Key Updates Explained: Implications of the UN Model Regulations Rev. 20 for International Chemical/Dangerous Goods Logistics
Background
The United Nations Model Regulations on the Transport of Dangerous Goods (commonly known as the "Orange Book") serve as the foundational international standard for harmonizing dangerous goods regulations across all modes of transport. The 20th Revised Edition of these Model Regulations was officially issued in July 2017.
Summary of Major Technical Changes
1. New Entries for Specific Dangerous Substances
🔬 Self-Reactive Substances
Added a new entry for "O-[(Cyanophenylmethylene)hydrazinyl] O,O-diethyl thiophosphate" (concentration 82-91%, Z isomer), UN 3227, with packing instruction OP8.
🧪 Organic Peroxides
Added three new entries, including:
- Diisobutyryl peroxide (≤42% as a stable dispersion in water), UN 3119, control temperature -20°C, emergency temperature -10°C.
- Di-(4-tert-butylcyclohexyl) peroxydicarbonate (≤42% as a paste), UN 3116, control temperature 35°C, emergency temperature 40°C.
- 1-Phenylethyl hydroperoxide (≤38%, with ≥62% type B diluent), UN 3109.
2. Clarified Classification Procedure for Ammonium Nitrate Based Fertilizers
Introduced a new flowchart in section 2.5.2.1.2, providing a more detailed and explicit classification procedure for ammonium nitrate based fertilizers according to the UN Manual of Tests and Criteria.
3. Revised Classification System for Corrosive Mixtures (Chapter 2.8)
A new tiered approach for classification and packing group assignment was introduced:
📊 Tier 1: Test Data
If sufficient in vivo or in vitro test data for the mixture is available, use the substance criteria directly.
🔗 Tier 2: Bridging Principles
If the mixture itself has not been tested, but sufficient data on its individual components and/or similar tested mixtures is available, use principles such as Dilution, Batching, Concentration, Interpolation, and Substantially Similar Mixtures to determine the packing group.
🧮 Tier 3: Calculation Method
If the concentration, packing group, and concentration limits of all corrosive ingredients are known, a calculation using a specified formula can be applied. If the sum of the weighted averages is ≥1, the mixture can be assigned the corresponding packing group.
4. New Entries in the Dangerous Goods List
Fourteen new UN Numbers (3535 through 3548) were added to Chapter 3.2 for "Articles containing [dangerous substance], n.o.s." This covers a wide range of hazards from Classes 2.1 through 9.
| UN Number | Description |
|---|---|
| UN 3536 | Lithium batteries or lithium metal batteries installed in cargo transport units |
| UN 3537 | Articles containing flammable gas, n.o.s. |
| UN 3538 | Articles containing non-flammable, non-toxic gas, n.o.s. |
| UN 3539 | Articles containing toxic gas, n.o.s. |
| UN 3540 | Articles containing flammable liquid, n.o.s. |
| UN 3541 | Articles containing flammable solid, n.o.s. |
| UN 3542 | Articles containing substances liable to spontaneous combustion, n.o.s. |
| UN 3543 | Articles containing substances which emit flammable gases when in contact with water, n.o.s. |
| UN 3544 | Articles containing oxidizing substances, n.o.s. |
| UN 3545 | Articles containing organic peroxides, n.o.s. |
| UN 3546 | Articles containing toxic substances, n.o.s. |
| UN 3547 | Articles containing corrosive substances, n.o.s. |
| UN 3548 | Articles containing miscellaneous dangerous goods, n.o.s. |
5. Amendments to Special Provisions
- Revised: Special Provisions 188, 193, 301, 307, 308, 363, and 376 were revised.
- Deleted: Special Provisions 186, 240, 312, 380, and 385 were deleted.
- New: Five new Special Provisions (387, 388, 389, 391, and 392) were added.
• Document Access: A free electronic version of the 20th Revised Edition was not publicly available at the time of this writing. It is advised to monitor the UNECE website for updates.
• Modal Regulation Alignment: Stakeholders must note the different update cycles for modal regulations. The then-current IATA Dangerous Goods Regulations (58th Ed.) and the IMDG Code (38-16) were aligned with the 19th Revised Edition. It was anticipated that subsequent editions (e.g., IATA DGR 59th Ed. and IMDG Code 39-18) would incorporate the technical content of the 20th Revised Edition.
• For actual shipping operations, compliance with the currently effective edition of the IATA DGR and the IMDG Code is mandatory.
- IATA DGR 58th Ed. and IMDG Code 38-16 aligned with Rev. 19
- Later editions (59th/39-18) anticipated to incorporate Rev. 20
- Always comply with currently effective IATA DGR and IMDG Code editions for actual shipments
✅ 14 new UN Numbers (3535-3548) for articles containing dangerous goods, including UN 3536 for lithium batteries in cargo transport units
✅ New tiered classification system for corrosive mixtures (Test Data → Bridging Principles → Calculation Method)
✅ New organic peroxide entries with specific temperature control requirements
✅ Monitor UNECE website for official Rev. 20 documentation
✅ Always verify current IATA DGR and IMDG Code editions for compliance