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IMDG Marking, Labelling, and Placarding

Contents

The marks, labels, and placards you see on a chemical drum, a sea container, or a tank truck are not decoration. They are a layered identification system that lets a stevedore, a port firefighter, or a chief officer recognize a hazard from across a yard, in the dark, after three months of salt spray, without opening a single package. The rules that govern every one of those marks sit in Part 5 of the International Maritime Dangerous Goods (IMDG) Code, the part titled Consignment Procedures. This article explains how that system works: what each class label looks like and means, which special marks exist and when they are required, how a cargo transport unit gets placarded, what goes on the dangerous goods declaration, and where the common mistakes happen. The companion tool for quick lookups is the IMDG dangerous goods finder, which returns the class and placard requirement for a UN number; the IMDG segregation calculator, the IMDG packing group calculator, the IMDG EmS lookup, the IMDG limited quantity calculator, the container IMDG class lookup, and the IMDG tank container calculator cover the related calculations. The full set is in the calculator catalogue.

What the IMDG Code is and where Part 5 sits

The IMDG Code is the global rulebook for moving dangerous goods in packaged form by sea. It is published by the International Maritime Organization (IMO), the United Nations agency for shipping based in London. The Code is not a stand-alone treaty. It draws its mandatory force from two parent conventions, and that distinction matters because it determines which flag states must enforce it and against which legal benchmark a deficiency is measured.

The first parent is SOLAS, the International Convention for the Safety of Life at Sea, 1974. Chapter VII of SOLAS, “Carriage of dangerous goods,” makes compliance with the IMDG Code mandatory for packaged dangerous goods on ships to which SOLAS applies. The IMDG Code is, in IMO’s own framing, an extension of SOLAS Chapter VII. The second parent is MARPOL, the International Convention for the Prevention of Pollution from Ships. MARPOL Annex III sets mandatory provisions for harmful substances carried by sea in packaged form, and those provisions are also carried through into the IMDG Code. This is why the marine pollutant rules live inside the same document as the fire and toxicity rules: one Code, two conventions feeding it. The reporting duty for a marine pollutant lost overboard traces back to Protocol I of MARPOL 73/78, and the dangerous goods manifest duty traces to SOLAS Chapter VII regulation 4.5 read with MARPOL Annex III regulation 4(3).

How the Code is organized

The IMDG Code ships as a two-volume set plus a supplement. Volume 1 holds the regulatory text in Parts 1, 2, and 4 through 7. Volume 2 holds the Dangerous Goods List, the limited quantities tables, and the appendices. The regulatory text is split into seven parts that follow the life cycle of a consignment:

  • Part 1, General provisions, definitions, and training.
  • Part 2, Classification: how a substance is assigned to a class and packing group.
  • Part 3, the Dangerous Goods List, special provisions, and the limited and excepted quantity rules.
  • Part 4, Packing and tank provisions.
  • Part 5, Consignment procedures: marking, labelling, placarding, and documentation.
  • Part 6, Construction and testing of packagings, IBCs, large packagings, portable tanks, and road tank vehicles.
  • Part 7, Provisions for transport operations, which includes stowage and the segregation rules.

Part 5 is the bridge between the warehouse and the ship. Parts 2, 3, and 4 decide what the goods are and how they are packed. Part 5 decides how that decision is communicated to everyone who handles the goods afterward. Part 7 then decides where on the ship the goods may go and what they must be kept apart from. Read Part 5 wrong and the cargo is still correctly classified and correctly packed, but nobody downstream can tell.

