IMDG Class 5 covers two distinct types of oxidizing substances, each with fundamentally different chemistry and hazard profiles. Class 5.1 oxidizers intensify fires by releasing oxygen — they are not necessarily combustible themselves. Class 5.2 organic peroxides are both oxidizers and fuels, capable of self-sustaining decomposition and, in some cases, explosion. Proper classification, packaging, and segregation are the three pillars of safe Class 5 transport from China.
Class 5.1 — Oxidizing Substances
These substances readily yield oxygen and cause or contribute to the combustion of other materials. They are assigned to Packing Groups I, II, or III based on their oxidizing power in standardized burn-rate tests.
Product examples:
- Hydrogen peroxide, aqueous solution (UN2014/UN2015/UN2984): Concentration-dependent classification. >60% is PG I (UN2015). 20-60% is PG II (UN2014). 8-20% is PG III (UN2984). China is a major global producer. Ships in vented drums or IBCs.
- Ammonium nitrate (UN1942): Fertilizer-grade (UN2067) and technical-grade. China exports millions of tons annually. PG III. Must be kept strictly away from organic materials, acids, and heat. Ships in bulk or big bags.
- Potassium nitrate (UN1486): Used in fireworks, glassmaking, and food preservation. China is the dominant global supplier.
- Sodium nitrate (UN1498): Fertilizer and industrial chemical. Major export from China, sourced from natural deposits in Qinghai.
- Sodium chlorate (UN1495): Herbicide and bleaching agent. PG II. Can react explosively with organic materials.
- Calcium hypochlorite (UN1748/UN2208/UN2880): Pool chlorine / bleaching powder. PG II or III depending on available chlorine content. Ships in sealed drums. Must be kept absolutely dry.
- Potassium permanganate (UN1490): Water treatment, chemical oxidation. Ships in drums or bags. Purple crystals are easily identifiable.
- Sodium perborate (UN3247/UN3377): Laundry detergent bleach component. PG II or III.
Class 5.2 — Organic Peroxides
Organic peroxides are thermally unstable substances containing the bivalent -O-O- structure that may undergo exothermic self-accelerating decomposition. They may be shock-sensitive, friction-sensitive, and heat-sensitive. Many require temperature-controlled transport.
Product examples:
- Benzoyl peroxide (UN3102/UN3104): Polymerization initiator, acne medication ingredient. Typically ships as a paste or granular solid with water/phlegmatizer. Temperature control required for some formulations (SADT typically ~50°C).
- MEKP — Methyl Ethyl Ketone Peroxide (UN3105): Curing agent for unsaturated polyester resins. Highly reactive. Typically requires refrigeration (0-10°C).
- Dicumyl peroxide (UN3110): Cross-linking agent for polyethylene, EPDM rubber. SADT typically 80°C — often does not require temperature control but must avoid direct heat.
- Tert-butyl peroxybenzoate (UN3103): Polymerization initiator. Temperature control may apply depending on formulation.
- Cumene hydroperoxide (UN3109): Chemical intermediate. Requires temperature control below SADT (typically 50-55°C).
Packaging Requirements
5.1 Oxidizers
- UN-approved drums (steel or plastic), bags, or IBCs rated for the assigned packing group
- Vented caps for hydrogen peroxide (to allow oxygen release)
- Stainless steel or compatible plastic for hydrogen peroxide; never carbon steel or copper alloys
- Moisture-barrier packaging for calcium hypochlorite and ammonium nitrate
- Packaging must be clean and free of organic residues (oil, grease, wood dust) before filling
5.2 Organic Peroxides
- UN-approved combination packaging as specified in the organic peroxide approval certificate
- Temperature-controlled containers (reefers) for SADT ≤50°C substances
- Temperature logging devices inside and outside the packaging
- Phlegmatized / desensitized forms where possible to reduce sensitivity
- Never repack organic peroxides at port — packaging must be done at the manufacturer under controlled conditions
Segregation Requirements
Segregation is arguably the most critical operational factor for Class 5 shipping. The IMDG Code mandates:
- Class 5.1 vs Class 3, 4.1, 8: "Separated from" (minimum 3 meters in same compartment, or separate compartment). Never mix in same container.
- Class 5.1 vs Class 5.2: "Separate from" (different compartments or holds).
