Dangers of Shipping Direct Reduced Iron (DRI): IMSBC Code, Hydrogen Risk, DRI Fines, and Safe Carriage

Direct Reduced Iron (DRI) is one of the most sensitive and potentially dangerous metallic bulk cargoes carried by sea. Although the commercial names used in fixtures may vary, the central risk remains the same: many DRI products can react with moisture and oxygen, generate heat, release hydrogen, and create conditions in which fire or explosion may occur inside a cargo hold. For this reason, DRI cargoes require careful identification, strict documentary control, competent supervision, and full compliance with the applicable IMSBC Code schedule before loading is accepted.

The expression Direct Reduced Iron covers several related but distinct products. Some are shipped as pellets, lumps, cold-moulded briquettes, hot-moulded briquettes, fines, by-products, remet material, metallic fines, or residues from iron-making processes. The danger for shipowners and Ship Masters is that cargo may be offered under a trade description that appears harmless, while the chemical behaviour of the material is still consistent with DRI. Names such as HBI fines, hot briquette fines, metallic fines, remet fines, re-oxidised iron fines, iron residues, oxide fines, clarification mud, or lodos should therefore be treated with caution unless the shipper provides reliable evidence proving the true identity and safe carriage requirements of the cargo.

In chartering practice, the label applied to the cargo is not enough. The Ship Master and shipowners must look at the cargo’s production process, particle size, metallic iron content, moisture content, ageing history, reactivity, and the exact Bulk Cargo Shipping Name under the International Maritime Solid Bulk Cargoes Code. If a cargo contains metallic iron or has been derived from DRI production, it may require treatment as a DRI cargo even if the commercial name does not expressly say DRI. When there is uncertainty, the prudent approach is to obtain independent expert advice before loading and to insist that the shipper supplies complete technical documentation.

Why Direct Reduced Iron is Dangerous at Sea

Direct Reduced Iron is produced by removing oxygen from iron ore without melting the material. The result is a highly metallised iron product that is valuable for steelmaking, especially in electric arc furnace operations. However, because DRI has a porous and reactive structure, it can re-oxidise when exposed to air or moisture. This oxidation may generate heat, and when the reaction becomes uncontrolled, cargo temperatures can rise sharply within the hold.

The most serious hazard is the generation of hydrogen gas. When DRI reacts with water, especially seawater containing chlorides, hydrogen may be produced. Hydrogen is colourless, odourless, highly flammable, and explosive over a wide concentration range. If hydrogen accumulates in a cargo hold or in adjoining enclosed spaces, a spark, hot surface, or other ignition source may be sufficient to cause an explosion. The risk is aggravated where the hold is poorly ventilated, where the cargo is wet, where oxygen control is ineffective, or where cargo temperature is not monitored.

DRI can also create an oxygen-depleted atmosphere. Inerting arrangements, cargo reaction, and oxidation may reduce the oxygen concentration within a hold. This creates a fatal enclosed-space hazard for crew members. No person should enter a cargo hold, access trunk, duct, or adjacent enclosed space unless the atmosphere has been properly tested, the space has been declared safe for entry, and the ship’s enclosed-space entry procedures have been followed.

Another danger is that DRI cargo may appear externally stable while internal heating is developing below the surface. A cargo hold can contain hidden hot spots that are not visible from above. For this reason, temperature monitoring points, gas sampling arrangements, oxygen readings, and hydrogen readings are not paperwork formalities; they are essential safeguards throughout loading, passage, and discharge.

Main Types of Direct Reduced Iron Cargoes

The IMSBC Code divides DRI cargoes into specific schedules. Each schedule reflects a different form of the cargo and a different safety regime. The categories should not be mixed casually, and shipowners should not accept a cargo merely because the shipper describes it as “not dangerous” or “not restricted.” The correct classification must be established by reference to the cargo’s actual properties and the applicable Code schedule.

