The short answer: traceability links each piece of steel in a finished structure back to the test certificate for the batch it came from, identified by its heat number. AS/NZS 5131 defines three levels (lot, piece-mark and piece), with lot traceability as the baseline for construction categories CC2, CC3 and CC4. The fabricator's job is to keep that link unbroken from receiving through cutting, fabrication and dispatch.
What a heat number is
Steel is made in batches called heats. Each heat has a number, and the steel mill issues a test certificate recording its chemical composition and mechanical properties. Steel products are marked so they can be linked back to that certificate. For example, BlueScope stencils its structural plate with the grade and standard, the heat number and a traceable plate number.
What a test certificate should show
When steel arrives, check the certificate against the material. It should include the manufacturer's name, the certificate number and date, the product, standard and grade (for example AS/NZS 3679.1-350), the heat number, and the chemical and mechanical test results.
Third-party certification adds confidence that the steel actually complies. In Australia, ACRS (the Australasian Certification Authority for Reinforcing and Structural Steels) certifies steel mills and also downstream processors and fabricators, so the chain of certification continues past the mill.
The three types of traceability in AS/NZS 5131
| Type | What it means |
|---|---|
| Lot | A lot of identically fabricated components can be traced back to a set of test certificates, but you can't say which certificate applies to which individual piece. |
| Piece-mark | Each piece-mark can be traced to its parent test certificates at every stage, from raw material through fabrication to the structure on site. |
| Piece | Each individual piece of steel can be traced to its parent test certificate at every stage. |
Lot traceability is the baseline for CC2, CC3 and CC4, with no specified traceability for CC1. The specifier can call for piece-mark or piece traceability on CC3 and CC4 work. Read the project specification to see what's required.
How to keep the chain unbroken
- At receiving: check the material against the purchase order and the certificate, and record the heat number against the delivery.
- In stock: keep the identification on the material. When a part-length goes back into stock, transfer the marking before it's allocated to another job.
- At cutting: record which heat each cut piece came from, against the job and piece-mark.
- Through fabrication: carry the identification through to the finished piece, especially after blasting and coating, when original marks can disappear.
- At dispatch: compile the certificates for the job into the data report the customer expects.
Where traceability breaks
- offcuts returned to the rack without their marking;
- marks lost during blasting or painting;
- certificates filed by delivery, not linked to jobs;
- substituted material with no record of the change.
How we help
Factory Hub records grade and heat number at receiving against the purchase order, keeps it with the stock and offcuts, links cut pieces to jobs, and gives you the trace from heat to part to job to customer. With CompliHub, ITPs, weld records and NCRs attach to the same job, so the data report builds as the work happens.
This guide is a plain-English summary. Always check the traceability requirements in AS/NZS 5131 and your project specification.
Common questions
What is a heat number on steel?
The identifier for the batch (heat) of steel it was made from. It links the material to the mill test certificate showing its chemistry and mechanical properties.
What traceability does AS/NZS 5131 require?
Lot traceability is the baseline for construction categories CC2, CC3 and CC4, with none specified for CC1. The specifier can require piece-mark or piece traceability for CC3 and CC4.
What is ACRS?
The Australasian Certification Authority for Reinforcing and Structural Steels, which certifies steel mills and downstream processors and fabricators so the chain of certification continues beyond the mill.