as loaded with a bulldozer is

recommended. This will tend to form a

dense mass, pushing the short turnings

into the bundles of long turnings, tending

to exclude air from the stow. However

some authorities argue that compacting

the stow tends to break up the long

turnings, creating greater surface areas

for the oxidation process. However

25

shorter turnings should compact more

readily than the longer forms and thus

reduce the area exposed to oxidation.

The reference to trimming level

ensures that there is less cargo surface

exposed to the air than cargo in a peaked

condition. Furthermore, theoretically air

will pass across the top of a level trim, but

can pass through the stow if loaded in a

peaked condition creating a ‘chimney’

effect, thus accelerating the heating

process.

The requirements for entry into cargo

spaces are very important, many lives

have been lost by officers and

crewmembers entering a hold to inspect

a heating problem without taking

adequate precautions. Oxygen is

essential for the oxidation process and in

a sealed space the oxygen is reduced by

the heating reaction of the turnings or

borings. The concentration of oxygen in

air is 20.8%. Exposure to an atmosphere

of 16% oxygen concentration causes an

impairment of mental and physical state.

Concentrations of 10% will cause

immediate unconsciousness and death

will follow if not removed to fresh air and

resuscitated. The symptoms which

indicate an atmosphere is deficient in

oxygen may give inadequate notice to

most people who will then be too weak

to escape when they eventually recognise

the danger. Ventilation of the hold and

testing the atmosphere or use of

breathing apparatus is essential for safe

entry to a hold which is loaded with these

cargoes.

Metal dross and residues

Aluminium dross

Aluminium dross is formed during the

recovery of aluminium from scrap and in

the production of ingots. Dross may

constitute about 5% of the metal where

clean mill scrap is involved but will

constitute greater quantities where

painted or litter scrap is recovered. The

main components of dross are aluminium

oxide and entrained aluminium. Small

amounts of magnesium oxide, aluminium

carbide and nitride are also present.

The dross is recovered and re-melted

under controlled conditions to provide

aluminium metal which is then treated to

remove hydrogen and other impurities

including trace elements. Storage or

transport of aluminium dross should be

conducted under carefully controlled

conditions. Contact with water may

cause heating and the evolution of

flammable and toxic gases, such as

hydrogen, ammonia and acetylene.

Hydrogen and acetylene have wide

ranges of flammability and are readily

ignited.

Aluminium dross, aluminium salt slags,

aluminium skimmings, spent cathodes

and spent potliner as aluminium smelting

by-products are included in the IMO Code

of Safe Practice for Solid Bulk Cargoes.

The Code recommends that hot or wet

material should not be loaded and a

relevant certificate should be provided by

the shipper stating that the material was

stored under cover or exposed to the

weather in the particle size in which it is

to be shipped for not less than three days.

The material should only be loaded under

dry conditions and should be kept dry

during the voyage. The material should

only be stowed in a mechanically

ventilated space. In our opinion the

ventilation equipment should be

intrinsically safe.

Zinc dross

Zinc dross, zinc skimmings, zinc ash and

zinc residues are all materials obtained

from the recovery of zinc. The zinc types

may be recovered from galvanised sheets,

batteries, car components, galvanising

processes, etc. Zinc ashes are formed on

the surface of molten zinc baths, and

whilst primarily zinc oxide, particles of

finely divided zinc will also adhere to the

oxide. The various types of zinc are

treated by processes to produce pure zinc

metal.

The ashes, dross, skimmings and

residues are all reactive in the presence of

moisture liberating the flammable gas

hydrogen and various toxic gases.

The materials are also listed in the

IMO Code for Solid Bulk Cargoes which

states that any shipment of the material

requires approval of the competent

authorities of the countries of shipment

and the flag state of the ship.

The Code recommends that any

material which is wet or is known to have

been wetted should not be accepted for

carriage. Furthermore the materials

should only be handled and transported

under dry conditions. Ventilation of the

holds should be sufficient to prevent

build up of hydrogen in the cargo spaces.

All sources of ignition should be

eliminated which would include naked

light work such as cutting and welding,

smoking, electrical fittings etc.

We have knowledge of one incident

where the cause of an explosion in a hold

containing zinc ashes was said to be a

lamp used to warm the sealing tape used

to seal the hatchcovers. The flame of the

lamp was stated to have ignited

hydrogen gas leaking from the hold. The

flame flashed back into the hold to ignite

an explosive concentration of hydrogen/

air. The explosion lifted the hatchcovers

and collapsed a deck crane.

Unfortunately there was also loss of life.

The hydrogen had been generated by

reaction of the zinc ashes with water,

zinc ashes which had been loaded in a

damp condition.

The zinc ashes were discharged and

later spread on the quayside in a thin

layer to dry. Seven days later hydrogen

was still being evolved to the

atmosphere, as proved by tests with a

hydrogen gas detector ■

Surface temperature reading.

26

Hold cleaning: bulk cargoes– preparing a ship for grain

Surveyors inspection/requirements

Prior to loading grain, all ships are usually

subject to a survey by an approved

independent surveyor. The surveyor will

require the vessels particulars and details

of at least the last three cargoes carried.

He will then inspect the holds for

cleanliness and infestation, or the

presence of any material which could

lead to infestation.

When the surveyor is satisfied with

the condition of the hold, he will issue

the ship with a certificate stating which

holds are fit to load grain.

Purpose:

To ensure cargo holds are prepared to

receive the next cargo.

