IMSBC Code: solid bulk cargo classification and carriage

The International Maritime Solid Bulk Cargoes Code (IMSBC Code) is the IMO instrument governing the carriage of solid bulk cargoes other than grain. It was adopted as the annex to IMO resolution MSC.268(85) on 4 December 2008 and became mandatory on 1 January 2011 through SOLAS regulation VI/1-2, inserted by the companion resolution MSC.269(85). The Code sorts every listed cargo into Group A, Group B or Group C, tells the shipper what to declare, prescribes the laboratory procedures that fix a cargo’s moisture limit, and carries an individual schedule for each cargo in appendix 1. The text in force today is amendment 07-23, IMO resolution MSC.539(107), mandatory since 1 January 2025.

Two things about the Code catch practitioners out. It is not a self-contained safety manual: large parts of it are recommendatory, and section 1.4.2 names which. And it is not the only instrument at the berth, because grain is carved out by the same regulation that makes the Code mandatory, and packaged dangerous goods stay with the IMDG Code .

The instrument, and the regulation that makes it mandatory

SOLAS regulation VI/1-2 is the mandatory hook, and it is one sentence: the carriage of solid bulk cargoes other than grain shall be in compliance with the relevant provisions of the IMSBC Code. That regulation was inserted into the SOLAS Convention by IMO resolution MSC.269(85), adopted 4 December 2008 and in force 1 January 2011. Regulation VI/1-1.1 does a different job: it defines the IMSBC Code by reference to MSC.268(85) as it may be amended, provided each amendment follows SOLAS article VIII.

The distinction matters when a fixture dispute turns on what the Code obliges. MSC.268(85) adopted the Code; it did not make it mandatory. Every amending resolution since recites regulation VI/1-1.1 as the gateway.

The Code replaced the Code of Safe Practice for Solid Bulk Cargoes, 2004, IMO resolution MSC.193(79), a recommendatory instrument usually called the BC Code. Operative paragraph 7 of MSC.268(85) resolves that the IMSBC Code supersedes it. There was no transitional period during which a ship could still work to the older document, because the older document had never been mandatory in the first place. That history is covered in the article on the BC Code .

Scope: which ships, which voyages, which cargoes

The Code reaches every ship carrying a solid bulk cargo under SOLAS chapter VI, including cargo ships of less than 500 gross tonnage. SOLAS regulation VI/1 applies the chapter to the carriage of cargoes, except liquids in bulk, gases in bulk and those aspects covered by other chapters, in all ships to which the regulations apply and in cargo ships below 500 GT. For those small ships the Administration may take other effective measures where the sheltered nature and conditions of the voyage make part A or part B unreasonable or unnecessary. That is a case-by-case flag-State discretion, not a size exemption, and it is a common misreading.

A solid bulk cargo is defined at section 1.7 as any cargo, other than a liquid or a gas, consisting of a combination of particles, granules or larger pieces generally uniform in composition, loaded directly into the cargo spaces without any intermediate form of containment. Break the last limb and the Code stops applying: a mineral concentrate in one-tonne flexible intermediate bulk containers is packaged cargo, not solid bulk, and it is regulated under the IMDG Code if it is dangerous goods.

Three exclusions run alongside. Grain is carved out by regulation VI/1-2 itself. Liquids in bulk go to the IBC Code or MARPOL Annex I. Gases in bulk go to the IGC Code . Everything else that arrives loose in a hold, from iron ore to wood pellets to scrap , is inside.

The Code’s structure: 13 sections and five appendices

The Code has 13 sections and five appendices, and it uses sections rather than chapters. Section 1 general provisions; 2 general loading, carriage and unloading precautions; 3 safety of personnel and ship; 4 assessment of acceptability of consignments for safe shipment; 5 trimming procedures; 6 methods of determining angle of repose; 7 cargoes that may liquefy or undergo dynamic separation; 8 test procedures for group A cargoes; 9 materials possessing chemical hazards; 10 carriage of solid wastes in bulk; 11 security provisions; 12 stowage factor conversion tables; 13 references to related information and recommendations.

The appendices carry the material a superintendent actually opens. Appendix 1 holds the individual schedules. Appendix 2 holds the laboratory test procedures, associated apparatus and standards. Appendix 3 holds properties of solid bulk cargoes, including the closed list of cargoes that are non-cohesive when dry. Appendix 4 is the index, which carries secondary and trade names with cross-references to the Bulk Cargo Shipping Name . Appendix 5 carries the shipping names in English, French and Spanish, and was added by amendment 03-15; the 2008 text had four appendices.

The schedules are in appendix 1. They are not in section 9, which is a frequent citation error: section 9 holds classification and segregation only.

Mandatory against recommendatory: what section 1.4.2 carves out

Section 1.4.2 is the provision that decides what a port State control officer can write up, and it makes more of the Code advisory than most readers expect. Recommendatory or informative: section 11 except paragraph 11.1.1; section 12; section 13; the appendices other than appendix 1 and appendix 5; and, within each appendix 1 schedule, the Description, the Characteristics other than the Hazard classification, the Hazard field and the Emergency procedures.

Read that against a schedule and the consequences are sharp. The bulk density and stowage factor printed on a schedule are informative, so the figure a loading plan is built on is the declared figure under section 4.2.2.6 and 4.2.2.7, not the printed one. Section 1.2.1 says as much: the properties are given only for guidance, and current valid information must be obtained from the shipper before loading.

The Emergency procedures block on a Group B schedule is informative too. That is counter-intuitive, and it is what the Code says. What is mandatory in a schedule is the Hazard classification block and the operational cells from Stowage and segregation through Clean-up. The mandatory and informative fields are worth reading in full before a dispute turns on one of them.

The three cargo groups at section 1.7

Section 1.7 defines three groups, in an unnumbered alphabetical definitions list.

