Heat Number
/glossary/heat-numberAlphanumeric designator that identifies one steelmaking heat on the pipe and on the MTC.
A heat number names one steelmaking lot so the stencil on the pipe matches the test sheet. Kanpur receiving at Bartan Bazar treats a missing or mismatched heat as a hold. ASTM A941 calls it the designator for a specific heat. The mill sheet that names that melt travels with every yard load. Bundles leave 83/124, Steel Market, Basanti Nagar (208014) on a Kanpur ex-warehouse basis, GST 18% extra as the budgeting basis; the tax invoice applies the rate in force.
In detail
A heat number is the alpha, numeric, or alphanumeric designator used to identify a specific heat of steel. ASTM A941 defines a heat as a specific lot of steel based on steelmaking and casting considerations, and may mean a primary heat, a multiple heat, or a remelted heat. The number on the stencil, the bundle tag, the [MTC](/glossary/mtc), and the dispatch challan must be the same number. When they diverge, the lot fails traceability and stays on hold. Kanpur PWD, JJM, and sugar-mill stores check that match before they cut the first length.
What a heat number is, and what it is not
ASTM A941, Standard Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys, defines heat as a generic term denoting a specific lot of steel based upon steelmaking and casting considerations. Where more precision is needed, the standard uses primary heat, multiple heat, and remelted heat. Product specifications usually say heat without that qualifier.
The same terminology standard defines heat number as the alpha, numeric, or alphanumeric designator used to identify a specific heat of steel. That string is what the mill stamps or stencils and what the certificate reprints.
A heat number is not a grade. Two heats can both be YST 210 Medium and still be different melts. It is not an ISI mark. The mark is mill licence. It is not Form III-B. The IBR tube form must reprint the same heat that sits on the tube.
A factory ISO 9001 certificate is not a heat identity. It proves a quality system. It does not prove that this melt of 65 NB Medium met the ordered chemistry.
Who must match the heat, and who still needs a second report
Every industrial pipe lot that leaves Kanpur needs heat identity on the steel and on the paper. PWD and JJM contractors, fire-system installers, borewell contractors, and sugar-mill stores all cut lengths after that match.
Hydraulic and printing-cylinder shops in Dada Nagar, about 8 km from the yard, still need the tube heat on EN 10204 3.1. A drawing that names H8 or a Ra limit also wants a bore or roughness sheet. That second sheet is not the heat record.
Do not skip the heat on a 15 NB house-connection bundle because the run looks small. The IS 1239 product manual marks batch number on a bundle tag for sizes up to 20 mm NB, and on the tube itself from 25 mm NB upward.
Do not treat Type 3.2 as a replacement for heat identity. Type 3.2 adds a second signature to the same heat results. It does not invent a heat that the stencil omitted.
Where the heat appears on a Kanpur lot
Use the table to walk the receiving desk. Each row is one place the same string must appear. The last column is the Kanpur action when it does not.
| Location | What it should show | Governing reference | If it does not match |
|---|---|---|---|
| Tube body, 25 NB and above | Batch or heat, plus IS 1239 and L/M/H | PM/1239 marking 3.2-3.3 | Hold the bundle |
| Bundle tag, 20 NB and below | Batch or identification mark | PM/1239 marking 3.3-3.4 | Hold the bundle |
| EN 10204 3.1 or 3.2 | Specific heat results | EN 10204:2004 | Reject Type 2.1 as a heat sheet |
| IS 3589 test certificate | Cast or control-unit number | PM/IS 3589 para 6 | Hold large-OD pipe |
| IBR form | Same heat as the component | III-A pipe, III-B tube, III-C mounting | Do not register the lot |
An IS 3589 control unit is the same size, type, and grade, from the same cast or heat, made on one mill in one day. That is tighter than a casual batch nickname. Write the mill's actual identifier on the PO.
How to specify heat identity on an RFQ
Write the marking and the certificate on the same line as the steel. Heat-identity RFQs from the yard get a technical and commercial reply within 4 working hours.