Large claims have arisen when cargo

holds have not been cleaned sufficiently

to prevent cargo contamination.

The requirements for cleaning the

holds are dependent upon the previous

cargo carried, the next cargo to be

carried, charterers’ requirements, the

requirements of shippers and/or the

authorities at the port of loading and the

receivers.

It is becoming common practice for

receivers to have an inspector at the load

port.

General

Regardless of the previous cargo, all

holds should be thoroughly cleaned by

sweeping, scraping and high-pressure

sea water washing to remove all previous

cargo residues and any loose scale or

paint, paying particular attention to any

that may be trapped behind beams,

ledges, pipe guards, or other fittings in

the holds.

If the ship has been carrying DRI

(direct reduced iron), the dust created by

this particular cargo during loading or

discharging, will be carried to all areas of

the ships structure and the reaction

between iron, oxygen and salt will create

an aggressive effect wherever the dust

may settle. This is particularly noticeable

on painted superstructures. (The IMO

Bulk Cargo Code contains guidelines).

Whenever salt water washing is used

to clean hatches, the relevant holds

should always be rinsed with fresh water

to minimise the effects of corrosion and

to prevent salt contamination of future

cargoes. In this respect, arrangements

should be made in good time to ensure

sufficient fresh water is available for this

operation.

Before undertaking a fresh water

rinse, the supply line (normally the deck

fire main or similar) will need to be

flushed through to remove any residual

salt water. Accordingly, it is suggested

that fresh water rinsing of the holds is

left until the end of hold cleaning

operations to minimise the amount of

fresh water required.

Grain preparation andsafe carriageOne of the most difficult hold cleaning

tasks is to prepare a ship for a grain

cargo after discharging a dirty or dusty

cargo such as coal or iron ore,

particularly if the last cargo has left ‘oily’

stains on the paintwork or other

deposits stubbornly adhering to the steel

surfaces. Greasy deposits which remain

Cargo hold, coal sticking and discharging salt.

on the bulkheads will require a

‘degreasing chemical wash’ and a fresh

water rinse in order to pass a grain

inspection. The degreasing chemical used

should be environmentally acceptable for

marine use, and safe to apply by ships

staff, who have had no special training

and do not require any specialised

protective equipment. Product safety

data sheets of the chemical should be

read, understood and followed by all

persons involved with the

environmentally friendly degreasing

chemical.

To avoid taint problems, fresh paint

should not to be used in the holds or

under the hatch lids at anytime during

the hold preparation, unless there is

sufficient time for the paint to cure and

be free of odour as per the

manufacturer’s instructions. Most marine

coatings require at least seven days for

the paint to be fully cured and odour

free. All paint used in the holds and

underside of the hatchcovers should be

certified grain compatible and a

certificate confirming this should be

available onboard. Freshly painted

hatches or hatchcovers will normally

result in instant failure during the grain

inspection, unless the paint has had time

to cure.

Processed grains or grain cargoes that

are highly susceptible to discolouration

and taint should only be stowed in holds

that have the paint covering intact. It is

important that there is no bare steel,

rust, scale, or any rust staining in the

hold.

Dependent upon the quality of the

grain to be carried, the charter may

27

require the holds to be fumigated. This

may be accomplished on passage with

fumigant tablets introduced into the

cargo on completion of loading.

Fumigation can also be undertaken at the

port of loading (or occasionally

discharge). The ship will normally be

advised how the fumigation is to be

carried out and of any special

precautions that will have to be taken.

In all cases, the preparations (i.e.

inspecting the holds and hatchcovers for

gas-tight integrity) and fumigation must

be carried out in accordance with the

IMO document Recommendation on the

Safe Use of Pesticides on Ships. Gas-

detectors and proper personal protective

equipment should be available and

relevant ship’s officers should receive

appropriate training in their use. After

introduction of the fumigant, an

appropriate period should be allowed

(normally 12 hours) for the gas to build

up sufficient pressure so that any leaks

can be detected: the vessel must not

depart from port before this period has

expired. The entire process should be

certified by a qualified fumigator. The

holds must not be ventilated until the

minimum fumigation period has expired,

and care must be taken to ensure that

subsequent ventilation does not

endanger the crew.

Alongside the dischargeport

On non-working hatches, remove all

cargo remnants, loose scale and flaking

paint from the underside of the hatch lids

and from all steelwork within the hold,

provided safe access can be obtained.

Then commence washing the underside

of the hatchcovers using liquid soap

(such as teepol), followed by a fresh

water rinse with a high-pressure water

gun.

The hatch rubber seals should also be

washed to remove cargo grime.

However, caution is required to ensure

that the hatch rubber seals are not

damaged by the high pressure from the

fresh water gun.

probably assist the removal of cargo

remains from all of the holds using the

shore crane or other cargo-handling

facilities, which will avoid lengthy

difficulties for ships staff during the

ballast voyage.

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

Hatchcover underside and clean hatch rubber.

After washing, depending on weather

conditions, cargo dust may lightly

contaminate the underside of the hatch

lids; however, the dust particles can easily

be removed at a later date using a high-

pressure portable fresh water gun.

Ballast hold

If the ship has a ballast hold, this should

be discharged as soon as possible during

the discharge

sequence. This will

allow ships staff the

time to remove all

cargo debris and

prepare the hold for

ballasting.

A good working

relationship with the

stevedores will

Hatch undersides and rubber packing.

Shore bulldozer/cocoa beans and shore

personnel cleaning holds.