The two-year amendment cycle

The IMDG Code is revised on a two-year cycle, locked to the biennial revision of the UN Recommendations on the Transport of Dangerous Goods (the “Orange Book”) produced by the UN Economic Commission for Europe. Most IMDG changes flow down from that UN source so that sea, air, road, and rail stay harmonized; the rest come from proposals by member governments. Amendments that do not touch the principles of the Code are adopted by IMO’s Maritime Safety Committee on its own authority. Each amendment carries a number and a year: Amendment 41-22 was the 2022 edition; Amendment 42-24, the 2024 edition, became mandatory on 1 January 2026 after a voluntary year through 2025. Amendment 42-24 added new entries for sodium-ion batteries (UN 3551, UN 3552), vehicles powered by lithium-ion, lithium-metal, or sodium-ion batteries (UN 3556 to UN 3558), and a fire-suppressant device entry (UN 3559), among more than 300 changes. The practical rule for a shipper is to apply one edition consistently to a given shipment, never to mix the old and new editions on the same consignment.

Because the Code changes every two years, every dimension, threshold, and wording requirement in this article should be checked against the edition in force on the date of carriage. The numbers here are stable across recent editions, but the obligation to verify is permanent.

The nine hazard classes and their divisions

The classification system has nine classes. Several are split into divisions because the substances inside differ enough in behavior to need different handling. Each class has a label, and the label is the first thing the system communicates. ShipCalculators.com carries a full article on each class; the descriptions below summarize the class and the appearance of its label, with the detail in the linked articles.

Class 1, explosives, covers substances and articles with a capacity to explode, from mass-detonating cargoes to small arms cartridges. The class label is an exploding-bomb symbol in black on an orange background with the figure 1 in the bottom corner. Class 1 is divided by hazard behavior into six divisions: 1.1 (mass explosion hazard), 1.2 (projection hazard but not mass explosion), 1.3 (fire hazard with minor blast or projection), 1.4 (no significant hazard, the small-package consumer-fireworks and cartridge tier), 1.5 (very insensitive substances with a mass explosion hazard, such as blasting agents), and 1.6 (extremely insensitive articles with no mass explosion hazard). Class 1 labels also carry a compatibility group letter, a code from A to S that controls which explosives may travel together. For divisions 1.4, 1.5, and 1.6 the division number sits in the upper half of the label and the compatibility group letter in the lower half.

Class 2, gases, splits into three divisions. Division 2.1 flammable gases use a flame symbol on a red background. Division 2.2 non-flammable, non-toxic gases use a gas-cylinder symbol on a green background. Division 2.3 toxic gases use a skull-and-crossbones on a white background. All three carry the figure 2 in the bottom corner. The color carries the message before the symbol does: red for flammable, green for inert pressure, white with a skull for toxic.

Class 3, flammable liquids, uses a flame symbol, black or white, on a red background with the figure 3. This is the largest class by entry count and covers gasoline, diesel, ethanol, acetone, paints, and thousands of solvents.

Class 4, flammable solids and related hazards, splits three ways. Division 4.1 flammable solids, self-reactive substances, and desensitized explosives use a black flame on a white background broken by seven vertical red stripes. Division 4.2 substances liable to spontaneous combustion use a black flame on a background that is white on the upper half and red on the lower half. Division 4.3 substances which emit flammable gases on contact with water use a flame, black or white, on a blue background. All carry the figure 4, and division 4.3 in particular is covered in the Class 4 flammable solids article.

Class 5, oxidizers and organic peroxides, splits two ways. Division 5.1 oxidizing substances use a flame-over-circle symbol in black on a yellow background with the figure 5.1. Division 5.2 organic peroxides use a flame, black or white, on a label whose upper half is red and lower half yellow, with the figure 5.2. The current 5.2 label superseded an older single-color version that was permitted only until 1 January 2011.

Class 6, toxic and infectious substances, splits two ways. Division 6.1 toxic substances use a skull-and-crossbones in black on white with the figure 6. Division 6.2 infectious substances use a symbol of three crescents superimposed on a circle, in black on white, with the figure 6; the lower half may carry the words INFECTIOUS SUBSTANCE and an instruction to notify the public health authority in case of damage or leakage.

