Due to the safety risks associated with the international shipping of dangerous goods, the declaration process is subject to strict regulations (corely based on the IMDG Code). The UN number and MSDS (Material Safety Data Sheet) serve as the “entry credentials” for declaration. Missing or incorrectly using them can directly lead to declaration failure and cargo detention at port.
In this article, Weefreight will share a complete breakdown of the declaration process, along with key considerations, which we hope will be helpful.
- Pre-Declaration Essentials: Prepare the “Two Core + Three Supporting” Documents
Before initiating a declaration, you must first confirm the completeness and accuracy of the documents, especially the “two core” documents—the UN number and MSDS. They must match perfectly, without any inconsistencies.
- Two Core Documents: UN Number and MSDS (Declaration is Invalid Without One)
UN Number: The “Identity Card” of Dangerous Goods
The UN Number is a unique 4-digit code assigned by the United Nations to each dangerous good (e.g., ethanol UN1170, lithium batteries UN3480, sulfuric acid UN1830). It directly determines the hazardous properties, packaging requirements, and transportation restrictions of the goods.
Note: The same type of dangerous goods may be assigned different UN Numbers (e.g., 98% concentrated sulfuric acid UN1830, 50% dilute sulfuric acid UN2807). Please check the actual composition and purity of the goods. Do not use similar numbers based on “experience.” Otherwise, shipping companies or customs will deem it a “false declaration.”
MSDS: “Safety Data Sheet” for Dangerous Goods
Also known as an “SDS,” this document must be compiled in strict accordance with the IMDG Code and contain 16 mandatory items, including: cargo composition, physical and chemical properties (flash point, boiling point, explosion limits, etc.), hazard classification, first aid measures, firefighting measures, transportation precautions, and leak handling procedures.
Key requirements: ① It must be issued by the manufacturer or a qualified third-party organization and cannot be independently compiled; ② The English version must be accurate (customs at the port of destination prioritizes English versions); ③ The “hazard class” and “UN number” must be identical to the actual cargo and the declared information (e.g., if an MSDS is labeled “Class 3 Flammable Liquid, UN1230,” it cannot be changed to a different class or number during declaration).
- Three Types of Supporting Documents: Ensuring a Closed-Loop Declaration Process
In addition to the two core documents, the following documents are required to demonstrate compliance with cargo packaging and consignment information:
“Dangerous Goods Ocean Shipping Letter of Authorization”: Completed by the shipper or freight forwarder, this document specifies the shipper, consignee, and notifying party, along with the cargo name, weight, volume, hazard class, and special transportation requirements (e.g., whether refrigeration is required, whether transshipment is permitted, etc.).
“Dangerous Goods Packaging Performance Test Result Sheet”: Provided by the packaging manufacturer, this document certifies that the packaging used for the cargo (e.g., drums, hazardous materials cartons, IBCs) meets the IMDG Code requirements for impact resistance, leak resistance, and temperature resistance (e.g., Class 3 flammable liquids require “leak-proof hazardous materials packaging” and cannot be shipped in ordinary cartons).
“Dangerous Goods Packaging Usage Appraisal Result Sheet”: Issued by the local customs inspection and quarantine department, this document certifies that the packaging is properly loaded with the cargo (e.g., seals are intact, gaskets are in place, and the hazardous materials labeling on the packaging is in compliance with regulations).
- The entire declaration process: 6 interconnected steps; any mistake can lead to delays.
Declaration must begin 7-10 days before cargo loading (shipping company review and space confirmation take time). The specific steps are as follows:
Step 1: Confirm the cargo’s hazard level and match it to the IMDG classification.
First, based on the cargo’s characteristics (flammability, corrosiveness, toxicity, radioactivity, etc.), classify it according to the IMDG Code into the corresponding category and sub-category within the nine major categories of dangerous goods. For example:
Methanol (flash point -16°C) → Class 3 (Flammable Liquids), Division 3.1 (Low Flash Point Flammable Liquids);
Sodium hydroxide (solid) → Class 8 (Corrosive Substances), Division 8.2 (Alkaline Corrosives);
Lithium-ion batteries → Class 9 (Miscellaneous Dangerous Goods).
The hazard level must be consistently indicated on all declaration documents. Ambiguous classification (e.g., simply stating “dangerous goods” without specifying the specific category) is prohibited.
Step 2: Submit a pre-declaration to the shipping company to secure shipping space.