• Group A consists of cargoes which possess a hazard due to moisture that may result in liquefaction or dynamic separation if shipped at a moisture content in excess of their transportable moisture limit.
• Group B consists of cargoes which possess a chemical hazard which could give rise to a dangerous situation on a ship.
• Group C consists of cargoes which are classified as neither group A nor group B.

There is no fourth group. “A and B” is a combined classification for a cargo that carries both hazards, and it is a declared value rather than a defined term: section 4.2.2.2 requires the shipper to give the cargo group as A and B, A, B or C, and the section 4.2.3 form carries four checkboxes. The COAL schedule reads “B (and A)” in its Group cell, which is the Code’s own drafting singularity.

Group membership is a property of the cargo as offered, not a property of the commodity. BAUXITE is Group C; BAUXITE FINES is Group A. IRON ORE is Group C; IRON ORE FINES is Group A. The particle size distribution and the moisture regime decide, which is why the Group A , Group B and Group C hubs are organized by hazard rather than by commodity family.

Group A: moisture, the transportable moisture limit and liquefaction

Section 7 carries the Group A regime, and section 7.3.1.1 is the operative rule and the sentence to quote: group A cargoes shall only be accepted for loading when the actual moisture content of the cargo is less than its transportable moisture limit. The single exception is a specially constructed or fitted ship under section 7.3.2.

The mechanism is set out at section 7.2.1 in three steps. Void volume reduces as the cargo compacts under ship motion. That reduction raises pore water pressure. The raised water pressure reduces inter-particle friction, and with it the shear strength of the mass. Section 7.2.4 explains why the consequence is sudden rather than gradual: the viscous fluid flows to one side on a roll and does not fully return, so heel accumulates and capsize can follow without warning.

Section 7.2.2 gives the exclusion, and it is the paragraph that free-draining test results point back to: liquefaction does not occur when the cargo consists of large particles or lumps and water passes through the spaces between the particles and there is no increase in the water pressure.

Dynamic separation is the second failure mode, added to the Code by amendment 06-21, IMO resolution MSC.500(105), adopted 28 April 2022. Section 1.7 defines it as the phenomenon of forming a liquid slurry of water and fine solids above the solid material, resulting in a free surface effect which may affect the ship’s stability. The same amendment retitled section 7 to cover both and rewrote the Group A and Group C definitions. The mechanism and its arrival through bauxite fines is covered in dynamic separation , and the wider physics in cargo liquefaction .

Section 7.2.3 adds the case that catches ships shipping within the limit. Some cargoes susceptible to moisture migration may develop a dangerous wet base even where the average moisture content is less than the transportable moisture limit. Section 1.7 defines moisture migration as the movement of moisture by settling and consolidation under vibration and ship’s motion, progressively displacing water. Section 4.2.2.11 is the declaration item that asks whether a wet base is likely, and it is routinely left blank.

Two more section 7.3.1 provisions carry directly onto the loading plan. Under 7.3.1.3 no cargoes containing liquids are stowed in the same space above or adjacent to a Group A cargo, other than packaged canned goods and the like. Under 7.3.1.5, a self-heating Group A cargo shall not be cooled by applying water at sea, because water may bring it to a flow state; spray only where necessary.

The six test procedures in appendix 2, and the limit each one produces

Appendix 2 paragraph 1 lists six methods, not three, and each produces the transportable moisture limit by a different rule. That is the single most important correction to make to any secondary account of the Code.

So there is no general law that the transportable moisture limit equals 0.9 times the flow moisture point. The 90 percent relation belongs to the flow table and penetration routes. The three Proctor/Fagerberg routes never compute a flow moisture point at all; they read a critical moisture content off a compaction curve at a stated degree of saturation. An article or a surveyor’s report that states 0.9 times the flow moisture point as the Code’s definition is wrong for iron ore fines, coal , bauxite and every concentrate tested by Proctor/Fagerberg.

Two of the methods can return an answer that removes the cargo from Group A altogether. Under paragraph 1.5, where the moisture drains freely so the compaction curve never reaches 70 percent saturation, the test indicates a cargo within section 7.2.2 and not liable to liquefy. Paragraph 1.6.1.4 says the same for a free-draining bauxite sample: the cargo is not classified as Group A.

One special case sits inside the flow table procedure. For peat moss the transportable moisture limit is 85 percent of the flow moisture point where the dry-basis bulk density exceeds 90 kg/m3, and 90 percent at 90 kg/m3 or less. It is the only place in the Code where the 90 percent rule is displaced.

Section 8 itself contains no test. It is four short subsections that point to appendix 2 and add the can test at 8.4: half fill a cylindrical container of 0.5 to 1 litre with the sample, bring it down sharply onto a hard surface from about 0.2 m, and repeat 25 times at one or two second intervals. If free moisture or a fluid condition appears, arrange laboratory tests before accepting the material. Section 8.4.2 states the limit of the test plainly: a dry result does not prove the moisture content is below the transportable moisture limit. It is evidence to refuse, not evidence to load. See transportable moisture limit for the certificate practice around it.

Sampling, testing intervals and who does the work

Two intervals govern a Group A cargo, and they are different lengths for a reason. Section 4.5.1 makes the shipper responsible for ensuring a transportable moisture limit test is conducted within six months to the date of loading, and for repeating it once it is reasonably assumed the composition or characteristics have varied. Section 4.5.2 requires sampling and testing for moisture content as near as practicable to the date of commencement of loading, and states that the interval shall never be more than seven days.

The limit is a property of the material and moves slowly. The moisture content is a property of the stockpile on the day and moves with the weather. Hence six months against seven days.

Section 4.5.2 carries the rain clause, and its anchor is easy to misread. If the cargo has been exposed to significant rain or snow between the time of testing and the date of completion of loading, the shipper is responsible for ensuring the moisture content is still less than the transportable moisture limit and for providing evidence to the master as soon as practicable. A shower on the last day of a five-day load is inside the clause. Section 4.5.3 requires frozen samples to be tested only after the free moisture has completely thawed.

