Acid Condensate Corrosion | Materials And Corrosion Control - PDFYAR

Acid Condensate Corrosion | Materials And Corrosion Control

Damage Mechanism	Acid Condensate Corrosion
Damage Description	· This is caused by carbon dioxide, hydrogen sulfide and other acids dissolved in the condensing water leading to acid formation and low pH with subsequent corrosion · Condensation depends on the amount of water present and on the water returning from the reflux. Use of a cold carrier for the inhibitor injection, if required, can also lead to shock condensation and localized corrosion. · This damage can occur in the amine stripper overhead piping, exchangers, accumulator and the reflux circuit
Affected Materials	· Carbon steel
Critical Factors
Affected Units or Equipment
Appearance or Morphology of Damage
Prevention/Mitigation	· A low concentration of amine in the overhead keeps the pH from dropping too low. A slipstream of lean amine is sometimes used to keep 500 ppm amine residual in the reflux water. · Some refineries employ corrosion inhibitors to maintain a neutral pH and provide protection
Inspection and Monitoring	· Visual and UT measurements for internal equipment inspection · UT scans or Profile Radiography for external inspection · Reflux water analysis for pH and Fe levels
Inspection Frequency	· per On-Stream Inspection output
Key Performance Indicators (KPIs)	· Corrosion rates above 5 mpy. · # Deviations of amine residual amount of ? · # Deviations of pH level of ? · # Deviations of Fe count of ?
Plant Integrity Windows (PIWs)	· Corrosion rate 0-5 MPY · Amine Residual >500 ppm ? · pH ?-? · Fe ?-?
Reference Resources (Standards/GIs/BPs)	· SABP-A-013, Amine Unit Corrosion Control · J. Gutzeit “Process Industries Corrosion – The Theory and Practice” NACE International, TX, 1986, pages 171-189.