Section 8.7: Other Cargoes (e.g., Cement, Sugar, Sulphur, Salt, Scrap Metal) – Unique Considerations

Beyond the major commodities like iron ore, coal, grains, and specific hazardous concentrates, bulk carriers transport a diverse array of other materials. While some of these may appear less overtly hazardous than Group A or highly reactive Group B cargoes, each possesses unique characteristics and requires specific considerations for safe and effective carriage. This section will touch upon several such cargoes: Cement, Sugar, Sulphur, Salt, and Scrap Metal, highlighting their particular properties, IMSBC Code classifications, and key handling precautions.

A. CEMENT (IN BULK)

Cement is a fine, powdery hydraulic binder used in construction. When carried in bulk, its primary concerns are its extreme dustiness and high sensitivity to moisture.

Characteristics:

Very fine powder, highly susceptible to becoming airborne (dust).

Hygroscopic: Readily absorbs moisture from the air or from contact with wet surfaces. If it becomes wet, it will hydrate and harden, rendering it useless and extremely difficult to remove from holds.

Stowage Factor: Varies, but typically around 0.65 – 1.00 m³/tonne.

IMSBC Code Classification:

BCSN: CEMENT

Group: C (Generally, though some specialized cement clinkers might have different properties).

Key Hazards and Precautions:

Moisture Contamination (Primary Concern):

Holds: Must be scrupulously clean and BONE DRY. No traces of previous cargo, rust scale, or any moisture. Even minor damp patches can cause caking and hardening of cement at the boundaries.

Hatch Covers: Must be perfectly weathertight. Sealing arrangements (rubber gaskets, compression bars) must be in excellent condition. Consider additional sealing measures like hatch cover tape if there’s any doubt or if a long voyage through potentially wet weather is anticipated.

Ventilation: Generally, holds should be kept sealed throughout the voyage to prevent ingress of moist ambient air. Ventilation is usually not recommended unless specifically advised for a particular grade or if condensation within the hold (ship’s sweat) becomes a severe problem despite dry loading conditions (a rare scenario if loaded dry into dry holds).

Loading/Discharge in Rain: Must be stopped immediately if rain occurs. Hatches closed.

Dust Generation:

Cement dust is extremely fine and pervasive.

Health Hazard: Can cause respiratory irritation, eye irritation, and skin problems. Crew and stevedores involved in operations must wear appropriate PPE (high-quality dust masks/respirators – FFP2/FFP3 or N95/N100, goggles, coveralls).

Equipment Damage: Dust can penetrate machinery, electrical equipment, and accommodation if not controlled.

Dust Control:

Loading is often done via pneumatic systems directly into the hold through sealed connections to minimize dust.

If loaded by grabs or conveyors, dust suppression measures at the terminal are important.

Keep non-working hatches and accommodation/engine room openings closed and sealed.

Consider wind direction when planning operations.

Cargo Shifting:

While a powder, cement in bulk can shift, especially if the hold is not full and the vessel encounters heavy weather.

Trimming: Trim reasonably level as per IMSBC Code Section 5 to minimize void spaces and reduce the risk of shifting.

Tank Top Strength: Cement is moderately dense. Ensure tank top loading limits are not exceeded.

Hold Cleanliness After Discharge: Cement residues, especially if they have become damp and hardened, can be very difficult to remove. Thorough cleaning is essential before loading the next cargo, particularly if it’s a sensitive one. Hardened cement may require mechanical chipping.

Master’s Key Responsibilities for Cement:

Absolute insistence on bone-dry holds.

Verification of hatch cover weathertightness.

Strict dust control measures and ensuring crew PPE usage.

Careful monitoring of weather during loading/discharge.

B. SUGAR (RAW, IN BULK)

Raw sugar is a crystalline organic product. Its main concerns are hygroscopicity, susceptibility to contamination, and potential for minor fermentation or caramelization if not handled correctly.

Characteristics:

Crystalline, varies in color from light yellow to dark brown.

Hygroscopic: Absorbs moisture, which can lead to caking, stickiness, and microbiological activity (molds, yeasts).

Susceptible to contamination by odors, previous cargo residues, and dirt.

Can be slightly corrosive when wet.

Stowage Factor: Typically around 1.00 – 1.30 m³/tonne.