Class 7, radioactive material, has no single class label. Instead it uses a graded set of trefoil labels keyed to the radiation level outside the package: category I-WHITE (label 7A, white background, one red bar after the word RADIOACTIVE), category II-YELLOW (label 7B, yellow over white, two red bars), and category III-YELLOW (label 7C, three red bars). A separate fissile label (7E) carries the word FISSILE and a criticality safety index box. The transport index and contents and activity values are written onto the label itself, which is unusual; for most classes the label is fixed artwork. ShipCalculators.com does not yet carry a dedicated Class 7 wiki article, but the radioactive entries are in the IMDG dangerous goods finder.

Class 8, corrosive substances, uses a symbol of liquids spilling from two glass vessels and attacking a hand and a metal bar, in black, on a label whose upper half is white and lower half is black with a white border, figure 8. The class 8 label is one of the few where the text and class number print in white rather than black, because the lower half of the label is black.

Class 9, miscellaneous dangerous goods, uses seven vertical black stripes across the upper half on a white background, with an underlined figure 9 in the bottom corner. Class 9 is the catch-all for hazards that do not fit classes 1 through 8: lithium batteries, environmentally hazardous substances, elevated-temperature substances, dry ice, and asbestos among them. Because Class 9 is so broad, several of the special marks in the next section exist precisely to distinguish one Class 9 hazard from another.

Subsidiary risk labels

Many substances present more than one hazard. A toxic liquid that also burns, or a corrosive that is also toxic, gets a primary risk label for its dominant hazard plus one or more subsidiary risk labels for the others. A subsidiary risk label is the same diamond artwork as the corresponding class label, with one difference: it does not show the class or division number in the bottom corner, because the substance is not assigned to that class, it merely has that risk. The Dangerous Goods List drives this. Column 3 gives the primary class and so the primary label; column 4 gives the subsidiary risks and so the subsidiary labels. A substance shown in column 4 as having a class 3 and class 8 subsidiary risk gets the flame label and the corrosion label in addition to its primary label, both without numerals.

Marks and signs

The IMDG Code draws a working distinction between labels and marks. A label is the diamond-shaped hazard symbol. A mark is any other required graphic or text: the marine pollutant symbol, the elevated temperature triangle, the fumigation warning, orientation arrows, the limited and excepted quantity marks, and the lithium battery mark. Each has its own trigger and its own dimensional rules.

The marine pollutant mark

The marine pollutant mark is the dead-fish-and-tree symbol: a fish lying on its side beside a leafless tree, both inside a triangle, the artwork in black on a contrasting background or black and white when used as a sticker. It warns that the contents are harmful to the marine environment. The trigger comes from classification under MARPOL Annex III criteria, not from the fire or toxicity class; a substance of any class can be a marine pollutant.

The mark is required on packages containing a marine pollutant, with small-inner-packaging exceptions: it is not required where a marine pollutant is in inner packagings of 5 litres or less for liquids or 5 kilograms or less for solids, and for severe marine pollutants the thresholds drop to 0.5 litres or less for liquids and 500 grams or less for solids. On the package it is placed next to the hazard label, or in an appropriate place if there is no hazard label. The triangular mark on a package has sides of at least 100 mm, except where the package is too small to bear that size. On a cargo transport unit the same symbol appears, sized larger, with sides of at least 250 mm, and it must be displayed on the unit whenever the unit contains marine pollutants, in the same positions as placards, even when none of the individual packages inside were large enough to require the package mark.

The elevated temperature mark

The elevated temperature mark is a triangle, shown in red, that warns the substance is hot enough to burn on contact and may behave unpredictably. The trigger is purely thermal. A substance is an elevated temperature substance, and the mark is required on the cargo transport unit, when it is carried or offered for carriage in a liquid state at a temperature of 100 degrees Celsius or above, or in a solid state at a temperature of 240 degrees Celsius or above. Molten sulphur, hot bitumen, and molten metals are typical cases.