Discharging soya meal; tapioca cargo sticking

and; cargo hold after discharging minerals.

> continued over

28

Hold cleaning continued

The bilges and strums of the ballast

hold should be thoroughly cleaned and

all traces of previous cargo removed. The

bilge suctions should be tested and

confirmed as clear prior to any washing

out of the cargo holds and the bilge

spaces pumped out and secured with the

bilge blanks.

To prevent ballast water ingress into

the bilge area, it is essential that the

rubber joint/gasket is in good condition

and all the bilge-blank securing bolts are

fitted tightly. The un-seamanlike practice

of securing the bilge blank with four

bolts is unacceptable and may result in

pressurising the bilge line. This must be

avoided.

tightness should be attached by a chain

to the drain. These blanking caps or plugs

are provided if the drains do not have an

approved automatic means of preventing

water ingress into the hold.

If time permits, when the cargo has

been discharged from respective hatches,

all inner hatch coamings’ should be

teepol washed and fresh water rinsed

with the fresh water high-pressure gun

because it is more convenient to wash

this area in port rather than at sea.

If permitted by the port authority, all

hatch tops should be dock water

washed, ensuring that cargo remains are

retained onboard and not washed into

the dock. The fitting of plugs to all deck

scuppers should help prevent any

pollution claims alongside.

It is essential that permission is given

by the port authority for this washing

operation.

All hatch corner drains, including the

non return valves, should be proved clean

and clear. The blanking caps on the hatch

corner drains, used to ensure hold air-

Coaming/trackway covered in fertiliser.

Hatch drain with cap attached by small chain.

Under normal circumstances, when it

rains during cargo operations,

discoloured water from the decks will

flow into the dock and this is normally

accepted by the port authority. The

washing of cargo debris into the dock is

not acceptable.

In some loading ports, where

helicopter operations are used for

embarking and disembarking the pilot, it

is a normal requirement of the port to

wash down the helicopter area and at

least one hatch length either side of the

helicopter area, ensuring that cargo

debris is not washed into the dock.

Preparation at sea

To prevent cargo debris from the main

deck being walked into the

accommodation and tramped into freshly

washed cargo holds, wash down the

main decks and accommodation block as

soon as possible after clearing the port of

discharge, mindful of pollution from the

cargo remains.

Cement staining on decks and hatchcovers.

Prior to the commencement of the

hold-cleaning, a quick safety pre-brief

meeting should take place, which should

include all the personnel who will be

involved in the hold cleaning. During the

pre-brief the hold-cleaning schedule

should be discussed and the equipment

and chemicals to be used must be fully

explained and the safety data sheets

understood by all involved. Basic safety

routines should be established and the

wearing of suitable attire throughout the

hold cleaning must be of paramount

importance.

The wearing of oilskins, safety shoes/

safety seaboots, eye protection, hand

protection and safety helmets complete

with a chin strap, should be made

mandatory during the hold cleaning

process. The wearing of high visibility

waistcoats will help to improve safety in

the hold. The ‘permit to work’ should be

completed on a daily basis, as this will

help reduce the risk of accidents.

Ship’s main deck covered by previous cargo.

Scupper plug fitted.

Hatchcovers

Prior to closing the hatchcovers, all the

hatch track-ways should be swept clean,

then carefully hosed down. If a

compressed air gun is used, it should be

used with caution and suitable safety

equipment should be worn to ensure

both face and body protection.

Hold suction arrangement and filter.

29

Hold cleaning

Prior to high pressure hold washing,

excess cargo residue on the tank top

should be removed by hand sweeping

and lifted out of the holds via the use of a

portable mucking winch. As explained

earlier, a good working relationship with

the stevedores at the discharge port may

help to expedite this operation.

After all excessive cargo residue has

been removed then the holds can be

washed with salt water using a high-

pressure hold cleaning gun,

supplemented by the deck air line to

provide increased pressure. This is the

most commonly used method of hold

cleaning, however the hold cleaning gun

normally requires two seamen to safely

control the increased water pressure.

Some ships are fitted with fixed hold

cleaning equipment, normally fitted

under the hatchcovers. This method of

hold cleaning is less labour intensive.

A flexible high-pressure hose is

connected between a flange on the

hatchcover and the deck high-pressure

hold washing line.

All cargo residues washed down must

be removed via the hold eductors or

mucking winch. Special attention should

be given to cargo residues wedged

behind pipe brackets, hold ladders, and

on the under-deck girders and

transversals. Special attention should be

paid to ventilators to ensure that

remnants of previous cargo have been

removed and the area is grain clean.

Binoculars are quite useful for spotting

cargo remains in high places. Hold bilges

and recessed hatboxes should be cleaned

out and all cargo remains removed. Bilge

suctions must be tested both before and

after washing and the results entered in

the cargo notebook and/or deck log

book.

Salt water chemical wash andhand scraping

To remove any greasy deposits from the

hold steelwork, all the holds should be

high-pressure chemical washed using the

hold cleaning gun complete with air line

booster. The degreasing chemical used, as

previously advised, should be

environmentally acceptable for marine

use, and safe to apply by ships staff, who

have had no special training and do not

require any specialised protective

equipment.

Numerous degreasing chemicals are

available (eg. Sea Shield detergent) and

work quite effectively, if they are directly

injected into the firemain via the general

service pump strainer cover.

Manufacturer’s instructions must always

be followed, but in general the

recommended chemical injection rate is

approx. 5 litres/min.

A typical 110,000 dwt bulker will

require around 100 litres per hold, or 25

litres of degreasing chemical on each

bulkhead.

