Skip to content

Product comparison

GP vs Galvalume vs ZAM — Choosing a Metallic Coating

How galvanized (GP / GI), galvalume (GL / AZ) and zinc-aluminium-magnesium (ZAM) coated steel compare for procurement and specification.

All three are hot-dip metallic-coated flat steels. They differ in coating chemistry, and therefore in corrosion behaviour, cut-edge protection, formability and weldability.

	GP / GI	Galvalume (GL)	ZAM
Coating	Zinc	55% Al – Zn	Zn with Al and Mg
Designation	Z120, Z180, Z275…	AZ70, AZ100, AZ150	ZM coating mass
Standard	IS 277	IS 15961	IS 18513
Typical use	Ducting, enclosures, general fabrication, tubes	Roofing and cladding substrate, building components	Solar structures, cable trays, outdoor electrical
Cut-edge behaviour	Zinc protects cut edges sacrificially	Less edge protection than zinc in some environments	Good cut-edge protection — reason for use in punched parts

Substitution

Coatings are not interchangeable on thickness alone. A change from GI to ZAM, or GI to galvalume, should be approved against the design, environment and coating mass. If a specification allows alternatives, it will say so; otherwise quote the specified coating.

Related: GP sheets · GL coils · ZAM coils

More resources

Other guides

Procurement guideHow to Write a Steel RFQ That Gets an Accurate QuoteThe information a steel supplier needs to quote accurately — by product type — and the omissions that cause re-quotes and wrong deliveries.Product comparisonHR vs CR Steel — Choosing Between Hot Rolled and Cold RolledWhen to buy hot rolled, pickled & oiled or cold rolled (CRCA) steel — by thickness, surface, tolerance, forming and cost.Roofing guideTCT vs BMT — Reading Roofing Sheet Thickness CorrectlyWhy two roofing sheet quotations at "0.50 mm" can contain different amounts of steel, and how to compare them.Reference chartPipe NB to OD Chart (IS 1239)Nominal bore to outside diameter for IS 1239 steel tubes, and how NB, OD and class relate when ordering MS and GI pipes.Procurement guidePrimary Producer vs Rolling Mill Sections — What Buyers Should KnowHow structural sections from integrated producers differ commercially from rolling-mill sections, and how to write the requirement.Procurement guideISI Mark, TC and MTC — What They Mean When Buying SteelWhat "ISI & TC" means on a steel indent, how an ISI mark differs from a test certificate or mill test certificate, and how to write documentation requirements into an enquiry.Product comparisonPrimary CR vs Re-rolled CR — What Buyers Should KnowHow cold rolled steel from integrated producers differs from re-rolled CR from secondary re-rollers, and how to specify the one your application needs.Product comparisonMagnelis vs PosMAC vs Magsure — ZAM Brands ComparedHow the zinc-aluminium-magnesium (ZAM) coated steels sold by AM/NS India, POSCO, JSW, Tata Steel and Dongkuk relate to each other, and when a switch between them needs approval.Product comparisonISI Pipes vs Patra Pipes — What's the Difference?What "patra" pipes are, how they differ from ISI-marked pipes and hollow sections, and where each can and cannot be used.

Request a quotation

Send your requirement

Share the product, grade, size and quantity — or attach your BOQ, drawing or specification on WhatsApp or email. A quotation is prepared against the actual requirement.

BOQs, drawings, indents and long product lists — send them as they are
Recurring monthly requirements quoted as a schedule
Specified producer, or approved alternatives where the specification allows

Send requirement on WhatsApp +91 98990 11143 sales@mrpenterprises.in