Section 5.3 Cleaning Methods and Equipment (Chemicals, High-Pressure Washing, Manual Cleaning)

Achieving the required standard of cargo hold cleanliness on a bulk carrier is a demanding task that involves a combination of methods, appropriate equipment, and sheer hard work by the crew. The choice of method depends on the previous cargo, the next intended cargo, the required standard of cleanliness, the vessel’s design, and the available resources (time, manpower, equipment, consumables). The Master and Chief Officer must select and supervise these methods effectively to ensure both cleanliness and safety.

1. Manual Cleaning (Dry Cleaning Methods):

Manual cleaning forms the backbone of most hold preparation operations, especially for removing loose residues and preparing surfaces for washing or finer cleaning.

A. Sweeping and Brushing:

Purpose: To remove loose dry cargo residues, dust, and debris from tank tops, accessible frames, ledges, and other surfaces.

Equipment:

Brooms: Heavy-duty deck brooms, softer brooms for finer dust.

Brushes: Hand brushes, wire brushes (for more stubborn, non-painted areas or removing loose rust – use with caution on coated surfaces).

Shovels and Scrapers: For removing larger accumulations or more compacted residues.

Shovels: Flat-edged and pointed shovels.

Scrapers: Long-handled and short-handled steel scrapers for dislodging adherent material. Non-sparking scrapers (e.g., brass, beryllium copper) must be used if there’s any risk of flammable atmospheres, though this is less common during general hold cleaning unless specific cargo residues pose such a risk.

Technique:

Work from top to bottom: Clean overhead structures (underside of hatch covers, deck beams, upper parts of frames) first, so dislodged debris falls onto areas yet to be cleaned.

Systematically sweep residues towards a collection point for removal (e.g., into piles for bucketing out or for removal by grabs if permissible and safe).

Pay close attention to corners, recesses, behind frames, pipe guards, and ladder structures where residues accumulate.

Pros: Relatively simple, requires basic equipment, can be done in most weather conditions (if holds are dry).

Cons: Labor-intensive, can be dusty (requiring PPE), may not remove all fine particles or adherent residues.

B. Scraping:

Purpose: To remove tenacious, caked-on cargo residues, loose rust scale, and flaking paint that cannot be removed by sweeping alone.

Equipment: Steel scrapers of various types and sizes. Pneumatic de-scaling tools (needle guns, chipping hammers) may be used for heavy rust scale on un-coated areas or areas where coatings have failed, but this is more akin to surface preparation for painting than routine cleaning. Extreme caution is needed with power tools to avoid damaging sound coatings or the steel structure itself.

Technique: Apply firm pressure to dislodge material. Work systematically.

Pros: Effective for stubborn residues.

Cons: Very labor-intensive, can damage paint coatings if not done carefully, generates debris that needs to be collected. Risk of eye injuries from flying particles.

C. Use of Compressed Air (Blowing Down):

Purpose: To dislodge dust and fine residues from overhead structures, frames, ledges, and hard-to-reach areas. Often used as a final dry cleaning step before washing or inspection for grain clean standards.

Equipment: Air hoses connected to the ship’s compressed air system, fitted with suitable nozzles. Extension lances may be needed to reach high areas.

Technique: Direct the air jet to blow dust and particles downwards and towards collection areas. Ensure adequate ventilation if large amounts of dust are generated.

Pros: Reaches inaccessible areas, effective for fine dust.

Cons: Primarily relocates dust rather than removing it from the hold unless combined with effective extraction or collection; can create a very dusty atmosphere requiring enhanced PPE (respirators, goggles); consumes compressed air. Not suitable if the dust is hazardous or could contaminate other parts of the ship.

D. Collection and Removal of Dry Residues:

Methods:

Buckets and Bags: Manually filling buckets or heavy-duty bags with collected residues and hoisting them out of the hold.

Ship’s Cranes/Derricks (if geared): Using grabs (if suitable and residues are voluminous) or specialized skips/bins to lift larger quantities of residues out. This must be done carefully to avoid damaging the hold or hatch coamings.

Portable Conveyors or Vacuum Systems: Less common as standard ship’s equipment for routine cleaning but may be used by specialized cleaning gangs in port.

Disposal: All collected cargo residues must be disposed of strictly in accordance with MARPOL Annex V. (This will be detailed further in a later section).

2. High-Pressure Washing:

Washing with water, especially using high-pressure systems, is often essential for achieving higher standards of cleanliness (e.g., Grain Clean, Hospital Clean) or for removing water-soluble or adherent residues.

Purpose:

To remove adherent cargo residues, dirt, dust, and soluble contaminants.

To wash away loose rust and paint flakes dislodged by manual cleaning.

To prepare surfaces for inspection or subsequent cargoes that require a very clean environment.

Equipment:

High-Pressure Washers: Electric or diesel-driven pumps delivering water at high pressure (typically 150-500 bar, or ~2000-7000 psi, though specialized ultra-high-pressure units exist).