- Product: process, standard, grade, NB or OD, wall or class, then length, quantity, ends, and coating.
- Identity: heat or control-unit number on the body or tag, repeated on the MTC and the dispatch challan.
- Certificate type: EN 10204 3.1 or 3.2. Type 2.1 has no heat results.
- IBR: Form III-A for steam pipe, Form III-B for tubes, Form III-C for mountings and fittings, each carrying the same heat.
- TPI: name SGS, Bureau Veritas, Lloyds, TUV, or the buyer-nominated authority to witness the match.
- Cut lengths: transfer the heat mark before any dressing grind. Lost identity is a new hold.
- Collect the marked lengths at the Kanpur yard, or send them FOR the named city. Budget GST 18% extra on the steel.
Worked receiving check on 65 NB Medium
Take 65 NB Medium from the site pipe-weight table: OD 76.1 mm, wall 3.6 mm, 6.44 kg/m, 38.6 kg per 6 m length. Check: W = (76.1 − 3.6) × 3.6 × 0.02466 = 72.5 × 3.6 × 0.02466 = 6.44 kg/m.
Thirty lengths are 30 × 38.6 = 1,158 kg, about 1.16 MT. On the MS ERW price list dated 24 May 2026, 65 NB Medium sits at ₹53-59 per kg from the Kanpur yard. That steel line is 1,158 × 53 = ₹61,374 to 1,158 × 59 = ₹68,322 before GST and freight.
The certificate that travels with those thirty lengths must name IS 1239, Medium, 65 NB, the heat or batch number, chemistry, yield and tensile for the ordered YST grade, and the 5 MPa leak-proof or eddy-current result. If the stencil says one heat and the PDF says another, hold all 1,158 kg. Theoretical mass is a commercial check. Acceptance still follows heat identity.
Common heat-number failures at receiving
In practice, the first failure is a stencil that does not appear on the certificate. The quality hub treats that as a broken traceability file. Do not cut the first 65 NB length while someone searches for another PDF.
The second failure is one Type 2.1 letter offered for three heats on a truck. Type 2.1 has no test results. It cannot support a PWD clause that asked for specific inspection.
The third failure is grinding the stencil off while dressing a bevel. Transfer the heat mark to the remaining body first. A clean bevel with no identity is scrap for any lot that needed traceability.
The fourth failure is mixing leftover cuts from two heats into one site crate and keeping only the thicker MTC. Later failure analysis then cannot find the melt.
Standards that define heat identity
ASTM A941-26a is the current ASTM store listing for the terminology standard (retrieved 2026-09-05). The heat and heat-number definitions used above follow the SA-941 text published as identical with ASTM A941-22a.
IS 1239 (Part 1):2004 marking on PM/1239 (Part 1)/4, February 2022, requires the manufacturer name or trade mark, IS 1239 (Pt.1), and class L, M, or H embossed at about one-metre intervals. Batch number goes on each tube from 25 mm NB, and on the bundle tag up to 20 mm NB. The test certificate, when the purchaser asks for it, carries the Standard Mark, the cast or control-unit number, type, class, size, and test results.
IS 3589:2001 on PM/IS 3589/1, May 2020, uses cast or control-unit number on the specimen certificate and defines the control unit as one size, type, and grade from the same material heat, made in one day on each mill.
EN 10204:2004 Type 3.1 is specific inspection validated by the manufacturer's authorised representative. Type 3.2 adds the purchaser or an officially designated inspector. On the DPIIT forms index, steam pipe uses Form III-A, a tube uses Form III-B, and a mounting or fitting uses Form III-C. Each of those forms must reprint the heat of that component.
Matching heats at the Kanpur yard
Receiving at Bartan Bazar starts with the stencil, then the tag, then the PDF. Panki fabricators who pick up the same day still need that three-way match before the first cut. Jajmau GI lots use the same rule after zinc: the heat on the black-pipe certificate must still be readable on the tag.
