Introduction to GI Coil Codes

In general, Z stands for pure zinc coating and ZF refers to zinc-iron alloy coating. The number represents the thickness of the zinc layer. For example, Z120 or Z12 means the weight of zinc coating (double-sided) per square meter is 120 grams. While the zinc coating of the single side will be 60 g/㎡. Below is the recommended zinc layer thickness for different use environments.

How to Choose Base Metal Based on Applications?

Send Us Your Requirements:

Size: the thickness, width, zinc coating thickness, coil weight?
Material and Grade: Hot rolled steel or cold rolled steel? And with spangles or not?
Application: What is the purpose of the coil?
Quantity: How many tons do you need? The MOQ is 25 tons.
Delivery: When is it needed and where is your port?
If you have special requirements, please let us know.

Spangles on Galvanized Steel

Spangle is formed during the hot-dip galvanizing process. The size, brightness, and surface of spangles mainly depend on the composition of the zinc layer and the cooling method. According to the size, it includes small spangles, regular spangles, big spangles, and free spangles. They look different, but the spangles almost will not influence the quality of galvanized steel. You can choose according to your preference and use purpose.

1. Big or Regular Spangles

Spangle-promoting elements are added to the zinc bath. Then beautiful spangles are formed as the zinc layer solidifies. It looks good. But the grains are coarse and there is slight unevenness. In a word, its adhesion is poor but weather resistance is good. It is most suitable for guardrails, blowers, ducts, rolling shutters, drain pipes, ceiling brackets, etc.

2. Small Spangles

During the solidification process of the zinc layer, zinc grains are artificially restricted to form as fine spangles as possible. The spangle size can be controlled by cooling time. Generally, the shorter the cooling time, the smaller the size. Its coating performance is great. Therefore, it is perfect for drainage pipes, ceiling brackets, door columns, the substrate for color coated steel, car body panels, guardrails, blowers, etc.

3. Zero Spangles

By adjusting the chemical composition of the bath, the coating has a uniform surface without visible spangles. The grains are very fine and smooth. It has excellent corrosion resistance and good coating performance. It is also ideal for drainage pipes, automobile components, back panels for home appliances, automobile body panels, guardrails, blowers, etc.

Galvanized Steel Coil Uses

Galvanized coil features lightweight, aesthetics, and excellent corrosion resistance. It can be used directly or as the base metal for PPGI steel. Therefore, GI coil has been a new material for many fields, such as construction, shipbuilding, vehicle manufacturing, furniture, home appliances, etc.

1. Construction

They are often used as roofing sheets, interior and exterior wall panels, door panels and frames, the surface sheet of the balcony, ceiling, railings, partition walls, windows, and doors, gutter, sound insulation walls, ventilation ducts, rainwater pipes, rolling shutters, agricultural warehouses, etc.

2. Home Appliances

GI coil is widely applied to home appliances, such as the back panel of air conditioners, and the outer casing of washing machines, water heaters, refrigerators, microwave ovens, switch cabinets, instrument cabinets, etc.

3. Transportation

It is mainly used as decorative panels for cars, corrosion-resistant parts for cars, decks of trains or ships, containers, road signs, isolation fences, ship bulkheads, etc.

4. Light Industry

It is ideal for making chimneys, kitchen utensils, garbage cans, paint buckets, etc. At Wanzhi Steel, we also make some galvanized products, such as chimney pipes, door panels, corrugated roofing sheets, floor decks, stove panels, etc.

5. Furniture, such as wardrobes, lockers, bookcases, lampshades, desks, beds, bookshelves, etc.

6. Other Uses, such as post and telecommunication cable, highway guardrails, billboards, newsstands, etc.

Why Choose Galvanized Steel Coil?

1. Cost-effective Solution

Compared to GL or color coated steel coils, the galvanized coil is the most cost-effective solution but with similar features, such as great corrosion resistance, good appearance, etc.

2. Wide Applications

GI sheet roll is easy to process for different purposes. It is widely used in construction, home appliances, automobile containers, transportation, etc. Besides, it has good coating adhesion and weldability. That’s why it is also an ideal base metal for PPGI products.

3. Easy to Transport

Compared to GI steel sheets, coils are easier to transport. In this way, it will save your shipping cost.

Surface Treatment of Galvanized Steel Coil

There are some different surface treatment methods to reduce the risk of corrosion during storage and transportation.

1. Passivation

After being passivated, it can reduce rust (white rust) during storage and transportation. However, passivation hinders the adhesion of most coatings. In general, other types of galvanized layer, except for zinc-iron alloy coating, will go through passivation treatment at the factory.

2. Oiling

Oiling can reduce the corrosion of steel sheets under wet conditions. Please note that the oil layer should be removed with a degreaser that does not damage the zinc layer.

3. Organic Coating Film

Using a thin transparent organic coating film on the surface can provide additional corrosion protection, as well as fingerprint resistance. It can also serve as the adhesion for subsequent coating.

4. Phosphating

Phosphating treatment also is able to improve the adhesion and corrosion resistance of zinc coating. And it can be coated without further treatment in addition to normal cleaning.

If you have special requirements, please let us know.