CARGO HANDLING AND STOWAGE-II Unit 2
CARGO HANDLING AND STOWAGE – II Unit 2
Deck cargo
The phrase ‘deck cargoes’ refers to items and/or commodities
carried on the either-deck and/or hatchcovers of a ship and thereon
exposed to sun, wind, rain, snow, ice and sea, so that the
packaging must be fully resistant to, or the commodities themselves
not be denatured by such exposure.
Deck cargo is shipping cargo carried on the deck
instead of inside the ship. Certain types of cargo must be carried
on the deck by law, while others may be carried on deck by
convenience or to address space concerns while loading the ship.
Such cargo must be carefully secured to prevent losses and reduce
the risk of injury on the part of the ship's crew, as people will
be directly exposed to the deck cargo while working on the ship
Livestock is often carried as deck cargo when there are concerns
about ventilation and safety below decks. Specialized pens may be
built on deck or livestock can be carried in crates. Another object
carried in this manner is explosives. In many regions, people
cannot carry explosives below decks for safety reasons. In addition
to being carried on deck, they also need to be clearly labeled so
people are aware of the risks.
Aircraft, trucks, and other large cargoes may be carried on deck
as it may not be possible to stow them below decks. Either they are
so large that they cannot fit inside the cargo space, or the
openings to the cargo hold are not large enough, or the cranes and
other devices used for cargo handling in the hold are not rated for
such heavy loads. Sometimes, large cargo is carried in pieces, as
seen with aircraft, where the wings may be detached and carried
separately to allow the whole plane to fit on a ship. Timber and
other building materials can also be classified as deck cargo,
along with things like prefabricated materials for
construction.
Deck cargo can be carried in containers in some cases, while in
others, it may be lashed directly to the decks of the ship and
covered with protective materials. For bulky and large cargoes too
big for containerization, this may be necessary. In all cases,
the cargo is thoroughly inspected when it is placed and the load is
carefully balanced for safety. Papers documenting the type of cargo
and its history must also be carried, including lading papers
detailing where the cargo originated and where it is going.
Dangerous Cargoes not permitted below deck.
Stowage on deck only has been prescribed in cases
where:
.1 constant supervision is required; or
.2 accessibility is particularly required; or
.3 there is a substantial risk of formation of explosive gas
mixtures, development of highly toxic vapours, or unobserved
corrosion of the ship.
Where, for certain dangerous goods, protection from sources of
heat is required, this shall be taken to include sparks, flames,
steam pipes, heating coils, top or side walls of heated fuel and
cargo tanks, and bulkheads of machinery spaces; alternatively, for
the latter, such bulkheads shall be insulated.
Where stowage clear of living quarters is required, in
deciding the stowage, consideration shall be given to the
possibility that leaking vapours may penetrate the accommodation,
machinery spaces and other work areas via entrances or other
openings in bulkheads or through ventilation ducts.
Ships are divided into two groupings for the purpose of making
appropriate stowage recommendations:
.1 cargo ships or passenger ships carrying a number of
passengers limited to not more than 25 or to 1 passenger per 3 m of
overall length, whichever is the greater number;
.2 other passenger ships in which the limiting number of
passengers transported is exceeded.
Stowage categories
Substances, materials and articles shall be stowed as indicated
in the Dangerous Goods List in accordance with one of the
categories specified below
Stowage category A
.1
ON DECK OR UNDER DECK
.2
ON DECK OR UNDER DECK
Stowage category B
.1
ON DECK OR UNDER DECK
.2
ON DECK ONLY
Stowage category C
.1
ON DECK
ONLY
.2
ON DECK ONLY
Stowage category D
.1
ON DECK
ONLY
.2
PROHIBITED
Stowage category E
.1
ON DECK OR UNDER DECK
.2
PROHIBITED
Efficient means of securing deck cargoes.
Requirements of the IMO Cargo Securing Manual and the IMO Code
of Safe Practice for Cargo Stowage and Securing should be followed.
If timber is carried then the Code of Safe Practice for Ships
Carrying Timber Deck Cargoes should be followed.
All securing of cargo units shall be completed before the ship
leaves the berth. Deck cargoes, because of their very location and
the means by which they are secured, will be subjected to velocity
and acceleration stresses greater, in most instances, than cargo
stowed below decks. The stowage, lashing, and securing of cargoes
therefore require special attention as to method and to detail if
unnecessary risks are to be avoided.
Deck cargo are mostly lost due to the following reasons:
● Severe adverse weather conditions. ● Lack of appreciation of
the various forces involved. ● Ignorance of the relevant rules and
guiding recommendations. ● Cost limitation pressures to the
detriment of known safety requirements. ● Insufficient time and/or
personnel to complete the necessary work before the vessel leaves
port. ● Dunnage not utilised in an effective manner. ● Inadequate
strength, balance and/or number of lashings. ● Wire attachment eyes
and loops made up wrongly, including incorrect methods of using
bulldog grips. ● Lack of strength continuity between the various
securing components. ● Taking lashing materials around unprotected
sharp edges. ● Incorrect/unbalanced stowage and inadequate weight
distribution. ● Inefficient shore-based labour. ● Securing
arrangements, both supplied and approved, not fully utilised on the
voyage under consideration.
Deck cargo shall be so distributed and stowed:
1) as to avoid excessive loading having regard to the strength
of the deck and integral supporting structure of the ship;
2) as to ensure that the ship will retain adequate stability at
all stages of the voyage having regard in particular to: a) the
vertical distribution of the deck cargo; b) wind moments which may
normally be expected on the voyage; c) losses of weight in the
ship, including in particular those due to the consumption of fuel
and stores; and d) possible increases of weight of the ship or deck
cargo, including in particular those due to the absorption of water
and to icing;
3) as not to impair the weathertight or watertight integrity of
any part of the ship or its fittings or appliances, and as to
ensure the proper protection of ventilators and air pipes;
4) that its height above the deck or any other part of the ship
on which it stands will not interfere with the navigation or
working of the ship;
5) that it will not interfere with or obstruct access to the
ship’s steering arrangements, including emergency steering
arrangements;
6) that it will not interfere with or obstruct safe and
efficient access by the crew to or between their quarters and any
machinery space or other part of the ship used in the working of
the ship, and will not in particular obstruct any opening giving
access to those positions or impede its being readily secured
weathertight.”