The ship is not a bystander in the sampling . Section 4.4.3 requires the shipper to facilitate access to stockpiles for inspection, sampling and subsequent testing by the ship’s nominated representative. Section 4.4.6 requires moisture samples to be placed immediately in airtight, non-absorbent containers with a minimum of free air space. Section 4.4.8 restricts stationary stockpile sampling of unprocessed mineral ores to cases where access to the full depth of the stockpile is available.

Section 4.6.4 sets the subsampling scale for concentrate stockpiles: one 200 g subsample per 125 tonnes up to 15,000 tonnes, per 250 tonnes from 15,000 to 60,000 tonnes, and per 500 tonnes above 60,000 tonnes, each drawn about 50 cm below the surface under 4.6.3. Section 4.6.1 preserves automatic sampling that achieves equal or superior accuracy.

Section 4.7 lists example sampling standards for information only, among them ISO 3082:2017 for iron ores, ISO 1988:1975 for hard coal, ASTM D2234/D2234M-17, BS 1017-1:1989 and IS 1405:2010. The Code adds its own notes: under ISO 3082:2017 the in situ sampling of ships and stockpiles is not permitted, while IS 1405:2010 does cover in situ stockpile sampling up to 3 m height.

Who is a competent authority, and why the Code says it twice

Section 1.7 defines a competent authority as any national regulatory body or authority designated or otherwise recognized as such for any purpose in connection with the Code, and then adds the sentence that settles most arguments: the competent authority shall operate independently from the shipper. A laboratory owned or controlled by the shipper is not a competent authority, whatever its technical accreditation, and a certificate issued on that basis is open to challenge.

The Code names no accreditation standard for a test laboratory. Section 4.1.4 and section 8.1 require procedures approved or determined by the appropriate authority, and nothing more. Accreditation to a general laboratory standard is widespread commercial practice and it is not an IMSBC requirement. SOLAS regulation XII/10.2 does name an accredited testing organization, but for a different job: verifying a declared bulk density in the 1,250 to 1,780 kg/m3 band. The role is set out in competent authority .

Section 4: the shipper’s declaration

Section 4 is titled “Assessment of acceptability of consignments for safe shipment”, and section 4.2.2 is the eighteen-item list that fills the declaration. In Code order: the Bulk Cargo Shipping Name when listed, with secondary names permitted; the cargo group; the IMO class if applicable; the UN number preceded by “UN” if applicable; the total quantity offered; the stowage factor; the bulk density as required by SOLAS regulation XII/10; the need for trimming and trimming procedures; the likelihood of shifting including angle of repose; a certificate of moisture content and transportable moisture limit in the case of a Group A cargo; the likelihood of formation of a wet base; toxic or flammable gases which may be generated; flammability, toxicity, corrosiveness and propensity to oxygen depletion; self-heating properties and the need for trimming; properties on emission of flammable gases in contact with water; radioactive properties; whether the cargo is harmful to the marine environment under appendix I of MARPOL Annex V ; and any other information required by national authorities.

Seven of those items carry “if applicable” qualifiers that hand them to Group B and take them from Group C: the class, the UN number, gases generated, flammability and toxicity, self-heating, water-reactive gas emission and radioactive properties. Item .10 is Group A only. There is no MHB line item; the codes reach the paperwork through the section 4.2.3 form.

Section 4.2.3 requires the information to be accompanied by a declaration and sets out an example form, while permitting another form to be used. The form carries four group checkboxes, two MARPOL Annex V checkboxes, a field for chemical properties naming class, UN number and MHB hazards, and four additional-certificate checkboxes: certificate of moisture content and transportable moisture limit, weathering certificate, exemption certificate, and other.

Section 4.3.6 is the general rule behind every schedule-specific certificate on a Group B cargo. Where certification is required by an individual schedule for a cargo possessing chemical hazards, the certificate shall contain or be accompanied by a statement from the shipper that the chemical characteristics are, to the best of their knowledge, those present at the time of loading. The full item-by-item treatment is in the shipper’s cargo declaration .

Section 4.8 covers documentation carried on board and is often skipped. Section 4.8.1 requires a special list, manifest or detailed stowage plan under SOLAS regulation VII/7-2.2. Section 4.8.2 requires appropriate emergency response instructions aboard. Section 4.8.3 requires a Document of Compliance for a cargo ship of 500 GT and over built on or after 1 September 1984, or under 500 GT built on or after 1 February 1992, subject to SOLAS regulation II-2/19.4, when carrying dangerous goods in solid form in bulk, except class 6.2 and class 7.

That document is triggered by dangerous goods, not by Group B. SOLAS regulation VII/7 defines dangerous goods in solid form in bulk by IMDG Code coverage, so an MHB-only cargo such as COAL or petroleum coke does not trigger it, while ferrosilicon at class 4.3 or sulphur at UN 1350 does. It is also not the ISM Document of Compliance, which is issued to the Company under SOLAS chapter IX and the ISM Code . The distinction is worked through in the Document of Compliance for dangerous goods .

Group B: chemical hazards, the MHB codes and two mandatory segregation matrices

Section 9.1 gives Group B three populations, not two: dangerous goods under section 9.2.2 without additional chemical hazards; MHB cargoes under section 9.2.3; and dangerous goods that also possess the additional hazards in 9.2.3. Section 9.2.2 covers eight classes: 4.1, 4.2, 4.3, 5.1, 6.1, 7, 8 and 9.

MHB means materials which may possess chemical hazards when carried in bulk other than materials classified as dangerous goods in the IMDG Code. Section 9.2.3.1.5 carries the seven notation codes: combustible solids CB, self-heating solids SH, solids that evolve flammable gas when wet WF, solids that evolve toxic gas when wet WT, toxic solids TX, corrosive solids CR, and other hazards OH. In a schedule the MHB cell carries bare letters joined by “and/or”: COAL reads “CB and/or SH and/or WF and/or CR”. The criteria and their test methods are in MHB classification and materials hazardous only in bulk .