On a cargo transport unit the elevated temperature mark goes on each side and each end, with sides of at least 250 mm, in red. There is a second requirement that catches operators by surprise: in addition to the triangle, the maximum temperature the substance is expected to reach during transport must be durably marked on both sides of the portable tank or insulation jacket, immediately next to the triangle, in characters at least 100 mm high. The triangle says “hot”; the figure next to it says how hot. The proper shipping name reflects the same condition: if the name does not already convey it through a word like MOLTEN, the word HOT precedes the proper shipping name on the document.

The fumigation warning sign

A fumigated cargo transport unit, such as a container gassed with phosphine or sulphuryl fluoride to kill pests in timber or grain, is itself a confined-space poisoning hazard. The fumigation warning sign exists to keep people from walking into that atmosphere. It is rectangular, not less than 300 mm wide and 250 mm high, printed in black on a white background with lettering not less than 25 mm high.

The wording is fixed and must be completed with the specifics of the treatment. The sign carries the heading DANGER, then a statement that the unit is under fumigation with a named fumigant (the fumigant is written in), the date and time it was applied, the date it was ventilated, and the line DO NOT ENTER. The fumigant name, the application date and time, and the ventilation date are blanks the applicator fills in, because the response to an accidental exposure depends on which gas was used. The sign is affixed where a person trying to enter the unit will see it, and it stays on the unit until two things are true: the unit has been ventilated to remove harmful concentrations of the fumigant gas, and the fumigated goods have been unloaded. A fumigated unit carrying no other dangerous goods does not need the FUMIGATED UNIT proper shipping name or the UN 3359 number marked on it, and a Class 9 placard is not applied to a fumigated unit unless other Class 9 goods inside call for one. If the unit also holds dangerous goods, those goods’ own marks and placards apply on top of the fumigation sign.

Orientation arrows

Orientation arrows, the “this way up” mark, are two black or red arrows pointing up, on a white or contrasting background, with an optional rectangular border. They tell handlers which way is up so that a package holding liquid keeps its closures at the top. They are required on combination packagings with inner packagings holding liquid dangerous goods, on single packagings fitted with vents, and on open cryogenic receptacles for refrigerated liquefied gases. The arrows go on two opposite vertical sides, both pointing up, and may follow ISO 780 specifications.

There are several exemptions. Orientation arrows are not required on pressure receptacles, on packages with inner packagings of not more than 120 ml that have enough absorbent between inner and outer packaging to soak up the whole liquid content, on Class 6.2 infectious substances in primary receptacles of not more than 50 ml, on Class 7 radioactive material in IP-2, IP-3, A, B(U), B(M), or C packages, and on articles that are leak-tight in any orientation such as a mercury thermometer or an aerosol. One rule that trips people up: once a package is marked with proper orientation arrows, no other arrows for any other purpose may appear on it, so a logistics “stack here” arrow cannot share the package face.

The limited quantity mark

Small retail-sized quantities of dangerous goods packed inside a larger outer package can move under the relaxed regime of Chapter 3.4 if the per-inner-receptacle quantity stays within the limit shown in the Dangerous Goods List. Those packages do not carry the full hazard labels. Instead they carry the limited quantity mark: a square set on its point (a diamond) with the top and bottom corner areas filled black, the center white or contrasting, and a black border line. The minimum dimensions are 100 mm by 100 mm, with the diamond’s line at least 2 mm wide; where the package is too small, the mark may be reduced to not less than 50 mm by 50 mm provided it stays clearly visible. The mark must survive open-weather exposure without losing effectiveness. A cargo transport unit carrying only limited quantities does not need placards or the usual CTU marks, but it must be marked on the outside with LIMITED QUANTITIES or LTD QTY in letters not less than 65 mm high, in the same positions placards would occupy.

The excepted quantity mark

Even smaller quantities can move under Chapter 3.5 as excepted quantities, with quantity codes E1 through E5 in the Dangerous Goods List that set the inner and outer limits. The excepted quantity mark is also a square set on its point, with a hatched border, dimensions of not less than 100 mm by 100 mm. The first hazard class (or, where assigned, the only class) number is shown in the lower part of the mark, and the name of the consignor or consignee is shown if not given elsewhere on the package. The excepted quantity tier carries fewer obligations than the limited quantity tier, which is why the mark differs: the hatched border is the visual signal that this is the excepted, not the limited, regime.