Thumb Rule of lashing.– the ‘3-times rule’ – tends to be that
the sum of the safe working load of all the lashings shall equal
the static weight of the cargo item to be secured; the safe working
load being arrived at by dividing by 3 the minimum breaking-load/
slip-load/holding power of the lashings. In other words, if the
breaking-load/slip-load/holding power of all the lashings is 30
tonnes, then they can safely hold an item whose static weight is 10
tonnes – again on the assumption that all securing arrangements are
deployed in a balanced, efficient, and non-abrasive manner
Need of battening of cargohold before loading deck cargo.
Hatch covers need to be water tight to prevent water ingress and
subsequent flooding. Also if the hatch cover is not secured tightly
to the ship, the hatch cover along with the deck cargo can fall
overboard. This will expose the ship to flooding in addition to
instability as a huge amount of weight is removed from one side or
part of the ship suddenly.
Safe access to equipment and spaces.
Loading of deck cargo should not impede safe access to equipment
and living spaces. It should not obstruct fire fighting and life
saving appliances. The crew should be able to move around freely
for performing their duties.
Standard Safety precautions during cargo work.
The following list of safety precautions should be
observed by all cargo handlers.
Wear safety shoes and helmets.
Use the accommodation ladder for boarding or leaving
the ship.
Use the ladders in the square of the hatch only when hoist is
not in motion.
Use the walkway on ship’s side away from the side on which cargo
is being worked.
Secure all lashings to
permanent deck fastenings.
Secure hatch Covers properly.
Lower blocks, crowbars, slings, bridles, and other objects
into the hold by cargo falls or other lines. Do not
drop or throw
Do not enter dark places (holds, decks, or compartments) without
a light.
Stand in the clear away from suspended loads
Be particularly careful when handling objects with sharp or
rough edges
Learn and practice proper lifting techniques to prevent strains
and sprains.
Never walk backward.
Step down from elevations, do not jump.
Report all defects in tools, materials, and equipment.
Report all injuries, however slight,
and get immediate first aid or
medical attention.
Do not smoke in holds or storerooms. Learn the location of
fire alarm boxes and firefighting
equipment.
Do not engage in horseplay, practical jokes, or
arguments while working cargo.
Check mooring lines regularly.
Check gangway rigged properly and ensure it is clean and well
lit and manned at all times.
Regular Security and Fire rounds to be made and entered in log
books
Sufficient illumination and ventilation provided in all areas
where cargo is being worked.
Do not walk over the edge of hatch coaming when the hatch cover
is open.
Maximum permissible load on deck. Should not exceed the load
density of the hatch covers else the hatch covers will collapse.
This will result in loosing water tight integrity and flooding.
High Density Cargo: Structural Hazard and Precautions,
High Density Solid Bulk Cargo means the cargo with stowage
factor (SF) of 0.56 Cu.M. per ton or less
High density cargoes have a greater weight than their volume.
Lighter cargoes occupy more space. For example, the stowage factor
for corn is 1.42 m3/tonne while for iron ore, the stowage factor
can be as small as 0.24 m3/tonne. Tanktop strength is provided in
the ship's stability booklet . However, as a ship ages, this
strength reduces and a greater safety margin is recommended for
older ships.
Another peculiar characteristic of high density cargoes is that
they do not provide much support to the internal structure of the
cargo hold, which may increase the risk of damage from panting
stresses. This is particularly true with ships where the maximum
safe load for cargo holds is either not given or is not considered
when loading such cargoes.
Panting is a term used to describe the movement of the ship
caused by the shock of contact with a succession of waves at the
bow or the stern. It can be thought of as breathing-like movement
in the fore and aft plane of the vessel.
An extra 10% load on a vessel's structure increases the still
water bending moments by 40% and shearing forces by 20%. These
small variations in loads can easily be caused by inappropriate
and/or careless loading/discharging. For example, in the loading
port, if the rate of discharge of ballast water is not similar to
the rate of cargo being loaded then stresses are likely to cause
severe damage to the ship's structure.
It is the job of the ship's officers to ensure that this does
not happen and the procedure should be established in the cargo
plans. If it is suspected that a vessel has been overloaded, tank
top and deck structures (particularly deck plates between hatchways
and at hatch corners) should be carefully inspected for any signs
of cracking or buckling.
The small volume taken up by the cargo in the ships' holds
results in a large unoccupied space. This provides potential in a
flooding scenario for large volumes of water to rapidly destroy the
ship's residual buoyancy and, in the case of smaller vessels, its
stability. Larger vessels are also highly susceptible to structural
failure due to increases of weights caused by the influx of
water.
Heavy cargoes place high loads on the structure, and structural
failure is therefore more probable when subjected to the additional
forces associated with flooding.
Over-stressing of the local structure may also occur when the
weight of cargo loaded into an individual hold has insufficient
support of upward buoyancy force; this circumstance can occur when
cargo is transported by the ship in a shallow draught condition
(for example, partial load condition with some holds full and
remaining holds empty).
The proposed Stowage Plan must ensure that the permissible
forces and movements are not exceeded during loading taking into
consideration the rate of loading, number of pours and
de-ballasting capability of the vessel
When loading high density cargoes there is a risk of overloading
tank tops and proper precautions should be taken. Heavy lifts
require plenty of strong, good quality dunnage, laying as much
dunnage as feasible on the tank top, in order to spread the load
evenly. The tank top limitations are laid down when the ship is
built and provided that the structure remains within class
specifications, remain unchanged throughout the life of the ship.
If through damage or wastage, the structure is reduced, then
reduced limitations may well have been imposed as a condition of
class
Great care is required to avoid over stressing the vessel and
doing structural damage. Carefully planning of the load and the
discharge must be made, and at all times the maximum loading of the
tank top must not be exceeded.
In addition, the maximum loading for each hatch must not be
exceeded. Care must be taken to ensure that the peak height of an
untrimmed cargo is not excessive thereby increasing the tank top
loading.
In tween deck vessels, high density cargoes such as iron ore
should be loaded in the lower hold only, to avoid damage to the
tween deck.
Shifting
Some cargoes may have a tendency to shift across the ship in
heavy weather and so correct trimming of the cargo is required.
Some cargoes such as grain may need extra measures to be taken to
secure the surface. For example, bulk grain may be over stowed with
bagged grain.
As a general rule all cargoes should be trimmed level or nearly
level and whenever possible spaces should be filled as fully as
practicable without putting excessive stress on the structure.
Liquefaction
Some cargoes, particularly metal concentrates, may become
semiliquid on top when loaded "wet". This is due to the vibration
of the ship at sea causing the moisture in the cargo to migrate to
the surface.
The surface may then act as a liquid and seriously affect the
stability of the vessel. Examples of this are coal, duff and lead
concentrates.