DRI (A): Briquettes, Hot-Moulded

DRI (A) normally refers to hot-moulded briquettes, commonly known as Hot Briquetted Iron (HBI). HBI is produced by compressing DRI at high temperature, generally above 650°C, into dense briquettes. Because the product is compacted, it is usually less reactive than ordinary DRI pellets or fines. Nevertheless, HBI is still a dangerous bulk cargo and must be carried according to the relevant IMSBC Code schedule.

DRI (A) should consist essentially of whole briquettes. Fines and dust are restricted because broken material increases the surface area available for reaction. The cargo must be protected from water, hatch covers and weather deck openings must be checked, and hydrogen concentration must be monitored during the voyage. Surface ventilation may be required, but mechanical ventilation, where used, must be suitable for explosive atmospheres and must not create ignition risk.

DRI (B): Lumps, Pellets, and Cold-Moulded Briquettes

DRI (B) covers lumps, pellets, and cold-moulded briquettes. This type is much more reactive than properly produced HBI. DRI (B) can overheat when exposed to moisture and can produce hydrogen gas. It is therefore subject to strict moisture limits, ageing requirements, loading controls, inerting requirements, gas monitoring, and temperature monitoring.

DRI (B) must be kept dry before loading, during loading, and throughout the voyage. Conveyor systems and loading equipment should also be dry. The cargo should not be loaded if it is wet, has been exposed to additional moisture, is steaming, is excessively warm, or shows signs of active reaction. Where the IMSBC Code requires carriage under inert gas, nitrogen is normally used, and the oxygen concentration in the cargo space must be maintained below the required level throughout the voyage.

DRI (C): By-Product Fines

DRI (C) covers by-product fines. These are small particles generated during the production, handling, screening, or processing of DRI and related metallic iron products. DRI (C) has been associated with serious casualties because fines react more readily than larger briquettes or pellets. Their small particle size gives a large surface area, and if moisture is present, heat and hydrogen may be generated rapidly.

DRI (C) is particularly dangerous because cargo may be offered under alternative names that conceal its true nature. Cargoes described as remet fines, metallic residues, iron residues, re-oxidised fines, oxide residues, spent iron fines, lagoon residues, or similar terms may still contain DRI fines. If metallic iron is detected in a cargo described as iron ore fines or another non-DRI product, the cargo should be investigated carefully and may need to be treated as DRI (C).

Where the cargo falls within DRI (C), the shipper must provide a certificate from a competent person recognized by the National Administration of the loading port. The certificate should confirm that the cargo is suitable for carriage, complies with the IMSBC Code, has been properly aged, remains below the specified moisture limit, and does not exceed the permitted temperature. During loading, the cargo temperature should be monitored and recorded for each lot or section of cargo.

DRI (D): By-Product Fines with Higher Moisture Content

The modern IMSBC framework now also includes DRI (D), a schedule addressing certain by-product fines with higher moisture characteristics. The introduction of this schedule reflects the industry’s experience that some DRI by-product fines do not fit neatly into older categories yet still present serious risks. DRI (D) is associated particularly with hydrogen generation, and it may also present self-heating and liquefaction-related concerns depending on the cargo’s condition and documentation.

For shipowners and Ship Masters, the key point is that DRI (D) does not make the cargo “ordinary” or simple. It imposes a separate safety regime. The shipper’s cargo information, risk assessment, ventilation requirements, hydrogen monitoring, moisture documentation, and emergency procedures must be examined carefully. If a cargo offered as fines has a moisture content outside the traditional DRI (C) limit, the parties should not improvise. They should identify the correct IMSBC schedule, obtain competent advice, and ensure that the ship is suitable for the required carriage conditions.

Misleading Cargo Names and Charterparty Risk

One of the recurring problems in DRI transportation is the use of informal or commercial cargo names. Some descriptions may be accurate within a production plant or sales contract but insufficient for safe carriage by sea. A charterparty may exclude DRI, dangerous cargo, or cargo requiring inerting, yet the cargo may be offered as HBI fines, remet, metallic fines, or another name that appears outside the wording of the exclusion.

