A container number seems like a small decision and it determines what the fleet can be asked later. A number that identifies only the batch can answer questions about age. One that identifies the unit can answer questions about history. Deciding which questions matter – before the containers are marked – is what makes the numbering useful rather than decorative.
Batch-level numbering
A code shared by everything from one production run or one purchase order. It answers “how old is this container” and “which order did it come from”, which is enough for a replacement forecast and for a warranty conversation. It is cheap, it can be moulded in at manufacture, and it does not require any per-unit marking operation.
Unit-level numbering
A unique code per container. It answers “where has this container been”, “how many trips has it made”, and “what was repaired on it” – all of which require a per-unit identity. It costs a marking operation and a scanning operation, and it is only worth it where the fleet needs to answer those questions.
What the code should contain
As little as possible that can change. A type code and a serial is usually enough; a batch date is useful; anything about the current contents, the customer or the lane is not, because it goes stale immediately. Where a code encodes something variable, it becomes wrong and then misleading, which is worse than no code.
Where to put it
Moulded in during manufacture where possible, because it then cannot be removed. On two faces so it can be read without turning the container. And away from the wear areas, so it survives. Where a code is applied as a label, it is a consumable and it has to be replaced – which is a recurring cost and a recurring opportunity for error.
Reading it
A number a person can read at a distance is useful for manual operations. A barcode or an RFID tag is useful where reading is automated. Many fleets need both, and both can be carried in the same area without conflict – a printed number above a barcode is standard and costs nothing extra.
What it costs to add later
A numbering scheme applied after the fleet arrives means labelling every container, by hand, with a durable label – which is expensive, slow and never quite finished. Applied at manufacture it is a tooling detail and essentially free. Where a fleet is being specified, deciding the numbering at that point is one of the cheapest decisions available. The durability of the marking is covered in keeping identification readable for the life of the container.
What to avoid
Sequential numbers that run out. Codes that look alike when handwritten or partially worn. Anything that requires a lookup table to interpret, where the table will be lost. And codes that identify the customer, which creates a problem when the container is reassigned.
What happens when a fleet outgrows its code
A scheme designed for one type and a few hundred containers runs out when a second type arrives or the fleet passes a thousand. Leaving room in the serial – more digits than currently needed – costs nothing and avoids a renumbering exercise later. Where a fleet is being numbered for the first time, designing for three times the current size and for two more types than are in use today is the cheap version of the decision.
The minimum viable scheme
A type code, a two-digit year, and a serial. That is enough for a replacement forecast, enough to identify a production run, and short enough to read at a distance. Where a fleet has nothing, that is the scheme to start with, and it can be applied to existing containers during a normal inspection round.