The notation arrived in three steps, and crediting it to one amendment is a common error. Amendment 02-13, MSC.354(92), created the categories with names and no letters. Amendment 03-15, MSC.393(95), inserted the letter codes at 9.2.3.1.4 and 9.2.3.1.5. Amendment 05-19, MSC.462(101), moved the notation out of the Class cell into its own MHB cell, giving the Hazard classification table its current four columns.

Section 9.3 carries two mandatory segregation matrices, on the same four-term model the IMDG Code uses. Section 9.3.3 governs a bulk cargo against packaged dangerous goods; section 9.3.4 governs bulk against bulk. The four terms are away from, meaning a minimum horizontal separation of 3 metres projected vertically; separated from, meaning different holds under deck; separated by a complete compartment or hold from; and separated longitudinally by an intervening complete compartment or hold from, where vertical separation alone does not suffice.

The MHB row is the interesting one. In section 9.3.3 it reads X against every packaged class except class 7, and in 9.3.4 X against every bulk class except class 7. X means the segregation, if any, is shown in the individual schedule. So an MHB-only cargo takes almost all of its segregation from its own schedule rather than from the matrix, which is why the COAL schedule refers the reader to its own appendix. Section 9.3 implements SOLAS regulation VII/7-3, per the Code’s own reference at 13.2.10. The detail is in segregation requirements .

Section 9.3.1.8 sets four foodstuff rules that apply regardless of matrix: separated from toxic materials; separated by a complete compartment or hold from all infectious materials; separated from radioactive materials; and away from corrosive materials.

Group C: what still applies when no group hazard is declared

Group C is a residual category and not a safe category. A Group C cargo is one classified as neither Group A nor Group B, and the classification says only that the Code has found no moisture hazard and no chemical hazard. Everything in sections 2, 3, 4, 5 and 6 still applies: cargo distribution and hull stress under section 2.1, hold preparation under 2.2, personnel safety and enclosed-space discipline under section 3, the shipper’s declaration under section 4, and the trimming ladder under section 5.

Two schedule cells are read wrongly on Group C cargoes more than anywhere else. A hold cleanliness cell reading “No special requirements” is an answer, not a blank: it means the standard is contractual, set by the charter and the receiver rather than by the Code. And a Group C schedule carries no Emergency procedures block, which is the cleanest checkable marker distinguishing it from a Group B schedule. The category is set out in the Group C hub.

Reading an individual cargo schedule

Section 1.3.3 publishes the authoritative field order, and every appendix 1 schedule follows it: Bulk Cargo Shipping Name in capitals; Description; Characteristics, as one table in two blocks, physical properties (size, angle of repose, bulk density, stowage factor) and hazard classification (class, subsidiary hazards, MHB, group); Hazard; Stowage and segregation; Hold cleanliness; Weather precautions; Loading; Precautions; Ventilation; Carriage; Discharge; Clean-up; and Emergency procedures, itself four cells covering special emergency equipment, emergency procedures, emergency action in the event of fire, and medical first aid.

Some schedules carry a trailing Remarks field, and COAL carries a full appendix of its own holding stowage and segregation, ventilation and carriage content.

Three cells are absent rather than empty on particular cargoes, and each absence carries meaning. The Angle of repose cell is empty on a cohesive cargo because section 5.3.2 excludes the parameter. The MHB cell is empty where no MHB hazard exists, so FERROSILICON reads class 4.3, subsidiary 6.1, MHB blank, group B. And transportable moisture limit and moisture content are never schedule fields at all: they are declaration items under 4.2.2.10 and certificate items under 4.3.2, Group A only. The structure is worked through in the individual cargo schedule .

Cargoes not listed, exemptions, and cargoes prohibited in bulk

Section 1.3 is the route for a cargo with no schedule, and it splits on hazard. Under section 1.3.1 the shipper provides the loading-port competent authority with the section 4 characteristics before loading, and that authority assesses acceptability. Under section 1.3.1.1, where the cargo may present hazards as defined by Group A or B, advice is to be sought from the competent authorities of the port of unloading and of the flag State, and the three competent authorities set the preliminary conditions for carriage. Under section 1.3.1.2, where no specific hazard is assessed, the loading port authorizes unilaterally and advises the unloading port and the flag State. The second limb is a notification, not an agreement.

The industry calls the first route a tripartite agreement. The Code never uses the word; it appears nowhere in MSC.539(107). Guidance is MSC.1/Circ.1453/Rev.2 of 26 June 2023, approved at MSC 107, which expressly superseded Rev.1. Section 1.3.2 then requires the certifying authority to submit an application to IMO within one year from the issue of the certificate, to bring the cargo into appendix 1. See cargoes not listed and tripartite agreements .

Section 1.5 is the separate exemption route, and it is often forgotten. A competent authority, meaning the port State of departure, the port State of arrival or the flag State, may authorize any other provision if satisfied it is at least as effective and safe. Validity is not more than five years, a copy goes to IMO and to the ship, and the authorizing authority shall take action to amend the Code to include the provisions covered by the exemption, as appropriate. Read with section 1.3.2, that gives the Code two self-amending feedback loops. See exemptions and equivalent measures .

Some cargoes are simply not carried loose. The appendix 4 index marks them, and the list is set out in cargoes prohibited in bulk .

Sections 2 and 3: cargo distribution, hull stress and personnel safety

Section 2 has two subsections and one number. Section 2.1.2 records that a general cargo ship is normally constructed to carry cargoes in the range of 1.39 to 1.67 cubic metres per tonne when loaded to full bale and deadweight capacities, and warns that exact rules for distribution are not practicable for all ships. Section 2.1.3 requires a stability information booklet aboard all Convention ships, having regard to SOLAS regulation II-1/5-1, and requires the master to be able to calculate stability for the anticipated worst conditions during the voyage as well as on departure. High-density cargoes go into lower holds in preference to tween decks so far as practicable.

