top of page
Search

Safe Carriage of Coal


Safe Carriage of Coal

🚢 Safe Carriage of Coal – What Mariners Must Know

Coal is one of the most commonly transported bulk commodities at sea — but it also presents significant hazards that require specific precautions. This guide summarizes key best practices based on industry standards and the "Coal Handling Guidelines".


🧱 Types of Coal and Their Properties

Coal is classified into four main ranks:

Type

Rank

Features

Anthracite

High

Hard, shiny black, 86–98% carbon, low moisture, slow combustion

Bituminous

Medium-High

Widely used, may emit CO and methane, risk varies

Sub-bituminous

Medium-Low

Young coal, self-heating risk, high moisture

Lignite

Low

High moisture, low energy, domestic use only

  • Blended coals may combine properties: e.g. methane emission + self-heating risk.

⚠️ Key Hazards of Coal Cargo

  1. Methane Emission (CH₄)

    • Flammable in air between 5–15%

    • Lighter than air → accumulates in headspace

  2. Carbon Monoxide (CO)

    • Odorless, toxic

    • Present especially in anthracite/bituminous types post-loading

  3. Self-Heating

    • Mostly with low-rank coals (sub-bituminous, lignite)

    • Moisture, oxygen, and temperature can initiate heating

  4. Oxygen Depletion

    • Can fall to 4–8% in sealed holds → asphyxiation risk

  5. Corrosive Bilge Water (low pH)

    • Sign of advanced heating or sulfur/methane offgassing

  6. Dust & Instrument Damage

    • Coal dust/moisture can damage gas monitors


📋 Before Loading

  • Confirm cargo temperature < 55°C

  • Verify moisture, sulfur, ash, volatile matter from Shipper’s Declaration

  • Check cargo hold condition and cleanliness

  • Ensure gas monitoring and ventilation systems are working

  • Identify coal origin (Indonesia, South Africa = higher self-heating risk)


🛳 During Safe Carriage of Coal: Monitoring & Ventilation

  1. Gas Monitoring

    • Use non-catalytic or IR LEL sensors for accuracy in low O₂

    • Monitor CO & CH₄ daily (twice if CO > 30 ppm)

    • pH checks of bilge water if heating suspected (pH < 5.5 = warning)

  2. Ventilation Strategy

    • Natural ventilation only (no mechanical fans)

    • Use leeward vent open, windward cracked

    • Avoid over-ventilation → fresh oxygen accelerates heating

    • Use time-based prediction method:

      • Vent → Close → Wait 1 hr → Sample → Adjust timing

      • Ideal: 20–30 min ventilation to reduce CH₄, keep O₂ < 13–15%

  3. Temperature Control

    • Monitor cargo/hatch steel with IR thermometer

    • Alert if > 60°C (may affect hold coatings)


🧯 When Coal Heats Up

  • Rising CO + CH₄ = sign of oxidation

  • 70°C = potential acceleration

  • 120°C = moisture gone, high combustion risk

  • DO NOT apply water unless advised by experts — may worsen heating


🧰 Equipment & Sensor Maintenance

  • Use gas monitors with external pump, moisture/dust filters

  • Dry and replace filters regularly

  • Avoid catalytic sensors if O₂ often < 10%


📘 Special Tips & Observations "Safe Carriage of Coal"

  • Self-heating usually begins ~1/3 from top, or at water ingress zones

  • Anthracite/bituminous may show CO without heating → normal in first week

  • pH < 4 bilge water → corrosion risk to tanktop & piping

  • Keep cargo holds sealed unless ventilating











Comments

bottom of page