The lithium battery mark

Lithium-ion and lithium-metal cells and batteries are a fast-growing maritime hazard and have their own mark for consignments moving under Special Provision 188, the relaxed regime for smaller cells and batteries. The lithium battery mark is a rectangle with a hatched (red) edge, minimum 120 mm wide by 110 mm high, with the hatching at least 5 mm wide; where the package is too small, it may be reduced to not less than 105 mm wide by 74 mm high. The symbol is a group of batteries, one of them damaged and emitting flame, in black on white, above a space for the UN number. The mark carries the UN number, preceded by UN, of the batteries inside: UN 3480 or UN 3481 for lithium-ion, UN 3090 or UN 3091 for lithium-metal. The mark replaces the full Class 9 lithium battery hazard label for SP 188 consignments; fully regulated lithium batteries that exceed the SP 188 limits carry the Class 9 lithium battery label (model 9A) instead. Sodium-ion batteries (UN 3551, UN 3552), added under Amendment 42-24, follow an analogous marking scheme. The IMDG dangerous goods finder lists the four core lithium UN entries and their class.

The environmentally hazardous substance mark

The environmentally hazardous substance (EHS) mark uses the same dead-fish-and-tree artwork as the marine pollutant mark. The two are visually identical because the underlying environmental hazard is the same; the EHS label in the wider transport world (under the UN Model Regulations and the road and rail codes) and the marine pollutant mark in the IMDG Code share the symbol. In sea transport the term used is marine pollutant, and the generic catch-all entries UN 3077 (environmentally hazardous substance, solid, n.o.s.) and UN 3082 (environmentally hazardous substance, liquid, n.o.s.) are both Class 9. When a named substance is also a marine pollutant, the marine pollutant mark goes on the package next to its hazard label and the words MARINE POLLUTANT go on the document.

Marking of packages

A package mark is the text that identifies what is inside, as distinct from the diamond labels that signal the hazard. The core requirement is simple and old: every package must show the proper shipping name of the goods and the UN number, with the UN number preceded by the letters UN. A typical mark reads as the proper shipping name in full followed by, for example, UN 3265. For unpackaged articles the mark goes on the article itself or on its cradle, handling, storage, or launching device. For division 1.4 compatibility group S, the division and compatibility group letter are marked unless the 1.4S label is shown.

The proper shipping name is the technical descriptor from the Dangerous Goods List, not a trade name or a chemical formula. Where the entry is an “n.o.s.” (not otherwise specified) or generic entry assigned special provision 274, the technical or chemical group name is added in parentheses so the goods can actually be identified. Salvage packagings carry the additional word SALVAGE. Intermediate bulk containers of more than 450 litres and large packagings are marked on two opposing sides so the mark is visible regardless of orientation.

Durability and visibility

The IMDG Code sets a hard durability standard for package marks and labels: they must remain identifiable on packages that have survived at least three months’ immersion in the sea. This is not a metaphor. It is the design case for a container lost overboard and washed up months later, and it drives the choice of ink, stencil, adhesive, and substrate. The marks must be readily visible and legible, displayed on a background of contrasting color on the external surface, and not crowded together with other markings (shipping labels, handling instructions, advertising) that would reduce their effectiveness. Labels themselves are affixed or stencilled by a method that survives the same three-month immersion test.

Class 7 has extra package marking rules. Each radioactive package is marked with an identification of the consignor or consignee, or both; non-excepted packages also show the UN number and proper shipping name, while excepted packages show only the UN number. A radioactive package of gross mass over 50 kg has its permissible gross mass marked. Type IP-1, IP-2, IP-3, A, B(U), B(M), and C package designs are marked with their type designation, and the more rugged Type B and Type C designs carry a trefoil embossed or stamped so it survives fire and water, with the basic trefoil sized from a central circle of radius X where X is at least 4 mm.