Shipowners should not rely on the cargo name alone. The proper questions are: What is the production origin? Does the material contain metallic iron? What is the particle size distribution? Has the cargo been aged? What is the moisture content? What is the cargo temperature? Does the cargo generate hydrogen? Which IMSBC Code schedule applies? Has the shipper provided the Bulk Cargo Shipping Name? Has a competent authority issued any exemption or special approval? Has the flag state accepted the proposed carriage regime?

Where the answer is incomplete or uncertain, the safest commercial response is to pause the fixture or loading operation until the cargo is properly identified. If the cargo is misdeclared and loaded without suitable precautions, the result may be catastrophic: heating, hydrogen accumulation, explosion, death or injury to crew, loss of ship, damage to cargo, pollution, salvage costs, delay, disputes over unsafe cargo, and possible prejudice to insurance cover.

Important Casualty Lessons from DRI Cargoes

The shipping industry’s caution toward DRI is not theoretical. Serious incidents involving DRI and DRI-related fines have shown how quickly a cargo can become dangerous when moisture, heat, hydrogen, and confined holds combine. The loss of life on ships carrying cargoes described as HBI fines demonstrated the severe consequences of loading reactive material without an adequate classification and carriage regime.

Such incidents led to intensified scrutiny by the IMO, P&I Clubs, flag states, class societies, surveyors, and cargo specialists. The development of DRI (C), and more recently DRI (D), reflects the industry’s attempt to close gaps created by cargoes that were previously difficult to classify. The lesson for Ship Masters is clear: if the cargo behaves like DRI, it must be treated with the caution required for DRI, regardless of the name used in a sales contract or fixture recap.

Documents Required Before Loading Direct Reduced Iron

Before DRI is loaded, the Ship Master should receive complete cargo information in accordance with SOLAS and the IMSBC Code. The documentation should identify the correct Bulk Cargo Shipping Name, cargo group, hazard class or MHB status where applicable, moisture content, temperature, particle size, production date or ageing period where required, and the safety measures necessary during loading, carriage, and discharge.

For DRI (B) and DRI (C), documentation should normally include evidence that the cargo is dry enough for shipment and that the cargo has been treated, aged, or prepared in accordance with the applicable schedule. For DRI (C), particular attention should be given to certificates confirming that the cargo has completed the required ageing period, that the moisture content is below the permitted level, and that the temperature does not exceed the prescribed limit. General certificates or test results from an old stockpile should not be accepted as proof for a different cargo lot.

The Ship Master should also ask for the sampling and testing method. Where chemical analysis is supplied, it should identify total iron, metallic iron, moisture, and any other relevant reactive characteristics. If the cargo is presented as iron ore fines or a non-DRI residue but contains metallic iron, the explanation must be examined carefully. Metallic iron is a strong warning sign that the cargo may include DRI-derived material.

Moisture, Hatch Covers, and Weather Precautions

Moisture control is fundamental to safe DRI carriage. DRI cargo should not be exposed to rain, spray, wet loading equipment, wet stockpiles, or water ingress through defective hatch covers. Even small amounts of moisture can accelerate oxidation and hydrogen generation, particularly where the cargo is in fines form. Seawater is especially dangerous because dissolved salts can intensify the reaction.

Before loading, hatch covers, access covers, ventilators, sounding pipes, air pipes, and other openings should be inspected and tested where required. Ultrasonic hatch cover testing or equivalent methods may be necessary for cargoes that must remain dry. The ship’s bilge systems, hold cleanliness, drainage arrangements, and weather-tightness should be verified. Loading should be stopped during rain or when there is a realistic risk that the cargo may become wet.

If cargo has been wetted before loading, becomes wet during loading, or shows signs of reaction after loading, the Ship Master should seek immediate advice and may need to reject or discharge the affected cargo. A ship should not sail with reactive cargo unless the required conditions under the IMSBC Code and any competent authority instructions have been satisfied.