To avoid long lengths of hose

delivering chemical, the chemical station

should be situated as close as possible to

the injection point of the fire and GS

pump. The easiest way to control the rate

of chemical flow is by fitting a temporary

small hand operated valve on top of the

strainer cover. An alternative method is to

use an eductor system to suck the

chemical direct from the drum into the

Typical hold cleaning equipment: crew

operating a Toby gun and a Toby gun from

Stromme.

Other ships have permanent high-

pressure hold cleaning equipment that

can be lowered through a flange on the

main deck, turned ninety degrees and

bolted to the high-pressure deck wash

service line.

Fixed hold cleaning gun under hatch lids and

fixed hold cleaning connection on deck.

Hold cleaning equipment in the stowed

position above the deck. Note the flange on

the deck wash line.

> continued over

30

Hold cleaning continued

discharge nozzle. The quantity of

chemical introduced is controlled by the

operator or an assistant, lifting the

nozzle clear of the drum. However, this

method of educting the chemical from

the drum into the discharge nozzle is

time consuming and more awkward for

the operator and restricts his movement

around the hold. In addition it carries a

greater risk of an accident or spillage of

degreasing chemical because the

chemical drums have to be lowered into

each and every hold, whereas the first

method allows all the degreasing

chemical to be situated at one place i.e.

by the GS pump.

One degreasing chemical injection

station used successfully aboard a vessel

consisted of: a transparent container of

120-litre capacity, graduated in 10 litre

units; a 5 metre transparent length of

reinforced hose with one end fitted with

a 40cm long steel uptake branch pipe

and the other end open. The branch pipe

was inserted into the chemical container

and the open end of the transparent

reinforced pipe was connected to the

hand valve on the pump strainer cover

using two jubilee clips. The small hand

valve on the strainer cover was used to

control the flow of chemical into the fire

pump.

Prior to starting the high-pressure sea

water chemical wash, all fire hydrants

and anchor wash hydrants on deck

should be checked and confirmed as fully

closed.

The hydrant serving the hold cleaning

gun should be opened and the fire and

GS pump started.

To avoid unnecessary chemical waste,

predetermined times of injecting the

chemical into the fire main should be

agreed between the hold cleaning party

and the person controlling the rate of

chemical injection. On a 110,000 dwt

bulker it takes approx. 20 minutes to

complete a chemical wash in each hatch,

after which the chemical should be

washed off using high-pressure salt

water. Concurrent with the chemical

wash the hold should be hand scraped

with sharp long handled steel scrapers.

All loose scale and flaking paint must be

removed.

Fresh water rinse and holdpreparation

The final stage of hold washing is the

fresh water rinse. A ship preparing for a

grain cargo would be advised to carry

additional fresh water in a convenient

tank. This is often the after peak, which

can be pumped into the fire main via a GS

pump. A typical 110,000 dwt bulk carrier

will require around 30 tonnes of fresh

water per hatch. Prior to commencing

the fresh water rinse, the fire line is

flushed through with the after peak fresh

water to remove all traces of salt water. If

a GS pump is used, the flushing through

takes a few minutes and only uses a few

tonnes of fresh water. Once the fire main

is clear of salt, all deck fire hydrants and

anchor washers should be sighted and

confirmed that they are closed.

If a GS pump is to be used for the hold

rinse, to prevent possible pump damage,

a return line into the after peak should be

set up using a hose connected from the

fire main into the after peak vent.

On completion of the hold fresh water

rinse, all hatch entrances, hatch

trunkings and hand ladders should be

hand washed and fresh water rinsed

using the fresh water high-pressure gun.

It is not advisable to rinse and clean the

access ladders and hatches before

washing the main hold, because

splashings from the hold bulkheads will

often contaminate the freshly washed

ladders. Bulkheads either side of all the

hand ladders should be hand cleaned and

jet washed as far as one can safely reach,

using long handled turks heads. Safety

body harnesses and (if required) a bosun’s

chair should be used when undertaking

this task.

When it is safe to open the hatches, all

the hatch coamings should be hand

washed using long handled turks heads

and jet washed with fresh water using the

high-pressure fresh water gun.

With the hatch lids open, binoculars

should be used to sight the holds for any

cargo remains.

To prevent possible condensation in

the hold, all the recessed hold eductors (if

fitted) must be drained of any water

residue, be clean dry and odourless. There

is usually a small stainless steel drain plug

on the underside of the eductor which

can be temporarily removed to allow the

eductor water to drain into the bilge area.

When the eductor is empty the drain plug

must be replaced and secured. The

eductor hold plate must be secured with

all the securing bolts and duct tape

should be used to cover both the securing

bolts and recessed lid handles.

Hold bilges should be completely dried

out, odourless and in a fully operating

condition. The surveyor will usually

require to sight one bilge in each hold to

ensure that they have been cleaned out

correctly.

The tank top must be completely dry

and any indentations on the tank top

must be wiped dry. The hold should be

made completely odourless, by

maximising hold ventilation. Two layers of

clean hessian cloth should be fitted to the

bilge strainer plate to further restrict

cargo particles entering the bilge area.

Duct tape is used to cover the small gap

between the bilge strainer and tank top.

The hold hydrant area, if fitted, should be

cleaned and dried out. The steel cover

refitted and secured in place with all its

bolts/screws.

Hatch undersides

When it is safe to open the hatches all the

hatchcover undersides should be hand

washed and fresh water jet washed using

Holds drying after washing.

