3 Causes Of Corrosion Of Stainless Steel Tubes

While stainless steel can resist corrosion better than carbon and steel alloys, certain conditions can affect the integrity of the material over time. For example, as it comes in contact with an electrolyte such as water, oxygen, or other metal, it causes a chemical reaction, due to which it can lose electrons and become weak. Hence, it renders the stainless-steel product vulnerable and can succumb to rust, cracks, and holes, due to which it can collapse.

Stainless steel corrosion is of different types. Uniform corrosion spreads evenly across the surface of stainless steel material and causes a uniform metal loss across the entire surface. Pitting corrosion is a form of localized corrosion occurring in a confined area in pits and spots due to exposure to aggressive chemical species like chloride, which can cause oxide breaks on the metal. Finally, crevice corrosion in stainless steel occurs in the microenvironment where there is a difference in ion concentration between two metal areas.

Intergranular corrosion is a form of selective attack in the vicinity of grain boundaries in stainless steel. It can severely affect the mechanical properties of the metal. Tensile stress and a specific corrosive environment can also crack stainless steel and can result in axial cracks in the pipeline. The fine cracks may emerge in the microstructure of the metal, and hence it is hard to spot.

To prevent the metal integrity of your 416 stainless steel tube and other stainless steel grades, you need to protect the metal against these corrosive atmospheres that can critically affect its lifespan.

Chlorides

The chromium content of stainless steel alloys is vulnerable to chlorides. In wet and humid environments that contain chloride ions, it can cause pitting corrosion and crevice corrosion in the stainless steel tubes. Chloride breaks down the passive film on the surface of stainless steel. Corrosion accelerates in an alkaline environment and coastal areas with salt-spray exposure, resulting in the rusting of the metal.

Acids

While stainless steel is resistant to acidic corrosion, strong acids can destabilize the passive layer on the stainless steel surface. Intermediate concentrations of sulfuric acid and hydrochloric acid can cause surface corrosion. These are strong reducing acids and, when present in higher concentrations, can trigger the degradation of stainless steel.

Iron And Carbon Steel Particles

Iron and carbon steel particles can deposit on the surface steel and damage the oxide layer. At the site of contamination, it can produce localized or pitting corrosion. The rust spots can compromise the chromium oxide surface of the stainless steel tubes. Carbon contamination of stainless steel can occur due to the breakdown of organic materials when exposed to materials from nearby welding, combustion of sooty gas flames, or because of paint, pen, or pencil markings.