Galvanized steel is a material widely used in the production of items for construction and finishing work. Specifically, galvanized steel sheets serve as the primary raw material for manufacturing facade panels, metal fence components, and more.
The quality of the galvanization directly impacts not only the mechanical properties of the products but also their durability. A high-quality zinc coating prevents corrosion, ensuring that facade panels, ceiling rails, and metal fence slats can last for an extended period, even with regular exposure to moisture and temperature fluctuations.
Choosing high-quality galvanized metal for any product manufacturing is crucial. While low-grade products may be cheaper, their poor zinc coating quality often leads to reduced corrosion protection. As a result, the perceived cost savings are illusory: products begin to rust much sooner, requiring repair or replacement.
The quality of galvanized metal is determined by several standards, the most important of which are:
These documents outline the requirements that galvanized steel must meet. In this section, we’ll briefly discuss the most critical parameters.
The first aspect is the quality of the steel base. Any products can be galvanized, but for manufacturing profiled products, sheet steel with a thickness ranging from 0.4 to 2.0 mm is used. The ideal option is to use metal intended for cold stamping (CS) or cold profiling (CP). General-purpose steel (GPS) is also acceptable.
The next important detail is the type of applied coating:
However, the key parameter affecting both the coating’s strength and its effectiveness in corrosion protection is the coating thickness. Based on this parameter, galvanized steel is divided into three classes.
|Class||Zinc Coating Consumption, g/m2||Zinc Layer Thickness, μm|
|1||258 – 570||18-40|
The higher the coating class, the higher the cost of the metal (and consequently, the products made from it). However, this also means greater reliability and effectiveness in protecting the steel base from corrosion.
Determining the quality of the protective zinc coating is a crucial task for quality control staff and companies that produce raw materials, as well as those involved in processing such metal. Quality control methods are described in GOST 9.307-89.
Here are the most commonly used technologies:
The main drawback of most laboratory methods used for checking the quality of zinc coating is their high complexity. It is often impossible to implement them “at home,” so when purchasing raw materials or finished products, customers often rely solely on the product labeling provided in the documents.
However, it is still possible to assess the quality of galvanizing, even approximately, outside the laboratory, and it can be done in just a few minutes. The most simple, accessible, and reliable method is visual inspection (which is also used in quality control according to industry standards).
During visual inspection, pay attention to:
Visual assessment of the coating thickness is also possible. Yes, thin-layer application makes it difficult to assess quality accurately without using special instruments (micrometers, thickness gauges). Therefore, it is advisable to:
Or estimate the thickness of the galvanizing by comparing it with a reference sample (accuracy will still be low, but better than without a reference).
Another “folk” method is the mechanical assessment of strength. In simpler terms, a steel tool is used to try to scrape off the zinc coating from the metal substrate (similar to the scratch grid application described in the industry standards). If the metal is of sufficient quality, hardened steel can certainly scratch the galvanization (especially with enough force), but it won’t lead to material delamination. However, when the hot-dip galvanizing process is compromised, the coating will detach from the substrate in characteristic patches.
The downside of this method is that it is indicative, meaning it can only distinguish very low-quality galvanized steel. On the other hand, when purchasing relatively cheap raw materials, this method can help identify the most obvious defects.
Experienced builders know how important it is to have reliable and high-quality thin sheet metal for construction and industrial projects. Choosing the wrong metal can lead to bending problems, corrosion, and even safety hazards. Here are expert tips on checking the quality of thin sheet metal to help you make the right choice and ensure the reliability of your project.
Quality control of thin sheet metal can be carried out using various instruments and tools. Below are several key instruments that can be used to assess the quality of thin sheet metal:
Using these instruments will help effectively check the quality of thin sheet metal, identify possible defects, and ensure the reliability of your project. However, it should be noted that some instruments may be more complex to use and require a certain level of expertise, so it’s best to consult specialists for precise measurements and analysis.
There is no room for compromise when it comes to quality control of thin sheet metal. Considering criteria such as thickness, chemical composition, surface quality, strength, and durability, as well as certification and standardization, will ensure the success of your construction project. Always consult specialists and follow the manufacturer’s recommendations. Be diligent and invest time and effort in checking the quality of the metal to ensure the safety, strength, and reliability of your project.
Quality control of galvanized steel is crucial for both producers of construction and finishing materials and for consumers. In the first case, it is important to determine how well the actual characteristics of the coating match the stated ones, and in the second case, to understand whether the product can effectively withstand external influences, primarily temperature fluctuations and corrosion. In any case, even without special tools, you can assess the quality of galvanization and make a choice in favor of more durable, albeit slightly more expensive, products!