Section 2.2 covers preparation. Cargo spaces are inspected and prepared for the particular cargo. Bilge wells and strainer plates get special preparation, to drain the space and keep cargo out of the bilge system, and bilge lines, sounding pipes and other service lines are proved in good order. Section 2.2.4 notes that the loading velocity of high-density cargoes can damage cargo space fittings, and names sounding the bilges after loading as the detection method. Sections 2.2.5 and 2.2.6 deal with dust: ventilation shut down or screened and air conditioning on recirculation during cargo work, and dust kept off moving parts of deck machinery and external navigational aids. See cargo hold bilge well preparation and hold cleanliness inspection .

Section 3 is qualitative throughout. It contains no temperature threshold, no gas concentration and no alarm setpoint, which is worth knowing before quoting it. Section 3.2 covers poisoning, corrosive and asphyxiation hazards and names the liable cargoes at 3.2.3: most vegetable products and forest products, ferrous metals, metal sulphide concentrates and coal cargoes. Section 3.2.4 requires appropriate procedures before entry, taking into account the recommendations developed by the Organization, and warns that small oxygen-deficient or fume-bearing areas may persist after a space has tested safe. Section 3.2.5 requires appropriate gas and oxygen measuring instruments, which is the Code’s reflection of SOLAS regulation VI/3.

One cross-reference in section 13 is stale in the Code itself. Section 13.2.12 still cites resolution A.1050(27) on entering enclosed spaces. The current instrument is IMO resolution MSC.581(110) of 27 June 2025, whose operative paragraph 3 invites the Assembly to revoke A.1050(27), and it is the one to work to. See enclosed space entry and the full procedure at enclosed space entry and tank inspection .

Section 5: trimming, and the angle of repose ladder

Trimming is keyed to whether a cargo is cohesive or non-cohesive, not to its group. Section 5.1.1 gives the reason for trimming in one sentence: it reduces the likelihood of the cargo shifting and minimizes the air entering the cargo, which could lead to spontaneous heating. Section 5.1.3 gives the master the right to require the cargo be trimmed level where there is any concern regarding stability. Section 5.1.2 adds that alternate hold loading restrictions under SOLAS chapter XII may also need to be taken into account.

Section 5.3.2 states the rule that empties the angle of repose cell on most schedules: the angle of repose is not an indicator of the stability of a cohesive bulk cargo and is not included in the individual schedules for cohesive cargoes. Appendix 3 paragraph 1.3 makes cohesion the default. All cargoes other than those listed in appendix 3 paragraph 1 are cohesive, and cargoes not listed should be treated as cohesive until otherwise shown.

For a non-cohesive cargo the ladder runs through three paragraphs, and the numbering matters:

The 30 degree limb is the cleanest link between this Code and the grain regime: a free-flowing cargo drops out of the IMSBC trimming provisions and is stowed under the grain rules instead. Section 6.1 requires the angle of repose to be measured by a method approved by the appropriate authority as required by section 4.1.4, and section 6.2 recommends two: the tilting box method at appendix 2 paragraph 2.1, for grain sizes not greater than 10 mm, and a shipboard test at appendix 2 paragraph 2.2 that gives an approximate value. See angle of repose and section 5 trimming provisions .

Specially constructed and fitted ships under section 7.3

Section 7.3.2 describes the one route by which a Group A cargo may be carried above its transportable moisture limit, and it is a ship design, not an operational allowance. A specially constructed ship under 7.3.2.1 has permanent structural boundaries that confine any shift to an acceptable limit. A specially fitted ship under 7.3.2.2 uses specially designed portable divisions that restrain the flow forces and limit the heeling moment, with the bounding structure strengthened as necessary; the divisions shall not be constructed of wood. Both carry evidence of Administration approval, granted on the package at 7.3.2.3: structural drawings with scaled longitudinal and transverse sections, stability calculations taking cargo shift into account, and any other information assisting assessment.

Section 7.3.3 covers a second design case: a ship built to carry solely dry powdery cargoes and to handle them by means of closed pneumatic systems that prevent exposure to weather. That is the route the dedicated cement carrier and the alumina carrier take.

What follows from either approval is substantial. Section 7.3.1.2 disapplies sections 4.2.2.9, 4.2.2.10, 4.3.2 to 4.3.5, 4.5, 4.6 and the whole of section 8, notwithstanding section 1.4. The entire moisture testing and certification apparatus is switched off by ship type.

Sections 10 to 13: wastes, security, conversions and references

Section 10 governs solid wastes carried in bulk, and section 10.2.1 defines them narrowly: cargoes containing or contaminated with constituents subject to the Code’s provisions for classes 4.1, 4.2, 4.3, 5.1, 6.1, 8 or 9, for which no direct use is envisaged but which are carried for dumping, incineration or other disposal. Radioactive contamination is expressly excluded from section 10 by 10.3.2 and handled under the radioactive provisions instead. Section 10.4 is the Basel Convention gate: movement may begin only after notification from the competent authority of the country of origin to the country of final destination, and only after that origin authority, holding written consent from the destination, has authorized the movement. Section 10.5 requires a waste movement document to accompany the shipment through to disposal.

Section 11 is recommendatory except paragraph 11.1.1, which applies SOLAS chapter XI-2 and the ISPS Code part A to the companies, ships and port facilities handling solid bulk cargoes to which chapter XI-2 applies. Section 11.3 identifies high-consequence solid bulk cargoes as those with potential for misuse in an unlawful act producing mass casualties or mass destruction, giving class 5.1 ammonium nitrate UN 1942 and ammonium nitrate based fertilizers UN 2067 as the examples, and sets out eight elements of a consignor security plan at 11.3.4.

Section 12 carries the stowage factor conversion tables, at 1 m3/t equals 35.87 ft3/ton and 1 ft3/ton equals 0.02788 m3/t, both rounded lookups and both recommendatory. Section 13 is the reference list, a three-column table in thirteen blocks running from dangerous goods classification through to the avoidance of excessive stresses, and section 13.1 states that the list is not exhaustive. The relation between the stowage factor and the loading plan is covered in stowage factor and tank top strength and loading limits .

