Pipeline corrosion and how to prevent it

Pipeline, corrosion, pitting, galvanic, africa, oil, gas, water, wasteOn average, oil and gas companies, and water/wastewater industries, use 6 per cent of their annual income to combat corrosion; here are some of the causes and preventatives - Image credit to www.mero.cz

On average, oil and gas companies, and water/wastewater industries, use six per cent of their annual income to combat corrosion; here are some of the causes and preventatives.

Product quality, sanitation and health issues are major concerns in all process industries. Industries cannot afford to tolerate corrosion in the processing equipments and operations, as this increases the total cost of ownership of the equipment, as well as pose a threat to the environment.

 

Types of Corrosion

  • Uniform or Generic Corrosion: This can be said to have occured when the metal loss is uniform from the surface. It is often characterised with high velocity fluid erosion, with or without abrasives.
  • Pitting Corrosion: In this type of corrosion the metal loss is randomly located on the metal surface. This often combines with stagnant fluid or in areas with low fluid velocity.
  • Galvanic Corrosion: Happens when two metals with different electrode potentials are connected in a corrosive electrolytic environment. The anodic metal develops deep pits in the surface.
  • Crevice Corrosion: This type of corrosion can only occur at places with gaskets, bolts, and cap joints where crevices exist. Crevice corrosion creates pits similar to pitting corrosion.
  • Concentration Cell Corrosion: This occurs when the metal surface is exposed to an electrolytic environment where the concentration of the corrosive fluid or the dissolved oxygen varies. This often combines with stagnant fluid or in areas with low fluid velocity.
  • Graphitic Corrosion: This type of corrosion occurs mostly in cast irons and occurs when the cast iron loses its iron ion in salt water or acids, which leaves the graphite in place, resulting in a soft weak metal.
  • Microbiological Induced Corrosion (MIC): This is usually caused by biological growth in pipes and piping systems, causing corrosion by providing an enabling an environment for physical and chemical interactions to occur. A layer of biofouling on any surface in the condenser water system acts as a safe place for aerobic and anaerobic activity, potential corrosion and accumulation of scale and bacteria formation. By reducing bio-fouling, the potential for corrosive activity is greatly eliminated.

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