PART 4: PACKING AND TANK PROVISIONS

Part 4 of the IMDG Code defines the requirements for packaging, intermediate bulk containers (IBCs), portable tanks, MEGCs, and bulk containers used to transport dangerous goods by sea.
The primary objective is to ensure that packaging and containment systems are fit for purpose, capable of withstanding normal transport conditions, and compatible with the chemical nature of the dangerous goods being transported. Proper packing not only prevents leaks, spills, and reactions during transit, but also supports safe handling and emergency response.

Chapter 4.1 – Packaging & Intermediate Bulk Containers (IBCs)

Purpose

Packaging and IBC provisions ensure that dangerous goods are contained securely, preventing accidental release and minimizing risk during handling, storage, and maritime transport.

Approved Packaging Types

Packaging commonly used for dangerous goods includes:

• Drums (steel, plastic, fiberboard)

• Jerricans (metal or plastic)

• Boxes (wooden, fiberboard, plastic)

• Bags (multi-wall paper, plastic film, woven materials)

• Composite packaging (combined materials for enhanced safety)

• Pressure receptacles (for gases)

Each packaging type is assigned a UN packaging symbol and tested to ensure suitability for its intended hazard class and packing group.

Performance Tests

Packages must pass performance testing before approval, including:

• Drop test: to ensure resistance to impact during handling

• Stacking test: to validate structural stability during stowage

• Leakproofness test: especially for liquids and pressure containment

• Vibration test: simulating transport movement

• Hydraulic pressure test: for pressure receptacles and liquid containers

• Puncture resistance: ensuring robustness against sharp objects

These tests ensure packages maintain integrity under normal transport conditions, including ship motion, temperature fluctuations, and loading operations.

UN Markings

All approved packaging must bear a UN identification marking indicating:

• Type of packaging (e.g., 1A1 = steel drum, non-removable head)

• Packing group capability (X, Y, Z)

• Year and country of manufacture

• Manufacturer’s code and approval details

Example:
UN 1A1/Y1.8/200/23/IND/SMC001

• 1A1: Steel drum, non-removable head

• Y: Suitable for PG II and III substances

• 1.8: Specific gravity rating

• 200: Test pressure in kPa

• 23: Year of manufacture

• IND: Country code

• SMC001: Manufacturer certificate

Material Compatibility

Packaging materials must be chemically compatible with their contents.
For example:

• Strong acids may corrode metal drums

• Solvents may weaken plastic containers

• Water-reactive substances must never be packed in moisture-absorbing containers

Selecting incompatible packaging may lead to container degradation, spills, and hazardous reactions.

Chapter 4.2 – Portable Tanks & Multiple-Element Gas Containers (MEGCs)

Portable tanks and MEGCs are used for larger quantities of dangerous goods, particularly liquids, liquefied gases, and certain solids requiring containment under pressure or controlled environments.

Tank Design Codes

Portable tanks are categorized by tank codes indicating:

• Construction material

• Pressure rating

• Fittings and valve arrangements

• Internal heating or insulation options

Common codes include:

• T1–T22 for chemical and flammable liquids

• T50 for liquefied gases

• T75 for refrigerated liquefied gases (e.g., LNG, liquid nitrogen)

Tank design ensures protection against:

• Mechanical shock,

• Overpressure,

• Thermal expansion,

• Structural failure during ship motion.

Pressure Relief Systems

Tanks must have pressure relief devices (PRDs) to prevent rupture.
Systems include:

• Spring-loaded pressure relief valves,

• Burst discs,

• Fusible plugs (temperature-activated)

Functions:

• Release internal pressure safely if it rises beyond limits,

• Prevent catastrophic tank failure in fire exposure,

• Maintain integrity during voyage, including temperature changes.

Periodic Inspection Requirements

To ensure ongoing safety, portable tanks and MEGCs undergo:

• Initial inspection before first use,

• Periodic inspections typically every 2.5 to 5 years,

• Interim checks depending on regulatory requirements and cargo type.

Inspection components:

• Structural integrity evaluation,

• Pressure testing,

• Valve and gasket condition,

• Internal cleaning and corrosion assessment

Failure to maintain inspection compliance results in prohibition of tank use and possible regulatory penalties.

Chapter 4.3 – Bulk Containers

Bulk containers are used to transport solid dangerous goods in loose form, such as powders, granules, or solid lumps.

Types of Bulk Containers

Procedures for Solid DG in Bulk

Bulk loading requires careful control to prevent:

• Dust emissions,

• Chemical reactions with air or moisture,

• Load shifts compromising vessel stability.

Key operational procedures:

• Inspect container integrity before loading,

• Ensure compatibility between container materials and cargo,

• Avoid overloading to maintain stack and stability,

• Secure access hatches to prevent accidental spillage,

• Monitor temperatures for self-heating substances,

• Segregate incompatible bulk loads to avoid cross-contamination.

Proper bulk handling reduces environmental contamination risk and prevents operational hazards during transit.

PART 4 SUMMARY TABLE