IMDG Dangerous Goods from China: A Working Guide

The IMDG Code is the rulebook that governs every dangerous-goods sea shipment from China. For chemical importers, mastering DG is the single highest-impact piece of the import chain, most of the costs and delays in chemical sourcing happen at DG control points, and most of those costs are preventable with discipline at the factory.

This guide walks the chain end to end: classification, packaging, documentation, carrier booking, inspection, shipping, and destination handling. Twenty years of running DG cargo from Shanghai Pudong is the basis. The failure modes described are ones we have lived through or watched up close.

The 9 IMDG classes

The IMDG Code groups dangerous goods into nine classes by physical hazard. The five classes most relevant to industrial chemical sourcing:

The other four classes (1 explosives, 2 gases, 7 radioactive, 9 miscellaneous) come up rarely in routine industrial chemical exports and are out of scope for this guide. If you are shipping any of those, the documentation chain is more involved than what is described here and we recommend engaging a specialist DG forwarder.

Within each class, the packing group (PG I, II, or III) sets the relative severity. PG I is most hazardous; PG III is minor. Packing group determines the packaging strength required and influences the stowage and segregation rules the carrier applies.

Step 1: Classify the substance under IMDG

Classification is not optional. Every DG export from China must have a defensible IMDG classification before booking. Three pieces of identity:

1. UN number, four-digit identifier
2. Class and any subsidiary risk, e.g. “8” for a corrosive, or “8 (6.1)” for a corrosive that is also a toxic substance
3. Packing group. I, II, or III

The factory has the primary responsibility for classification. They know the substance, they have the test data, and they certify it on the DG Declaration. But the importer’s sourcing partner should verify the classification independently against the IMDG Code before the cargo loads. The most expensive misclassification we have caught was a factory that classified a substance as Class 8 PG III when the destination authority subsequently classified it as Class 6.1 PG II, different class, different packing group, completely different documentation set. The cargo would have been held at destination port for re-classification and re-packaging at six-figure cost.

Step 2: Confirm UN-certified packaging

UN-certified packaging is the second non-negotiable. Every drum, IBC, or pail carrying DG cargo must have a UN code stamp on the package showing it has been tested and certified to the relevant performance level.

The UN code looks like: 1A1/Y1.4/250/24/CHN/12345

Decoded:

• 1A1, package type (steel non-removable head drum)
• Y, packing group (Y = tested for PG II, X = PG I, Z = PG III)
• 1.4, relative density of contents tested
• 250, hydrostatic pressure tested in kPa
• 24, year of manufacture (2024)
• CHN, country of manufacture (China)
• 12345, registered manufacturer ID

The second character (X, Y, or Z) is the one that matters most. It must match the assigned packing group of your cargo:

• PG I cargo needs X-stamped packaging (or higher)
• PG II cargo needs Y-stamped packaging (or higher)
• PG III cargo needs Z-stamped packaging (or higher)

Y packaging can carry PG II or PG III. X packaging can carry any. Z packaging can only carry PG III. A PG II cargo in Z packaging is a misclassification and grounds for rejection at the load port or the destination port.

For the SGS or Bureau Veritas pre-shipment inspection, we require the inspector to photograph the UN code stamp on a sample of drums and append the photographs to the report. If the second character does not match the packing group on the DG Declaration, the cargo does not seal until reconciled.

Step 3: Prepare the MSDS in English

The MSDS (or SDS under modern terminology) must be in the destination-language, for US, EU, AU bound cargo, English. A Chinese-only MSDS is grounds for carrier booking refusal.

The 16-section GHS format is mandatory:

1. Identification
2. Hazards identification
3. Composition / information on ingredients
4. First-aid measures
5. Firefighting measures
6. Accidental release measures
7. Handling and storage
8. Exposure controls / personal protection
9. Physical and chemical properties
10. Stability and reactivity
11. Toxicological information
12. Ecological information
13. Disposal considerations
14. Transport information ← the section the carrier reads
15. Regulatory information
16. Other information

Section 14 must reconcile line-by-line with the DG Declaration:

If any field disagrees, the carrier rejects the booking. The carrier’s chemist cross-checks every line. Disagreements catch nothing close to all-or-nothing, even a typo in the proper shipping name (e.g. “Hydrocholric” vs “Hydrochloric”) triggers a rejection until corrected.

