Understanding the differences and applications of PPGI and PPGL Steel Coils

Summary: Pre-painted galvanized iron (PPGI) and pre-painted galvalume (PPGL) steel coils are two commonly used materials in vario...

Pre-painted galvanized iron (PPGI) and pre-painted galvalume (PPGL) steel coils are two commonly used materials in various industries, particularly in construction and manufacturing. Both types of steel coils are coated to enhance their durability, corrosion resistance, and aesthetic appeal. However, they differ in their base materials, coatings, and specific applications. Understanding these differences is crucial for selecting the right material for a given application.

Base Materials:

PPGI Steel Coils:

PPGI steel coils are made from hot-dipped galvanized steel. This means the steel is coated with a layer of zinc, which provides excellent corrosion resistance.
The zinc coating acts as a sacrificial layer, protecting the underlying steel from rust and other forms of corrosion.

PPGL Steel Coils:

PPGL steel coils are made from hot-dipped galvalume steel, which is a combination of zinc, aluminum, and silicon. The typical composition is about 55% aluminum, 43.5% zinc, and 1.5% silicon.
The aluminum in the coating provides better corrosion resistance compared to pure zinc, especially in environments with high moisture or salt content.

Coating and Paint:


The zinc coating on PPGI provides a robust barrier against corrosion. The pre-painting process involves applying multiple layers of paint, including a primer and topcoat, which enhances its aesthetic and protective qualities.
Common paint systems include polyester, silicon-modified polyester (SMP), high-durability polyester (HDP), and polyvinylidene fluoride (PVDF).


The galvalume coating on PPGL offers superior durability and corrosion resistance. The presence of aluminum helps in forming a protective oxide layer, which is self-healing in case of scratches or minor damage.
Like PPGI, PPGL also undergoes a pre-painting process with similar types of paint systems to enhance its performance and appearance.

Corrosion Resistance:


PPGI is highly resistant to corrosion due to its zinc coating, making it suitable for outdoor applications where it is exposed to the elements. However, it might not perform as well as PPGL in environments with high salinity or industrial pollution.


PPGL offers superior corrosion resistance, especially in harsh environments such as coastal or industrial areas. The aluminum in the coating provides additional protection against rust and corrosion, outperforming PPGI in many cases.



PPGI is widely used in construction for roofing, wall panels, and cladding due to its aesthetic appeal and adequate protection against the elements.
It is also used in home appliances, automotive parts, and furniture.


PPGL is preferred in more demanding environments where enhanced corrosion resistance is critical, such as coastal areas, industrial zones, and places with extreme weather conditions.
It is commonly used for roofing, siding, and structural panels in construction, as well as in industrial applications.

Cost and Availability:


Generally, PPGI is more affordable compared to PPGL due to the lower cost of zinc compared to the aluminum-zinc alloy.
It is widely available and can be sourced easily from various suppliers.


PPGL tends to be more expensive because of the higher cost of the aluminum-zinc alloy and the additional manufacturing processes involved.
It may not be as widely available as PPGI, depending on the region and supplier.