Inerting and Gas Monitoring During DRI Carriage

Many DRI cargoes require carriage under an inert atmosphere. Nitrogen is normally used because it reduces oxygen concentration without introducing the hazards associated with unsuitable inerting agents. Carbon dioxide should not be used for DRI cargoes where it may create additional chemical and toxic hazards. The ship must be capable of receiving, distributing, maintaining, and monitoring the inert atmosphere throughout the voyage.

For cargoes requiring inerting, oxygen levels must be kept below the required threshold in the cargo space. Hydrogen levels must also be monitored. The ship must have safe arrangements for taking gas readings without unnecessarily breaking the inert seal. The monitoring equipment should be suitable for the atmosphere being tested, calibrated, and operated by trained personnel.

Gas readings should be recorded regularly. Any rise in hydrogen concentration, oxygen concentration, or cargo temperature must be treated seriously. The Ship Master should not ventilate or open cargo spaces contrary to the cargo schedule or expert advice, because introducing oxygen into a reactive cargo space may worsen the situation. Emergency response should follow the IMSBC Code, shipper’s instructions, competent authority guidance, and specialist advice.

Temperature Monitoring and Hot Cargo

Cargo temperature is another critical control point. DRI should be monitored during loading, and records should be kept for each cargo lot. Cargo that is hotter than expected, steaming, emitting unusual vapour, or showing signs of reaction should not be loaded without competent advice. Cargo exceeding the permitted temperature must be rejected.

Thermocouples or other approved temperature monitoring systems may be installed in cargo holds, depending on the DRI schedule and the carriage requirements. Their positions should be planned, tested, recorded, and protected during loading. The purpose of these systems is to detect changes in temperature before a hidden reaction becomes uncontrollable.

If cargo temperature rises during the voyage, the Ship Master should avoid hasty action. Opening hatches, adding water, or ventilating incorrectly may worsen the reaction or create an explosive atmosphere. The correct response depends on the cargo type, gas readings, temperature trend, oxygen level, hydrogen concentration, and the applicable IMSBC schedule. Specialist advice should be sought immediately.

Stowage, Trimming, and Cargo Surface Management

Proper stowage and trimming reduce the risk of uneven cargo reaction. DRI should be trimmed in accordance with the IMSBC Code and the shipper’s instructions. Poorly trimmed cargo may create voids and channels where warm gases rise and fresh air is drawn into the cargo mass. This “chimney” or “funnel” effect can encourage localized heating.

Minimizing exposed surface area, avoiding unnecessary cargo breakage, limiting fines, and preventing contamination are important operational controls. The loading method should be arranged to reduce impact damage to briquettes or lumps. If excessive fines are generated during loading, the cargo condition may no longer match the declared cargo description, and the Ship Master should seek advice.

Direct Reduced Iron (A) Shipping Requirements

DRI (A), Briquettes, Hot-Moulded should be shipped mainly as whole briquettes. Moisture content must remain within the applicable limit, and fines or dust must not exceed the permitted proportion. Hatch covers and weather deck openings should be checked before loading. The cargo must be protected from water throughout loading and carriage.

Only surface ventilation should be used where required by the schedule. If mechanical ventilation is employed, fans must be suitable for explosive atmospheres and protected against spark creation. Vent outlets should be arranged so that hydrogen or other gases do not enter accommodation areas, machinery spaces, or other enclosed spaces. Hydrogen concentration must be monitored, and precautions must be taken if readings approach dangerous levels.

Direct Reduced Iron (B) Shipping Requirements

DRI (B), Lumps, Pellets, and Cold-Moulded Briquettes should be loaded only when the cargo is dry, properly aged or treated, and supported by valid documentation. The cargo should be within the required particle size limits, and excessive fines should not be accepted. The manufacturing date or relevant production information may be required for each cargo lot.