Step 4: Issue the DG Declaration

The DG Declaration is the shipper-signed transport certification. The IMO Multimodal Dangerous Goods Form is the standard format; some carriers use proprietary equivalents. Either format must contain:

1. Proper Shipping Name
2. UN Number
3. Class and any Subsidiary Risk
4. Packing Group (I, II, III)
5. Quantity and packaging type per substance
6. Marine Pollutant indicator
7. EmS (Emergency Schedule) reference
8. Flashpoint for flammable liquids
9. Shipper’s certification statement, signed and dated

The certification statement reads (paraphrased): “the contents of this consignment are fully and accurately described above by the proper shipping name, classified, packaged, marked, labelled, and in all respects in proper condition for transport according to applicable international and national governmental regulations.”

That is a legal certification. Misdeclaration of dangerous goods is a criminal offence in most jurisdictions and the carrier’s liability insurance will not cover misdeclared cargo. The factory signs as the shipper. The importer’s sourcing partner reviews before the document goes to the carrier.

Step 5: Apply hazard labels and placards

Two levels of marking are required:

Hazard labels on individual packages. Class-specific diamond labels affixed to every drum, IBC, or pail. Class 3 (flammable) is red with a flame symbol. Class 6.1 (toxic) is white with a skull symbol. Class 8 (corrosive) is white-and-black with a corrosion symbol. The labels must be visible after stowage and resistant to weather and seawater for the duration of the voyage.

Placards on the container. Larger versions of the same diamond labels, attached to all four sides plus the door end of the container. Placards make the container’s hazardous contents visible to anyone handling it at terminals, transhipment points, and the destination port.

For container with multiple DG substances, multiple placards are applied, one per class represented in the cargo.

The factory is responsible for label application and we verify during the SGS or Bureau Veritas pre-shipment inspection. Labels missing, wrong class, faded, or damaged trigger a rework before the cargo seals.

Step 6: Book the carrier slot for DG cargo

DG carrier booking is more involved than for general cargo. The carrier’s chemist (every major carrier. Maersk, MSC, CMA CGM, Hapag-Lloyd, has one or more on staff) reviews:

1. DG Declaration consistency. Proper Shipping Name + UN number + class + packing group all reconcile.
2. Quantity within carrier per-container DG limits. Some classes have absolute limits per container; some have ratio limits relative to other DG classes in the same container.
3. Packaging UN code matches packing group. As described in Step 2.
4. Substance permitted on that vessel and route. Some vessels and some routes prohibit certain DG classes. The carrier’s vessel-specific DG profile determines acceptance.
5. Stowage and segregation plan satisfies IMDG segregation tables. Some DG classes cannot share a container or even a deck position. The carrier’s stowage planner computes this.

If any check fails, the booking is rejected. The shipper has 24 to 72 hours to correct or the slot is released. Booking failures cost the cargo a sailing slot, typically a 1 to 2 week delay to the next vessel, plus rebooking fees of USD 200 to USD 800 per container.

DG bookings also have longer cut-off times than general cargo. General cargo cuts off 24 to 48 hours before vessel sailing. DG cargo cuts off 5 to 7 days before sailing to allow the carrier’s chemist review and stowage planning. Plan production to meet the DG cut-off, not the general-cargo cut-off.

Step 7: Pre-shipment inspection by SGS or BV

For DG cargo, pre-shipment inspection is non-negotiable. The risk profile is too high to ship without third-party verification at the factory.

The DG inspection scope adds three items beyond the standard chemical inspection:

1. UN code stamp verification on packaging with photographs
2. Hazard label verification on every package (or on a representative sample for very large lots)
3. Container placard verification before sealing

Plus the standard inspection: quantity verification, packaging integrity, sample collection for lab analysis, AQL sampling, loading supervision, container photography.

