Corrosion Classes & Surface Treatments

The life expectancy of a cable support system is dependent on the environment in which it is placed. Therefore, it is important to establish the corrosive properties of an environment to ensure that the right treatment and the right material are chosen. Do not use a component finish above the corrosion class targeted.

  • Classified per SS-EN ISO 12944-2
  • 8 surface treatments & materials

We briefly outline the various surface treatments and materials. As regards environmental corrosion, a steel design component can usually be assigned to one of the corrosion classes (C1 to CX) as shown in table A. Reference values for the average level of corrosion in steel and zinc are given in table B. The corrosion classes comply with those stipulated in SS-EN ISO 12944-2.

Corrosion classes C1 to CX overview - Wibe Group
Corrosion classes C1–CX at a glance
Corrosion classes and their recommended surface treatments and materials

C1 to CX at a glance

C1 electro-galvanized corrosion class - Wibe Group
C1

Electro-galvanized

Indoor environments: Schools, shops, hotels, offices, sports halls etc.

  • CheckmarkVery low environmental corrosion.
  • CheckmarkHeated areas.
  • CheckmarkArid atmosphere.
  • CheckmarkInsignificant quantities of pollutant.
ISO 2081
C2 pre-galvanized corrosion class - Wibe Group
C2

Pre-galvanized

Partly outdoor environments: Industries, sports halls, warehouses, shops, rural outdoor areas etc.

  • CheckmarkVery low environmental corrosion.
  • CheckmarkNon-heated areas with fluctuating levels of temperature and humidity.
  • CheckmarkFew instances of condensation and low levels of airborne pollution.
ISS-EN 10346
C3 hot-dip galvanized corrosion class - Wibe Group
C3

Hot-dip galvanized and Zinc+

Indoor- and outdoor environments: Urban and light industrial areas, breweries, dairies, laundries etc.

  • CheckmarkAverage environmental corrosion.
  • CheckmarkAreas with average levels of humidity and some airborne pollution caused by production processes.
  • CheckmarkAtmospheres containing some salt or average levels of airborne pollution.
EN-ISO1461/EN 10346 (Z+)
C4 hot-dip galvanized corrosion class - Wibe Group
C4

Hot-dip galvanized and Zinc+

Indoor- and outdoor environments: Chemical plants, industrial and coastal areas, swimming pools, farms, dockyards etc.

  • CheckmarkHigh environmental corrosion.
  • CheckmarkAreas with high levels of humidity and considerable airborne pollution.
  • CheckmarkAtmospheres with average salt content or discernible levels of airborne pollution.
EN-ISO1461
C5 Zinkpox and stainless steel corrosion class - Wibe Group
C5

Zinkpox® / Stainless steel AISI 304

Indoor- and outdoor environments: Chemical and heavy industries, tunnels, swimming pools, dockyards etc.

  • CheckmarkVery high (industrial) environmental corrosion.
  • CheckmarkAreas with almost permanent condensation, large quantities of airborne pollution, high levels of humidity and aggressive atmospheres.
EN 1.4301 acc. to EN 10088/AISI 304
CX stainless steel AISI 316L corrosion class - Wibe Group
CX

Stainless steel AISI 316L and GRP

Indoor- and outdoor environments: Heavy industries, coastal and offshore areas, purifying plants etc.

  • CheckmarkVery high (marine) environmental corrosion.
  • CheckmarkAreas with almost permanent condensation and large quantities of airborne pollution. Atmospheres with high salt content.
EN 1.4404 acc. to EN 10088/AISI 316L

Table A

Corrosion classes as stipulated by SS-EN ISO 12944-2 with atmospheric corrosion levels and examples of the environment in which they are most suitable for use.

Corrosion class Environmental corrosion Examples of typical environments in temperate climates (informative) Wibe Group designation
Outdoors Indoors
C1 Very low   Heated areas with arid atmosphere and insignificant quantities of pollutant, e.g. offices, shops, schools and hotels. Electro-galvanized
DIN 50961/ISO 2081
C2 Low Atmospheres with low levels of airborne pollution. Rural areas. Non-heated areas with fluctuating levels of temperature and humidity. Few instances of condensation and low levels of airborne pollution, e.g. sports halls and warehouses. Pre-galvanized
Z 275 in accordance with EN 10346
C3 Average Atmospheres containing some salt or average levels of airborne pollution. Urban and light industrial areas. Areas affected by coastal conditions. Areas with average levels of humidity and some airborne pollution resulting from production processes, e.g. breweries, dairies, laundries. Hot-dip galvanized after manufacture in accordance with EN-ISO 1461 Zinc+ coating
C4 High Atmospheres with average salt content or discernible levels of airborne pollution. Industrial and coastal areas. Areas of high humidity and considerable airborne pollution as the result of production processes, e.g. chemical plants, swimming pools and dockyards.
C5 Very high Industrial areas with high humidity and aggressive atmosphere, and coastal areas with high salinity. Buildings with almost permanent condensation and with high pollution. Zinkpox®
HDG+powder coating
Stainless steel
EN 1.4301/AISI 304
CX Extreme Offshore areas with high salinity, industrial areas with extreme humidity, and aggressive atmospheres, sub-tropical or tropical atmospheres. Industrial buildings with extreme humidity and aggressive atmosphere. Stainless steel
EN 1.4404/AISI 316L

GRP

Table B

Mass losses for zinc in various corrosion classes.

