Case studyFailure analysis of dissimilar weld in heat exchanger

- A dissimilar weld failure analysis of a heat exchanger in an H2S application has been conducted.
- Dissimilar weld is between a carbon steel and duplex stainless steel.
- Hardness profiles and SEM-EDS analysis are included.
- Failure was due to sulfide-assisted stress corrosion cracking.
- High hardness levels and local dilution of chemistry in the weld facilitated the failure.

The failure analysis of a dissimilar weld in a heat exchanger has been conducted. Within hours of being placed in service, the circumferential weld joining the carbon steel shell to the duplex stainless steel tubesheet experienced partial cracking as H2S was being introduced into the exchanger. The cracking of the weld was determined to be associated with sulfide-stress corrosion cracking facilitated by high weld hardness levels and local dilution of chemistry in the weld.