With increased requirement for deep desulfurization to meet market demand, old refineries are facing
higher risk of corrosion by ammonium salts. The paper describes failure of an ERW pipe in a high
pressure flash gas line through which gases from Hydrocracker and Hydrotreating units are sent to a
centralized amine unit. To prevent similar failures a two prong approach has been made. First to
minimize ammonium salt corrosion, specific limits of critical parameters have been developed which are
monitored on a regular basis and corrective actions taken as required maintaining the parameters.
Secondly, a risk analysis for all ERW piping in the refinery has been carried out and depending on risk
rating of a piping, a replacement/inspection strategy has been developed.
Key words: Ammonium salt corrosion, ERW, Hydrotreating, Hydrocracker, Flash Gas, Risk analysis
replacement strategy