How to check a TMT bar is genuine and ISI-marked
A genuine TMT bar can be checked on site in five steps: the marks rolled on the bar, the ISI licence number, the test report, the weight per metre and the invoice. None of them needs a laboratory.
1. Read the marks rolled on the bar
Every genuine bar carries the brand name and the grade rolled into its surface, repeated along the length. If a bar has no brand or grade on it, do not accept it.
2. Find the ISI mark and the licence number
TMT bars are covered by IS 1786. The ISI mark appears with the standard number and the maker's BIS licence number, written as CM/L followed by digits, on the bundle tag or the bar. You can check that licence number on the BIS Care app or the BIS website.
3. Ask for the test report
The test report lists the grade, the diameter and the tested values for that batch. Check that the brand, grade and diameter on the report match the bars in front of you. Our guide to reading a TMT test report explains each line.
4. Weigh one metre
Cut and weigh a one metre piece and compare it with the standard weight for that diameter. IS 1786 allows a small tolerance either way.
| Diameter | Standard weight per metre | Tolerance on a batch |
|---|---|---|
| 8 mm | 0.395 kg | ±7% |
| 10 mm | 0.617 kg | ±7% |
| 12 mm | 0.888 kg | ±5% |
| 16 mm | 1.58 kg | ±5% |
| 20 mm | 2.47 kg | ±3% |
| 25 mm | 3.85 kg | ±3% |
| 32 mm | 6.31 kg | ±3% |
A bar well under the lower limit has less steel in it than you are paying for.
5. Check the invoice
The tax invoice should name the brand and the grade. Keep it with the test report.
How Amrit Steels supplies TMT
We do not supply material that is not approved to ISI grades. All our TMT is Fe 550 or Fe 550D grade and comes with test reports.
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WhatsApp us nowFrequently asked questions
How can I tell if a TMT bar is original?
Check that the brand name and grade are rolled on the bar, that the ISI mark carries a BIS licence number, that the test report matches the bar, and that one metre of the bar weighs within the tolerance for its diameter.
Where is the ISI licence number on a TMT bar?
The ISI mark appears with the standard number IS 1786 and a licence number written as CM/L followed by digits, on the bundle tag or the bar. The number can be checked on the BIS Care app.
How much can the weight of a TMT bar vary?
Under IS 1786, a batch may vary from the standard weight by 7 percent for bars up to 10 mm, 5 percent for bars over 10 mm and up to 16 mm, and 3 percent for bars over 16 mm.