Gas Production
Explosive gasses such as methane and poisonous gasses such as
carbon monoxide may be produced by some cargoes. For example
coal
SelfHeating
Some cargoes are liable to heat up on voyage. Temperatures
should be taken and a log kept of each space. For example coal and
steel scrap.
Corrosive
The cargo itself may be corrosive or the liquid draining out of
the cargo into the bilge's may be corrosive. In some ships severe
damage has occurred. For example coal and sulphur.
Dust Very dusty cargoes may be hazardous to humans and the
environment and so measures may have to be taken to control the
level of dust created e.g. stop load/discharge in high winds. For
example alumina and phosphates.
Trimming Requirements
Trimming a cargo reduces the likelihood of the cargo shifting
and minimizes the air entering the cargo, which could lead to
spontaneous heating. To minimize these risks, cargoes shall be
trimmed reasonably level, as necessary.
Cargo spaces shall be as full as practicable without resulting
in excessive loading on the bottom structure or ‘tween-deck to
prevent sliding of a solid bulk cargo. Due consideration shall be
given to the amount of a solid bulk cargo in each cargo space,
taking into account the possibility of shifting and longitudinal
moments and forces of the ship. Cargo shall be spread as widely as
practicable to the boundary of the cargo space.
The Master has the right to require that the cargo be trimmed
level, where there is any concern regarding stability based upon
the information available, taking into account the characteristics
of the ship and the intended voyage.
When high density bulk cargoes are loaded, the cargo should be
levelled to ensure an even pressure over the tank top. There are no
safety factors and all cargo must be carefully trimmed.
Required to keep the stresses under limits.
Required to ensure proper departure trim.
Required in case of light cargoes to fill up all the empty
spaces to prevent cargo shifting in rough weather.
Required to fill up empty spaces which forms after cargo settles
down some time after loading.
INTERNATIONAL MARITIME SOLID BULK CARGOES (IMSBC) CODE
Aim is to facilitate the safe transport of solid bulk
cargoes,
The prime hazards associated with the shipment of solid bulk
cargoes are those relating to structural damage due to improper
cargo distribution, loss or reduction of stability during a voyage
and chemical reactions of cargoes. Therefore the primary aim of
this Code is to facilitate the safe stowage and shipment of solid
bulk cargoes by providing information on the dangers associated
with the shipment of certain types of solid bulk cargoes and
instructions on the procedures to be adopted
Table of Contents
Section 1 General provisions and definitions
Section 2 General loading, carriage and unloading
precautions
Section 3 Safety of personnel and ship
Section 4 Assessment of acceptability of consignments for safe
shipment
Section 5 Trimming procedures
Section 6 Methods of determining angle of repose
Section 7 Cargoes that may liquefy
Section 8 Test procedures for cargoes that may liquefy
Section 9 Materials possessing chemical hazards
Section 10 Carriage of solid bulk wastes
Section 11 Security provisions
Section 12 Stowage factor conversion tables
Section 13 References
Appendix 1 Individual schedules of solid bulk cargoes
Appendix 2 Laboratory test procedures, associated apparatus and
standards
Appendix 3 Properties of solid bulk cargoes
Appendix 4 Index of solid bulk cargoes
Angle of repose
Angle of repose means the maximum slope angle of non-cohesive
(i.e., free-flowing)
granular material. It is measured as the angle between a
horizontal plane and the cone slope of
such material
Bulk Cargo Shipping Name (BCSN) identifies a bulk cargo during
transport by sea.
When a cargo is listed in this Code, the Bulk Cargo Shipping
Name of the cargo is identified by capital letters in the
individual schedules or in the index. When the cargo is a dangerous
good, as defined in the IMDG Code, as defined in SOLAS Convention,
the Proper Shipping Name of that cargo is the Bulk Cargo Shipping
Name.
Cargoes which may liquefy means cargoes which contain a certain
proportion of fine particles and a certain amount of moisture. They
may liquefy if shipped with a moisture content in excess of their
transportable moisture limit.
Concentrates means materials obtained from a natural ore by a
process of enrichment or beneficiation by physical or chemical
separation and removal of unwanted constituents.
Consignment means a solid bulk cargo presented by a shipper for
transport.
Flow moisture point means the percentage moisture content (wet
mass basis) at which a
flow state develops under the prescribed method of test in a
representative sample of the material
Flow state means a state occurring when a mass of granular
material is saturated with liquid to an extent that, under the
influence of prevailing external forces such as vibration,
impaction or ships motion, it loses its internal shear strength and
behaves as a liquid.
High-density solid bulk cargo means a solid bulk cargo with a
stowage factor of 0.56 m3/t or less.
Incompatible materials means materials that may react
dangerously when mixed. They are subject to the segregation
requirements and the schedules for individual cargoes classified in
Group B.
Materials hazardous only in bulk (MHB) means materials which may
possess chemical hazards when carried in bulk other than materials
classified as dangerous goods in the IMDG Code.
Moisture content means that portion of a representative sample
consisting of water, ice or other liquid expressed as a percentage
of the total wet mass of that sample.
Moisture migration means the movement of moisture contained in a
cargo by settling and consolidation of the cargo due to vibration
and ship’s motion. Water is progressively displaced, which may
result in some portions or all of the cargo developing a flow
state.
Non-cohesive material means dry materials that readily shift due
to sliding during transport
Representative test sample means a sample of sufficient quantity
for the purpose of testing the physical and chemical properties of
the consignment to meet specified requirements.
Shipper means any person by whom or in whose name, or on whose
behalf, a contract of carriage of goods by sea has been concluded
with a carrier, or any person by whom or in whose name, or on whose
behalf, the goods are actually delivered to the carrier in relation
to the contract of carriage by sea.
Solid bulk cargo means any cargo, other than a liquid or a gas,
consisting of a combination of particles, granules or any larger
pieces of material generally uniform in composition which is loaded
directly into the cargo spaces of a ship without any intermediate
form of containment.
Stowage factor means the figure which expresses the number of
cubic metres which one tonne of cargo will occupy.
Transportable Moisture Limit (TML) of a cargo which may liquefy
means the maximum moisture content of the cargo which is considered
safe for carriage in ships
Trimming means any levelling of a cargo within a cargo space,
either partial or total.
Ventilation means exchange of air from outside to inside a cargo
space.
.1 Continuous Ventilation means ventilation that is operating at
all times.
.2 Mechanical Ventilation means power-generated ventilation.
.3 Natural Ventilation means ventilation that is not
power-generated.
.4 Surface Ventilation means ventilation of the space above the
cargo.
Group A consists of cargoes which may liquefy if shipped at a
moisture content in excess of their transportable moisture
limit.
Group B consists of cargoes which possess a chemical hazard
which could give rise to a dangerous situation on a ship.