Hoses: Heavy-duty, pressure-rated hoses.

Lances and Nozzles: Various types of lances (straight, angled) and nozzles (fan jet, pencil jet, rotating nozzles) to direct the water effectively. Telescopic lances are invaluable for reaching high areas like underdeck beams and upper frames.

Water Source: Seawater is often used for initial washing of robust residues (e.g., after coal or some ores). Freshwater is essential for final rinsing, especially when preparing for sensitive cargoes like grain, kaolin, or food-grade products, to remove salt residues and prevent contamination. The vessel’s freshwater generation capacity or bunkered quantity must be considered.

Technique:

Safety First: High-pressure water jets can cause serious injuries. Operators must be trained, wear appropriate PPE (waterproofs, face shield/goggles, safety boots, gloves), and never direct the jet at another person. Ensure secure footing.

Top to Bottom: Start washing from the highest points of the hold (underside of hatch covers, deck beams, upper frames) and work downwards. This allows dislodged dirt and residues to be washed down to the tank top for collection.

Systematic Coverage: Ensure all surfaces are thoroughly washed. Pay particular attention to ledges, corners, behind frames, and other areas where residues can accumulate.

Nozzle Distance and Angle: Vary the distance and angle of the nozzle to the surface for optimal cleaning effectiveness without damaging paint coatings unnecessarily. A pencil jet can dislodge stubborn material but can also strip paint; a fan jet covers a wider area.

Bilge Well Management: Ensure bilge wells are clear and suctions are ready to pump out wash water as it accumulates. Strum boxes should be in place but may need frequent cleaning during washing.

Rinsing: If seawater has been used for initial washing, a thorough final rinse with freshwater is usually necessary to remove salt crystals, which can be corrosive or contaminate the next cargo.

Pros: Very effective for removing a wide range of residues, including those that are adherent or in difficult-to-reach areas. Can achieve high standards of cleanliness.

Cons: Consumes significant amounts of water (especially freshwater); generates large volumes of wash water that must be managed and disposed of correctly; can be time-consuming; high-pressure jets can damage weak paint coatings or dislodge loose rust, creating more debris; requires careful attention to safety. Operation can be physically demanding.

3. Chemical Cleaning:

In some situations, water washing alone (even high-pressure) may not be sufficient to remove certain types of stubborn or chemically bonded residues. In such cases, chemical cleaning agents may be employed.

Purpose:

To dissolve or break down specific types of cargo residues that are resistant to water washing (e.g., oily residues, some hardened chemical deposits, certain types of stains, tenacious rust stains).

To sanitize or deodorize holds.

Types of Cleaning Chemicals:

Detergents/Surfactants: Help to emulsify oily or greasy residues, making them easier to wash away. General-purpose biodegradable detergents are common.

Solvent-Based Cleaners: Used for heavy oil, grease, or asphaltic residues. Often have flammability and toxicity concerns, requiring good ventilation and PPE.

Acidic Cleaners: Used for removing rust stains, mineral deposits (e.g., lime scale, cement residues). Highly corrosive and require extreme care in handling, appropriate PPE, and thorough rinsing to neutralize. Can damage coatings and steel if not used correctly.

Alkaline Cleaners: Used for removing fats, oils, and some protein-based residues. Can also be corrosive.

Specialized Cleaners: Formulated for specific residues (e.g., molasses removers, cement removers).

Deodorizers: To neutralize strong odors from previous cargoes.

Application Methods:

Spraying: Diluted chemicals are often sprayed onto surfaces using low-pressure sprayers or sometimes injected into high-pressure washing streams (if the equipment is designed for this).

Brushing/Swabbing: Applying concentrated or diluted chemicals directly to affected areas with brushes or mops.

Soaking: For small, heavily contaminated items (though less common for entire hold surfaces).

Important Considerations for Chemical Cleaning:

Cargo Compatibility: Crucially, any chemical used must be compatible with the next intended cargo. Residues of the cleaning chemical itself must not contaminate or react with the new cargo. Always check with chemical manufacturers and cargo compatibility guides.

Material Safety Data Sheets (MSDS/SDS): Obtain and review the MSDS/SDS for any chemical used. This provides vital information on hazards, PPE requirements, handling, storage, first aid, and disposal.

Personal Protective Equipment (PPE): This is non-negotiable. Appropriate PPE (e.g., chemical-resistant gloves, suits, boots, face shields, respirators with correct cartridges) must be worn as specified in the MSDS.

Ventilation: Ensure adequate ventilation when using solvent-based or volatile chemicals to prevent build-up of hazardous vapors.

Environmental Regulations (MARPOL): The discharge of wash water containing chemicals is strictly regulated under MARPOL. Only chemicals that are approved as “not harmful to the marine environment” (and often only in limited concentrations) can be discharged overboard, and even then, only outside of Special Areas and specific distances from land. Many chemical cleaning operations will require the wash water to be retained onboard for discharge to shore reception facilities.

