Corrosion prevention is easier than you think
Corrosion is inevitable. In a broad sense, it is the gradual deterioration of materials (primarily metals) through reactions with their environments. When left unchecked, corrosion can cause significant impairments, such as the loss of a building’s structural integrity, which can be extremely costly to repair. More importantly there is also increased risk of workers’ safety.
With this in mind, you probably want to know how to prevent corrosion from occurring. Before we move to that, let’s learn a bit about the cause and process of corrosion.
The causes of corrosion
Most commonly, electrochemical corrosion occurs when most atoms on the metal’s surface lose electrons to oxygen (mainly with the air or water), becoming oxidised as it forms an oxide, which damages the metal’s surface entirely. Many causes contribute to general corrosion, including:
- Moisture, mainly through rain, humidity, or condensation
- Physical factors, like high and low temperatures
- Chemical factors, such as sulphur dioxides and chlorides
- Biological factors, like organic acids, salts or fungi
- Or air pollution
Corrosive conditions can damage some metals quite easily, while others resist corrosion because of their natural passivity. Therefore, you must understand both the installation environment and the type of metal you plan to use.
The consequences of corrosion
Depending on the metal type, surface protection, and environment, corrosion can occur over a couple of years to. In more extreme metal-to-environment incompatibility it could happen even within a few months. This deterioration of metals can cause significant financial and safety consequences, including high costs in amending corrosion damages, waste of valuable resources, machine and plant downtime to repair, and reduction of structure’s integrity, which can lead to risking workers’ safety.
How to prevent corrosion?
Despite corrosion being nearly impossible to stop, proper planning and design methods before installations significantly help to counter the effects of corrosion, in some cases, for 20 years or longer.
By identifying the environmental conditions of the installations using the EN ISO 14713 guidelines and applying the appropriate surface protection and metal type for the environmental conditions, you’ll be able to ensure long-lasting quality, cost savings, and increased workers’ safety amongst new and old installations.
1. Understand environmental conditions
The first step is to understand the environment. EN ISO 14713 classifies environments by corrosion severity, ranging from C1 with minimal corrosive factors to CX with extreme corrosive conditions. Based on the table below, carrying out this planning sets the basis for the rest of the installation design, including selecting the materials and surface protection, which can save unnecessary costs and time.
| Applications* | Corrosivity class** |
|---|---|
| Dry Indoor spaces | C1, C2 |
| Indoor spaces with occasional condensation | C1, C2 |
| Outdoor areas with low pollution | C2, C3 |
| Outdoor areas with moderate pollution | C3, C4 |
| Coastal areas | C4, C5, CX |
| Outdoor areas with heavy pollution | C4, C5, CX |
| Extreme/special applications | Please consult us for more information |
* Please consider the content of the table as guidance over the explicit recommendations for a particular material or product.
**According to EN ISO 14713
2. Selecting your surface protection
After determining your environment’s corrosivity, choose the surface protection method that best matches the conditions. Several options are available:
- Zinc coating is ideal for indoor spaces with lower corrosivity classes such as C1 or C2.
- Hot dip galvanised, a slightly more durable method than zinc-coating, can withstand C3 environments and, therefore, can already be used outdoors.
- And you, of course, can choose Stainless Steel, which is often the preferred indoor and outdoor choice as it can be applied in highly corrosive environments. It’s important to note that not all Stainless Steel products are the same. Two grades are commonly offered for Stainless Steel: A2 (304) and A4 (316). While their component composition is similar, only A4 contains molybdenum, which brings additional advantages. Molybdenum makes the A4 grade suitable for use near saltwater, marine, and coastal areas. In addition, the molybdenum component also provides the metal with better protection against chemicals such as chlorine and other.
Halogenic ions like fluorine. The latter is essential, as while A2-graded metals are recommended to be cleaned only with clean water, the A4 grade can be cleaned with water containing chemicals.
Helping customers make informed choices
At Walraven, next to having decades of experience in surface protection and deep expertise in the installations market, we also provide surface protection products for your project needs. For example, for environments, C1-C2, one of the options available is an affordable yet durable range of zinc-coated fixings, which can withstand about 100 hours of salt spray test*. When it comes to harsher environments, we offer the option of hot dip galvanised fixings (durable up to 600 hours of salt spray test*) and the in-house created Walraven BIS UltraProtect® 1000. The latter is suitable for both indoor and outdoor use and is unique in terms of scope, composition and corrosion resistance compared to similar surface protections. Walraven BIS UltraProtect® 1000 features an organic layer that protects against many different types of pollution and withstands 1,000 hours of salt spray test*.
Protection for extreme environments
For more extreme environments, we offer a complete range of A4-graded Stainless Steel for most application areas, ensuring lifetime guarantee and safety under virtually any conditions. See the table below for guidance on which surface protection method to apply depending on the environment’s corrosivity.
Choosing the right surface protection
| Applications* | Corrosivity class** | Zinc coating | Hot-dip galvanised | BUP (Bis UltraProtect 1000) | Stainless Steel |
|---|---|---|---|---|---|
| Dry Indoor spaces | C1, C2 | ✔ | ✔ | ✔ | ✔ |
| Indoor spaces with occasional condensation | C1, C2 | ✔ | ✔ | ✔ | ✔ |
| Outdoor areas with low pollution | C2, C3 | ✔ | ✔ | ✔ | |
| Outdoor areas with moderate pollution | C3, C4 | ✔** | ✔ | ||
| Coastral areas | C4, C5, CX | ✔ | |||
| Outdoor areas with heavy pollution | C4, C5, CX | ✔ | |||
| Extreme/special applications | Please consult us for more information | ||||
Quality and installation support
We believe in ensuring high-quality surface protection across all environmental situations and our entire product portfolio. Ease of installation is the essence of our product design, making installation on the field as safe and fast as possible, as well as offering appropriate support for the design, pre-assembly of the system, and general support before and after installation completion.
* Until the appearance of maximum 5% red rust, in accordance with EN ISO 14713.
Every project has unique environmental challenges. If you need support selecting the right materials or surface protection for your installation, please feel free to contact our experts for tailored advice.