> continued over

31

the high-pressure fresh water gun. If all

the hatchcover undersides were hand

cleaned at the discharge port, this

operation will be completed very quickly

and a high-pressure jet wash may suffice.

All loose scale and any flaking paint

from the hatchcover undersides must be

removed. All ledges on the hatch

undersides must be checked to see that

they are clean. All hatch rubbers and

centre line drain channels should be

clean and clear of any cargo remains or

other debris.

Hatch watertight integrity

To prevent cargo claims due to water

ingress, all hatch seals (both longitudinal

and transverse), hold access lids and

seals around the hatch sides should be

chalk marked and water tested using

deck wash hoses.

Faulty or suspect sections of hatch

rubber should be replaced in their

entirety; localised replacement or

‘building up’ of hatch rubbers using

sealing tape is discouraged.

The first team to enter the open hold

should comprise the grain inspector, a

deck officer and a seaman. Under no

circumstances should grain inspectors be

allowed to inspect the hatches unescorted

by a deck officer.

A second team consisting of a deck

officer and some crewmembers should be

standing by at the top of the hatch being

inspected. The second team should have

available additional clean brooms, clean

mops, scrapers, buckets, clean heaving

lines and clean white rags.

The engineers should be on standby to

test the bilges (dry sucking only).

Radio contact is essential between all

three teams to prevent lengthy delays.

Any personnel entering the holds

should have clean safety shoes or clean

safety sea boots. It is essential that any

debris on the main deck is not walked into

the clean holds. Some ships issue

overshoes to personnel entering the hold.

If the inspector finds a fault with a

hold, if at all possible, the fault should be

identified and recorded, and remedial

action agreed with the inspector. If

possible the fault should be rectified

immediately and preferably before the

inspector leaves the ship. If this is not

possible a time should be agreed for his

re-inspection.

Ballast hold

The ballast hold is usually de-ballasted

and prepared alongside during the

loading period. If the hold and bilges were

cleaned at the discharging berth, the

ballast hold preparation will be quickly

completed.

Loading grain

Hatches not being loaded should be kept

closed. All hatches after passing the grain

inspection and prior to loading, must be

inspected on a daily basis to ensure that

they are still completely dry. Hatches

containing grain cargo must not be

entered due to a possible lack of oxygen.

During the load, it is important to keep

the grain cargo dry. If the grain is allowed

to become wet, high cargo claims will

result.

Regular visual checks by ships staff

throughout the load should ensure that

Hose testing and a typical hose test.

A more accurate method of testing a

hatch for leakage is to use ultrasonic

equipment. However this is usually

completed by shore personnel who are

trained in the use of this equipment.

Ultrasonic hatch testing for leaks.

Grain inspection

Prior to the grain inspection all hatches

and access lids must be open and safely

secured with all locking pins/bars.

All hatches should be checked for

loose scale or flaking paint. Invariably

there will be a little scale on the tank top,

which can quickly be removed. If weather

conditions permit during the day, the

holds should be opened to allow fresh air

to assist the hold drying process. All small

pools of water should be mopped dry. All

hatch rubbers and centre line seals

should be wiped over with a clean dry rag

to confirm their cleanliness.

Poor practice: hatch tape used to build up

cross joints. This is discouraged.

Prior to the inspection, ships staff

should lower into the first hold an

aluminium ladder together with a small

number of clean brooms, scrapers,

dustpan and brush, a clean bucket and a

few clean white rags. If possible the

second hold to be inspected should also

be equipped with similar items.

Hold ready to load wheat.

> continued over

32

Hold cleaning continued

the grain being loaded is not in a wet

condition. These inspections should be

recorded in the deck log book.

Loading grain; other hatches closed.

During the loading of grain, dust

clouds often develop. These are a health

hazard and additional safety

requirements, such as the wearing of eye

protection goggles and dust masks

should be observed by all personnel in

the vicinity of the dust cloud.

If the master is in any doubt about the

condition of the grain during the load, he

must issue a note of protest and seek

advice from his operators and/or the UK

P&I Club.

Completion of a hatch

All holds to be filled must be absolutely

full. It is essential that the loading spout,

Grain dust cloud presents a health hazard.

Loading barley (bottom).

or other mechanism, is directed to all

corners, to avoid any void spaces. Time

should be allowed for the grain to settle

then refill any spaces (such as hatch

corners).

Grain settling in the cargo hold.

When the loading of a hatch has been

completed, the trackways, hatch drains,

and channel bars must be swept clean

and the hatch closed. Water must not be

used to wash down hatch trackways.

DRY compressed air is very useful, but

crew safe working practices must be

observed when using compressed air.

Ventilators should be tightly secured.

Loading grain to all corners.

are applied. Foam compound should not

be used to ensure hatch watertight

integrity.

Hatch vent to secure.

Loaded voyage

Regular checks of all hatch sealing tape (if

fitted) should be completed and damaged

or lifting tape immediately replaced.

During the voyage, entry into any cargo

space must be strictly prohibited.

Ventilation during the voyage will depend

on weather conditions and a comparison

between the dew point of the air inside

the hold and outside the hold. Under no

circumstances should hold ventilation be

permitted during adverse weather

conditions or before fumigation in transit

has been completed.

In good weather, basic cargo

ventilation rules should be observed.

Guidance can be obtained from Bulk

Carrier Practice: A Practical Guide (ISBN

928 0114 581).