The amendment sets, and which text governs a voyage

The Code is amended on a roughly two-year cycle, and every amending resolution carries the same four operative paragraphs: adoption, a tacit acceptance date, entry into force upon that acceptance, and an agreement that Contracting Governments may apply the amendments in whole or in part on a voluntary basis from a stated earlier date. The voluntary period runs before mandatory application, and the permission is addressed to Contracting Governments rather than to individual ships.

The two-digit suffix is the drafting cycle year, not always the adoption year: it matches for 01-11 through 05-19 and for 07-23 and 08-25, but 06-21 was adopted in 2022.

On 4 September 2026, amendment 07-23 is the mandatory text and governs every voyage to 31 December 2026. Amendment 08-25 was tacitly accepted on 1 July 2026 but is not in force until 1 January 2027, and has been applicable on a voluntary basis since 1 January 2026.

MSC.539(107) is worth knowing for a mechanical reason: its annex opens by replacing the complete text of the Code, so 07-23 is a consolidated reprint rather than a list of changes. What 07-23 added cannot be read off the resolution, and any count of new schedules attributed to it is not derivable from the primary text.

What 08-25 changes at the framework layer is narrow, and it is entirely within sections 9 and 13. The section 9.3.3 table is reformatted, division 1.6 is added to a column heading, the word MHB is deleted from the second column, and one segregation definition is reworded. Section 13.2.3 moves from MSC.1/Circ.1395/Rev.6 to Rev.7, and sections 13.2.6 and 13.2.9 move to MSC.1/Circ.1264/Rev.1. Everything else is individual schedules, including 11 new ones: ALUMINIUM SULPHATE GRANULAR, APATITE CONCENTRATE, ASPHALT GRANULATES, CRUSHED GRANODIORITE COARSE, FERRIC SULPHATE GRANULAR, FISH MEAL (FISH SCRAP) STABILIZED, IRON ORE BRIQUETTES, PEA PROTEIN CONCENTRATE PELLETS, PHOSPHATE ROCK FINES (uncalcined), TUFF COARSE and ZINC SLAG (coarse).

Amendment 09-27 is in preparation, with cargoes agreed in principle at CCC 11 in September 2025 and referred to the Editorial and Technical group for drafting. No resolution number and no date exists for it. See the amendment cycle .

The IMSBC Code against the IMDG Code, the Grain Code and the BLU Code

Three neighbouring instruments meet the IMSBC Code at the hold, and each boundary is drawn by a different rule.

The IMDG Code covers dangerous goods in packaged form. The boundary is the form of containment: loose in the hold is IMSBC, in packages is IMDG. A dangerous cargo can appear in both, because the IMSBC schedule for a class 4.1 or 5.1 cargo carries the same UN number as the IMDG entry. What decides whether SOLAS chapter VII bites as well as chapter VI is regulation VII/7, which defines dangerous goods in solid form in bulk by IMDG coverage. An MHB-only cargo is regulated wholly through chapter VI, which is why COAL needs no Document of Compliance.

The International Grain Code, IMO resolution MSC.23(59) of 23 May 1991, effective 1 January 1994, applies instead of the IMSBC Code rather than alongside it. SOLAS regulation VI/1-2 excludes grain from the IMSBC Code, and SOLAS chapter VI part C makes the Grain Code mandatory and requires a document of authorization. Grain Code paragraph A 3.5 is blunt: a ship without such a document shall not load grain. Grain Code paragraph A 2.1 defines grain as wheat, maize, oats, rye, barley, rice, pulses, seeds and processed forms thereof whose behaviour is similar to that of grain in its natural state. See the International Grain Code and the grain clean standard .

The BLU Code, IMO resolution A.862(20) of 27 November 1997, is recommendatory. Its content acquires legal force through SOLAS regulation VI/7, which is where the obligations sit: the terminal representative at VI/7.1, the seven-part booklet at VI/7.2, the agreed loading or unloading plan lodged with the port State at VI/7.3, the master’s right to suspend at VI/7.5, and continuous monitoring with each draught and tonnage observation recorded in a cargo logbook at VI/7.6. The ship and shore safety checklist is a BLU Code appendix and is recommendatory in itself; the mandatory object is the VI/7.3 plan.

The BLU Code has been amended twice, which secondary accounts routinely miss. IMO resolution MSC.238(82), adopted 1 December 2006 and effective 1 January 2007, extended it to grain and gave the Grain Code precedence on conflict. IMO resolution MSC.304(87), adopted 14 May 2010 and effective 1 January 2011, inserted definitions of Bulk Cargo Shipping Name, IMSBC Code and solid bulk cargo. The IMSBC Code’s own reference at 13.2.13 cites it as “as amended”. See the BLU Code and BLU Manual , whose guidance document is MSC/Circ.1160 of 16 May 2005.

SOLAS chapter XII sits alongside all three for bulk carriers, and regulation XII/10 is the one that reaches into the IMSBC declaration: before loading bulk cargo on bulk carriers of 150 m in length and upwards, the shipper shall declare the density of the cargo. See SOLAS chapter XII regulation 10 and SOLAS chapter XII .

Enforcement: flag State, port State control and class

Enforcement of the Code runs through SOLAS, so it reaches a ship the same way any other SOLAS obligation does. The flag State, or a classification society acting as its recognized organization, certifies the ship. The port State control officer inspects against the convention, under the Paris MoU , the Tokyo MoU or another regional regime. The Code itself creates no certificate.

A port State control officer working a bulk carrier normally starts with documents rather than holds. The shipper’s declaration under section 4 and the certificates it references; the agreed loading or unloading plan under SOLAS regulation VI/7.3, which the port State authority should already hold a copy of; the cargo information under VI/2; the density declaration under XII/10; the stability booklet and the loading instrument output under VI/6 and VI/7.2; and the gas and oxygen measuring instrument and its instructions under VI/3. A missing or internally inconsistent declaration on a Group A cargo is the finding most likely to stop the operation, because the acceptance rule at section 7.3.1.1 has no evidential basis without it.