IMSBC Code Classification:

BCSN: SUGAR (RAW, BROWN OR WHITE)

Group: C

Key Hazards and Precautions:

Moisture Absorption and Caking:

Holds: Must be clean, DRY, and free from salt residues (which are also hygroscopic and can taint sugar).

Ventilation: This is critical and complex. The aim is to prevent condensation (ship’s sweat or cargo sweat).

Generally, ventilate only if the dew point of the ambient air is lower than the dew point of the air in the hold.

Avoid over-ventilation with very dry air, which could dry out the sugar excessively (though this is less common than moisture damage).

If in doubt, or if reliable dew point measurements are difficult, keeping holds sealed is often the safer option, provided the sugar was loaded dry into dry holds.

Hatch Covers: Must be weathertight.

Contamination:

Hold Cleanliness: Requires a very high standard, often approaching “grain clean” or even “hospital clean” if specified, to remove all traces of previous cargoes, rust, dirt, and especially odors.

Odor Tainting: Sugar readily absorbs odors. Ensure holds are free from any smells from previous cargoes, paints, or cleaning chemicals.

Separation: Do not stow near odorous cargoes or chemicals.

Fermentation/Caramelization (Minor Risks):

If sugar becomes excessively wet and warm, slight fermentation can occur, producing alcohol and CO₂.

Localized overheating (e.g., near hot engine room bulkheads) could theoretically lead to caramelization (browning and hardening), though this is rare in well-managed bulk carriage. Stow away from heat sources.

Dust: Sugar dust can be generated during handling. While not as problematic as cement dust, good housekeeping and PPE are advisable. Sugar dust can also be a slip hazard if it gets wet on decks.

Pest Infestation: While refined sugar is less prone, raw sugar can attract insects or rodents if holds are not clean or if there’s spillage.

Master’s Key Responsibilities for Sugar:

Ensuring exceptionally clean and dry holds, free of odors.

Careful management of ventilation based on dew point readings.

Protecting cargo from any moisture ingress.

Preventing contamination.

C. SULPHUR (BULK, CRUDE/REFINED/CRUSHED LUMP & FINES)

Sulphur is a yellow, combustible solid. Its primary hazards are its flammability (especially as dust), corrosivity when wet, and potential to generate toxic/flammable gases under certain conditions.

Characteristics:

Yellow crystalline or powdery solid.

Combustible. Sulphur dust can form explosive mixtures with air.

Corrosive to steel, especially when moist (forms acidic compounds like sulphurous and sulphuric acid).

Can generate static electricity during handling.

Low melting point (around 115°C).

Stowage Factor: Around 0.70 – 1.00 m³/tonne.

IMSBC Code Classification:

BCSN: SULPHUR (CRUSHED LUMP AND COARSE GRAINED) or SULPHUR UN 1350 (if meeting criteria for Class 4.1 Flammable Solid) or SULPHUR (formed, prilled, granulated or pelletized).

Group: Typically Group B (due to flammability and corrosivity). Some forms meeting specific criteria might be Group C, but always verify.

IMO Class (if applicable): Often Class 4.1 (Flammable Solid) or Class 9 (Miscellaneous) if it has corrosive properties only in bulk.

Key Hazards and Precautions:

Flammability and Dust Explosion:

Dust Clouds: Fine sulphur dust suspended in air can ignite easily and explode violently. This is the primary fire/explosion hazard.

Ignition Sources: Strictly prohibit smoking, naked lights, welding, cutting, or any spark-generating activities in or near cargo holds containing sulphur or where sulphur dust may be present.

Electrical Equipment: All electrical equipment in cargo spaces or adjacent areas must be certified safe (explosion-proof) for use in dusty, flammable atmospheres.

Static Electricity: Sulphur can generate static electricity during pneumatic loading or free fall. Ensure proper grounding/bonding of loading equipment and the ship.

Fire Fighting: Water is the primary extinguishing agent for sulphur fires (preferably as a spray or fog to cool and smother). CO₂ may not be effective on deep-seated fires and can create static. SCBAs are essential due to toxic fumes (SO₂).

Corrosivity:

Sulphur, especially when moist, reacts to form acidic compounds that are highly corrosive to steel.