If the vessel has any oil tanks adjacent

to or under the cargo holds, any steam

heating to these tanks should be

minimised, but in any case carefully

monitored and full records maintained to

Do not use foam to seal hatches.

Security seal in place.

If the voyage instructions require

hatch sealing tape to be used, as an

additional precaution to prevent water

ingress, then the hatch surfaces must be

scrupulously clean before the sealing

tape is applied. In cold climates, some

brands of tape will adhere better if

warmed in the engine room before they

To prevent unauthorised access to the

oxygen depleted grain holds, and where

fumigation in transit is to be undertaken,

all the hold access lids should either be

padlocked or have steel security seals

fitted.

33

prevent cargo heating and possible cargo

damage. This is a point that is often

overlooked by ships staff.

Grain cleaning ‘operational’checklist

Prior to commencing the grain clean the

master should check and confirm the

following:

✔ If the previous cargo is likely to cause

problems during the cleaning voyage,

the master must advise his operator

well in advance, so that sufficient

cleaning time, manpower and

materials can be planned. A lack of

communication between ship and

shore may result in difficulties for

the ship and costly off hire for the

operator.

✔ As soon as the ship starts cleaning

preparations, the master should make

regular daily reports of the hatch

cleaning progress to his operator.

✔ If the after-peak is to be used for the

carriage of additional fresh water –

confirmation that the after-peak tank

can be discharged via the deck service

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

fresh water, the ship can still maintain

the minimum bow height as per

classification rules. (Details in stability

book).

✔ The ship has fully operational mucking

winch.

✔ All bilge sounding pipes and

temperature sounding pipes (if fitted)

are clear with no ‘old’ sounding rods or

any obstructions or blockages.

✔ All sounding pipes have a fully

operational screw thread and the

gasket is in good condition i.e.

sounding cap that can be screwed

down tightly to prevent water ingress.

✔ The ship has no ballast tank leaks.

✔ Advise his operator if there are any

problems with the ship’s ballast pumps,

eductor(s) or general service pumps.

✔ The ship has a ‘grain certified’ paint

certificate for inside the hatches.

(assuming that the hatches were

previously painted some months

earlier).

✔ All hatch corner drains and non-return

valves are working correctly and are

complete in all respects.

✔ All hatch ladders on fwd and aft

bulkheads are in good condition to

allow safe access for all personnel.

✔ All hold bilge plates have all the

securing bolts fitted and the ships

approved ballast holds have the

blanks. This is often a spectacle piece

which can be rotated on deck.

✔ All ballast line hold cover plates have

all the bolts fitted and they are all in

good condition.

✔ All hatch access lids can have a hatch

seal or padlock fitted after loading, to

prevent unauthorised entry into

oxygen depleted area.

✔ No infestation is onboard. This

includes all the storerooms, as these

areas are also liable to be inspected by

grain inspectors.

✔ Approved grain stability books

onboard and the pre-calculated load

conditions (using appropriate grain

shift moments) have been completed.

In some ports, these calculations have

to be approved by the local authorities.

✔ A hold-cleaning schedule using

realistic times has been prepared.

The ‘simplified’ example, below, is not an

actual working schedule.

Under normal circumstances It often

takes one day to clean a hold.

This figure of one day per hold is

usually acceptable to charterers.

The ‘simplified’ schedule assumes that

the vessel’s previous cargo was coal or

iron ore. If the vessel’s previous cargo was

grain, then the chemical wash may not be

required, but the holds should still be

hand scraped to remove any loose scale

and paint.

Grain cleaning ‘equipment’checklist

✔ A fully working high-pressure hold

cleaning gun (Toby gun or Semjet or

similar) – complete with sufficient deck

wash down hoses and air-lines all in

good condition.

Fire hoses must not be used as wash

down hoses as they are part of the

ships safety equipment.

✔ Ship has a fully operational salvage

pump (Wilden pump) and approved

spares.

✔ Sufficient fresh water to complete a

high-pressure fresh water rinse of all

the holds. It will be more cost effective

to over-supply fresh water for hold

cleaning than the ship to run out

during the hold cleaning. (A typical

100,000dwt bulker requires around

30 tonnes per hatch).

Simplified schedule.

> continued over

Order of events Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day7

(In port)Hatch undersides

Wash downdecks

HP saltwaterwash holds

Chemical washholds – scrape –and SW rinse

FW rinse andhold preparation

Clean hatch lidsundersides

Check holdsand hatchwatertightness

x

x x

x

x x

x

x

x

x

34

✔ 1 x portable pressurised fresh water

gun, complete with extended handle

and 30 metres of pressurised hose.

✔ 6 x long handle steel scrapers

complete with handles.

✔ 3 x lightweight, strong, aluminium

extension poles with capability to

extend to approx 5 metres.

✔ 6 x long handled rubber squeegee

complete with 1 metre rubber blades.

✔ 10 x heavy-duty bass brooms, c/w

handles, suitable for hold cleaning.

✔ 6 x corn brooms c/w with handles.

✔ 6 x heavy-duty mops, c/w handles.

✔ 6 x spare mop heads suitable for above.

✔ 4 x galvanized, roller wringer, mop

buckets.

✔ 6 x turks heads, round head 4 inch,

c/w handles.

✔ 6 x small 6 inch wide, hand shovels,

steel, suitable for digging out hold

bilges.

✔ 3 x 25 metre length, lint free soogee

cloth, width approx 30cm.

✔ 1 x 50 metre length burlap, 1 metre

wide.

