Difference Between PPGI and PPGL

PPGI and PPGL sheets are two different color-coated steel sheets, which are widely used in various industries, such as advertising, construction, transportation, home appliance industry, etc., and they are very similar. But there are still some differences. So, what is the difference between PPGI and PPGL ?

1. Different substrates

PPGI is the abbreviation of pre-painted galvanized steel, and PPGL is the abbreviation of pre-painted galvalume steel. As the name implies, PPGI uses galvanized sheet (with a zinc coating) as the parent material. PPGL is based on galvanized sheet, which is coated with 55% aluminum, 43.3% zinc and 1.6% silicon. This is the main difference between PPGI and PPGL, which will further affect their characteristics and applications.

2. Service Life

As mentioned, both zinc coating and Al-Zn coating are used to protect the metal from rusting to prolong its service life. For the GI sheet, the base metal will be damaged when the zinc coating is all corroded. Generally, a galvanized sheet may last for 10 to 15 years. While aluminum and zinc alloy forms microscopic particle areas. The Zn-rich phase will corrode preferentially, while the Al-rich phase will corrode very slowly. So Al-Zn coating is more corrosion-resistant than zinc-coated steel sheet. According to data, the service life of PPGL is 3 times longer than that of PPGI.

3. Weight Difference

With the same coating thickness, Al-Zn coating is lighter than zinc coating. It is because the specific weight of aluminum is lower than that of zinc. That is to say, with the same weight, Al-Zn coating can cover 3% more space than the GI sheet.

4. Appearance Difference

The surface of the PPGL sheet is smoother than that of the PPGI sheet. It is because of the better adhesion of aluminum than zinc. For the same reason, PPGL sheets can be painted directly without pre-treatment. However, it is necessary to be pre-treated for galvanized sheets.

5. Different Features

The heat resistance of the PPGL sheet is better than that of the PPGI sheet. PPGL sheet can withstand temperatures of 315 ℃. Also, PPGL sheets have better corrosion resistance than PPGI. It is because that the dense layer made of aluminum can prevent the base metal from further eroding.

6. Different Applications

Both PPGI and PPGL sheets are widely used in wall paneling and roofing. By comparison, PPGL has better resistance to corrosion, which means it is more suitable for severe outdoor environments. Also, due to its good heat resistance and good surface conductivity, it is widely used in chimney pipes, oven and lampshade, etc. However, the cut edges of PPGL are less protected. So you can use anti-rust paint or zinc-rich paint to the cut edges.

In general, PPGL is more heat and corrosion resistant. Its service life can reach more than 50 years under normal conditions. The service life of PPGI is about 20-30 years. But PPGL roof panels are more expensive than PPGI roof panels. It depends on your budget and usage environment.