- Class 5.2 vs almost all other DG: "Separate from" at minimum. Must ship in dedicated containers — no co-loading with other DG classes.
- All Class 5 vs heat sources: Minimum 2.4 meters from any heat source (engine room bulkhead, heated fuel tanks, direct sunlight on deck).
Carrier Acceptance Table
| Carrier | Class 5.1 (PG II/III) | Class 5.1 (PG I) | Class 5.2 |
|---|---|---|---|
| MSK | Accepted | Restricted | Limited (case-by-case) |
| HPL | Accepted | Case-by-case | Not accepted |
| MSC | Accepted | Restricted | Case-by-case |
| COSCO | Accepted | Case-by-case | Case-by-case |
| HMM | Accepted | Not accepted | Not accepted |
| OOCL | Accepted | Not accepted | Not accepted |
| EMC | Accepted | Not accepted | Not accepted |
| YML | Accepted | Case-by-case | Not accepted |
| CMA CGM | Accepted | Case-by-case | Case-by-case |
Port Recommendations
For 5.1 oxidizers, all three ports (Qingdao, Shanghai, Tianjin) are viable. Qingdao has the strongest DG infrastructure for bulk ammonium nitrate and hydrogen peroxide. For 5.2 organic peroxides, Qingdao is strongly preferred — it has refrigerated container monitoring at the DG yard and the most DG-experienced terminal staff. The key consideration for 5.2 is temperature-controlled container availability and power supply at the port of loading — Qingdao's DG yard has dedicated reefer plug points for DG containers.
Documentation Checklist
- MSDS — must state concentration, SADT (for 5.2), and control/emergency temperatures
- DG Packaging Certificate (危包证)
- Organic Peroxide Approval Certificate from competent authority (for Class 5.2, specific to the formulation)
- Maritime DG Declaration
- Port Filing Approval with segregation declaration
- Temperature control plan (for 5.2 requiring refrigeration)
- Container loading plan showing segregation compliance
- Commercial Invoice, Packing List, B/L with DG endorsement
- Carrier DG Booking Confirmation
Frequently Asked Questions
Can hydrogen peroxide be shipped as non-DG from China?
Only if the concentration is below 8%. Solutions of 8-60% are Class 5.1 PG III or II (UN2984/UN2014). Above 60% is PG I (UN2015). The threshold is strict. Even 8% needs the full DG declaration chain. A common mistake is exporters assuming "diluted" peroxide is non-DG — always check the MSDS concentration. Below 8% is the only non-DG threshold for sea freight under IMDG.
What is the Self-Accelerating Decomposition Temperature (SADT) and why does it matter?
SADT is the lowest temperature at which an organic peroxide in its packaging will undergo self-accelerating decomposition — a runaway exothermic reaction that can lead to fire or explosion. If the SADT is ≤50°C, temperature-controlled transport is mandatory (typically 10-15°C below SADT). If the SADT is >50°C, a non-refrigerated container may be acceptable depending on route climate. The SADT is specific to the peroxide formulation and packaging configuration, and must be stated on the MSDS and transport documents.
Can pool chlorine (calcium hypochlorite) ship from China in containers?
Yes. Calcium hypochlorite (pool chlorine, bleaching powder) is a major Chinese export. It is Class 5.1 UN1748 (dry, >39% available chlorine), UN2208 (hydrated, 5.5-16% water), or UN2880 (hydrated, 5.5-10% water). Key requirements: absolutely dry and sealed packaging (moisture triggers decomposition), UN-approved drums with secure lids, segregation from all organic materials and acids, on-deck stowage preferred, and advance carrier booking (some carriers restrict or prohibit it). At Great Hensen, we have handled regular calcium hypochlorite exports from Shandong chemical plants for over 5 years.
What happens if temperature control fails during an organic peroxide (5.2) sea freight shipment?
If a refrigerated container carrying temperature-controlled organic peroxide fails and the internal temperature approaches the SADT, this is a serious emergency. The vessel's emergency response plan activates: the container must be monitored continuously, cooling measures attempted, and if the temperature cannot be controlled, the container may need to be jettisoned. This is why we use dual-redundant reefer units with remote temperature monitoring for all 5.2 shipments — the cost of a failed unit far exceeds the cost of redundancy.