Corrosion class Mass loss per surface unit and thickness reduction (1 year of exposure)
Zinc
Mass loss (g/m2) Thickness reduction (μm)
C1< 0.7< 0.1
C2> 0.7 to 5> 0.1 to 0.7
C3> 5 to 15> 0.7 to 2.1
C4> 15 to 30> 2.1 to 4.2
C5> 30 to 60> 4.2 to 8.4
CX> 60 to 180> 8.4 to 25

*Corrosion speed is generally higher when the material is first exposed.

Materials & finishes

Surface treatments

Products are manufactured in accordance with ISO 2081. Such products are intended for use only in warm, dry areas with negligible pollutant levels.
Products are manufactured from Z 275 pre-galvanized sheet steel in accordance with SS-EN 10346. Under normal conditions, surface sections created during cutting and drilling will repair themselves, providing superb anti-corrosion protection.
Wibe Group has one of the most modern hot-dip galvanization plants in the Nordic countries. The hot-dip process is continuous, guaranteeing a high and even quality. The manufactured products are hot-dip galvanized in accordance with EN-ISO 1461:2009 whilst nuts and bolts are hot-dip galvanized in accordance with SS-EN ISO 10684. This form of galvanization affords very good value-for-money anticorrosion protection in atmospheres with a pH value of between 6 and 13. However, in acidic environments where pH levels fall below 6 and in alkaline environments where the pH value exceeds 13, the protective zinc layer breaks down relatively quickly. When cuts/perforations or other kind of operation that damage or remove coating in HDG items suitable to be installed in aggressive corrosion class, must be repaired with a zinc rich paint.
Zinc+ surface treatment for some accessories (EN 10346) with a metallic Zinc-based coating containing aluminium and magnesium that offers ultimate corrosion resistance in aggressive environments (e.g. chloride & highly alkaline). In many cases a good alternative to hot-dip galvanization. Excellent surface finish with self-repairing protection of cut edges (galvanic protection).
The Zinkpox® method involves applying a homogenous polyester coating to the zinc layer. Besides resisting light-initiated degeneration and weathering, this powder coating has excellent mechanical properties as regards impact resistance and adhesion. It is also resistant to most chemicals. Compared to hot-dip galvanizing, applying a polyester coating to the zinc layer more than doubles the service life of treated components. The zinc layer prevents the development of filiform corrosion. This might otherwise degrade the coating. Consequently, the polyester coating is subject only to atmospheric attack and thus protects the zinc layer. The certified coating plant that treats our components uses a modern and environment-friendly process. Before powder coating, the galvanized components undergo meticulous pre-treatment. This ensures superb adhesion. In addition to extremely good corrosion protection, the Zinkpox® method also offers a choice of colours. Powder coating is a very environment-friendly way of achieving a coloured surface. Because the coating contains no solvents, it has largely replaced solvent-based liquid coatings. Where installations are visible, cable ladders and fittings can be finished in a coating that matches the surrounding décor.

Products manufactured in accordance with AISI 304 acc. to ASTM / 1.4301 acc. to EN 10088-3 or /AISI 316L acc. to ASTM / 1.4404 acc. to EN 10088-3 are designed for use in highly aggressive environments, either indoors or outdoors, on industrial sites where there are high levels of potent airborne pollution such as in certain chemical industries, cellulose-related industries, refineries or artificial fertilizer factories, high humidity tunnels, etc. Stainless steel products are also ideal for use in environments where special hygiene requirements are in force, such as dairies, abattoirs, other food industries and pharmaceutical factories.

The deciding factor in choosing between stainless steel AISI 304 or AISI 316L is the aggressiveness of the environment in which it is to be used, and for this atmospheric chlorine content plays a significant role. Environments with a high chlorine content, coastal areas being a prime example, are aggressive and usually require the use of AISI 316L materials. When assessing the needs of factories, consideration should be given to the materials previously used to suspend equipment such as pipe tubing, and from this determine whether stainless steel AISI 304 or AISI 316L material is required.

GRP (Glass Fibre Reinforced Polymer) is a lightweight, high-strength composite material designed for harsh environments. It offers excellent resistance to corrosion, chemicals, UV exposure and weathering, while providing long service life with minimal maintenance.

Key benefits

  • Corrosion resistant
  • High chemical resistance
  • UV resistant
  • Non-conductive electrical insulator
  • Lightweight and strong
  • Low maintenance
  • Fire-resistant options available
  • Suitable for offshore and industrial environments
  • Pultruded for strength

Mita Flex GRP profiles are manufactured using a pultrusion process, combining glass fibres and resin to create strong, durable structures with consistent performance and long-term resistance to corrosion.

Resin options

Mita Flex is available with different resin types to meet specific project requirements:

  • Polyester Class 1 (PC1): General industrial use with good corrosion resistance and Class 1 fire performance.
  • Acrylic (AC): Low flame, smoke and toxicity properties for tunnels, transport and enclosed spaces.
  • Vinylester (VE): Enhanced resistance to chemicals, fuels and marine environments.
  • Anti-Static Polyester (AS): Designed for applications requiring anti-static properties.

Not sure which corrosion class applies to your project?

Our team can help you select the right corrosion class and surface treatment for your environment.

Contact Our Experts