The tight-head steel drum: the code, the limits, the tests and how reconditioned drums are marked.
UN 1A1 is the packaging code for a steel drum with a closed head: 1 for drum, A for steel, 1 for a head that does not come off, filled and emptied through openings no wider than 7 cm. It holds at most 450 litres and 400 kg net.
Decode a full 1A1 mark Ask for 1A1 containers
| Character | Meaning |
|---|---|
1 | Drum: a cylindrical packaging with flat or convex ends, pail-shaped packagings included |
A | Steel, of any type and surface treatment |
1 | Non-removable head, with openings no wider than 7 cm |
| Maximum capacity | 450 litres (6.1.4.1.8) |
|---|---|
| Maximum net mass | 400 kg |
As a single packaging for liquids, packing instruction P001 sets the working limits by packing group. For a 1A1 that is 250 litres in packing group I and 450 litres in II and III.
Liquids or solids, in any packing group the mark allows. Body seams must be welded on a drum that holds more than 40 litres of liquid. Since Rev. 23 the regulations no longer ask for two rolling hoops on drums over 60 litres (6.1.4.1).
| Test | What the design has to survive | Paragraph |
|---|---|---|
| Drop | Filled to at least 98 per cent and dropped on its weakest points: from 1.8 m for packing group I, 1.2 m for II and 0.8 m for III. Tested with water, a liquid denser than 1.2 drops from its relative density times 1.5, 1.0 or 0.67 m. | 6.1.5.3 |
| Leakproofness | Held under water for five minutes at an air pressure of 30 kPa for packing group I or 20 kPa for II and III. Every container made for liquids passes the same test before its first use. | 6.1.5.4, 6.1.1.3 |
| Internal pressure | Held for five minutes at the hydraulic pressure the mark states, at least 250 kPa for packing group I. | 6.1.5.5 |
| Stacking | Carries the weight of a 3 m stack of identical full packages for 24 hours without leaking or losing strength. | 6.1.5.6 |
A design marked S for solids needs the drop and stacking tests only. The leakproofness and pressure tests belong to designs for liquids.
No period-of-use limit applies to steel drums: the five-year rule in 4.1.1.15 covers plastics only. A reconditioned drum carries the reconditioner’s mark and the letter R, and RL once it has passed a fresh leakproofness test. New steel drums over 100 litres also carry their metal thickness embossed on the bottom (6.1.3).
1A2 is the steel drum with a removable head, or any opening wider than 7 cm. It carries solids and packing group II and III liquids, and packing group I liquids only when they are viscous. 3A1 is a steel jerrican of up to 60 litres; 1A1 is cylindrical and goes to 450.
UN 1A1/X1.4/250/25/NL/VL824A closed-head steel drum, approved for packing groups I, II and III, for liquids up to relative density 1.4, pressure-tested at 250 kPa, made in 2025, design approved in the Netherlands.
| Part | On the mark | What it means |
|---|---|---|
| Packaging code | 1A1 | Closed-head steel drum (1 = drum, A = steel, 1 = non-removable head) |
| Performance level | X | Approved for packing groups I, II and III (high, medium and low danger) |
| Relative density | 1.4 | Tested for liquids up to a relative density of 1.4 (water is 1.0) |
| Test pressure | 250 | Passed a hydraulic pressure test at 250 kPa |
| Year of manufacture | 25 | Made in 2025 |
| Approving country | NL | Design approved in the Netherlands |
| Manufacturer or approval number | VL824 | Identifies the manufacturer or the approved design, as set by the approving authority |
Another 1A1 mark, decoded: UN 1A1/Y1.6/150/25/D/BAM 4521
Approval is per design and per plant, and each design carries its own level, density and test pressure. Send your contents and we confirm the design that matches your mark.
Both are steel drums. 1A1 has a fixed head with openings no wider than 7 cm and is the usual choice for liquids. 1A2 has a removable head or a wider opening and carries solids and packing group II and III liquids; in packing group I only viscous liquids.
450 litres and 400 kg net. As a single packaging for liquids, packing instruction P001 allows 250 litres in packing group I and 450 litres in II and III.
The standards and regulations this page relies on, at their issuing body. Where a market rule is named here, check the current revision before you specify against it.
Checked against the UN Model Regulations, Rev. 24, and ADR 2025 on 5 October 2026. Decode any other mark with our UN packaging code decoder.
Send what goes in them, the size and where they ship. We reply with the design certified to this code, the plant named on its certificate, and a price.
