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EFI  /  Dangerous goods resources

Will these classes travel together?

Pick the hazard classes going into one container or one trailer, or the battery you are booking on a flight. Every pair gets checked against the US tables and you get one answer: whether they ship together, or they do not.

01 Segregation checker

Check a load

Add two classes or twenty. The tool checks every pair, not just the first two, and reports the worst result it finds.

Class compatibility

Vessel stowage and segregation, 49 CFR 176.83(b)

Classes in the unit

    The class pair is where you start, not where you finish. The 172.101 table entry for your specific UN number can require stricter segregation than the class table, and where the two disagree, the entry wins. Check both UN numbers before you load.

    02 One box, or two

    What can go in the same container

    03 The tables

    The full segregation table

    Drag sideways to see every class. Hover a cell to trace its row and column.

    Three road prohibitions that never appear in the grid. 49 CFR 177.848(c) forbids these whatever the table shows, subject only to the lab-pack exception at 49 CFR 173.12(e): cyanides, cyanide mixtures or solutions with acids where the mixture would generate hydrogen cyanide; Division 4.2 with Class 8 liquids; and Division 6.1 Packing Group I Hazard Zone A with Class 3, Class 8 liquids, or Divisions 4.1, 4.2, 4.3, 5.1 and 5.2. Separately, 177.848(e)(3) bars Class 8 liquids loaded above or adjacent to Class 4 or Class 5 material, except truckload shipments where the mixture is known not to cause a fire or a dangerous evolution of heat or gas.

    04 Labels and placards

    Every hazard class, on one page

    Drawn from the label models in the UN Model Regulations and 49 CFR part 172 subpart F. Use them to recognize what turned up on your dock, not as artwork to print. Placards must be bought from a compliant supplier, in the right size, color and durability.

    Does the unit need a placard at all?

    49 CFR 172.504 sorts every hazard class into one of two tables, and the table sets the threshold. Text below is the eCFR, current as of September 3, 2026.

    Table 1  ·  any quantity

    1.11.21.32.34.35.26.17

    One package is enough. The unit gets placarded on each side and each end, whatever it weighs.

    In this table 5.2 means organic peroxide Type B, liquid or solid, temperature controlled. 6.1 means a material poisonous by inhalation. 7 means a Radioactive Yellow III label. The plain versions of those three sit in table 2. Class 7 reaches further than the label: the footnote to table 1 also pulls in unpackaged LSA-I and SCO-I, any shipment required by 173.427, 173.441 or 173.457 to move under exclusive use, and closed vehicles used under 173.443(d).

    Table 2  ·  454 kg / 1,001 lb

    1.41.51.62.12.234.14.25.15.26.16.289

    Under 454 kg (1,001 lb) aggregate gross weight of table 2 material, no placard is required. Combustible liquid sits in this table too. Division 6.2 has no placard listed at all.

    The 454 kg relief never reaches a bulk packaging, and never reaches anything subject to 172.505. Separately, a non-bulk package holding only residue is left out of the weight under 172.504(d)(1), and that carve-out has the same 172.505 exception, so poison inhalation residue still counts.

    The relief names two modes, and ocean is not one of them. 172.504(c) opens with “when hazardous materials covered by table 2 of this section are transported by highway or rail.” A light table 2 load can leave on a domestic trailer bare. Do not carry that habit onto a box you are tendering for export: placard it, and confirm with the line.
    DANGEROUS, and the trap inside it. Two or more table 2 categories in non-bulk packages may take a single DANGEROUS placard instead of one placard each, under 172.504(b). But once 1,000 kg (2,205 lb) aggregate gross weight or more of a single category is loaded at one loading facility, that category has to show its own placard. Same trailer, different answer, and it turns on where the freight was picked up.
    Class 9 is not placarded inside the United States. 172.504(f)(9), verbatim: “For Class 9, a CLASS 9 placard is not required for domestic transportation, including that portion of international transportation … which occurs within the United States.” Once the box is on the water it is a different rulebook: IMDG special provision 384 puts a Model No. 9 placard on the unit. The drayage leg and the ocean leg answer differently and the box never changes.A battery trailer running to the port carries no class 9 placard under 49 CFR. The export container it feeds does, under IMDG SP 384. Do not let the driver’s paperwork set the box’s. Bulk packagings still need the identification number displayed, on a placard, an orange panel or a white square-on-point.
    Two smaller ones worth knowing. Where more than one Class 1 division placard would apply, only the lowest division number is displayed, under 172.504(f)(1). And for domestic movement a POISON placard is not required on a unit that already has to show POISON INHALATION HAZARD or POISON GAS, under 172.504(f)(11).