Holds: Must be clean and DRY. Any moisture will accelerate corrosion.

Protective Coatings: Good quality, intact paint coatings are essential. Some operators apply a lime wash (calcium hydroxide slurry) to hold surfaces as a temporary protective barrier against acid attack. However, lime wash itself can be problematic for some subsequent cargoes and its disposal needs consideration.

Bilge Systems: Sulphur dust and acidic water can corrode bilge lines and pumps. Bilges should be kept dry and lines flushed after carriage.

Toxic Gas Emission (Sulphur Dioxide – SO₂):

If sulphur burns, it produces large quantities of sulphur dioxide (SO₂), a highly toxic and irritant gas.

Even without fire, some slow oxidation in the presence of moisture can release SO₂.

Ventilation: Surface ventilation is generally recommended to remove any accumulated SO₂ or hydrogen sulphide (H₂S – see below) from the ullage space. Ensure vents do not lead into accommodation.

Atmosphere Monitoring: Check for SO₂ (and H₂S) before any hold entry.

Hydrogen Sulphide (H₂S) Formation:

Some crude sulphurs may contain impurities or be contaminated with organic matter and moisture, leading to bacterial action that can produce H₂S, a highly toxic and flammable gas.

Monitor for H₂S, especially if a “rotten egg” smell is detected (though sense of smell is unreliable for H₂S).

Self-Heating (Less Common, but possible for some forms):

Some finely divided sulphur or sulphur with organic impurities may have a slight self-heating tendency, though it’s not usually the primary hazard like with coal.

Master’s Key Responsibilities for Sulphur:

Absolute priority on fire and explosion prevention (dust control, no ignition sources).

Ensuring holds are dry and corrosion protection measures are adequate.

Managing ventilation to remove hazardous gases.

Strict adherence to enclosed space entry procedures due to SO₂/H₂S/O₂ risks.

D. SALT (SODIUM CHLORIDE, IN BULK)

Salt, primarily sodium chloride, is carried in bulk for various industrial uses and for de-icing roads. Its main concerns are its extreme hygroscopicity and severe corrosivity when wet.

Characteristics:

Crystalline solid, white or off-white.

Highly hygroscopic: Readily absorbs moisture from the air, especially at high relative humidities.

Extremely corrosive to steel when wet, forming brine which accelerates rusting.

Can cake and harden if it becomes wet and then dries.

Stowage Factor: Around 0.80 – 1.20 m³/tonne.

IMSBC Code Classification:

BCSN: SALT

Group: C

Key Hazards and Precautions:

Corrosion (Primary Concern):

This is the most significant issue. Wet salt is aggressively corrosive to unprotected steel.

Holds: Must be clean and DRY. Intact paint coatings are essential. Any exposed steel will corrode rapidly. Some owners may opt for specialized coatings or even temporary barriers if carrying salt frequently.

Bilge Systems: Brine can severely corrode bilge lines, pumps, and wells. Ensure bilges are kept dry and systems flushed thoroughly after carriage.

Deck Structures: Spilled salt on deck, if wetted by rain or sea spray, will cause corrosion. Decks should be washed down frequently.

Hygroscopicity and Caking:

Salt will absorb atmospheric moisture if the relative humidity is high (typically above 75%).

This can cause the cargo to become damp, then wet, and eventually form a hard cake, making discharge very difficult.

Ventilation: Generally, holds should be kept sealed throughout the voyage to prevent moist air ingress, especially when sailing from cooler/drier regions to warmer/more humid regions. Ventilate only if the dew point of the hold air is significantly higher than the ambient air dew point (i.e., to remove moisture already in the hold), which is less common if loaded dry into dry holds.

Hatch Covers: Must be perfectly weathertight.

Contamination of Cargo:

Salt for industrial or food use can be contaminated by residues from previous cargoes (ores, coal, fertilizers). Holds must be thoroughly clean.

Damage to Equipment: Salt dust and brine can damage electrical equipment and machinery on deck.

Master’s Key Responsibilities for Salt:

Ensuring holds are exceptionally clean and dry, with good paint coatings.

Maintaining weathertight integrity.

Careful management of ventilation (usually keeping holds sealed).

Diligent washing down of decks and structures to remove salt deposits.

Thorough cleaning and flushing of holds and bilge systems after discharge.

