By David Moore
This is an update to our previous blog on cracking of refinery hydroprocessing REACs made of duplex stainless steel: View Original Post
2205 DSS (UNS S31803 or S32205) has been used in refinery hydroprocessing unit reactor effluent air coolers (REACs) since the mid 1980’s (1). 2205 was selected due to its good resistance to ammonium bisulfide (NH4HS) corrosion and perceived resistance to chloride stress corrosion cracking because it was an economical choice when compared to higher nickel alloy alternatives such as Alloy 825 or Alloy 625.
Many of these DSS REACs have remained in service successfully, with some in service for more than 30 years. However, several incidences of cracking failures of both REACs and associated piping have occurred in industry. Some failures have resulted in major plant damage and long outage time. Some refiners have been replacing DSS REACs with Alloy 825 to avoid in-service cracking risk. Others have made risk assessments and continue to operate with DSS REACs, often with periodic in-service crack detection inspection.