Before loading, hatch covers and closures should be tested for weather-tightness. Loading equipment should be dry, and cargo operations should stop during rain. Moisture content must be monitored during loading, and any cargo that becomes wet or reactive must be discharged without delay. Cargo spaces must be sealed and inerted as required, with oxygen maintained below the specified level throughout the voyage. Temperature, hydrogen, and oxygen readings must be taken and recorded.

Direct Reduced Iron (C) Shipping Requirements

DRI (C), By-Product Fines requires especially strict control because the cargo’s reactivity can vary widely. Particle size should be within the relevant Code limits, and the material should not contain larger particles beyond the permitted size. The cargo must be aged for the required period and certified as suitable for shipment by a qualified person recognized by the National Administration of the loading port.

The moisture content must comply with the applicable schedule. Temperature must be monitored during loading, and no cargo exceeding the permitted temperature should be accepted. If cargo becomes wet, reacts, or reaches a dangerous temperature after loading, immediate expert advice is required, and discharge of affected cargo may be necessary. Carriage requirements generally follow the strict inerting and monitoring regime applicable to highly reactive DRI cargoes.

Direct Reduced Iron (D) Shipping Requirements

DRI (D) is a newer IMSBC schedule dealing with certain by-product fines with higher moisture content. The principal hazard is hydrogen generation in cargo hold ullage spaces, with additional concerns including self-heating and potential liquefaction. The schedule places strong emphasis on shipper information, risk assessment, ventilation control, hydrogen monitoring, and safe operational procedures.

Before agreeing to carry DRI (D), shipowners should confirm that the ship can meet the ventilation, monitoring, documentation, and emergency response requirements. The Ship Master should receive clear instructions on permitted ventilation rates, gas measurement frequency, action levels, cargo temperature monitoring, emergency procedures, and discharge precautions. Because DRI (D) is not the same as ordinary iron ore fines, it should not be accepted under a vague description or without the precise Code-based carriage plan.

DRI Fines, Remet Fines, and Metallic Fines

DRI fines are among the most problematic cargoes because they may be traded under several names. The fact that a cargo is called remet fines, metallic HBI fines, iron residue, or oxide fines does not remove the risk. If the cargo is a by-product of DRI production or contains metallic iron from a DRI source, it should be treated as a DRI cargo unless competent evidence proves otherwise.

Shipowners should require a full laboratory analysis for such cargoes. The analysis should be specific to the cargo lot to be loaded, not a generic certificate for the product type. Sampling should be recent, representative, and performed according to recognized standards. If the shipper cannot prove the origin and properties of the cargo, the ship should not be used as the testing ground for a dangerous experiment.

Role of the Ship Master Before Loading DRI

The Ship Master has a central role in protecting the ship, crew, cargo, and environment. Before loading DRI, the Ship Master should ensure that the cargo declaration, IMSBC documentation, certificates, moisture results, temperature records, ageing certificates, competent authority approvals, and shipper’s emergency instructions are complete and consistent. Any discrepancy should be clarified before loading starts.

The Ship Master should also verify that the ship is operationally capable of carrying the cargo. This includes hatch cover integrity, hold condition, bilge arrangements, gas monitoring equipment, oxygen meters suitable for hazardous atmospheres, thermocouple systems where required, inert gas supply arrangements, sealing arrangements, crew training, and emergency procedures. If the charterparty terms conflict with safe carriage requirements, safety must be resolved before commercial pressure is allowed to influence the loading decision.

Charterers’ and Shippers’ Responsibilities

Charterers and shippers must provide accurate cargo information. Misdescription of DRI-related cargo can expose the ship to unacceptable danger and may create liability for cargo damage, ship damage, delay, salvage, personal injury, pollution, and loss of life. The shipper must declare the correct Bulk Cargo Shipping Name and provide all information required by SOLAS and the IMSBC Code.