The freight forwarder will submit all documents (UN number, MSDS, supporting documents, and letter of authorization) to the shipping company’s “Dangerous Goods Verification Department.” The shipping company will focus on three key points:
Whether the documents are complete and the UN number matches the MSDS;
Whether the cargo is on the shipping company’s “prohibited goods list” (for example, some shipping companies do not accept Class 1 explosives or Class 6.1 highly toxic substances);
Whether the packaging inspection form covers the cargo’s weight and volume (for example, if the cargo is 10 tons and the packaging inspection form states “maximum load 5 tons,” the cargo will be rejected).
After passing the inspection, the shipping company will issue a “Space Confirmation Letter,” at which point subsequent loading can be arranged. If the inspection fails, the documents must be revised and re-declared, which will directly delay the ship’s schedule.
Step 3: Compliant Packaging and Labeling to Avoid “Packaging Mismatches”
Cargo loading must strictly adhere to the “hazard class – packaging matching” principle and require labeling as required:
Packaging requirements: For example, Class 4.1 flammable solids must be packaged in “ventilated hazardous materials packaging” (to prevent heat accumulation and spontaneous combustion), and Class 5.1 oxidizers must be packaged separately from flammable materials.
Labeling requirements: The packaging must be affixed with a “hazardous goods category label” (e.g., a red flame label for Class 3, a white corrosive label for Class 8), a “UN number label” (font height ≥ 10mm), and the owner’s name and emergency contact number (must be consistent with the MSDS).
Missing or incorrect labeling (e.g., applying a Class 8 corrosive label to a Class 3 flammable label) will result in port interception and will require correction before release.
Step 4: Submit a formal declaration to the customs and obtain a “Customs Declaration Form”
The freight forwarder, armed with the shipping company’s space confirmation and a complete set of declaration documents, submits a dangerous goods export declaration to the local customs. Customs will use “risk management” to verify:
Whether the declared information is consistent with the documents (e.g., whether the “Goods Name” on the customs declaration form matches the MSDS);
Whether the packaging is in compliance (whether there is any damage, and whether the labeling is clear);
Whether the goods are dangerous goods prohibited from export by the state (e.g., some highly toxic chemicals require an additional “Export License”).
Once the declaration is approved, the customs will issue an “Export Declaration Form,” and the goods can enter the port.
Step 5: Loading Supervision and Retaining “Loading Supervision Photos/Report”
The loading of dangerous goods in containers must be supervised on-site by a qualified “Dangerous Goods Loading Supervisor” to ensure:
The cargo is securely loaded (no shaking or squeezing);
Cargo of different hazard categories is not mixed (for example, oxidizers and flammable materials should not be loaded together to prevent chemical reactions);
The container is equipped with appropriate emergency supplies (for example, a Class 3 flammable liquid container must contain a fire extinguisher and absorbent cotton).
After the loading supervision is completed, loading supervision photos (including the empty container before loading, the loading process, and the entire container after sealing) and the “Dangerous Goods Loading Supervision Report” must be retained for inspection by customs or shipping companies.
Step 6: Submit the “Dangerous Goods Declaration Form” in exchange for the “Cargo Manifest”
After loading and sealing the container, the freight forwarder must submit the final “Dangerous Goods Declaration Form” (including the loading supervision information and the container sealing number) to the shipping company. After the shipping company reviews and approves it, the cargo information will be entered into the “Cargo Manifest.” Only cargo listed in the cargo manifest can be shipped aboard. If errors are discovered at this point, the correction process is complex and there’s a high probability of missing the scheduled sailing date.
III. Common Mistakes Warning: Three “Small Mistakes” Can Lead to Major Losses
UN Number Mismatch with MSDS: For example, if the MSDS lists UN3480 (lithium batteries) but mistakenly declares UN3090 (lithium metal batteries), this will be considered “declared inconsistent,” the cargo will be detained at the port, and a fine will be imposed.
Omitting the “Packaging Identification Form”: If the “small quantity of dangerous goods does not require hazardous packaging,” the cargo will be shipped in ordinary packaging. This can lead to direct interception during port security inspections, delaying shipment and potentially imposing penalties.
Incomplete MSDS Information: If critical data such as “flash point” and “explosion limit” are omitted, the shipping company will require corrections during the review, resulting in space cancellation (especially during peak season when space is tight, and space may not be available during the correction period).
In short, the core of international maritime dangerous goods declarations is “compliance + accuracy”—the UN number and MSDS are fundamental. Every step of the process must strictly comply with the IMDG Code and customs and shipping company requirements. Don’t take chances. We recommend working with a freight forwarder certified in dangerous goods declarations to reduce operational risks.
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