At a Glance
Every international shipping container carries a unique 11-character ISO 6346 identification number for global tracking. The CSC Safety Approval plate acts as the container's passport, verifying its structural integrity and inspection history. These markings remain on the container when sold into the secondary market.
On This Page
1. The Identification Number (ISO 6346)
The 11-character sequence breaks down into four distinct components. For example, the number CBHU 344556 3 represents the following:
| Component | Characters | Meaning |
|---|---|---|
| Owner Code | CBH | Three capital letters identifying the registered owner or principal operator. All owner codes must be registered internationally with the Bureau International des Containers (BIC)[106]. |
| Equipment Category | U | A single letter identifying the equipment type. "U" designates all standard freight containers. "J" designates detachable freight equipment, and "Z" designates trailers and chassis[105]. |
| Serial Number | 344556 | Six numeric digits assigned by the owner or operator to uniquely identify the container within their fleet. If the serial number is shorter than six digits, it is padded with leading zeros[107]. |
| Check Digit | 3 | A single number, typically enclosed in a box, mathematically derived from the preceding 10 characters. It validates the accuracy of the full identification number during manual entry or electronic data interchange (EDI)[108]. |
The presence of the letter "U" indicates that the number belongs to a freight container, but it does not guarantee the container itself complies with all ISO structural standards. ISO 6346 mandates that all characters in the identification number must be at least 100 mm (4 inches) high and painted in a color that contrasts with the container body[105].
2. Size and Type Codes
Located directly below the identification number on the right-hand door, the Size and Type Code is a four-character sequence that describes the physical dimensions and specific capabilities of the container. The 1995 edition of ISO 6346 made these codes mandatory for all newly constructed ISO series one freight containers[107].
The code is divided into two parts: the first two characters define the container's external dimensions (length, height, and width), while the final two characters define the container type and any specialized characteristics.
Length, Height, and Width (First Two Characters)
The first character designates the container's length. The second character designates the container's height and width. The standard external width for ISO containers is 8 ft (2,438 mm).
| First Character (Length) | Meaning | Second Character (Height/Width) | Meaning |
|---|---|---|---|
| 1 | 10 ft (2,991 mm) | 0 | 8 ft (2,438 mm) height |
| 2 | 20 ft (6,058 mm) | 2 | 8 ft 6 in (2,591 mm) height (Standard) |
| 3 | 30 ft (9,125 mm) | 4 | 4 ft 3 in (1,295 mm) height (Half-height) |
| 4 | 40 ft (12,192 mm) | 5 | 9 ft 6 in (2,896 mm) height (High Cube) |
| L | 45 ft (13,716 mm) | C | 8 ft 6 in height, > 8 ft width |
Container Type (Final Two Characters)
The third character is a letter designating the primary container type. The fourth character is a number designating specific features within that type category, such as ventilation methods or door configurations[109].
| Type Code | Description |
|---|---|
| G0, G1 | General purpose container without ventilation (G0) or with passive vents in upper cargo space (G1). Commonly known as a dry van. |
| V0, V2 | General purpose container with mechanical ventilation. |
| U0, U1 | Open top container. |
| P1, P3 | Flat rack container with fixed ends (P1) or folding ends (P3). |
| R0, R1 | Thermal container, refrigerated and mechanically heated (reefer). |
| T0-T9 | Tank container for liquids or gases. |
Common Code Examples:
22G1 = 20 ft long, 8'6" high, general purpose dry van with passive vents.
42G1 = 40 ft long, 8'6" high, general purpose dry van with passive vents.
45G1 = 40 ft long, 9'6" high (High Cube), general purpose dry van with passive vents.
22R1 = 20 ft long, 8'6" high, refrigerated container.
3. Operational Marks
ISO 6346 requires specific operational marks to be displayed on the left-hand door panel, providing critical weight and capacity information for safe handling. These measurements must be expressed in both metric (kilograms/cubic meters) and imperial (pounds/cubic feet) units[105].
- Maximum Gross Weight (MGW): The maximum allowable combined weight of the container and its cargo. Also referred to as Maximum Operating Gross Mass.
- Tare Weight: The weight of the empty container.
- Net Payload: The maximum allowable weight of the cargo alone (MGW minus Tare). Also labeled as "Net" or "Max Payload."
- Cubic Capacity: The total internal volume of the container, labeled as "CU. CAP."
Containers exceeding 8 ft 6 in (2,591 mm) in height, such as High Cube units, must display mandatory height warning marks. This consists of a yellow and black alternating band pattern on the top edge of the frame, along with a measurement indicator showing the exact height[107].
4. The CSC Safety Approval Plate
The Convention for Safe Containers (CSC) plate is a mandatory certification plate affixed to every container used in international transport. Adopted in 1972 at a conference jointly convened by the United Nations and the International Maritime Organization (IMO), the CSC establishes uniform international safety regulations for container handling[110].
The plate must be a permanent, non-corrosive, fireproof rectangular metal plate measuring at least 200 mm by 100 mm. It is typically riveted to the outside of the left door. The words "CSC SAFETY APPROVAL" must be stamped or embossed with a minimum letter height of 8 mm[111].
Modern containers utilize a Combined Data Plate, which integrates the CSC approval with other mandatory certifications, including customs transport approval and timber treatment records for the wood flooring.
Data Fields on the CSC Plate
The safety approval section of the plate contains specific structural and manufacturing data required by the convention[111]:
- Date Manufactured: The month and year the container was built.
- Identification No.: The manufacturer's serial number or the container's ISO identification number.
- Maximum Operating Gross Mass: The maximum allowable weight, matching the operational marks on the door.
- Allowable Stacking Load (1.8g): The maximum weight the container can safely support when stacked under specific gravitational force conditions.
- Transverse Racking Test Force: The lateral force the container frame is certified to withstand without structural failure, measured in Newtons.
Inspection Programs
The CSC mandates regular inspections to ensure containers remain structurally sound. The plate indicates which inspection program the container follows[111]:
- Periodic Examination Scheme (PES): The container must be examined within five years of manufacture, and at intervals of no more than 30 months thereafter. The Next Examination Date (NED) is stamped directly on the plate.
- Approved Continuous Examination Programme (ACEP): The container is thoroughly examined every time a repair is carried out or when processed at a repair facility. Containers under this program display an ACEP scheme number on the plate, often as a decal, rather than a specific next examination date. Most major ocean carriers and leasing companies operate under the ACEP system.
Regardless of the inspection program, a CSC plate is only legally valid if the container is in good structural order. Severe damage sustained during service can invalidate the approval and require the container to be removed from international transport until repaired[110].