    Label 9A is not a placard. IMDG special provision 384 is explicit: lithium and sodium ion packages take the Model No. 9A label, but a cargo transport unit carrying them is placarded with Model No. 9. Package 9A, container 9. Putting the battery label on the unit is one of the most visible errors you can make on a box.

    05 Handling and marking

    Marks that travel alongside the diamond

    These aren’t hazard classes. They tell whoever handles the package how to treat it, and several of them are what actually gets a shipment rolled at the airline counter.

    On the excepted quantities mark, the single asterisk stands for the class or division number and the double asterisk for the name of the shipper or consignee where it isn’t shown elsewhere on the package.

    06 Before it ships

    Before the unit is sealed

    07 Class 9 batteries

    Lithium and sodium ion batteries

    Column 16b, the part that reaches our bench. UN 3480, UN 3551 and UN 3552 all carry a blank or dashed Column 16b, read directly from Amendment 42-24 as adopted in IMO resolution MSC.556(108). No specific segregation applies to the battery entries themselves. Stowage category and EmS sit on the same rows, but those tell the ship where to put the box and how to fight a fire in it, so they are the line’s call and not ours.
    Damaged, defective, and for disposal. By sea, damaged or defective cells ship under special provision 376 in P908 or LP904, and the high-risk ones in P911 or LP906 with competent authority approval. Cells going for disposal or recycling ship under special provision 377 in P909, marked “LITHIUM BATTERIES FOR DISPOSAL” or “LITHIUM BATTERIES FOR RECYCLING.” By air, batteries identified as damaged or defective are forbidden outside an approved arrangement. If a customer hands you a pallet of swollen cells, that is a sea shipment or a specialist, not an airline booking.

    Not sure what you’re holding?

    Send us the safety data sheet. We classify it, build the declaration, sort the packing and labeling, and book it by air, ocean or road with the paperwork that survives an inspection.

    Classification, declarations, segregation and the booking itself are covered on our dangerous goods consulting page.

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    Read this before you rely on it. This page is a reference tool. It is not a compliance determination and it is not legal advice. It reproduces the general segregation tables from 49 CFR parts 176 and 177, which govern US vessel and highway transport. The entry for your specific UN number in the 172.101 table can impose stricter segregation and takes precedence over the class table. For international carriage, work from the edition of the IMDG Code or the IATA Dangerous Goods Regulations in force, and check Column 16b of the Dangerous Goods List. Carrier and State variations can be stricter again. Verify against the current regulation and your carrier before you load.

    Sources

    • 49 CFR 176.83(b) General segregation requirements for hazardous materials, vessel. Table and legend, eCFR text current as of September 3, 2026, cross-checked against the GPO annual edition.
    • 49 CFR 176.83(c)(2) Definitions of the four segregation terms and their distances.
    • 49 CFR 176.83(f) Segregation of containers on board container ships, including the definition of a container space at (f)(4).
    • 49 CFR 177.848 Segregation of hazardous materials, highway. Table at (d), instructions at (e), extra prohibitions at (c), explosives compatibility at (f).
    • 49 CFR 172 subpart E and F for the marking and labeling specifications reproduced in sections 04 and 05.
    • 49 CFR 172.504 General placarding requirements. Tables 1 and 2 at (e), the 454 kg exception and its two named modes at (c), the DANGEROUS placard at (b), the Class 9 domestic exception at (f)(9).
    • 49 CFR 176.27(c) The container packing certificate, for a freight container or transport vehicle offered to a manned vessel in ocean or coastwise service.
    • 49 CFR 173.25(a) Authorized packagings and overpacks, including the Packing Group I prohibition at (a)(5).
    • 49 CFR 172.604 Emergency response telephone number, including the call-back exclusion at (a)(2) and the exception list at (d).
    • 49 CFR 177.834 paragraphs (a) and (b), securing packages in a motor vehicle and loading to the orientation markings.
    • IATA Dangerous Goods Regulations, 67th edition, effective January 1, 2026, and the IATA Lithium Battery Guidance Document dated January 1, 2026, for the air rules in section 06.
    • IMDG Code Amendment 42-24, mandatory from January 1, 2026, for the sea rules in section 06.

    Both segregation matrices on this page were checked for symmetry, cell by cell, against a second independent source before publication.

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