Group C consists of cargoes which are neither liable to liquefy
(Group A) nor to possess chemical hazards (Group B).
Information given by shipper to master when loading bulk
cargoes.
Regulation 4 of IMSBC
Cargo information
1 The shipper shall provide the master or his representative
with appropriate information on the cargo sufficiently in advance
of loading to enable the precautions which may be necessary for
proper stowage and safe carriage of the cargo to be put into
effect. Such information shall be confirmed in writing and by
appropriate shipping documents prior to loading the cargo on the
ship.
2 The cargo information shall include:
.1 in the case of general cargo, and of cargo carried in cargo
units, a general description of the cargo, the gross mass of the
cargo or of the cargo units, and any relevant special properties of
the cargo.
.2 in the case of solid bulk cargo, information as required by
section 4 of the IMSBC Code.
3 Prior to loading cargo units on board ships, the shipper shall
ensure that the gross mass of such units is in accordance with the
gross mass declared on the shipping documents.
Detailed cargo information by Shipper to Master when loading
bulk cargoes.
The shipper shall provide the master or his representative with
appropriate information on the cargo sufficiently in advance of
loading to enable the precautions which may be necessary for proper
stowage and safe carriage of the cargo to be put into effect.
Cargo information shall be confirmed in writing and by
appropriate shipping documents prior to loading. The cargo
information shall include:
- the BCSN when the cargo is listed in this Code. Secondary
names may be used in addition to the BCSN;
- the cargo group (A&B, A, B, or C);
- the IMO Class of the cargo, if applicable;
- the UN number preceded by letters UN for the cargo, if
applicable;
- the total quantity of the cargo offered;
- the stowage factor;
- the need for trimming and the trimming procedures, as
necessary;
- the likelihood of shifting, including angle of repose, if
applicable;
- additional information in the form of a certificate on the
moisture content of the cargo and its transportable moisture limit
in the case of a concentrate or other cargo which may liquefy;
- likelihood of formation of a wet base
- toxic or flammable gases which may be generated by cargo, if
applicable;
- flammability, toxicity, corrosiveness and propensity to oxygen
depletion of the cargo, if applicable;
- self-heating properties of the cargo, and the need for
trimming, if applicable;
- properties on emission of flammable gases in contact with
water, if applicable;
- radioactive properties, if applicable; and
- any other information required by national authorities.
Information provided by the shipper shall be accompanied by a
declaration.
Preparations of holds prior to loading bulk cargoes.
Reasons for rejecting cargo holds for loading
a. Cargo contamination problems
b. Problems stemming from previous cargo
c. Cargo stain
d. Rust, rust scale and paint flaking
e. Unsanitary conditions
f. Wetness
g. Odours
h. Infestation
Hold cleaning safety precautions:
• hold cleaning operations to be authorised by master and chief
officer. Bridge to be contacted and kept informed
• work permit system in place
• master should carry out risk assessments in poor weather
(enclosed space precautions to be taken in closed hatches)
• all personnel to wear correct personal protective equipment
(PPE)
• all personnel to be aware of the dangers and of their
duties
• only experienced and trained crew to use high-pressure wash
guns
• airlines and hoses should be in good condition
• if chemicals are used, safety data sheets must be consulted
and precautions taken
• all equipment to be checked before use and confirmed to be in
good condition
• all ladders and accesses to be in sound condition
• all portable ladders to be properly secured
• proper lighting to be used
• proper communications to be available between those in the
hold, on deck and on the bridge
• lifting equipment must be in good condition
Proper, diligent and recorded ballast tank inspections must be
carried out and form a part of the ship’s planned maintenance
system
• ballast tank inspections should form the basis of a
dry-docking defect list
• a proper system of inspections and checks must be carried out
to assess the integrity of ballast tanks after hold cleaning and
during the ballast voyage
• bulk carrier inspections should include all parts and areas
where water ballast can get into cargo holds: bilge systems,
manhole covers, and tank top and bulkhead welds
• proper guidance should be given to masters and officers with
respect to cargo carriage and ballast water management
• advice and training should be given that pumping ballast can
cause extreme pressures on the tank structures and fittings such as
manhole lids, even when tanks are fitted with class approved air
vents. Consider only gravitating water ballast so as to reduce
pressure on the tanks and manhole lids
• ship’s procedures should always include rigorous checks on the
ship’s watertight integrity, including daily tank and bilge
soundings, bilge alarm tests, checks on sounding pipe caps and
inspections of spaces not often visited, including cofferdams and
void spaces
Cargo contamination problems
Whatever the previous cargo, all holds should be swept clean,
and loose scale and rust removed. When reloading the same cargo
commodity, there is a tendency to leave the holds unswept. In
general terms, this is not good practice since the residual cargo
can hide damage to the hold or tank top. Traces of previous
cargoes, such as sulphur, sulphur traces in coal cargoes and some
fertiliser cargoes may corrode bare steel plate. It is recommended
that holds are swept clean after every cargo and the residues
removed or, if reloading the same cargo type, placed to one side so
that a tank top and hold inspection can be carried out. Large
amounts of cargo remaining onboard may not only cause outturn
problems, but hide damage to the tank top plate. The level of
cleanliness of the hold required will vary from port to port, and
shipper to shipper. As a general rule, if nothing specific is
stated, a double sweep, with a saltwater wash followed by
freshwater wash, is a sensible option.
In order to avoid delays or off hire of the ship, hold cleaning
requires
a. proper planning.
b. Problems stemming from previous cargo The holds will be
declared unfit for loading if any residue of the previous cargo,
other debris or substances, dunnage residue or a need for repair or
hot work is found. Action: Sweeping and removing all residues,
followed by a thorough wash-down using high-pressure air or water
cleaning equipment.
c. Cargo stain: Cargo stains are not acceptable if they rub off
and risk contaminating the next cargo.
d. Rust, rust scale and paint flaking All areas affected by rust
and flaking paint will be checked by the surveyor. The holds will
be declared unfit if loose rust or paint flaking is found
e. Unsanitary conditions If a hold is found to contain animal
filth, bird droppings, faeces or sewage, it will be rejected. There
must be no evidence of rats or rat droppings. If this is suspected,
specialist assistance and probably fumigation will be required by
the local authorities who should be notified accordingly.
f. Wetness All holds must be dry. If the holds contain water or
leaking water, the vessel will be declared unfit. Bilges and bilge
wells must be dry
g. Odours All grain storage areas must be odour-free. This
includes odour from paint and cleaning chemicals
h. Infestation Holds will be declared unfit to load grain if
three or more insects, dead or alive, are found in one hold. The
holds will also be declared unfit if larvae or unhatched insect
eggs are found. Under the Australian Quarantine Inspection Service
rules, there must be no bugs: any found will result in the hold
failing the cleanliness survey.