✔ 10 x rolls of 50 metre length, 10cm

wide, grey, industrial strength duct

tape.

✔ 6 x 20 metre length, ‘yellow’ wash

down hoses, duraline, 45mm dia

complete with couplings suitable for

ship’s fire main.

✔ 4 x plastic jet nozzles, suitable for

above hoses.

✔ 4 x 50 metre lengths, transparent

plastic, reinforced garden hose,

complete with male and female plastic

couplings to join each section.(for use

with Kew gun).

✔ 2 x universal tap connectors for above

reinforced transparent plastic garden

hose.

✔ Sufficient hatch sealing tape to comply

with operators instructions.

✔ 4 x 500 watt, portable lightweight

halogen lights to illuminate hatches

during cleaning. Each lamp to be

complete with 50 metres of cable and

have a waterproof plug fitted.

✔ 10 x spare halogen bulbs for above.

✔ 2 x 50 metre extension cables each

complete with three waterproof

outlet sockets and a waterproof plug.

✔ 5 x 20 litre drums concentrated

teepol.

✔ Sufficient drums of de-greasing

chemical wash suitable for use with

sea water (e.g. Sea Shield detergent

cleaner or equivalent).

Typical examples of holdfailures

The following images from a vessel which

failed a grain survey, would suggest that:

● Ships crew completed a very quick salt

water wash.

● No chemical wash was undertaken.

● No hard scraping of the bulkheads

was completed.

● Previous hold cleaning had not been

supervised (history of the ships

cargoes on the stiffeners).

Showing:

● Staining from the previous cargo

(coal).

● Cargo dust residues.

● Deposits of previous cargoes in hard

to reach places.

● Flaking paint and scale ■

Hold cleaning continued

References

Bulk Carrier Practice – A Practical Guide.

(ISBN 928 0114 581)

Recommendation on the Safe Use of

Pesticides on Ships. (ISBN 9280111205)

Product Safety Data Sheets – for

degreasing chemical used.

Bulk Cargo Code – IMO Publication. (ISBN

9280110616)

MARPOL. (ISBN 9280114174)

www.stromme.com

35

For a long period of time iron has been

produced in blast furnaces by reduction

of iron ore, that is removing the oxides of

the ore. High shipping costs are paid for

shipping the iron oxides from the ore

producing areas to the iron producing

furnaces. Reduction of the ore in blast

furnaces is then a high energy demand

process. Research in the steel making

industry has produced a method to

directly reduce the ores to metal, the

product known as direct reduced iron,

DRI. Iron ore is crushed and formed into

pellets. The pellets are then heated in a

furnace, at a temperature below the

melting point of any of the metal in the

ore, in the presence of reducing gases.

The ore is reduced to metal by the

removal of oxygen, leaving the metal in a

rigid but sponge-like structure. This

sponge-like structure has an extremely

high surface area to mass ratio, possibly a

thousand times greater than the surface

area of a piece of iron of the same mass.

It is well known that iron will readily

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

obviously increased with an increase in

surface area as exhibited by DRI pellets.

The rusting process is an exothermic

reaction, that is to say heat is evolved

during the process. Furthermore this

reaction is accelerated in the presence of

water or moisture and further

accelerated by the presence of an

electrolyte as in sea water. The reaction

between DRI and water results in the

production of the highly flammable gas

hydrogen.

Thus the safe carriage of DRI pellets

relies upon excluding oxygen and water,

particularly sea water, from the stow.

Certain manufacturers have developed

passivation techniques for the DRI pellets,

which supposedly prevent the effect of

moisture and oxygen reacting with the

pellets. However following a serious fire

in a ship carrying passivated pellets, there

are doubts whether the passivation

technique is satisfactory for the safe

carriage of the pellets.

During a period of six months in

2003/2004 there were three serious

casualties related to the carriage of DRI

and DRI fines including loss of life and

sinking of two of the ships.

The most positive method of carrying

DRI safely, free from the effects of

oxygen and sea water is to ensure that

the cargo compartments are effectively

sealed and inerted. The compartments

should be inerted to the extent that the

oxygen content of the atmosphere is less

than 5%.

Direct reduced iron such as lumps,

pellets and cold moulded briquettes are

included in the IMO Code of Safe

Practice for Solid Bulk Cargoes under BC

No.015. Direct reduced iron, briquettes,

hot moulded are included in the Code

under BC No.016. It is important to note

that the entries in the Code relate to:

“Direct Reduced Iron DRI” and “Direct

Reduced Iron”

Examples are indicated “such as

lumps, pellets, briquettes etc”. However

this does not exclude fines. Fines are fine

particles of direct reduced iron created

during the manufacturing, handling and

storage of the material. Fines as

marketed normally have specifications

relating to total iron and metallic iron.

The fines may thus evolve hydrogen if in

contact with water, which is also stated

in the Code.

Apparently one shipper and one

author considers that DRI fines and HBI

fines are not included in the IMO Code.

However this is not the case, the IMO

entry clearly states, direct reduced iron,

which would include fines derived from

direct reduced iron.

The IMO Code of Safe Practice for

Solid Bulk Cargoes under the title ‘Special

Requirements’ states:

“Certification: A competent person

recognised by the National

Administration of the country of

shipment should certify to the ship’s

Master that the DRI at the time of

loading, is suitable for shipment.

Direct reduced iron including DRI fines

Shippers should certify that the material

conforms with the requirements of this

Code.”