Charterers should not offer cargo under ambiguous descriptions where the cargo’s true nature is known or suspected. If the cargo is DRI, DRI fines, DRI by-product fines, or a DRI-derived residue, the fixture should identify the correct cargo and the required carriage conditions. A shipowner agreeing to carry iron cargo should insist on wording that allows refusal of cargo if documentation, moisture, temperature, ageing, or safety requirements are not satisfied.

Competent Authority Exemptions and Tripartite Agreements

The IMSBC Code allows competent authorities to approve alternative arrangements in limited circumstances, but such approvals should not be treated casually. Where an exemption or alternative carriage regime is proposed, shipowners must confirm that the loading state, discharge state, and flag state requirements have been satisfied. The relevant approval should be available onboard, and the Ship Master should understand the operating conditions attached to it.

Where a cargo is not listed in Appendix 1 of the IMSBC Code, carriage may require a tripartite agreement. However, if the cargo is actually a DRI cargo or contains DRI-derived metallic iron, it should not be forced into an unlisted cargo procedure merely because a commercial description avoids the word DRI. Correct classification is the foundation of safe carriage.

Insurance and P&I Considerations

DRI carriage has important insurance implications. P&I Clubs, hull underwriters, cargo insurers, flag states, and class societies may all have an interest in whether the cargo has been properly declared and carried. If shipowners knowingly accept misdeclared or non-compliant DRI cargo, insurance cover may be affected. Even where cover remains available, the operational and legal consequences of a DRI casualty can be severe.

Before accepting DRI or suspicious iron fines, shipowners should consult their P&I Club, technical managers, class, and cargo experts. If a dispute arises during loading, early notification is essential. The cost of delaying a fixture to clarify cargo safety is minor when compared with the consequences of a hydrogen explosion, fire, total loss, or crew fatality.

Practical Safety Checklist for DRI Cargoes

Confirm the exact Bulk Cargo Shipping Name under the IMSBC Code.
Reject vague commercial descriptions such as remet fines or metallic fines unless fully explained by technical evidence.
Obtain cargo-specific certificates for moisture, temperature, ageing, particle size, metallic iron content, and suitability for carriage.
Check whether DRI (A), DRI (B), DRI (C), or DRI (D) applies.
Verify hatch cover weather-tightness before loading any cargo that must remain dry.
Stop loading during rain or where cargo exposure to moisture is likely.
Reject wet, steaming, hot, or reactive cargo unless competent authority and expert advice confirms safe handling.
Use nitrogen inerting where required and maintain the required oxygen level throughout the voyage.
Monitor hydrogen, oxygen, and temperature according to the applicable cargo schedule.
Keep cargo spaces sealed where required and avoid unauthorized ventilation.
Do not enter enclosed spaces without full atmospheric testing and enclosed-space entry procedures.
Consult the P&I Club and technical experts whenever cargo identity or safety is uncertain.

Conclusion

The dangers of shipping Direct Reduced Iron (DRI) arise from the cargo’s ability to react with moisture and oxygen, generate heat, release hydrogen, and create explosive or oxygen-deficient atmospheres. The risk is especially serious where the cargo is carried as fines, by-products, residues, or under trade names that do not clearly identify the material as DRI.

Safe carriage depends on accurate cargo classification, reliable documentation, strict moisture control, proper ageing or treatment, hatch cover integrity, suitable inerting, continuous monitoring, and disciplined shipboard procedures. Shipowners, Ship Masters, charterers, and shippers must treat DRI cargoes with the seriousness they deserve. If the cargo description is unclear, if metallic iron is present, or if the product appears to be derived from DRI production, the safest assumption is that the cargo requires DRI-level precautions until competent evidence proves otherwise.

In practical terms, no DRI or DRI-related cargo should be loaded because of commercial pressure alone. The ship must be suitable, the documentation must be complete, the cargo must comply with the applicable IMSBC Code schedule, and the Ship Master must have clear instructions for loading, voyage monitoring, emergency response, and discharge. With DRI cargoes, caution is not delay; caution is the central condition for safe carriage by sea.