All adjacent spaces to the holds, (for example, mast houses and
storage spaces) should be inspected to ensure that they are also
infestation-free.
Different types of hatch cleaning
1. hospital clean, or ‘stringent’ cleanliness
2. grain clean, or high cleanliness
3. normal clean
4. shovel clean
5. load on top
Hospital clean is the most stringent, requiring the holds to
have 100% intact paint coatings on all surfaces, including the tank
top, all ladder rungs and undersides of hatches. The standard of
hospital clean is a requirement for certain cargoes, for example
kaolin/china clay, mineral sands including zircon, barytes, rutile
sand, ilmenite, fluorspar, chrome ore, soda ash, rice in bulk, and
high grades of wood pulp. Generally, these high standards of
cleanliness will only be met by vessels trading exclusively with
such cargoes. It will rarely be required in the tramp trades.
Grain clean The most common cleanliness requirement for bulk
carriers is that of grain clean. The usual instructions a master of
a tramping conventional bulk carrier will receive, particularly if
his ship is unfixed for next employment, is Clean to grain clean on
completion of discharge. This guideline is aimed at the majority of
bulk carriers engaged in the carriage of ‘usual’ bulk cargoes in
conventional ships, which are cleaned to a grain clean standard. As
noted above, there are certain cargoes, such as kaolin, which
require the higher standard of cleanliness or hospital clean.
“Compartments are to be completely clean, dry, odour-free, and
gas-free. All loose scale is to be removed.”
The definition is clear:
1. all past cargo residues and any lashing materials are to be
removed from the hold
2. any loose paint or rust scale must be removed
3. if it is necessary to wash the hold, as it generally will be,
the holds must be dried after washing
4. the hold must be well ventilated to ensure that it is
odour-free and gas-free
Normal clean means that the holds are swept clean, with no
residues of the previous cargo, and washed down (or not, depending
on charterer’s requirements), that is, cleaned sufficiently for
taking cargoes similar to or compatible with the previous
shipment.
Shovel clean means that all previous cargo that can be removed
with a ‘Bobcat’ or a rough sweep and clean with shovels by the
stevedores or crew. The master should clarify what standard is
expected.
Load on top means exactly what it says – the cargo is loaded on
top of existing cargo residues. Usually, this means ‘grab cleaned’.
This standard will commonly be required where a ship is trading
continuously with the same commodity and grade of that commodity.
This will typically occur when a ship is employed under a Contract
of Affreightment to carry, for example, a single grade of coal over
a period. With such a trade, there is no commercial need for holds
to be cleaned between successive cargoes, and each cargo is simply
loaded on top of any remaining residues from the previous cargo.
With load on top, guidance may be necessary for the master on any
cleaning requirements, including the use of bulldozers and cleaning
gangs.
Case study 1
A 24-year-old panamax bulk carrier was chartered out for a
single voyage time charter to load barley in a Black Sea port in
the Ukraine. The voyage orders from the head charterers gave the
following instructions to the master based on the charter party
terms.
“On arrival at the load port, vessel to be clean, swept/washed,
dried and ready in every respect and in all compartments to receive
charterer’s cargo to local surveyors’ and/or competent authorities’
satisfaction – failing which the ship to be offhire and owners to
take immediate steps to expedite cleaning as fast as possible
including the use of shore labour. If ship fails inspection the
bunkers consumed and extra directly related costs to be for owner’s
account until ship has been passed in all loading holds.”
The ship left the last port having discharged a cargo of
petcoke. The voyage to the next loading port was four days. Poor
weather hampered the hold cleaning by the crew. It is evident that
for a ballast voyage of this short duration, taking account of the
age, size of ship and the last four cargoes, four days to carry out
hold cleaning ready for grain was not going to be sufficient. The
master advised the owners of this fact. The sequence of the
previous four cargoes had been petcoke, coal, coal, bauxite. As a
guide, with a normal crew complement who are experienced, organised
and have the correct equipment, it will take one day to clean a
hold of a panamax bulk carrier, although drying the holds will
obviously take longer and will normally require the hatch lids to
be opened to air. Holds with previous cargoes such as petcoke or
bauxite may take longer to achieve a grain clean condition. The
cleaning time will also be longer if the vessel encounters heavy
weather, if access to the deck is restricted, if hatch covers
cannot be opened or if the use of crane or davit winches to lift
out cargo residue is restricted.
An inspection took place on arrival at the load port and all
seven holds were rejected because of the presence of residue and
dust from previous cargoes, and remaining water in the holds and
bilges. The following day, shore cleaning gangs attended the ship
and six days later, the ship was again presented to the surveyor.
Again, the ship failed for similar reasons plus the fact that loose
rust scale was present on the tank top. It was found that the
cleaning gangs did not have sufficient personnel or equipment (15
persons for a 24-hour operation, when 30 people would have been
more appropriate); they did not use high-pressure wash-down guns;
and used only cold water without chemicals.
The charterers decided to send the ship to another port for
another cargo, and a day later, the grain surveyor again found the
holds unfit to carry cargo. Another set of shore cleaning gangs
came aboard to clean the holds and three days later, the holds were
finally passed as clean and dry, and ready to load. It is worth
noting that even on the survey which the ship passed, there was
evidence of petcoke staining on the hold bulkheads.
The claim from the charterers was that the ship was not ready to
load under the terms of the charterparty and that there was a loss
because the first cargo of grain could not be loaded. The claim
amounted to some $400,000.
A benchmark for considering a ship grain clean is given by the
US Department of Agriculture: “To be considered fit the holds must
be clean, dry, free of odour and infestation, and otherwise
suitable to receive and store grain insofar as the suitability may
affect the quality, quantity or condition of the grain.”
Lessons learnt
• owners’ chartering departments should have a good
understanding about what can practically be achieved in hold
cleaning and having the ship ready to load
• owners’ operations departments should be consulted by their
chartering departments as to the condition of the ship and the time
required to get the holds cleaned
• owners’ operations departments should have a good
understanding of what is required in terms of personnel and
equipment to carry out an efficient hold cleaning operation
• owners’ management should train personnel and institute
guidelines for chartering departments about hold cleaning
procedures
• masters must take a robust stand when asked to carry out hold
cleaning operations that are patently unrealistic. Masters should
not be forced into taking undue risks over hold cleaning in trying
to comply with unrealistic laycan dates
• masters should ensure that good records, with photographs, are
maintained for hold cleaning operations, particularly for sensitive
cargoes
Case study 2
A ship loaded a full cargo of aluminium hydroxide in Australia
for discharge in the USA. The ship was equipped with box holds,
which allowed for easier cleaning and inspection before
loading.
