Seawater Corrosion Resistance of Stainless Steel Tubes
Stainless Steel Tubes are susceptible to crevice or pitting attack in chloride bearing waters. Their behavior has been studied by a number of investigators. There is considerable variation in the percentage of apparently identical sites where attack occurs, when it occurs. It is useful to describe results in terms of the percentage of apparently identical sites where attack occurs at a given chloride concentration. Very tight crevices increase the likelihood of attack. Roughness surface, sheared edges, scratches and similar imperfections also tend to increase the incidence of attack.
Relative resistance can be described by the chloride concentration below which there is little likelihood of crevice attack occurring. The ability of chlorides to concentrate in some crevices means that occasional attack may occur at lower concentrations than shown in the following table. Crevice or pitting attack also occurs under deposits and under biofouling growths attached to the metal surface. Nevertheless, the table provides useful guidelines.
The 4 1/2% Mo and duplex stainless steel pipe are more resistant than type 316L stainless steel tube, but suffer varying degrees of crevice attack in brackish water and seawater. The 6% Mo stainless steel tubing have excellent resistance to crevice attack in seawater.
For further information: NiDI 11 003 Guidelines for Selection of Stainless Steel for Marine Environments, Natural Waters and Brines.
Guidelines for relative resistance of stainless steel to crevice attack in natural waters
| Alloy |
Chloride concentration below which
crevice corrosion is rare |
| 400 series: |
crevice attack occurs in fresh waters |
| 304SS: |
100-200 ppm |
| 316SS: |
1000 ppm |
Related References:
Corrosion of Zinc and Zinc Coated Steel in Sea Water
Seawater Resistance of Stainless Steel Tubes
Seawater Corrosion Resistance and Antifouling Conclusions
Copper Nickel Seawater Corrosion Resistance and Antifouling
Selection of 316 304 and 303 Types of Stainless Steel for Seawater Application
Metallographic Test - Metallography Testing
Metallographic Test Report
Stress Corrosion Cracking (SCC)
Chloride Stress Corrosion Cracking
Stainless Steel Corrosion
Corrosion of Piping
Corrosion Process
Surface Coatings for Corrosion
Corrosion Resistant Material
Bi- Metallic Corrosion.Galvanic Corrosion
Intergranular Corrosion
Intergranular Corrosion of Stainless Steel Tubes
Corrosion Resistant Stainless Steel Tube
Corrosion Resistance of Stainless Steel Tubes
Seawater Resistance of Stainless Steel Tubes
Corrosion Mechanism in Stainless Steel Tube
ASTM A262 Intergranular Corrosion Test IGC
ASTM E112 Standard Test Methods for Determining Average Grain Size
Methods of minimizing chloride stress corrosion cracking
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