Galvanized Coating Grades G30, G60, G90, G235
When it comes to choosing the right steel for your project, corrosion resistance is often at the top of the priority list-especially in industries like construction, automotive, HVAC, and agriculture. That's where galvanized steel shines. But not all galvanized steel is created equal.
The most common types-G30, G60, G90, and G235-offer different levels of zinc coating, which directly affects durability, performance, and cost.
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What Is Galvanized Steel?
Galvanized steel is carbon steel coated with a layer of zinc to protect it from rust and corrosion. The zinc acts as a sacrificial barrier, slowing oxidation by preventing moisture and oxygen from reaching the steel underneath.
The "G" designation refers to the zinc coating weight, measured in ounces per square foot (oz/ft²) for both sides of the sheet. Higher numbers mean thicker coatings and better corrosion protection.
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Zinc Coating Comparison Table
|
Type |
Zinc Coating (oz/ft²) |
Approx. Thickness (microns) |
Corrosion Resistance |
Common Uses |
|
G30 |
0.30 total (0.15 per side) |
~2.5 µm per side |
Light protection |
Indoor framing, appliance parts |
|
G60 |
0.60 total (0.30 per side) |
~5 µm per side |
Moderate protection |
HVAC systems, light-duty outdoor framing |
|
G90 |
0.90 total (0.45 per side) |
~7.5 µm per side |
High protection |
Roofing, siding, agricultural equipment |
|
G235 |
2.35 total (1.175 per side) |
~20 µm per side |
Maximum protection |
Guardrails, pole barns, marine/coastal structures |
Choosing the Right Coating for Your Project
G30: The most cost-effective for indoor or dry environments. Common in appliance components or interior studs.
G60: A balanced choice for moderate exposure-ideal for framing, ductwork, or areas with occasional humidity.
G90: A trusted standard for outdoor durability, offering solid performance in roofing, farm structures, and coastal regions.
G235: The thickest standard zinc coating available. Ideal for high-corrosion environments like marine, agriculture, and highway infrastructure (e.g., guardrails).
While heavier coatings offer better protection, they also increase cost and may be less suitable for deep forming or spot welding. Always balance coating weight with your application needs.
- Galvanized Steel Specifications
| Technical Standard | EN10147, EN10142, DIN 17162, JIS G3302, ASTM A653 |
| Steel Grade | Dx51D, Dx52D, Dx53D, DX54D, S220GD, S250GD, S280GD, S350GD, S350GD, S550GD; SGCC, SGHC, SGCH, SGH340, SGH400, SGH440, SGH490, SGH540, SGCD1, SGCD2, SGCD3, SGC340, SGC340 , SGC490, SGC570; SQ CR22 (230), SQ CR22 (255), SQ CR40 (275), SQ CR50 (340), SQ CR80(550), CQ, FS, DDS, EDDS, SQ CR33 (230), SQ CR37 (255), SQCR40 (275), SQ CR50 (340), SQ CR80 (550); or Customer's Requirement |
| Type | Coil/Sheet/Plate/Strip |
| Thickness | 0.12-6.00mm,or customer's requirement |
| Width | 600mm-1500mm, according to customer's requirement |
| Type of Coating | Hot Dipped Galvanized Steel(HDGI) |
| Zinc Coating | 30-275g/m2 |
| Surface Treatment | Passivation(C), Oiling(O), Lacquer sealing(L), Phosphating(P), Untreated(U) |
| Surface Structure | Normal spangle coating(NS), minimized spangle coating(MS), spangle-free(FS) |
| Quality | Approved by SGS,ISO |
| ID | 508mm/610mm |
| Coil Weight | 3-20 metric ton per coil |
| Package | Water proof paper is inner packing,galvanized steel or coated steel sheet is outer packing , side guard plate,then wrapped by seven steel belt.or according to customer's requirement |
| Export market | Europe, Africa, Central Asia, Southeast Asia, Middle East, South America, North America, etc |