At the discharge port, at the same time as the ship was being
unloaded, seawater ballast was being taken onboard. It was later
found during the discharge that 500 tonnes of the cargo was water
damaged by the ballast, which was confirmed to come from a hole
measuring 100mm x 20mm in the hold/ballast tank steel plating. The
hole was most likely to have been caused by stevedore grab damage
in the discharge port. The cost of damage to the cargo was put at
around $150,000.
Cargo watch on deck should monitor
• stevedore grab handling and damage. Crane drivers should be
advised to take care not to damage ship structure
• cargo watch on deck should monitor ballast operations
• cargo watch on deck when the ship is carrying water-sensitive
cargoes should identify the potential for water to leak from a
crack or damage in the hold plating following grab damage
• consider gravitating ballast, to reduce pressure on ballast
tank structures
• a rigorous sounding regime should be maintained in port
• hopper sides and indents paint coating: damaged areas to be
repaired
• attention to tank top damage and indents
• tank top double bottom or side tank access lid damage. If
double bottom lids are removed to inspect the tanks, they must be
properly refitted. The condition and the fitting of the gaskets
must be checked by a competent person, and nuts should be
screwed down securely and pressure-tested before the next cargo is
loaded
• hold ladders, platforms and hand rails should be in a sound
and safe condition
• checks on hold piping, air vent and water ballast sounding
lines, and piping protection brackets
• bilge wells, including bilge covers, strum boxes, and bilge
well valves, including non-return valves should be in a clear and
sound condition. Bilge systems are an increasing cause of wet
damage cargo claims. Non-return valves must be checked to ensure
they are fully operational. They should be included in the planned
maintenance system and formally checked every three to four months,
operations permitting. Bilge lines should be blown back to confirm
the effectiveness of the valves
• bilge high-level alarms should be checked
• lights and light fittings should be checked as operational.
There have been claims, including some of high value, where the
ship and the cargo have been in jeopardy after the hold lights were
left on and/or the lighting wiring was in poor condition, leading
to fires in the cargo hold or the ladder trunking. All hold
lighting circuits should be disarmed prior to loading.
Case Study 3
In 2008, a 20-year-old panamax bulk carrier loaded a cargo of
cement in Taiwan for the USA. The ship was not loaded to her marks
and for some reason, the master considered it necessary to take
additional water ballast for the voyage across the Pacific.
During the voyage, it was decided to carry out a ballast water
exchange as provided for in the ballast management plan. This
ship’s double bottom ballast tanks were connected with the upper
wing tanks by a ballast trunking. Therefore, the upper wings had to
be filled through the double bottoms, pumping ballast water up the
ballast trunking into the upper wing tanks.
During the ballast water exchange, water seeped into one of the
holds containing a full cargo of cement, through a corrosion hole
in the trunking between the double bottom and the upper wings.
It was found the next day after filling the upper wing tanks
that one ballast wing tank was not full – so more ballast was
pumped in. There was no consideration given as to why the upper
wing tank had become slack.
On arrival at the discharge port, the draft survey appeared to
show that there was more than 1,000 tonnes of ‘cargo’ onboard than
loaded. Of course, this was not the case and that extra weight was
seawater ballast in the cargo hold. The 1,000 tonnes of seawater
and 11,000 tonnes of cement combined to make a substantial ‘cement
box’. This cement lump in the hold took over six weeks to dig out
and the claim amounted to more than $2m, excluding offhire and
ongoing ship operation costs.
Protection of deck machinery from dust. In the dusty environment
proper protection to be provided to deck machinery. Else they may
not function well
Prewash chemicals
The use of a prewash can protect the paint coating of the holds
and allow for a much easier cleaning after cargoes which are liable
to stain. The prewash coating is applied in the same way as the
cleaning chemicals (see below) and dries off as a clear protective
film. This is then washed off after discharge. Such prewash
chemicals are also known as ‘fat cargo slip’.
The prewash prevents the cargo adhering to the hold surfaces.
Prewash is less effective on rough, uncoated surfaces such as the
hold tank top. Application in a handymax ship takes about three
hours per hold. Prewash protects the paintwork and can reduce time
required for painting in preparation for the next cargo.
Cleaning chemicals
There are a number of products available and the manufacturer’s
instructions for mixing proportions and the safety precautions
should always be followed. If the recommendation is to use only
freshwater to apply the chemical, this should be followed,
otherwise the application may be ineffective. Equally, without use
of the proper equipment, the application may not work.
The chemicals are usually applied using special equipment
including:
• chemical tank
• mini-jet with air pressure of about 7 bar
• lance with foam nozzles and extensions
• personal protective equipment (PPE)
After leaving the applied chemical on the bulkhead for a
prescribed time, the chemicals are washed off using a full seawater
wash. The operation should always be finished with a freshwater
wash. Always check the manufacturer’s guidance on compatibility
with paint systems. Always check with the charterer and/or
shippers
regarding compatibility with the next cargo.
A four-year-old bulk carrier loaded a part soya bean meal/grain
cargo at a South American port before proceeding to a second port
to complete loading, for discharge in the Mediterranean.
After leaving the first load port, water was found in two of the
cargo hold bilges. The ship was not carrying any ballast water.
These bilges were pumped out and the following day a similar
quantity of water was found in the hold sounding pipes. This
continued for a few more days until the bilge lines were blanked
off.
At the discharge port, a surveyor investigated the cause of
water ingress into the cargo holds and concluded:
· a butterfly valve on the bilge and ballast pump line was
faulty and leaking
• all the pressure gauges on the eductor system were
defective
• one of the non-return bilge suction hold valves could not
close properly because a rag was blocking the valve
• butterfly valves on the bilge line did not seat or close
properly
• no non-return valve was fitted to one of the hold suction
lines – a defect that presumably stemmed from the time the vessel
was built
• there were no bilge high-level alarms fitted
Case Study
A claim arose over which party was responsible for carrying out
the hold cleaning of a panamax bulk carrier following a cargo of
petcoke. The charterers had engaged a shore cleaning company to
carry out hold cleaning. The main issue was to decide who was
responsible for ensuring that the holds were ‘swept clean’ after
discharge and who was responsible for ensuring that the bilges were
cleaned out after the wash-down. The charterers maintained that the
crew should have ensured that the holds were swept clean before the
wash-down began so that minimal debris was washed into the bilges;
the owners maintained that the cleaning and washing of the holds,
including the sweep-down and cleaning of the bilges, was the duty
of the charterers’ agents, in other words the cleaning company. The
crew neglected to carry out proper monitoring of the cleaning
process, with the result that the hold bilges were full of residue
cargo. The problem resulted in delays and offhire, the ship missing
the laycan for the next charter, and additional cleaning costs.
