Abstract
Since ADNOC Sour Gas Processing Plant was commissioned, the steam condensate collection system presented repetitive failures in elbows and other fittings from 4" and bellow bore pipe size. It is important to highlight that hazard of the leakage is directly associated on the people and environmental concerns due to high temperature operation of the steam condensate system.
ADNOC Sour Gas has developed comprehensive analysis approach to identify the root cause of the failures using destructive laboratory testing along with research library to identify the mitigating actions required to avoid the frequent downtime of the system.
Despite of what shown in the visual examination, the damage mechanism has not been associated with erosion phenomena due to operating regime at low velocity in comparison to erosional limit and further supported by microscopic examination evidence.
Flow-accelerated corrosion has been identified as primary damage mechanism affecting the condensate collection system and mostly affecting the flow pattern enhancers (i.e. elbows, tees) under the normal operating envelope. The mechanism is found influenced by the combination of flow pattern, pH behavior and temperature profile of the system. The highest failure rates are associated with the highest temperature/ velocities locations.
Mitigation actions identified to avoid the recurrent failure are related to the pH control above 9 and deployment of enhanced material for the fittings in susceptible areas. Material change has been implemented for the elbows/tees in these pipe sizes to avoid the thickness loss and/or failures. Material upgradation was deployed and satisfactory performing using following specification from SA-234 WPB to WP22.