There is no port state control deficiency code named after the IMSBC Code, which is worth knowing before reading any statistic about IMSBC compliance. A finding is recorded against the document code, such as 01313 for the bulk cargo loading, unloading and stowage booklet required by SOLAS regulation VI/7.2 or 01316 for cargo information under regulation VI/2, or against a cargo operation code in the 061 series. IMSBC non-compliance is therefore distributed across several codes and understated in the published totals. Detention follows the general judgement test rather than a code flag: the defect must make the intended voyage unsafe. A bulk carrier not loaded in accordance with its VI/7.2 booklet, particularly where hull overstressing may have occurred, is one of the cases the Paris MoU guidance directs an officer to consider for detention.

No concentrated inspection campaign has ever been run on the IMSBC Code or on solid bulk cargoes. The nearest were the Paris MoU campaign on stability in general in 2021 and the 2011 campaign on structural safety and load lines. The joint Paris MoU and Tokyo MoU campaign running from 1 September to 30 November 2026 addresses the securing of cargo units and cargo transport units, centred on the Cargo Securing Manual, so it does not reach solid bulk carried in bulk. See concentrated inspection campaigns .

The IMO response to the liquefaction losses ran through circulars rather than through the Code at first. MSC.1/Circ.1454, guidelines for developing and approving procedures for sampling, testing and controlling the moisture content for solid bulk cargoes which may liquefy, was approved at MSC 92 and issued in July 2013, and revised as MSC.1/Circ.1454/Rev.1 on 15 June 2015. Its stated purpose is to help shippers prepare the procedures IMSBC paragraph 4.3.3 requires, and to help the competent authority of the loading port approve them and check their implementation.

The master’s authority to stop work comes from several provisions rather than one, and it is worth knowing which to cite. SOLAS regulation VI/7.5 gives the right to suspend loading or unloading, with an obligation to notify the port State authority holding the plan. IMSBC section 5.1.3 gives the right to require trimming. IMSBC section 7.3.1.1 is the acceptance rule for a Group A cargo. ISM Code paragraph 5.2 carries the overriding authority. See the master’s right to refuse cargo and the Tokyo MoU inspection regime.

Casualties that shaped the Code

Cargo liquefaction is the leading cause of loss of life on bulk carriers. INTERCARGO’s Bulk Carrier Casualty Report 2026, published 7 July 2026 and covering 2016 to 2025, records 17 bulk carriers of 10,000 dwt and above lost totalling 1.63 million dwt, with 71 seafarer lives lost, and attributes 37 of those deaths to cargo liquefaction, more than half the total. Grounding causes more ship losses, at 41.1 percent of cases, but far fewer deaths. Ships of 50,000 to 59,999 dwt account for 4 of the 17 losses and 52.1 percent of the lives lost, a concentration INTERCARGO attributes to the nickel ore trade.

Emerald Star, 2017, is the case with the clearest official finding. The Hong Kong registered bulk carrier sailed from Buli, East Halmahera, Indonesia on 9 October 2017 with 55,000 tonnes of nickel ore for Lianyungang, and capsized east of Luzon on 13 October. Of 26 crew, 16 were rescued and 10 were lost, including the master. The Marine Accident Investigation Section of the Hong Kong Marine Department published its report on 11 May 2021 and concluded that the vessel was loaded with nickel ore with moisture content in excess of the transportable moisture limit, so that cargo liquefaction and shifting occurred and the vessel listed heavily and capsized. Its contributory findings go straight to section 4.5.2: re-certification of moisture content after significant rain was not carried out.

Bulk Jupiter, 2015, is the loss that produced the bauxite work. The Bahamas-flagged bulk carrier loaded 46,400 tonnes of bauxite at Kuantan, Malaysia between 17 and 30 December 2014 in heavy rainfall, and sank on 2 January 2015 with the loss of 18 of her 19 crew. The Bahamas Maritime Authority issued its report on 18 August 2015 and found liquefaction of the bauxite to be the most probable cause, with a higher proportion of fine material than the bauxite schedule then described and elevated moisture from exceptional pre-shipment rainfall as likely contributory factors. The owner disputed the liquefaction finding. What followed was the split of the bauxite entry into a Group C BAUXITE schedule and a Group A BAUXITE FINES schedule effective 1 January 2021, and the arrival of dynamic separation in the Code through amendment 06-21.

Cheshire, 2017, is the Group B counterpart and shows a different failure mode. The 2012-built supramax sailed from Norway for Thailand with about 50,000 tonnes declared as ammonium nitrate based fertilizer, non-hazardous, and declared not liable to self-sustaining decomposition. Elevated hold temperatures appeared in holds 4 and 5 on 12 August 2017 south of Gran Canaria, decomposition spread through the ship, and the crew were evacuated. There were no fatalities and the ship became a constructive total loss. The Isle of Man Ship Registry casualty investigation report CA 128 found that the decomposition occurred despite all required safeguards being in place, and recommended renaming the cargo from non-hazardous to not otherwise classified and reviewing the adequacy of the IMO self-sustaining decomposition test. See self-sustaining decomposition of fertilizers .

The 2010 to 2013 nickel ore cluster is what put liquefaction on the IMO agenda. Jian Fu Star on 27 October 2010, Nasco Diamond on 10 November 2010 and Hong Wei on 3 December 2010 were each lost on the Indonesia to China nickel ore run, with 13, 21 and 10 fatalities. Vinalines Queen went missing on 25 December 2011 carrying more than 54,000 tonnes of nickel ore from Morowali for Ningde, leaving one survivor from 23 crew. Harita Bauxite, whose cargo was nickel ore rather than the bauxite of its name, sank off western Luzon on 16 to 17 February 2013 with 15 lives lost. John Poulsen, a principal surveyor at Atlantic Marine Associates who investigated the losses, set the run out in Seaways in December 2013: five ships and over 80 seafarers since 2010. See nickel ore .