Hazards associated with bulk cargoes and precautions prior,
during and after loading of:,
Coal
Coals may emit methane, a flammable gas. A methane/air mixture
containing
between 5% and 16% methane constitutes an explosive atmosphere
which
can be ignited by sparks or naked flame, e.g. electrical or
frictional sparks, a
match or lighted cigarette. Methane is lighter than air and may,
therefore,
accumulate in the upper region of the cargo space or other
enclosed spaces.
If the cargo space boundaries are not tight, methane can seep
through into
spaces adjacent to the cargo space.
Coals may be subject to oxidation, leading to depletion of
oxygen and an
increase in carbon dioxide in the cargo space.
Some coals may be liable to self-heating that could lead to
spontaneous
combustion in the cargo space. Flammable and toxic gases,
including carbon
monoxide, may be produced. Carbon monoxide is an odourless gas,
slightly
lighter than air, and has flammable limits in air of 12% to 75%
by volume. It
is toxic by inhalation, with an affinity for blood haemoglobin
over 200 times
that of oxygen.
Some coals may be liable to react with water and produce acids
which may
cause corrosion. Flammable and toxic gases, including hydrogen,
may be produced. Hydrogen is an odourless gas, much lighter than
air, and has flammable limits in air of 4% by 75% by volume.
The carbon monoxide concentration in each cargo space should be
measured at regular time intervals to detect selfheating.
If at the time of loading, when the hatches are open, the
temperature of the coal exceeds 55oC, expert advice should be
obtained.
If the carbon monoxide level is increasing steadily, a potential
self-heating may be developing. The cargo space should be
completely closed down and all ventilation ceased. The master
should seek expert advice immediately. Water should not be used for
cooling the material or fighting coal cargo fires at sea, but may
be used for cooling the boundaries of the cargo space. Monitoring
the atmosphere of the cargo space is essential at least once daily,
twice daily if rapid changes are detected.
Dry sulphur does not react with bare steel, but wet sulphur
(sulphur containing free water) is potentially highly corrosive.
Cargoes of sulphur in bulk are normally afforded exposed storage
and are thus subject to inclement weather and consequent moisture
content. The stock will also include a percentage of sulphur dust
particles. In order to prevent contaminated air emissions, it is
the practice, especially in Canada and the USA, where loading
wharves are situated in built-up areas and the dust is considered
to be a pollutant, for the environmental authorities to insist upon
the use of a water spray during handling to keep down the dust
Corrosion When sulphur is loaded, any retained free water
filters to the bottom of the holds during the voyage. From there it
is pumped out via the bilges. Some water remains on the tank tops,
and together with the fines, produces a sulphurous mud. A great
deal of research has been undertaken to understand and mitigate
corrosion to vessels’ structures during the handling and
transportation of sulphur. There are two processes whereby a
corrosion reaction can occur, namely acidic and electrochemical
corrosion.
Acidic corrosion This involves a reaction between an acid and
elemental iron (steel). The acid involved is sulphuric acid
(H2SO4). Corrosion does not become significant until the acidity of
the solution increases to or below pH2.
Electrochemical corrosion It has been established that the
electrochemical reaction involves a redox (reduction/oxidation)
reaction between iron and sulphur. The specific requirements for
this reaction to take place are that sulphur and iron are in direct
contact and that the sulphur must be wet
The presence of chlorides – in the form of salts, such as sodium
and potassium chlorides - can hasten the interaction between the
moist sulphur and ship’s steel. Sodium chloride is for example, a
major constituent of both salt cake and dissolved materials found
in sea water, while potassium chloride (potash) is regularly
shipped from Vancouver. Any trace of these substances will lead to
an accelerated corrosion effect, so hold cleanliness prior to
loading is of the utmost importance.
Prior to loading sulphur, it is recommended that the receiving
holds should be in a ‘grain clean’ condition.
Handling iron ore in bulk carrierThe majority of incidents where
bulk carriers have been lost were when carrying iron ore. In the
carriage of iron ore, the following precautions should be
taken:
1. Iron ores are heavy cargoes which occupy a small area for a
large weight, ie they have a low stowage factor (between 0.24
m3/tonne). It is therefore important that the tanktop has
sufficient strength to carry certain iron ores.
2. trimming of these cargoes is generally required (even though
their angle of repose is mostly above 35°) to spread their weight
across the entire tanktop
3. the stability of vessels as iron ore is a high density cargo,
when loaded on an ordinary bulk carrier (not an ore carrier) it
will increase the vessel's GM to make it a `stiff' ship.
4. dust iron ore is commonly loaded with conveyor belts, grabs,
chutes and bucket belt unloaders, causing significant quantities of
dust during both loading and discharging. However, enclosed
conveyor belt systems generate less dust. The dust may damage
ship's machinery as well as the health of personnel.
5. moisture content iron ore is assumed to have a homogeneous
moisture content between 016%. However, if kept lying in the open,
the moisture content may increase due to absorption from air or
rain. If the exact moisture content is unknown, a proper laboratory
test may be called for. The Master must also ask the shipper to
detail the cargo's moisture content and TML
6. In recent years an increase incidents attributed to carrying
iron ore filings with excessive moisture content, causing sloshing
and adverse stability and in some cases the rapid loss of the ship.
During the monsoon season in the Indian sub-continent iron ore
filings are stored and transported open to the elements. It is
worth remembering that the cargo may remain stockpiled before being
shipped later in the dry season
7. It is imperative that the cargo moisture content is tested
prior to and monitored during all stages of loading as, once
onboard, cargo may be extremely difficult to remove. The
shipper's test certificate should be presented before loading, be
sound and no more than seven days old. A good indicator during the
load is the presence of splatter marks of iron ore filings on the
bulkheads. If splatter marks are evident, they should be taken very
seriously as an indication that the moisture content is above the
TML and the flow moisture point. If the Master is in any doubt, he
should contact the owners and the P&I Club correspondent.
8. stress monitoring stresses upon the ship, both in port and at
sea, should be monitored using an HSMS (Hull Stress Monitoring
System) if fitted, and the movement of cargo and ballast monitored
using stress calculating software
9. alternate hold loading bulk carriers sometimes carried iron
ore in alternate holds at the request of charterers owing to the
economic advantages of faster turnround and raised centre of
gravity. To do so ships must be specially strengthened.
