Traceability and RFID
What is a heat number in steel?
A heat number identifies one melt of steel and links every product made from it to its chemistry and test results. How heat numbers are marked and tracked.
Quick answer
A heat number is the unique identifier a steel plant gives to one melt (heat) of steel from a furnace. Every slab, billet, coil, plate or bar made from that melt carries the heat number, which links it to the chemical composition and mechanical test results recorded on the mill test certificate.
Updated 30 October 2026. Written by the Ajinkya Technologies engineering team, reviewed by Amey Kadle.
Heat number explained
A heat is the quantity of steel produced in one furnace cycle and treated together, so it shares one chemistry. The heat number therefore becomes the key that connects a physical product to its quality data. It is stamped, painted, stencilled or printed on the product or its tag, and printed on the mill test certificate that accompanies it.
Traceability gets harder downstream. When a slab is rolled into a coil and the coil is slit or cut into many pieces, each child item must carry the parent heat number, and the system must record which children came from which parent. Fabricators, service centres and construction sites then need to keep that link intact, often across several companies.
In India, steel products covered by quality control orders must carry the BIS Standard Mark under a licence, and buyers increasingly expect digital certificates and labels they can verify. Combining heat numbers with QR codes, barcodes or RFID tags, and recording parent and child relationships automatically at each cutting and dispatch step, keeps the chain unbroken from the melt shop to the customer.
Key concepts
- One melt, one chemistry, one heat number
- Links product to its mill test certificate
- Child items must inherit the parent heat number
- Marked by stamping, paint, labels, QR or RFID
- BIS Standard Mark for products under quality control orders
Questions
What is the difference between a heat number and a batch number?
A heat number identifies one melt of steel and its chemistry. A batch or lot number can be assigned later to a group of products, which should still record the heat numbers they came from.
How is a heat number marked on steel?
By hot or cold stamping, paint or stencil, printed tags or labels, and increasingly QR codes or RFID tags that link to digital records.
Why does heat number traceability break down?
Usually at cutting, slitting or regrouping, where child pieces are not labelled with the parent heat or the relationship is not recorded.
References
How we help with heat number
Our steel plant material tracking links heat numbers through rolling, cutting and dispatch with QR, barcode and RFID; in one integrated steel plant it tracks more than 720,000 material movements a day (company reported).
Traceability rules by industry, with dates and sources, and how to build for them.
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