What is flow induced corrosion?

Flow-accelerated corrosion (FAC), also known as flow-assisted corrosion, is a corrosion mechanism in which a normally protective oxide layer on a metal surface dissolves in a fast flowing water. The underlying metal corrodes to re-create the oxide, and thus the metal loss continues.

How does flow rate affect corrosion?

The corrosion rate gradually increases with the increase of flow velocity from 0~10.0 m/s. Then it gradually decreases after a peak, and the corrosion rate reaches the peak at 10.0 m/s. (2) The change of speed imposes a significant impact on the open circuit potential.

What causes flow accelerated corrosion?

What causes Flow-Accelerated Corrosion? The mechanical effect of fluid flow or velocity of a fluid combined with the corrosive action of the fluid causes accelerated loss of metal.

What is the difference between erosion corrosion and flow accelerated corrosion?

Abstract. Flow accelerated corrosion (FAC) is distinct from erosion and is primarily an electrochemical corrosion process aided by chemical dissolution and mass transfer. The forms of erosion including single and dual phase FAC and liquid droplet impingement are discussed and differentiated.

What is cavitation corrosion?

Cavitation-corrosion is the combined deterioration of a surface by the formation and collapse of bubbles in a liquid, as well as corrosion. Cavitation-corrosion may also be known as cavitation erosion.

What is FAC in boiler?

More than 40% of Heat recovery steam generator (HRSG) tube failures are due to Flow accelerated corrosion (FAC). FAC phenomenon occurs in carbon & low alloy steels, with poor chemical treatment & design. Identification, mitigation & preventive action of FAC is vital to improve the boiler performance.

What is the corrosion rate of steel?

Steel corrodes quickly in acidic environments and slowly or not at all as alkalinity is increased. The corrosion rate of steel in soil can range from less than 0.2 microns per year in favorable conditions to 20 microns per year or more in very aggressive soils.

Why does corrosion increase when seawater velocity increases?

the dissolved oxygen diffuses faster toward the cathode, increasing the corrosion rate of the metal, When the relative velocity of the sea increases with respect to the metal, In the atmosphere near the sea, there is a lot of water and salt, and there is sufficient oxygen and corrosion to the metal Relatively strong.

What is accelerated corrosion test?

Accelerated corrosion testing has been used since the early 1900s as a means for evaluating the performance of coatings when exposure to actual conditions is neither practical nor available, An accelerated corrosion test is usually defined as any test method from which results are obtained in a shorter period of time …

What is the difference between erosion and cavitation?

Erosive wear is caused by the impact of particles against a solid surface. Cavitation is caused by the localized impact of fluid against a surface during the collapse of bubbles.

What is cavitation materials?

Cavitation occurs when vapour cavities form in a liquid, resulting in small voids or bubbles in the material. Derived from the latin word cavitare, Cavitation literally means ‘caving out’. It usually arises upon rapid change of pressure or movement of the material, causing hollow spaces, also known as voids or bubbles.

What is FAC testing?

ATS provides FAC testing to help clients prevent major failures. Flow-accelerated corrosion (FAC) occurs when fast-flowing fluid or steam dissolves the protective layer on the interior walls of pipes and vessels.