IMDG Segregation & Stowage Tool Dangerous Goods Compatibility & Separation

IMDG 42-24 • General Segregation Table • Subsidiary Hazards • DGL 16b Override • Stowage Category A–E • Pairwise Cargo Matrix • Class 1 Review • Segregation Groups

IMDG Segregation & Stowage Tool Dangerous Goods Compatibility & Separation

Screen packaged dangerous goods against the current IMDG general segregation framework, then layer in subsidiary hazards, user-entered Dangerous Goods List column 16b precedence and stowage-category checks. Simple mode compares one pair. Advanced builds a manifest-style cargo register, analyzes every cargo pair, applies pair-specific DGL overrides, flags unresolved Class 1 / “X” cases, checks Category A–E deck restrictions and produces a compatibility matrix and review ledger.

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Need a multi-cargo pair matrix and DGL-specific overrides? Click Advanced above.Simple uses the general IMDG class table as a baseline and treats a single subsidiary hazard as controlling when it produces a more stringent result.

BaselineIMDG 7.2.4 class table

PrecedenceColumn 16b override

StowageCategory A–E screen

Dangerous Goods Pair

Cargo A primary class / division

Cargo A single subsidiary hazardIf two or more subsidiary hazards exist, use Advanced and verify DGL column 16b.

Cargo B primary class / division

Cargo B single subsidiary hazard

DGL column 16b pair resultLeave “not entered” unless the current DGL entry has been checked for this pair. A specific 16b result takes precedence over the general table.

Ship passenger profile

Cargo A stowage category

Cargo A planned stowage

Cargo B stowage category

Cargo B planned stowage

Ship & Stowage Context

Ship / cargo arrangement

Passenger profile

IMDG edition basis

Cargo Register

Rows are anonymous cargo positions, not UN-number lookups. Enter the current DGL primary class, subsidiary hazards, stowage category and any known segregation-group membership. A second subsidiary hazard automatically forces DGL 16b review because the general one-subsidiary rule is not sufficient.

Primary class	Subsidiary 1	Subsidiary 2	Stowage category	Planned stowage	Quantity regime	Segregation group

Pair-Specific DGL / Special Segregation Overrides

Use this register after consulting the current Dangerous Goods List column 16b and resolving any applicable SG/SGG instruction. The entered pair result supersedes the general class-table baseline. “DGL review unresolved” deliberately leaves the pair blocked for review.

Cargo A row	Cargo B row	Resolved pair requirement

IMDG Planning Checks

Current DGL entries verifiedUN number/PSN, primary class, subsidiaries and columns 16a/16b match Amendment 42-24. Special segregation codes resolvedSG/SGG instructions are translated into the actual pair requirement. Class 1 compatibility checkedCompatibility group provisions are reviewed where explosives are paired with explosives. Limited / excepted quantity rules checkedChapters 3.4 / 3.5 are applied where those regimes are used. Ship-type segregation chapter checkedContainership, ro-ro, general-cargo or barge implementation rules are applied. Stowage category / SW codes checkedColumn 16a and special stowage provisions match the planned deck location. Foodstuff / accommodation constraints checkedAny applicable foodstuff, living-quarter or heat/source restrictions are separately reviewed. Final plan checked in approved DG systemShipboard documentation and competent operational procedures remain controlling.

Regulatory limitation: this tool is a planning screen, not an IMDG Dangerous Goods List database or approved dangerous-goods stowage system. The current DGL must always be consulted for each UN entry. Under IMDG 7.2.3.1, column 16b takes precedence over the general segregation table where provisions conflict. “X” therefore means DGL review, not “no segregation.” Class 1 compatibility, multiple subsidiary hazards, limited/excepted quantities, special SG/SGG provisions and ship-type chapters can change the result.

Current basis: IMDG Code 2024 Edition, Amendment 42-24, mandatory from 1 January 2026. General segregation levels are 1 “away from”, 2 “separated from”, 3 “separated by a complete compartment or hold from”, and 4 “separated longitudinally by an intervening complete compartment or hold from”. The DGL column 16b takes precedence over the general table. Stowage Category A–E checks use the general classes 2–9 category framework; Class 1 stowage requires its own provisions.

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