See quality, the MTC sample, MTC verification, and steel pipes in Kanpur. Origin notes for the Bartan Bazar trade sit on the Kanpur steel market page.
TPI by SGS, Bureau Veritas, Lloyds, or TUV at the yard is a contract line that witnesses this match. It is not automatic because the buyer is a sugar mill.
Cut lengths, transfers, and lost marks
When the yard cuts to length, the remaining piece keeps the heat. Paint or stamp the number on the new cut before the offcut leaves the bench. A silent offcut cannot re-enter a documented lot.
Alloy boiler tube on indent already travels with heat on the tube and on Form III-B. Carbon SA210 and chrome-moly SA213 heats must not share a crate without two certificates.
Precision tube for Dada Nagar can lose the OD stencil under phosphate and oil. Keep a durable tag and put the heat on the bore cap label as well.
When a heat fails and the lot is held
A failed tensile, flatten, or hydro on one heat holds every length of that heat, not only the test piece. The IS 1239 product manual rejects the material represented by the failed samples after the retest path. Segregate the steel. Deface the Standard Mark if it was already applied.
Raise a rejection note with the heat, the failed check, and the clause. The next step is a retest, a concession, or a replacement heat under that PO and the quality plan.
Do not blend a replacement heat into the original packing list under the old number. Issue a new certificate and a new challan line. The Lucknow or Bareilly store will catch the mismatch on the second truck.
Documents that travel with the heat
The MTC or MTR is the test sheet. The challan is the count and heat list. The tax invoice is the GST document. Those three files stay together on a truck that leaves Kanpur for Lucknow or Patna.
The mill sheet for that heat already rides with the load. Ask for a scan before the lorry rolls when the ITP says so. RP Sales dispatches daily from Kanpur; Uttar Pradesh, Bihar, Madhya Pradesh, Delhi NCR, and Uttarakhand are the service area, not a same-day guarantee.
Send the RFQ with the marking and certificate type written beside the size. A store that writes MTC only, with no heat line, is how a Type 2.1 letter arrives against a 3.1 tender.
Where you'll meet this in procurement
You will meet Heat Number in inspection plans, dispatch packs, and tender checklists. Keep heat identity, certificate type, and any third-party witness tied to the order so Heat Number is usable evidence at site acceptance—not a loose attachment after delivery.
Related terms
Related resources
Key points
- A heat number identifies one steelmaking lot. ASTM A941 defines the heat and the designator.
- Stencil, tag, MTC, and challan must show the same string. A mismatch holds the bundle.
- IS 1239 marks batch on the tube from 25 mm NB and on the tag up to 20 mm NB.
- 65 NB Medium is 76.1 × 3.6 mm and 6.44 kg/m on the site weight table. Use that mass to check the billed lot, then match the heat.
- Heat-matched lots from Bartan Bazar budget GST 18% extra. The mill sheet for that melt rides with the load.
Frequently asked questions
Sources
- ASTM A941-26a. Standard Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys: current ASTM store listing, scope 1.1-1.4 (ASTM International)
- SA-941 / ASTM A941-22a. Definitions of heat (steelmaking and casting lot; primary, multiple, remelted) and heat number (alpha, numeric, or alphanumeric designator) (ASTM International / ASME Section II)
- PM/1239 (Part 1)/4 Feb 2022. Marking 3.2-3.5: class L/M/H, batch on tube from 25 mm NB, tag up to 20 mm NB, test certificate with cast/control-unit number (Bureau of Indian Standards)
- PM/IS 3589/1 May 2020. Control unit = same size, type, grade, cast/heat, mill, and day; test certificate carries cast/control-unit number (Bureau of Indian Standards)
- EN 10204:2004. Metallic products. Types of inspection documents (2.1 / 2.2 / 3.1 / 3.2) (European Committee for Standardization (CEN))
- Indian Boiler Regulations, 1950. Forms index: III-A steam pipes, III-B tubes, III-C boiler mountings and fittings (Central Boilers Board, Government of India)