Coil
Coil is strip 20 to 2 000 mm wide wound into a coil weighing several tonnes.
6
items with size and weight tables
24
standards for rolling and acceptance
Items in this category
Hot-rolled, cold-rolled, galvanized, colour-coated and stainless coil, slit strip
What it is and how it is supplied
Coil is the basic form of flat product: steel from a continuous mill is wound rather than cut into sheets. Hot-rolled coil leaves the hot strip mill at 1.5 mm and up with mill scale on the surface; cold-rolled coil is made from it by pickling, cold reduction and annealing, at 0.3 mm and up with a smooth surface. Galvanized and colour-coated coil is a cold-rolled base with a coating applied on a continuous line. Stainless coil is rolled from chromium-nickel or chromium-manganese steel and supplied with a 2B or BA finish.
Details
For Uzbekistan the base designations are GOST 19903 and GOST 19904 (dimensions), GOST 14637 and GOST 16523 (technical requirements), GOST 14918 (galvanized) and GOST 34180 (colour-coated). Mills in China roll to GB/T 709, GB/T 708, GB/T 2518, GB/T 12754 and GB/T 3280; export orders are placed to EN 10025, EN 10130, EN 10346, EN 10169 and ASTM A1011, A1008, A653, A755. Grades are matched by mechanical properties and chemical composition, not by name: the correspondence table below marks where the equivalent is exact and where it is the nearest analogue.
The bureau finds a mill for a specific specification: thickness and tolerance, width, coil inside diameter, coil weight to suit your decoiler, edge, surface condition, and for coated coil the zinc class and polymer type. Inspection at the mill before shipment: thickness measured with a micrometer across the width and on the wraps, width with a tape, the mill test certificate (MTC) checked against the heat number on the tag, edge and surface examined, packing checked. Rejects recorded in the inspection report are replaced; the replacement is supplied by the mill under its contract with the bureau.
Grade equivalents
Equivalents are the nearest, not identical: the exact grade and standard are written into the contract.
| GOST | GB (China) | ASTM | EN | Note |
|---|---|---|---|---|
| St3sp | GB (China)Q235B | ASTMA1011 CS Type B / A36 | ENS235JR | NoteCorrespondence by mechanical properties; the chemical composition and impact toughness requirements differ between the standards — check against the MTC. |
| 09G2S | GB (China)Q355B (Q345B) | ASTMA572 Grade 50 | ENS355JR | NoteNearest analogue: yield strength is comparable, but 09G2S carries more manganese and silicon alloying. |
| 08ps | GB (China)DC01 / SPCC | ASTMA1008 CS Type B | ENDC01 | NoteCold-rolled low-carbon steel for general use; deep drawing calls for DC03–DC04 or 08Yu. |
| 08ps ZN (GOST 14918) | GB (China)DX51D+Z | ASTMA653 CS Type B | ENDX51D+Z | NoteGalvanized base for bending and roll forming; the zinc class is specified separately (Z100–Z275). |
| 250 / 350 (GOST 14918) | GB (China)S250GD+Z / S350GD+Z | ASTMA653 SS Grade 37 / 50 | ENS250GD+Z / S350GD+Z | NoteStructural galvanized grades with a specified yield strength; ASTM SS is the nearest analogue by strength. |
| 08Kh18N10 | GB (China)06Cr19Ni10 | ASTM304 | EN1.4301 | NoteAustenitic chromium-nickel steel; the GOST grade allows a higher carbon content than 304L. |
| 03Kh17N14M3 | GB (China)022Cr17Ni12Mo2 | ASTM316L | EN1.4404 | NoteMolybdenum-bearing low-carbon austenitic steel; close correspondence. |
| 12Kh17G9AN4 | GB (China)12Cr17Mn6Ni5N | ASTM201 | EN1.4372 | NoteNearest analogue: chromium-manganese steel with nitrogen, nickel partly replaced by manganese; corrosion resistance is lower than that of 304. |
Equivalents are the closest match, not identical: chemistry and tolerances differ between standards. The exact grade and standard are written into the contract.
Buyer questions
How to read a mill test certificate (MTC) for coil
Four blocks in the certificate must agree: the heat number and coil number with the tag on the coil; the grade and standard with the specification; the chemical composition with the limits of the standard for that grade; the mechanical properties (yield strength, tensile strength, elongation) with the values required by the standard. For galvanized coil the zinc coating weight is added, for colour-coated coil the type and thickness of the paint layer. The bureau checks the MTC against the heat at the mill before shipment and hands over the original with the batch.
How hot-rolled coil differs from cold-rolled
Hot-rolled coil is rolled above the recrystallisation temperature: thickness from 1.5 mm, surface with mill scale, wider thickness tolerance. Cold-rolled coil is made from hot-rolled by pickling and cold reduction followed by annealing: thickness from 0.3 mm, smooth surface, tighter tolerance, and the steel is more ductile after annealing. Welded tube, profiles and structures take hot-rolled; pressing, body panels, galvanizing and painting take cold-rolled.
How coil tonnage is calculated
The theoretical weight of one square metre is 7.85 kg per millimetre of thickness; the coil weight is the strip area multiplied by that figure. Shipment and payment go by the actual weight from weighing, recorded in the certificate and on the tag; the difference from the theoretical weight comes from the thickness tolerance. The specification states tonnes, not the number of coils, and separately the maximum weight of one coil and the inside diameter to suit your decoiler.
What the bureau inspector checks at the mill before shipment
Thickness with a micrometer on the outer wrap at several points across the width and on the coil end face; width with a tape; telescoping and tightness of winding; condition of the edge and surface; the heat number on the tag against the MTC; for galvanized coil the uniformity of the coating and absence of bare spots, for stainless coil the grade with a positive material identification (PMI) analyser; packing and strapping. The result is an inspection report with photographs. Rejects recorded in the report are replaced; the replacement is supplied by the mill under its contract with the bureau.
How the batch is sized
The batch is sized to your volume — send your specification: grade and standard, thickness with tolerance, width, surface condition, for coated coil the zinc class and polymer type with the RAL colour, plus the inside diameter and maximum weight of a coil. Mills roll coil to order by width and thickness, so the more precise the specification, the fewer approvals are needed. The bureau selects a mill for that specification and returns confirmed delivery terms.
Price request
Send your specification and we will quote your batch
Price depends on grade, size, tonnage and delivery terms on the day of contract.
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