DG pre-shipment inspection cost typically runs USD 400 to USD 900 per inspection, slightly higher than general cargo because of the additional DG-specific scope. Worth every dollar. A DG misdeclaration caught at the factory is a phone call. A DG misdeclaration caught at the load port is a rebooking. A DG misdeclaration caught at the destination port can be five-figure cargo holds and re-classification fees.

Step 8: Sail under DG manifest

The vessel sails with the DG cargo on an approved stowage position. The carrier files a DG manifest with the port authority at both ends of the voyage. The manifest names every DG substance on board, every UN number, every packing group, and the stowage location of each container.

Vessel sailing with DG cargo:

• Some routes have transit-port restrictions on certain DG classes (e.g. some Suez Canal authorities restrict certain Class 5.2 organic peroxide cargoes)
• Some weather conditions require DG cargo to be stowed below deck rather than on deck (Class 4.2 spontaneously combustible substances are particularly weather-sensitive)
• DG cargo is logged separately from general cargo in the carrier’s tracking systems

For the importer the on-water phase is largely passive, the cargo is in the carrier’s hands until destination berth. The original B/L courier and the destination-port arrangements run on the same timeline as for general cargo.

Step 9: Destination port DG handling

DG cargo is more likely than general cargo to be flagged for inspection at the destination port. US Customs and Border Protection, EU customs, and Australian customs all have DG-specific inspection regimes. Inspections typically take 1 to 5 days; demurrage accrues during the inspection.

The destination importer of record needs to be ready with:

1. TSCA certification (for US imports) or REACH registration confirmation (EU) or AICIS declaration (Australia)
2. Original B/L to claim the cargo
3. Customs entry filing with the correct HS code
4. Trucking dispatch to collect the container once released

For DG cargo specifically, destination customs may inspect packaging condition, verify hazard labels are intact, and cross-check the substance against the regulatory regime. If anything is found wanting, degraded labels, packaging damage, documentation gap, the cargo is held until reconciled.

What DG cargo actually costs versus general cargo

A common buyer question: “how much more expensive is DG?” The honest answer: 15 to 35 percent more on the freight portion, plus USD 200 to USD 800 in additional documentation and inspection fees. Specifically:

For a 20-foot container of corrosive liquid in 80 drums, the DG premium typically adds USD 800 to USD 2,500 to the total landed cost compared to general cargo. Worth knowing in advance; not enough to redirect sourcing decisions for most use cases.

Common DG rejection reasons we have caught

Across hundreds of DG containers, the recurring failures are:

1. Trade name on the DG Declaration instead of Proper Shipping Name, most common. Factory writes “Hydrochloric acid technical grade” instead of the IMDG-approved “Hydrochloric acid”. Rejected.
2. Wrong UN number, factory pulled a similar but not identical UN entry from an old shipment. Rejected.
3. Packing group mismatch with packaging UN code. DG Declaration says PG II, drums carry Z code (PG III). Rejected.
4. Missing flashpoint on Class 3, required field omitted from DG Declaration. Held pending data.
5. Marine Pollutant flag missing on a substance that is a marine pollutant under Annex II of MARPOL. Held pending re-declaration.
6. MSDS in Chinese only. Held pending English version.
7. Mixed DG classes in same container without segregation plan, incompatible substances booked into one container. Cargo split into separate containers, additional booking and freight cost.

Every one of these is preventable with factory-side discipline and our review of the documentation before it goes to the carrier.

What we do for DG buyers

For US, EU, and Australian importers shipping DG cargo from China, our work covers: classification verification before factory production starts, UN packaging specification on the purchase order, MSDS review and English-version requirement, DG Declaration cross-check before submission to the carrier, pre-shipment inspection booking and report review with photographs of the UN codes and hazard labels, carrier booking review for DG-specific cut-offs and segregation, and destination customs documentation pre-filing review.

Most of our buyers come to us after at least one DG misadventure with a previous supplier or sourcing approach. The DG chain is unforgiving of casual handling. Done with discipline, it is just a chain of documentation and verification checks. Done casually, it is a series of expensive surprises.

If you are about to ship DG cargo from China and want the chain reviewed before the deposit goes out, send us the spec. We will look at it the way we look at our own bookings.