Stainless Steel Support Systems

Why bother about corrosion and surface protection

Corrosion refers to the physico-chemical interaction between the metallic material and its environment. It is important to realise that this interaction can result in changes in the properties of the metal, and this may lead to significant impairments in its performance.

To avoid changes in the properties of the metal, one needs to be mindful about selecting the right surface protection material. This primarily depends on the presence and concentration of corrosion factors in the environment. After identifying the most relevant corrosion factors, it is recommended to take the guidance as defined by ISO 12944 on which surface protection method suits your environment best.


Comparison A2 gradeA4 grade
Material composition 18% chromium and 8% nickel content >18% chromium, >8% nickel+ 3% of molybdenum content
Corrosion resistance Limited resistance, only for areas with low and moderate pollution. The A2 grade is not recommended to be applied near salt-water, marine and coastal areas
Very high corrosion resistance. Even resistance in areas with high pollution and salt content
Resistance to chemicalsNot resistant to chemicals, and it can even react sensitively to ordinary household detergentsResistant to aggressive chemicals
CleaningRecommended to be cleaned by clean water only. Chemicals and detergents can cause impairments in the functioning of the metalCan be cleaned with both water as well as detergents with high chemical content
HygieneA2 grade is recommended for areas with low and moderate pollution and only ordinary hygiene requirementsFor areas with high hygiene criteria, for example food production, the use of A4 grade is mandatory

* Please consider the content of the table as guidance over explicit recommendations for a certain material or product
** According to ISO 12944
*** BUP (Walraven  BIS UltraProtect 1.000) can be used depending on your environment. Please consult us for more information

application stainless steel

Stainless Steel

Stainless Steel has become a popular choice of product over the years, primarily thanks to its high corrosion resistance and aesthetic appeal. The high corrosion resistance of the product is enabled by its high (over 11-12%) chromium content. Unlike regular carbon steel, when getting exposed to corrosive factors, the chromium layer of Stainless Steel starts oxidising instead of the steel itself. The oxidised chromium forms a very thin and tight layer which protects the metal from oxygen attacks. The corrosion resistance of Stainless Steel can further be enhanced by adding more nickel.

A2 vs A4 Stainless Steel

The two most commonly produced grades of Stainless Steel are 304 (also known as A2) and 316 (also known as A4). Even though they share a lot in common, there are some fundamental differences between the two. Please see table below for more guidance.

Applications*Corrosivity class**Zinc coatingHot dip galvanizedBUP (BIS UltraProtect 1000)Stainless Steel
Dry indoor spacesC1, C2
Vinkje iconVinkje iconVinkje iconVinkje icon
Indoor spaces with occasional condensation
C1, C2Vinkje iconVinkje iconVinkje iconVinkje icon
Outdoor areas with low pollutionC2, C3Vinkje iconVinkje iconVinkje icon
Outdoor areas with moderate pollutionC3, C4Vinkje icon***Vinkje icon
Coastal areas C4, C5, CXVinkje icon
Outdoor areas with heavy pollutionC4, C5, CXVinkje icon
Extreme/special applications

Please consult us for more information

The Walraven offer

With over 70 years of experience in the installation and surface protection market, we understand the complexity of selecting the right materials and assessing the corrosion factors in the field. To this end, next to various surface protection options, we offer a complete and fully A4 graded range of Stainless Steel product portfolio suitable for the most typical application areas.

With our customer-oriented logistics concept, we ensure prompt delivery, which can even happen within a week. Furthermore,  upon request, we also support with the design, calculation and the prefabrication of the system.

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