Manufacturer’s Instructions: Always follow the chemical manufacturer’s instructions for dilution, application, contact time, rinsing, and safety precautions.

Patch Test: If unsure about a chemical’s effect on hold coatings or surfaces, conduct a small patch test in an inconspicuous area first.

Thorough Rinsing: After chemical application, surfaces must usually be thoroughly rinsed with copious amounts of freshwater to remove all chemical residues.

Pros: Can be very effective for specific, stubborn residues where water washing fails. Can save time and manual labor compared to purely mechanical removal of some contaminants.

Cons: Introduces chemical hazards for crew; requires careful handling and extensive PPE; potential for damage to coatings or vessel structure if misapplied; strict environmental regulations for disposal of chemical residues and wash water; cost of chemicals.

4. Specialized Equipment (Less Common as Standard Ship’s Gear):

Industrial Vacuum Cleaners: Heavy-duty vacuum systems (sometimes truck-mounted and brought onboard by shore gangs) can be very effective for removing large quantities of dry, dusty residues, especially from inaccessible areas.

Hold Cleaning Robots/Machines: Automated or semi-automated machines for washing or blasting hold surfaces exist but are not yet common on typical bulk carriers due to cost and complexity.

Ultra-High Pressure (UHP) Water Blasting: Uses water pressures exceeding 1700 bar (25,000 psi). Very effective for removing hard scale, old paint, and stubborn residues, but is a specialized operation usually performed by shore contractors, often in preparation for re-coating, rather than routine cleaning.

5. Planning, Safety, and Environmental Considerations (Overall):

Planning is Key: The Chief Officer, under the Master’s guidance, must develop a comprehensive hold cleaning plan considering:

Previous cargo and next cargo.

Required standard of cleanliness.

Time available.

Manpower available.

Equipment and consumables (water, chemicals, PPE) on board.

Weather conditions (washing may be difficult or unsafe in heavy seas or freezing temperatures).

Disposal arrangements for residues and wash water.

Safety of Personnel: This is paramount.

Risk Assessment: Conduct a thorough risk assessment before commencing any hold cleaning operation.

Permit to Work Systems: For activities like enclosed space entry (for inspection or cleaning inside), working at height (for cleaning upper structures), and potentially for chemical handling.

PPE: Ensure all crew involved wear appropriate PPE for the task (dust masks/respirators, eye protection, gloves, safety footwear, waterproofs, chemical suits as needed).

Ventilation: Provide adequate ventilation, especially when dealing with dust or chemical vapors.

Lighting: Ensure good, safe lighting in the holds.

Communication: Maintain clear communication between personnel working in the hold and those on deck.

Fatigue Management: Hold cleaning is arduous. Ensure crew get adequate rest.

Environmental Protection (MARPOL Annex V):

Cargo Residues: The discharge of cargo residues into the sea is strictly regulated. In general, residues (other than those from cargoes classified as HME) can only be discharged en route, outside Special Areas, and as far as practicable from the nearest land (specific distances apply). Residues of HME cargoes must generally be discharged to port reception facilities.

Cleaning Agents and Additives: Wash water containing cleaning agents or additives that are harmful to the marine environment cannot be discharged into the sea. Only those evaluated and found not to be harmful by IMO guidelines may be discharged under specific conditions.

Record Keeping: All disposal of cargo residues and wash water must be recorded in the Garbage Record Book.

Equipment Maintenance: All cleaning equipment (pressure washers, pumps, hoses, nozzles, scrapers, PPE) must be regularly inspected and maintained in good working order.

Analysis for the Master (Cleaning Methods & Equipment): The Master’s oversight ensures that hold cleaning is not just effective but also safe and environmentally compliant.

Resource Allocation: Ensure the Chief Officer has the necessary support and resources (manpower, time, equipment) to carry out the cleaning to the required standard.

Verification of Standards: Personally inspect or delegate reliable officers to inspect holds during and after cleaning to ensure standards are being met, before presenting them for external survey.

Prioritization of Safety: Emphasize safe working practices at all times. Stop any unsafe operations immediately.

Environmental Conscience: Instill a strong sense of environmental responsibility regarding the disposal of residues and wash water. Ensure strict MARPOL compliance.

Commercial Acumen: Understand the commercial implications of failed hold inspections (off-hire, delays, re-cleaning costs) and strive to avoid them through diligent preparation.

Training: Ensure crew are adequately trained in different cleaning techniques, safe use of equipment (especially high-pressure washers and chemicals), and PPE requirements.

Effective hold cleaning is a testament to a well-run ship. It requires a blend of hard physical labor, technical knowledge of methods and materials, and a strong commitment to safety and environmental standards. For your consultancy and bulkersguide.com, providing practical guides on selecting appropriate cleaning methods, equipment recommendations, safety checklists for cleaning operations, and summaries of MARPOL disposal requirements would be highly beneficial to your audience.