Placarding and marking of cargo transport units

Once individual packages are loaded into a freight container, a tank, a trailer, or a railway wagon, the package-level labels are usually hidden. The cargo transport unit (CTU) therefore carries its own enlarged version of the warning system. The governing idea in Chapter 5.3 is that enlarged labels, called placards, plus the relevant marks and signs, are affixed to the outside of the CTU to warn that the contents are dangerous, unless the package labels happen to be clearly visible from outside.

Placards

A placard is the enlarged form of the hazard label. It corresponds to the primary risk of the goods in the unit in both color and symbol, and it shows the class or division number (and, for Class 1, the compatibility group letter) in digits not less than 25 mm high. A placard is not less than 250 mm by 250 mm, with a line of the same color as the symbol running 12.5 mm inside the edge and parallel to it. Subsidiary risk placards are also displayed where a subsidiary risk label would be required on the package, except that a subsidiary placard is not needed if a primary placard already covers that hazard. For Class 1, only the placard for the highest risk division need be shown when the unit carries more than one division.

Placards are placed by unit type. A freight container, semi-trailer, or portable tank gets one placard on each side and one on each end, four in total. A railway wagon gets at least one on each side. A multiple-compartment tank carrying more than one substance gets placards along each side at the positions of the relevant compartments. Any other CTU gets at least one on both sides and one on the back. Three categories of goods are exempt from placarding the unit: division 1.4 compatibility group S in any quantity, dangerous goods packed in limited quantities, and excepted packages of radioactive material. Class 7 has its own placarding scheme using the model 7D placard, again at least 250 mm by 250 mm, yellow over white with a black trefoil, with the word RADIOACTIVE in the lower half or, where required, the UN number instead.

There is a removal rule that closes the loop. All placards, orange panels, marks, and signs must be removed from the CTU, or masked, as soon as both the dangerous goods and their residues that triggered them are discharged. An empty container still showing a Class 3 placard after the flammable liquid is gone is itself a deficiency, because it sends responders to a hazard that is no longer there.

The orange panel and the UN number display

For tanks and for large packaged consignments, the placard alone is not enough; the specific UN number must be shown so responders can look up the exact substance, not just the class. The UN number is displayed in black digits not less than 65 mm high, either against a white background in the lower half of the primary hazard class placard, or on a separate orange rectangular panel placed immediately next to each placard or marine pollutant mark. The orange panel is not less than 120 mm high and 300 mm wide, with a 10 mm black border. Where no placard or marine pollutant mark is required, the UN number goes next to the proper shipping name.

The UN number display is required on tank CTUs (including each compartment of a multi-compartment tank), on packaged dangerous goods loaded above 4,000 kg gross mass that carry a single UN number and are the only dangerous goods in the unit, on unpackaged LSA-I or SCO-I Class 7 material, on single-UN-number packaged radioactive material under exclusive use, and on solid dangerous goods in bulk containers. Goods of Class 1 are excluded from the UN number display requirement on the unit.

The proper shipping name itself is durably marked on at least both sides of tank transport units, bulk containers, and any other CTU holding packaged dangerous goods of a single commodity for which no placard, UN number, or marine pollutant mark is required (the UN number may be shown as an alternative). The elevated temperature mark, the marine pollutant mark, and the limited quantities marking, all described above, occupy the same set of positions on the unit as the placards.

Segregation and handling

Identifying a hazard is only half the job; keeping incompatible hazards apart is the other half. Segregation lives in Part 7 of the Code, not Part 5, but it is inseparable from the consignment procedures because the marks and labels are what make segregation enforceable on the quay and in the hold.

