A step-by-step guide to reading a mill test certificate for cold rolled, galvanized and galvalume coil — the EN 10204 document type, heat number traceability, grade chemistry, mechanical footnotes, coating mass notation, and why the mill name on the certificate decides your anti-dumping duty rate. Written for Pakistani importers and fabricators, with every figure attributed to the document it came from.

At spec grade, standard polyester, SMP and PVDF are all built to about 25 microns on the top side — so the paint name is not what decides how long a roof lasts. This is what the mill datasheets actually publish on film build, UV class, zinc coating mass and warranty limbs, how to compute BMT from a quoted TCT, and where Pakistan’s anti-dumping cases on colour coated coil and Galvalume currently stand.

Coating class is the mass of zinc across both surfaces of the sheet, not per side — so a Z275 coil carries about 137.5 g/m2, roughly 19.3 microns, on the exposed face. This guide gives the verified EN 10346, ASTM A653/A653M and JIS G3302 class charts, the mass-to-micron arithmetic, a corrected cross-standard equivalence table, the AZ galvalume density trap, the BMT versus TCT problem, and the checks that actually work when a coil lands.

Karachi stockists call 26 gauge 0.50 mm; the American galvanized sheet gauge calls it 0.551 mm. This is the conversion four ways, with weight per sheet, square feet per tonne, zinc coating classes, the BMT versus TCT question, and what the National Tariff Commission recorded about which standards local supply is actually written to.

Galvalume, aluzinc and aluminised coils of Chinese origin pay a flat 40.47% anti-dumping duty in Pakistan under four PCT codes, imposed by NTC’s notice of 28 June 2025 and running to 8 February 2027. What the measure covers, how Customs separates zinc-coated from aluminium-coated material, what fixes your liability at clearance, and why February 2027 is not a clean landing.