5a-solid bulk cargo(1)

KNR/Jan14 SP-SMA Slide 1

Learning Objectives 5ALearning Objectives 5ASolid Bulk CargoSolid Bulk Cargo

Define solid bulk cargo Describe the hazards associated with the carriage of

solid bulk cargo Define : Angle of Repose, Moisture Content, Flow

Moisture Point, Transportable Moisture Limit, Moisture Migration

Describe the preparations of holds prior to the carriage of solid bulk cargoes

State the precautions prior to the carriage of solid bulk cargoes

Describe the methods used for loading and discharging solid bulk cargoes


Solid Bulk CargoSolid Bulk Cargo


Carriage of solid bulk cargoes is governed by International Maritime Solid Bulk Cargoes Code (IMSBC Code) and supplement (2013 edition, amdt 02-13)

Code published by International Maritime Organisation (IMO).

Apply to carriage of “dry” and “wet” bulk cargo and do not apply to carriage of Grain in Bulk, which have separate regulations.

Introduction


Definitions

Angle of Repose is the angle between the horizontal and the slope of the cargo obtained when that cargo is poured onto the horizontal. The greater the angle-it is less likely to shift.

Angle of Repose


Definitions-Continue.. Flow Moisture Point is the percentage moisture content (on a

wet basis) at which a flow state develops.Vessels built specially for the carriage of bulk cargoes and sufficiently sub-divided are not so highly restricted in their loading procedures with concentrates as cargo vessels would be.

Flow State is the state that occurs 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 the ship’s motion, it loses its internal shear strength and behaves like a liquid.

Moisture Content is the portion of a representative sample of a material which consists of water, ice, or other liquid expressed as a percentage of the total wet weight of that sample.


Definitions-Continue.. Moisture Migration is the movement of moisture contained in a

bulk 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 bulk cargo developing a flow state.

Transportable Moisture Limit (TML) is the transportable moisture limit of a cargo which may liquefy represents the maximum moisture content of that cargo which is considered safe for carriage in ships which are not specifically fitted or constructed for cargoes for excessive moisture content. It is expressed as a percentage of the flow moisture point. The TML is 90% of the Flow Moisture Point.


General precautions with bulk cargoes

Bulk cargo must be properly distributed throughout the ship in order that the structure will never be over stressed.

1. A stability booklet provided giving relevant information pertaining to loading, precautions and any necessary data should be provided to the Master. Prior to sailing, the Master should calculate the stability for the anticipated worst conditions during the voyage as well as that on departure and ensure they are satisfactory.

2. An excessively stiff ship may roll very violently, resulting in

damage to the ship. However, a vessel with a relatively large GM is better able to resist the tendency to list, if a shift of cargo should occur.

3. When loading a high density bulk cargo with a S.F. of about

20ft3/ton (0.56m3/tonne) or lower, the loaded condition are different from normal and particular attention should be paid to the distribution of weights to avoid excessive stresses.


General precautions with bulk cargoes

A general cargo vessel is normally constructed to carry cargoes of about 50 - 60ft3/ton (1.39 to 1.67m3/tonne) when loaded to full bale and deadweight capacity. In such cases, the ship master should be provided with comprehensive loading information so that the ship may not be over stressed.

Where above information is not available, the following precautions should be observed :

a) The general fore and aft distribution of weight should not differ appreciably from that found satisfactory for general cargo.

b) The maximum number of tonnes of cargo loaded in any space should not exceed : 0.9 x L x B x D (tonnes)

c) If cargo is untrimmed, the height of the cargo pile above the floor (in Metres) should not exceed :

1.1 x D x Stowage Factor (m)where L=L of hold(m), B=Av breadth of hold(m), D=Summer Load Draft(m), stowage factor in m3/tonne.


General precautions with bulk cargoes (continue..)

d) If the cargo is trimmed, entire level, the maximum load in the lower hold may be increased by 20% subject in compliance with (a) in the preceding page.

e) In holds with a shaft tunnel, lower holds may be loaded to 10% in excess of the trimmed or untrimmed values subject to compliance with (a). A shaft tunnel has an extra stiffening effect.


Hazards associated with the Hazards associated with the carriage of Solid Bulk Cargoescarriage of Solid Bulk Cargoes

1 Improper weight distribution resulting in structural damagea) Excessive concentration on deck or inner bottomb) Improper distribution of weights between holds

2. Improper stability or reduction in stabilitya) Excessive stability (stiff ship) resulting in violent rolling and possible cargo shift and structural damage.b) Reduction of stability as a result of :i) A transverse shift of the cargo surface as in the case of “DRY” cargoes and cargoes which do not become fluid when wet.ii) A transverse shift of “WET” cargoes which become fluid and give rise to free surface effect.

