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 an installation’s structural integrity and other safety risks, which can be extremely costly to repair.
With this in mind, you probably want to know how to address corrosion prevention on your installations. 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 through contact with air or water), becoming oxidised as it forms an oxide, which damages the metal’s surface entirely. Factors that contribute to corrosion include:
- 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
- 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 and material finish you plan to use when considering corrosion prevention.
The consequences of corrosion
Depending on the metal type, material finish and environment, corrosion can occur over many years to even within a few months in more extreme metal-to-environment incompatibility. This deterioration of metals can cause significant financial and safety consequences, including high costs to fix corrosion damage, waste of valuable resources, machine and plant downtime to repair, and reduction of the structure’s integrity.
How to prevent corrosion
Despite corrosion being nearly impossible to stop, proper planning, design and product material selection significantly help to counter the effects of corrosion, in some cases, for 20 years or longer.
By identifying the environmental conditions of the installation using the EN ISO 14713 guidelines and selecting the appropriate metal type and material finish of fixings for the environmental conditions, you’ll be able to ensure long-lasting quality, cost savings, and increased safety on your 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 metal type or material finish/surface protection method that best matches the conditions for optimal corrosion prevention. 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.
- Advanced surface protection solutions such as Walraven BIS UltraProtect® 1000 provide corrosion protection in up to C4 environments
- And you, of course, can choose Stainless Steel, which is often the preferred indoor and outdoor choice for 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 we have decades of experience in corrosion prevention solutions and have a range of solutions 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 our 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* so is suitable in up to C4 environments.
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 galvanized | BUP (Walraven 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 | ||||
**Until the appearance of maximum 5% red rust, in accordance with EN ISO 14713.
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 in the field as safe and fast as possible, as well as offering appropriate support for the design and pre-assembly of the system, and general support before and after installation completion.
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.
