Sulfuric Acid Corrosion | Materials And Corrosion Control - PDFYAR

Sulfuric Acid Corrosion | Materials And Corrosion Control

Damage Mechanism	Sulfuric Acid Corrosion
Damage Description	Sulfuric acid promotes general and localized corrosion of carbon steel and other alloys. Carbon steel heat affected zones may experience severe corrosion. Corrosion of steel by dilute acid is usually in the form of overall metal loss or pitting and becomes more severe with increasing temperature and velocity.
Affected Materials	Carbon steel, 316L SS, Alloy 20, high silicon cast iron, high nickel cast iron, Alloy B-2 and Alloy C276.
Control Methodology	· Corrosion is minimized through materials selection and proper operation within design velocities. · Alloys such as Alloy 20, Alloy 904L and Alloy C-276 resist dilute acid corrosion and form a protective iron sulfate film on the surface. · Acidified product streams can be washed with caustic to neutralize the acid.
Monitoring Techniques	· Ultrasonic Testing or Radiography Testing inspection of turbulent zones and hottest areas. · Corrosion monitoring with coupons and ER probes.
Inspection Frequency	· The testing frequency shall be specified based on the severity of the susceptible location.
KPIs	Acid concentration, temperature, alloy content, velocity, contamination and presence of oxidizers. Carbon steel corrosion rates increase significantly if the flow velocity exceeds about 2 to 3 fps (0.6 to 0.9 m/s) or at acid concentrations below 65%. Moreover, the presence of oxidizers can greatly increase the corrosion rate.
Reference Resources (Standards/GIs/BPs)	· API RP 571