# Stainless Steel for Structural Applications

Guidelines for the selection of the appropriate grade of stainless steel in structural applications according to the service environment: Euro Codes 1 to 4 provide a procedure for choosing the appropriate grade of stainless steel for the service environment of structural members. Corrosion Resistance Factor (CRF) is used to evaluate the service environment and the stainless steel grades are placed in Corrosion Resistance Classes (CRC) I to V according to CRF value.

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## Calculation of Corrosion Resistance Factor (CRF)

The Corrosion Resistance Factor is comprised of three components: F1, F2 and F3.

• F1 rates the risk of exposure to chlorides from sea water/salt water or de-icing salts
• F2 rates the risk of exposure to sulfur dioxide
• F3 rates the cleaning regime or exposure to washing by rain

## Calculating F1: Risk of Exposure to Chlorides

M is the distance from sea, and S is the distance from roads where de-icing salts are employed.

F1 Value Description
1 Internal, Controlled Environment
0 Low Risk of Exposure: M.10 km or S > 0.1 km
-3 Medium Risk of Exposure: 1 km < M < 10 km or
0.01 km < S < 0.1 km
-7 High Risk of Exposure: 0.25 km < M < 1 km or S < 0.01 km
-10 Very High Risk of Exposure: Road Tunnels where de-icing salts used
-10 Very High Risk of Exposure: M < 0.25 km: North sea coast of Germany & All Baltic Coastal Areas
-15 Very High Risk of Exposure: M < 0.25 km - Incl All other European/UK Coastal Areas

## Calculate F2: Risk of Exposure to Sulphur Dioxide

Note: The sulfur dioxide value is usually low in European coastal environments. This value is either medium or low for inland environments. High values are mostly associated with specific environments such as tunnels or heavily industrialized locations.

In the following table, the deposition values are specified in micro-grams per cubic meter.

F2 Value Description
0 Low Risk of Exposure: 10 average deposition
-5 Medium Risk of Exposure: 10-90 average deposition
-10 High Risk of Exposure: 90-250 average deposition

## Calculate F3: Cleaning or Rain Washing

F3 is related to either the cleaning procedure or the exposure to washing by rain.

Note: If F1 + F2 = 0 then F3 = 0

F3 Value Description
0 Fully exposed to washing by rain
-2 Specified cleaning regime
-7 No washing by rain or specified cleaning regime

## Calculation of CRC

The Corrosion Resistance Class CRC needed for the specified environment is given by first calculating the CRF through adding F1+F2+F3.

CRF CRC
1 I
0 to Under -7 II
-7 to Under -15 III
-15 to Under -20 IV
Over -20 V

An appropriate grade of stainless steel for the environment can now be selected from the following table showing the CRC for various grades that are commonly available.

I 1.4003 / 1.4016 / 1.4512
II 1.4301 / 1.4307 / 1.4311 / 1.4541 / 1.4318 / 1.4306 / 1.4567 / 1.4482
III 1.4410 / 1.4404 / 1.4435 / 1.4571 / 1.4429 / 1.4432 / 1.4578 / 1.4462 / 1.4362 / 1.4062 / 1.4162
IV 1.4439 /1.4539 / 1.4462
V 1.4565 / 1.4529 / 1.4547 / 1.4410 / 1.4501 / 1.4507

This information has been sourced, reviewed and adapted from materials provided by Aalco - Ferrous and Non-Ferrous Metals Stockist.

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