10. The iron ore standard sampling procedure given in the IMSBC
Code should be followed.
Precautions for carriage of concentrates:
Iron concentratesConcentrates of iron are produced by
either:
1. the dry method, in which high grade ore is crushed to remove
waste material, leaving a low moisture content in the powdered ore.
Iron concentrates obtained by the dry method are susceptible to
spontaneous combustion because of the air already trapped within
the concentrate during the crushing process.Due to dampness within
the cargo, the sulphur can react with the oxygen to produce heat,
resulting in spontaneous combustion. Therefore, for concentrates,
the holds should be kept closed and ventilation avoided.
Additionally, due to sulphur and other metallic contents within
concentrates, these may emit poisonous/explosive gases. The cargo
spaces should be treated as enclosed spaces and appropriate entry
procedures followed
2. the wet method, in which the crushed rock is washed in water
to separate the sulphides. The concentrate has a high moisture
content that may liquefy and shift onboard ship. The moisture
content of these concentrates should therefore be checked prior to
loading and, if above TML, the cargo should be rejected
Sponge Iron, Pig Iron, Blended iron-ore etc are examples
Concentrates:
As the density of the cargo is extremely high, the tanktop may
be overstressed unless the cargo is evenly spread across the
tanktop to equalize the weight distribution. Due consideration
shall be paid to ensure that tanktop is not overstressed during
voyage and during loading by a pile of the cargo.
PRECAUTIONS
Appropriate precautions shall be taken to protect machinery and
accommodation spaces from the dust of the cargo. Bilge wells of the
cargo spaces shall be protected from ingress of the cargo. Due
consideration shall be paid to protect equipment from the dust of
the cargo. Persons, who may be exposed to the dust of the cargo,
shall wear goggles or other equivalent dust eye-protection and dust
filter masks. Those persons shall wear protective clothing, as
necessary.
Liquid cargoes
Oils and fats in bulk which solidify and require to be heated to
liquefy and be pumped out will give a false reading when gauges if
the contents of the tank are not completely liquefied. The
temperature of the liquid portion, if used in the calculations,
will not allow for expansion of the still-solidified portion and
the volume indicated will be less than it would be if all were
liquid. Quality samples would also be unrepresentative if taken an
only partly liquefied bulk. Too rapid heating may cause burning of
the commodity adjacent to the steam coils and shippers’
instructions in this respect should be observed. Unavoidable normal
losses by adhering of oil/fat to tank walls, pipelines, etc., are
often allowed for by the terms of the sales contracts and a
surveyor unfamiliar with bulk oil carriers, tank calibrations,
sampling procedures, significance of moisture content, etc., should
consult an expert. Where contamination is suspected or confirmed,
an analyst conversant with the commodity should be appointed to
sample and/or test. The sampling to be carried out, where possible,
in the presence of all interested parties
Hazards of Bulk Liquids
Flammability The volatility (i.e. the tendency of a product to
produce gas) is characterised by the vapour pressure. When a
product is transferred to a gas free tank or container, it starts
to vaporise, that is it liberates gas into the space above it.
Flammability is a primary risk in the handling of petroleum; this
creates an ever present hazard.
Density The gases from bulk liquids can be heavier than air and
handling of cargoes should take account of the hazard that this
property presents.
Toxicity Introduction Toxicity is the degree to which a
substance or mixture of substances can harm humans. Toxic means the
same as poisonous
Ingestion The oral toxicity of chemical products varies in a
wide range and the Material Safety Data Sheet (MSDS) should be
checked for the specific information on the product and for the
measures that have to be taken when a person swallows it. The MSDS
will also describe the required Personal Protective Equipment
(PPE). Petroleum has low oral toxicity, but when swallowed it
causes acute discomfort and nausea. There is then a possibility
that, during vomiting, liquid petroleum may be drawn into the lungs
and this can have serious consequences, especially with higher
volatility products, such as gasolines and kerosenes.
Absorption For chemical products the effect of absorption can
vary considerably. Products can have acute effects
(unconsciousness, dizziness, chemical burns, organ failure, death)
or chronic effects (cancer, organ damage, reprotoxic). The Material
Data Sheet should be checked for the specific information on the
product and for the measures that have to be taken when a person
has skin contact with it. Many petroleum products, especially the
more volatile ones, cause irritation and remove essential oils,
possibly leading to dermatitis, when they come into contact with
the skin. They can also cause irritation to the eyes. Certain
heavier oils can cause serious skin disorders on repeated and
prolonged contact. Direct contact with petroleum should always be
avoided by wearing the appropriate protective equipment, especially
impermeable gloves and goggles.
Product Vapours
Inhalation The effects of inhaling product gases can vary
considerably. Gases can have acute (unconsciousness, dizziness,
chemical burns, organ failure) or chronic (cancer, organ damage,
reprotoxic) effects. Of importance is the risk of pulmonary oedema.
Liquid in the lungs can cause serious shortness of breath and often
may occur hours after the inhalation. The Material Data Sheet
should be checked for the specific information and for the measures
that have to be taken when a person has inhaled the product vapour.
The MSDS will also describe the required PPE. The absence of smell
should never be taken to indicate the absence of gas. In general,
the danger of the product increases when the vapour pressure is
high and the Threshold Limit Value is low. Comparatively small
quantities of product gas, when inhaled, can cause symptoms of
diminished responsibility and dizziness similar to intoxication,
with headache and irritation of the eyes. The inhalation of an
excessive quantity can be fatal. This depends mainly on the
product, for which information should be sought from the MSDS.
These symptoms can occur at concentrations well below the Lower
Explosive Limit. However, petroleum gases vary in their
physiological effects and human tolerance to these effects also
varies widely. It should not be assumed that, because conditions
can be tolerated, the gas concentration is within safe limits. The
smell of product gas mixtures is very variable and in some cases
the gases may dull the sense of smell. The impairment of smell is
especially likely, and particularly serious, if the mixture
contains hydrogen sulphide.
Exposure Limits The exposure limits are always described in the
MSDS. Exposure limits set by international organisations, national
administrations or by local regulatory standards should not be
exceeded. The values quoted are expressed as Threshold Limit Values
(TLVs) in parts per million (ppm) by volume of gas in air.
Reprotoxicity Reproductive toxicity is a hazard associated
with some chemical substances, that they will interfere in some way
with normal reproduction; such substances are
called reprotoxic. It includes adverse effects on sexual
function and fertility in adult males and females, as well as
developmental toxicity in the offspring
Odema is a condition characterized by an excess of watery fluid
collecting in the cavities or tissues of the body.
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