3. Spontaneous heating may occur in some cargoes eg. Fine copper ore, metal turnings and borings are subject to spontaneous heating.

4. Chemical reaction. Some categories of bulk cargo may be liable to chemical reaction, eg coal cargo emits toxic or explosive gas and have the effect of causing corrosion to steel structure.


Assessing the acceptability of consignment

Before loading commences, the Master should be provided with appropriate information concerning the characteristics and properties of the cargo. Such information should contain as a minimum :

Chemical Hazards Flow Moisture Point Stowage Factor Moisture Content Angle of Repose

The Master should be given certificates which include : A certificate which states the Transportable Moisture Limit A certificate of moisture content A statement to indicate the actual moisture content of cargo at the

time the certificate is given to the Master Certificate listing the material with chemical hazards if carried.


Trimming ProceduresTrimming Procedures

Preferably bulk cargoes should be trimmed to entire level. Where a peak arises, following two categories should be considered:

Cargoes with angle of repose LESS THAN OR EQUAL TO 35 DEGRESS (non-cohesive).

Cargoes with angle or repose GREATER THAN 35 DEGRESS (non -cohesive).


Non-cohesive bulk cargoes having an Non-cohesive bulk cargoes having an angle of repose LESS THAN OR angle of repose LESS THAN OR

EQUAL TO 35 DEGREESEQUAL TO 35 DEGREES

More dangerous category, subject to liquefaction process Usually small granules – shift easily when ship moves Granules liable to absorb moisture, may form sludge

affecting ship’s stability Code recommends:1. Cargo be trimmed reasonable level, filing up all spaces-

no excessive cargo weight in one location2. If cargo flow like grain, stowage procedures for grain to

be considered


Non-cohesive Bulk Cargoes with angle Non-cohesive Bulk Cargoes with angle of repose GREATER THAN 35 of repose GREATER THAN 35

DEGREESDEGREES

Consists of lumps – interlocking – quite stable Can become heaped up to produce excessive pile

peak Major hazard if cargo shift, unable to return to

original position – may cause a permanent list Not usually subjected to liquefaction Code recommends:1. If loading in Lower Holds only, trim to cover all

tanktop to shipside, reduce pile peak2. Equalise distribution of weight


GENERAL PRECAUTIONS –PRIOR GENERAL PRECAUTIONS –PRIOR TO LOADING BULK CARGOTO LOADING BULK CARGO

Safety precautions for crew and others working onboard must be taken and to ensure minimum contact with moving machinery used in loading.

Holds inspected –in proper state for reception of cargo, paying particular attention to ; Bilge wells and lines, Sounding pipes & other service units with

Protective coverings- checked & strengthened Bilge wells & strainers plates- facilitates drainage

Prevent dust coming into contact with moving parts of deck machinery

Accommodation vents- screened or shut down Cargo hold lighting, fire detection & flooding system piping

covered Sound bilges at completion of loading Establish communication with terminal


METHOD OF LOADING / METHOD OF LOADING / DISCHARGING BULK CARGODISCHARGING BULK CARGO

Heavy duty conveyor belt systems used in most form of solid bulk cargo loading

Some forms of ore transported in “slurry” for – piping used for handling

Conveyor belt system led to ship loader equipped with vertical telescopic chutes

Control of dust is essential for loading fine powder bulk cargo- complying to local reg’n and avoid loss of cargo

Dust extraction equipment is fitted to ship’s loader conveyor transfer point

Loading controlled by one operator from elevated visibility clear cabin- speed and rate adjusted to meet loading pattern required by ship

Ship loader is mobile – travel on tracks along wharf Automatic arrangement provided for measuring & recording of

quantity of cargo loaded


METHOD OF LOADING / METHOD OF LOADING / DISCHARGING BULK CARGODISCHARGING BULK CARGO

Discharging of bulk cargo is mainly done using “Grabs” with ship’s/shore gears

Conveyor equipment may be installed directly from berth to stockpile/terminal

Conveyor equipment connects “bucket” unloader which by reason of arm extension “digs” into the ship bulk in the hold.

Elevator transports the bulk to stockpiles, terminal or shore transportation

This system is applicable to ore & coal commodities


Solid Bulk CargoSolid Bulk Cargo

5a-solid bulk cargo(1)

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