The Code continues with a section

‘Shipper’s Requirements’. This states that

prior to shipment the DRI should be aged

for at least 72 hours or treated with an air

passivation technique, or some other

equivalent method that reduces the

reactivity of the material to at least the

same level as the aged product.

It states under Paragraph A that the

shipper should provide the necessary

specific instructions for carriage either:

maintenance throughout the voyage of

cargo spaces under an inert

atmosphere containing less than 5%

oxygen. The hydrogen content of the

atmosphere to be maintained at less

than 1% by volume or

that the DRI has been treated with an

oxidation and corrosion inhibiting

process which has been proved to the

satisfaction of the competent authority

to provide effective protection against

dangerous reaction with sea water or

air under shipping conditions.

The provision of Paragraph A may be

waived or varied if agreed by the

competent authorities taking into account

the sheltered nature, length, duration, or

any other applicable conditions of any

specific voyage.

The Code then continues to describe

the relevant precautions, loading carriage

etc.

Despite all these problems, DRI cargoes

are safely carried to destination. However

if the precautions are not observed there

can be severe problems during discharge

of heated cargo. Expensive fire fighting

procedures involving the use of vast

quantities of solid inert materials, inert gas

etc, long delays to the discharge. Even

when removed from the ship’s hold a

heated cargo can cause problems on the

quayside. At one port there remained for

> continued over

36

Carefully to Carry

Edited by:

Karl Lumbers Tel: +44 (0)20 7204 2307

e-mail: karl.lumbers@thomasmiller.com

Colin Legget Tel: +44 (0)20 7204 2217

e-mail: colin.legget@thomasmiller.com

Fax: +44 (0)20 7283 6517

Published by:

Thomas Miller & Co Ltd

International House, 26 Creechurch Lane

London EC3A 5BA

Tel: +44 (0)20 7283 4646

Fax: +44 (0)20 7283 5614

http://www.ukpandi.com

For and on behalf of the Managers of

The United Kingdom Mutual Steam ShipAssurance Association (Bermuda) Limited

The United Kingdom Freight Demurrage andDefence Association Limited

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Carefully to Carry on-line

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can be viewed on the Club’s website:

http://www.ukpandi.com

Acknowledgements

The UK P&I Club would like to thank theCarefully to Carry Advisory Committee forthe following articles:

The carriage of liquefied gases / Liquefiednatural gas – Wavespec Limited

Bulk liquid cargoes – sampling – CWAInternational Limited

Carriage of potatoes – John BanisterLimited

Fumigation of ships and their cargoes –Igrox Limited

Scrap metal – Minton, Treharne & DaviesLimited

Hold cleaning – UK Club Loss PreventionDepartment

Direct reduced iron – Minton, Treharne &Davies Limited

Whilst the information given in this newsletter is believedto be correct, the publishers do not guarantee itscompleteness or accuracy.

a long period of time a solid lump of DRI,

possibly 5,000 tonnes – difficult to

remove.

The International Group of P&I Clubs

circulated a document to their members in

August 1981 relating to the problem in

the carriage of DRI. Following a meeting

of IMO in January 1982 the Group

circulated a further document relating to

the safe carriage of DRI. The first item to

be stressed in this latter circular quoting

the IMO amendments was to the effect

that throughout the voyage an inert

atmosphere should be maintained with an

oxygen content less than 5%.

In May 2001 the UK P&I Club published

a circular which indicated the following:

a) The undersigned Association continues

to believe that the only proven method

of carrying this cargo safely is by

maintaining the cargo holds in an inert

atmosphere and believe the most

effective method of providing an inert

atmosphere is by injecting inert gas at

the bottom of the stow in order to

force out the air within the stow (see

photos below).

b) On present information, it is not

thought that the length or nature of

the voyage contemplated (IMO

Paragraph B) can ever justify the waiver

of the requirement of maintaining the

cargo in an inert atmosphere.

Under the ideal conditions of carriage,

perfectly sealed hold spaces for all types of

ships under all weather conditions it may

be possible to complete the voyage

maintaining an inert atmosphere

throughout the stowed cargo following

injection of inert gas at the

commencement of loading. It may also be

possible to prevent the ingress of sea

water into the hold spaces. However,

under certain conditions the hatchcovers

may 'work' and not remain 'airtight', thus

Ramnek tape could assist in this respect.

If hatch coaming drains are not sealed

leakage may also take place from diurnal

breathing and dynamic wind effects. Loss

of gas can also take place through

sampling via access hatches rather than

hatch sampling valves. It may therefore

be necessary to 'top up' the inert gas for

safe carriage to destination.

Hot moulded briquettes

Hot moulded briquettes of DRI are a

different proposition. The mined ore

passes through a densification process

but is then moulded at a temperature in

excess of 650o C. The briquettes may be

stored in open storage conditions. Prior to

shipment the shipper or competent

authority should provide the master with

a certificate to the effect that the material

is suitable for shipment and conforms

with the requirements of the IMO Code.

Loading during rain is not acceptable

but briquettes can be discharged under

all weather conditions. Water spray to

assist dust control is also permitted during

discharge. Hold spaces should be clean

and dry, and all combustible materials

removed before loading. Briquettes with

a temperature in excess of 60o C should

not be loaded.

Hydrogen may be slowly evolved if the

briquettes had been in contact with water

thus adequate ventilation should be

provided. There are no requirements to

monitor hydrogen and oxygen levels nor

to record temperature effects in the

cargo. Normal precautions of entering the

hold spaces should be observed in case of

oxygen depletion ■

Direct reduced iron continued

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