The segregation table and groups

The Code reduces the chemistry of incompatibility to a segregation table indexed by class and division. Reading the row for one class against the column for another gives one of four segregation terms, in increasing severity: “away from,” “separated from,” “separated by a complete compartment or hold from,” and “separated longitudinally by an intervening complete compartment or hold from.” Each term maps to a physical separation distance or barrier that depends on whether stowage is on deck or under deck and on the ship’s construction. The table is the default; individual Dangerous Goods List entries can tighten or relax it through special provisions and segregation codes.

Beyond the class-versus-class table, the Code defines segregation groups, families of substances that react dangerously as a group regardless of their individual class, such as acids, alkalis, and chlorates. A substance assigned to a segregation group must be segregated from substances in conflicting groups even when the class-versus-class table alone would allow them together. The IMDG segregation calculator applies the table and the group rules to a pair of UN numbers and returns the required separation term. The container/vehicle packing certificate, discussed below, is where someone formally certifies that packages requiring segregation were not packed together in the same unit.

Documentation

The marks travel with the goods physically; the documentation travels with them on paper or in data. Chapter 5.4 sets out three documents that matter most: the dangerous goods transport document (commonly the dangerous goods declaration), the container/vehicle packing certificate, and the documents that must be aboard the ship.

The dangerous goods transport document

The consignor who offers dangerous goods for transport must describe them on a transport document. The document may be in any form, provided it contains all the required information; if it lists both dangerous and non-dangerous goods, the dangerous goods come first or are otherwise emphasized. It carries the name and address of the consignor and consignee and the date it was prepared.

The heart of the document is the dangerous goods description, five elements in a fixed order with nothing interspersed: (1) the UN number preceded by UN; (2) the proper shipping name, including any technical name in parentheses for n.o.s. entries; (3) the primary hazard class or division, including the compatibility group letter for Class 1; (4) any subsidiary hazard class or division numbers, in parentheses, matching the subsidiary risk labels; and (5) the packing group, where assigned, optionally prefixed PG. A worked example in the Code reads, in substance, UN 1098, proper shipping name allyl alcohol, class 6.1, subsidiary class 3 in parentheses, packing group I, with the closed-cup flashpoint of 21 degrees Celsius. The description is supplemented as needed: the word WASTE before the name for waste being moved for disposal, EMPTY UNCLEANED or RESIDUE LAST CONTAINED for empty means of containment, HOT before the name for elevated temperature substances not already named as MOLTEN, the words MARINE POLLUTANT for a marine pollutant, and the minimum flashpoint for goods with a flashpoint of 60 degrees Celsius closed-cup or below.

After the description comes the total quantity of each item (net explosive mass for Class 1), the number and kind of packages, and class-specific additions: the words limited quantity or LTD QTY for the limited quantity regime, SALVAGE PACKAGE for salvage packagings, and the control and emergency temperatures for self-reactive substances of Class 4.1 and organic peroxides of Class 5.2 that need temperature control, written as control temperature and emergency temperature in degrees Celsius. Class 7 carries an extended block: radionuclide, physical and chemical form, maximum activity in becquerels, package category (I-WHITE, II-YELLOW, III-YELLOW), transport index, criticality safety index for fissile material, and competent authority approval identifiers.

The document closes with a certification signed and dated by the consignor: a declaration that the contents are fully and accurately described by the proper shipping name and are classified, packaged, marked, labelled or placarded, and in proper condition for transport according to the applicable international and national regulations. Where the documentation is exchanged by electronic data processing or electronic data interchange, the signature may be replaced by the authorized person’s name in capitals.

The container/vehicle packing certificate

When dangerous goods are packed into a container or vehicle, those responsible for the packing provide a container/vehicle packing certificate. It specifies the unit’s identification number and certifies a checklist of conditions: the unit was clean, dry, and fit to receive the goods; packages that must be segregated were not packed together; all packages were inspected and only sound ones loaded; drums were stowed upright and the load braced; bulk goods were evenly distributed; the unit is structurally serviceable for Class 1 goods other than 1.4; the unit and packages are properly marked, labelled, and placarded; and, where dry ice is used for cooling, the unit is marked DANGEROUS CO2 (DRY ICE) INSIDE, VENTILATE THOROUGHLY BEFORE ENTERING. The certificate confirms a dangerous goods transport document was received for each consignment loaded. The packing certificate is not required for portable tanks. The transport document and the packing certificate may be combined into a single document; if combined, the document carries a signed, dated declaration that the packing was carried out in accordance with the applicable provisions, with the signer identified.