E. SCRAP METAL (FERROUS METAL BORINGS, SHAVINGS, TURNINGS, CUTTINGS, ETC.)

Scrap metal is a diverse cargo, ranging from shredded automobile scrap to heavy steel offcuts. Its hazards vary greatly with its form, cleanliness, and contamination. The IMSBC Code has schedules for different types. A common hazardous type is “FERROUS METAL BORINGS, SHAVINGS, TURNINGS OR CUTTINGS, UN 2793.”

Characteristics:

Highly variable in size, shape, density, and contamination.

Can include fine, oily turnings, sharp cuttings, or large, irregular pieces.

Often contaminated with cutting oils, grease, moisture, wood, rags, or other materials.

Stowage Factor: Highly variable, from dense (for solid pieces) to very high (for light, bushy turnings).

IMSBC Code Classification (Example: FERROUS METAL BORINGS, SHAVINGS, TURNINGS OR CUTTINGS, UN 2793):

BCSN: As above.

Group: B (This specific type is hazardous). Other types of scrap might be Group C if clean and inert.

IMO Class: 4.2 (Substances liable to spontaneous combustion).

Key Hazards and Precautions (for UN 2793 type):

Self-Heating and Spontaneous Combustion:

Fine ferrous metal particles, especially if contaminated with oil and moisture, can oxidize rapidly, generating heat and potentially leading to spontaneous combustion. The large surface area of borings and turnings facilitates this.

Prevention:

Cargo should be aged/weathered and substantially free from cutting oils or moisture. Shipper must provide a certificate stating this.

Temperature of cargo should not exceed 55°C at loading.

Avoid loading during precipitation.

Stow away from heat sources.

Monitoring: Monitor cargo temperatures during voyage.

Ventilation: Surface ventilation is usually recommended to dissipate heat and any flammable gases.

Emission of Flammable Gases (Hydrogen):

Ferrous metals can react with water (especially salt water or acidic water) to produce hydrogen, a highly flammable gas. Oily contaminants can also break down to produce flammable vapors.

Prevention: Keep cargo as dry as possible.

Monitoring: Monitor for flammable gases in holds.

Ventilation: As above, surface ventilation helps. Flame screens on vents.

No Ignition Sources.

Oxygen Depletion:

Oxidation of the metal consumes oxygen.

Strict enclosed space entry procedures.

Physical Hazards during Handling:

Sharp edges, unstable piles, falling objects.

Stevedores and crew must wear appropriate PPE (heavy-duty gloves, safety shoes, hard hats, eye protection).

Damage to Holds: Heavy, irregular pieces of scrap can damage tank tops and hold structures if dropped or dragged carelessly during loading/discharge. Use of dunnage or old rubber tires on the tank top may be considered for very heavy/sharp scrap.

Contaminants: Other hazardous materials (e.g., closed drums, gas cylinders, radioactive sources) can sometimes be inadvertently mixed with scrap. Vigilance during loading is needed.

Master’s Key Responsibilities for Scrap Metal (Hazardous Types):

Obtain and scrutinize shipper’s certificate regarding freedom from oil/moisture and weathering.

Strict control of ignition sources.

Diligent monitoring of temperature and flammable gas levels.

Ensuring safe handling practices by stevedores to prevent injury and vessel damage.

Awareness of the specific IMSBC Code schedule for the type of scrap being carried.

General Analysis for “Other Cargoes”:

For all these “other” cargoes, and indeed any bulk cargo not explicitly detailed, the Master’s approach should be:

Always Identify the Correct BCSN.

Consult the Specific IMSBC Code Schedule: This is the primary source of information on properties, hazards, and precautions.

Scrutinize the Shipper’s Declaration: Ensure it is complete and matches the Code’s requirements.

Prioritize Safety: Never compromise on safety procedures, especially regarding hold preparation, ventilation, ignition control, and enclosed space entry.

Protect the Vessel: Take measures to prevent corrosion, structural damage, and contamination.

Protect the Cargo: Implement appropriate cargo care measures to prevent damage or deterioration.

By understanding the unique considerations for each type of bulk cargo, the Master can navigate the complexities of the trade safely and efficiently, ensuring the well-being of the crew, the integrity of the vessel, and the quality of the cargo.