When it comes to hot dip galvanizing specifications, most contractors understand that 7mm steel requires an average coating thickness of "85 microns" to be standards compliant. It is a straightforward industry standard that is simple to remember and adaptable to a wide range of building demands. However not all hot dip galvanizing suppliers use the same thicknesses or coatings so it's important to verify the specification with your contractor.
The best way to determine the correct thickness for your project is by using our Galvanized Steel Plate Calculator. It allows you to input various dimensions for your metal stock and then calculates the appropriate coating thickness required for hot dip galvanizing. You can also view these calculations on our Galv Zinc website where we have compiled a large database of galvanized steel plate sizes and prices from which to choose.
Once you have determined the correct coating thickness you will need to purchase a hot dip galvanizing bath. These baths are available in two main varieties - hand pumped and automatic. Hand pumped baths require manual cleaning and maintenance but provide superior quality work compared to automatic baths. Automatic baths are programmed to fill, soak, spray, drain and repeat this process continuously without human intervention. They are more efficient than hand pumped baths but may not produce as high-quality results.
In conclusion, hot dip galvanizing is a simple process that provides excellent protection against corrosion for building components that are exposed to water during construction or renovation projects.
A single standard, EN ISO 1461: "Hot dip galvanized coatings on iron and steel items-specifications and test methods," defines the fundamental specification for hot dip galvanized coatings on iron and steel products. There are, however, certain exceptions to this rule (see thicker coatings below). The purpose of this standard is to provide manufacturers with a consistent method for comparing the quality of different hot dip galvanized products and also to help ensure product reliability over time.
The standard was developed by International Organization for Standardization (ISO). It specifies coating chemistry, process conditions, sample preparation, and testing procedures for evaluating the quality of hot dip galvanized products. This standard has been adopted worldwide by national standards bodies in more than 100 countries. Its compliance status has been confirmed by the United States Food and Drug Administration (FDA) as being equivalent to FDA requirements for food contact surfaces.
Galvanizing is the process of applying a protective layer of zinc to metal surfaces via electroplating or hot dipping. The term "galv" as used by manufacturers is generally reserved for coatings obtained from solutions containing zinc ions and usually including other elements such as aluminum, copper, magnesium, or silicon. In contrast, anodic oxidation which creates a porous oxide surface treatment that can withstand acidic cleaning compositions but not mechanical stressors such as scraping tools.
There are two types of galvanizing processes currently used by industry: Hot dip and cold dip.
The technique of immersing iron or steel in a bath of molten zinc to create a corrosion-resistant, multi-layered coating of zinc-iron alloy and zinc metal is known as hot-dip galvanizing. The technique is essentially simple, which gives it a significant advantage over other corrosion prevention approaches. Galvanizing is used primarily on metals that are not painted or coated with other materials that protect their surfaces from oxidation and corrosion.
Iron and steel are commonly used in construction because of their strength and ability to be formed into any shape required by the builder. However, they will rust if exposed to moisture and bacteria in soil or water. This can be prevented by applying a layer of zinc or another metal using the hot-dip galvanizing process.
There are two main types of hot-dip galvanizing: single stage and two-stage. In both cases, the material being coated is first cleaned then immersed into a bath of molten zinc. In the single-stage process, after immersion the material is immediately taken out of the bath and cooled in a furnace. In the two-stage process, the material is first heated outside the bath to remove surface contaminants such as oil or grease before being dipped into the bath. After cooling, it's removed from the bath and again heated outside the bath to cure the zinc coating.
Single-stage processes require more heat input than two-stage processes and thus increase energy costs.
Hot-dip galvanizing is widely used to protect steel immersed in soil, concrete, or submerged in water, in addition to the atmosphere. Though the corrosion processes and life expectancy varies in each of these conditions, galvanized steel has a demonstrated track record of longevity in all of them. Galvanized steel is also recommended for use where rust prevention is important but aesthetic appeal is not critical, such as on fences.
It's easy to apply hot-dip galvanizing to any number of metal objects. The process starts by cleaning the item with a solvent or abrasive blast to remove any surface contaminants or oxidation. Next, it's sprayed with a protective coating that contains zinc. This is done by dipping the item into a vat of the coating material or spraying it onto the item from an aerosol can. The item is then heated to cure the coating. When applied properly, this process should result in a coated item that is at least as durable as plain steel.
Items that are best left uncoated include wood, fiberglass, plastic, rubber, and nonferrous metals. These items cannot be sprayed with zinc because it would not cure well enough to provide protection against deterioration. Instead, they are treated with other materials that will coat the item without burning off under heat exposure.
The choice of coating depends on how the item will be used.
Galvanized coatings are resistant to high cold and heat. The suggested maximum temperature for long-term, continuous exposure is 392 F. (200 C). Continuous exposure to temperatures over this can cause the free zinc layer on the outside to peel away from the zinc-iron alloy layer on the inside. This can lead to corrosion of the metal beneath the coating.
The best way to keep galvanized iron safe from heat is to avoid exposing it to temperatures at which it will melt or burn. If you must work with hot objects that contain galvanized iron, use caution not to touch them without washing first. If you do get burned, go to a hospital right away so they can check out your skin.
Not only does heat damage galvanized iron, but so too does acid. If you come into contact with an acid solution, rinse off the acid immediately with plenty of water. Do not try to wash it off with soap because that will just make the problem worse. Contact a professional emergency room if you are exposed to acids.
If you have any questions about whether or not galvanized steel is heat resistant, ask when you're not going to be using it as an option. There are many types of metals that can be used in place of galvanized steel that may be more suitable for certain situations or projects.