Documents aboard the ship, EmS, and the MFAG

A ship carrying dangerous goods and marine pollutants must have a special list or manifest, or a detailed stowage plan, setting out the goods and their location aboard, per SOLAS Chapter VII regulation 4.5 and MARPOL Annex III regulation 4(3). The manifest is built from the documentation and certification already described, adding the stowage location and total quantity, and a copy is made available before departure to the port State authority.

Emergency response information must be immediately available at all times, away from the packages and accessible during an incident. Two IMO documents carry that information. The EmS Guide, the Emergency Response Procedures for Ships Carrying Dangerous Goods, gives a fire schedule and a spillage schedule for each substance, coded with an F-prefix for fire and an S-prefix for spillage; the Dangerous Goods List assigns each entry its EmS codes. The IMDG EmS lookup returns the schedule codes for a UN number. The MFAG, the Medical First Aid Guide for Use in Accidents Involving Dangerous Goods, gives the medical response for exposure, poisoning, burns, and other casualties, organized so a ship’s officer without medical training can act before professional help is reached. Both are used together with the transport document. Other documents are required in specific cases: a weathering certificate, an exemption certificate for substances such as charcoal, fishmeal, or seedcake, and competent authority classification statements for new self-reactive substances and organic peroxides.

Common compliance errors

Inspection findings cluster around a short list of recurring mistakes, and most of them are failures of the Part 5 communication system rather than of classification or packing.

The most common is leaving placards, panels, or marks on an empty unit after the goods and residues are gone, which violates the removal rule and misdirects responders. Close behind is the orientation-arrow conflict: a logistics or handling arrow left on a package that already carries proper orientation arrows, which the Code prohibits outright. A third is using a trade name or chemical formula in place of the proper shipping name, or omitting the technical name in parentheses on an n.o.s. entry, so the goods cannot be identified from the document. A fourth is mis-ordering the five elements of the dangerous goods description or interspersing other text between them. A fifth is treating the marine pollutant mark on the CTU as optional when no single package required it, when in fact the unit must carry the mark whenever marine pollutants are inside. A sixth is undersized digits or marks: a placard with a class number under 25 mm, an orange panel under the 120 mm by 300 mm minimum, or a UN number under 65 mm high. A seventh is forgetting the temperature figure that must accompany the elevated temperature triangle, or the control and emergency temperatures on the document for temperature-controlled Class 4.1 and 5.2 cargoes. An eighth, increasingly common, is applying the wrong lithium battery graphic: the SP 188 lithium battery mark where the full Class 9 lithium battery label is required, or the reverse.

Limitations

This article is an educational reference, not a substitute for the Code itself. Several limits apply. The IMDG Code changes on a two-year cycle, and the edition in force on the date of carriage governs; the dimensions, thresholds, and wording here are stable across recent editions but must be checked against the current text. The detailed label artwork, the segregation table, the EmS schedules, and the Dangerous Goods List entries are IMO copyright and are described here in summary, not reproduced; the operative text is the Code as published by IMO. National competent authorities can impose additional requirements, and flag and port states enforce against their own implementing legislation, so a consignment compliant with the bare Code can still face local requirements. Classification under Part 2, packing under Part 4, and stowage and segregation under Part 7 each carry their own detailed rules that interact with the Part 5 marking system and are only summarized here. For an actual shipment, the controlling authorities are the current IMDG Code, the relevant national regulations, and the competent authority, in that order, and where doubt exists the consignor should obtain a determination from the competent authority rather than infer one.

See also

Sources