Two corrections are worth making because both circulate widely. Stellar Daisy is not an IMSBC casualty. The converted very large ore carrier, 266,141 dwt, sank on 31 March 2017 on passage from Ilha Guaiba to Qingdao with iron ore, leaving 2 rescued and 22 missing. The Republic of the Marshall Islands Office of the Maritime Administrator released an 83-page report in April 2019 finding the likely direct cause to be catastrophic structural failure of the hull, probably starting in the number 2 port water ballast tank, with material fatigue, corrosion, unidentified structural defects, multi-port loading and weather as contributing factors. Cargo liquefaction is not the finding, and the case belongs to a discussion of bulk carrier structure rather than to this Code. And Trans Summer sank in 2013, not 2017, southwest of Hong Kong during Typhoon Utor, with all 21 crew rescued and no fatalities.

The most recent loss remains open. The Singapore-flagged Devon Bay sank near Scarborough Shoal on 22 January 2026 on passage from the Philippines to Yangjiang with a nickel ore cargo, and of 21 Filipino crew 15 were rescued and 6 died. The Maritime and Port Authority of Singapore is the investigating flag administration and no report has been published. The cause is not established.

Regional overlays

The Code is the global baseline. Four jurisdictions add machinery on top of it, and none of them displaces MSC.539(107).

The European Union has no instrument transposing the Code itself. Directive 2001/96/EC of 4 December 2001 does something narrower and more consequential: it makes BLU Code loading and unloading practice binding at terminals in EU Member States, for bulk carriers of any flag calling there. Agreed plans, terminal suitability, terminal representative duties, ship and shore information exchange and an authority power to halt operations all become law rather than guidance in an EU port.

The United States works through 46 CFR part 148 , Carriage of Bulk Solid Materials That Require Special Handling. The IMSBC Code is incorporated by reference at 46 CFR 148.8, and 148.55(b) permits a bulk solid material classed, described, stowed and segregated in accordance with the Code to be offered, accepted and transported within the United States, with a carve-out for a material listed in Table 148.10 that is not subject to the Code. Packaged dangerous goods by vessel remain under 49 CFR part 176.

Australia gives the Code and the BLU Code effect through Marine Order 34 (Solid bulk cargoes) 2016 , commenced 1 January 2017 under the Navigation Act 2012, adding AMSA approvals, notice of intention to ship, notice of fumigation, and the route for a cargo not listed in appendix 1.

Canada uses the Cargo, Fumigation and Tackle Regulations , SOR/2007-128, whose BC Code definition was repealed by SOR/2021-60. Section 115 requires a shipper loading solid bulk cargo in Canadian waters to comply with SOLAS regulations VI/2 and XII/10 and the applicable appendix 1 schedule, and requires the authorized representative and master to refuse the cargo where the shipper does not provide the required documents.

Readings of the Code that recur and are wrong

Six errors appear often enough in trade guidance, surveyor reports and secondary summaries to be worth naming.

“The transportable moisture limit is 90 percent of the flow moisture point.” True for the flow table and penetration routes only. Four of the six appendix 2 methods never compute a flow moisture point.

“Grain is Group C.” Grain has no IMSBC group. SOLAS regulation VI/1-2 excludes it and the International Grain Code governs it.

“The IMSBC Code has no segregation matrix.” It has two, at sections 9.3.3 and 9.3.4, both mandatory.

“The schedules are in section 9.” They are in appendix 1. Section 9 holds classification and segregation.

“Everything in a schedule is mandatory.” Section 1.4.2 makes the Description, the Hazard field, the Emergency procedures and the physical Characteristics informative.

“MSC.268(85) made the Code mandatory.” MSC.268(85) adopted the Code. MSC.269(85), adopted the same day, amended SOLAS to make it mandatory.

Limitations

This article states the Code as amended by IMO resolution MSC.539(107), amendment 07-23, which is the mandatory text on 4 September 2026, and notes where amendment 08-25 (MSC.575(110)) differs. It is a reference summary, not a substitute for the Code text, and a loading decision is made against the current Code and the schedule for the actual cargo.

Three specific limits are worth stating. First, the Code publishes no total number of schedules, in section 1, in appendix 4 or in any resolution, and independent parses of appendix 1 disagree with each other, so no count is given here. Second, section 1.2.1 states that the properties in a schedule are given only for guidance and that current valid information must be obtained from the shipper before loading, so nothing printed in appendix 1 substitutes for the declaration. Third, a national overlay can add requirements the Code does not carry, and the four named above are not an exhaustive survey; the loading port, the discharge port and the flag State each need checking for the specific voyage.

The casualty record above is limited to losses with an identified official investigation report, and two gaps in it are worth naming. No Panamanian flag-State report on Jian Fu Star, Nasco Diamond or Hong Wei could be obtained, so the fatality figures for the 2010 cluster are given from John Poulsen’s account in Seaways rather than from an investigation document, and no cause is attributed to an investigation for Harita Bauxite. The Devon Bay investigation is open and its cause is not established.

Where a cargo carries a moisture hazard, the acceptance decision under section 7.3.1.1 rests on a certificate whose validity depends on sampling the master did not witness. The Code’s answer to that is section 4.4.3, the right of the ship’s nominated representative to attend, and it is worth exercising rather than assuming.

Related Articles

• IMSBC Group A cargoes
• IMSBC Group B cargoes
• IMSBC Group C cargoes
• Transportable moisture limit
• Cargo liquefaction
• The IMSBC individual cargo schedule
• Bulk Cargo Shipping Name
• IMSBC segregation requirements
• The IMSBC Code amendment cycle
• SOLAS chapter VI: carriage of cargoes and oil fuels
• SOLAS chapter VII: carriage of dangerous goods
• The International Grain Code
• The BLU Code and BLU Manual
• The IMDG Code
• Bulk carriers
• Bulk carrier loading plan and sequence