IRISNDT Engineering provides laboratory and failure analyses services to assist our customers in optimizing equipment and pipeline reliability. Our laboratory conducts failure analyses on ferrous and non- ferrous materials; including carbon steels, alloy materials, fiber-reinforced plastics, composites, elastomers, and polymers (plastic and rubber).
Deethanizer Feed Drum
Magnetic particle inspections highlighted the cracks of a brittle appearance in the 40 year old vessel. The cracks:
- Initiated on the inside surface of the deposited weld metal.
- Propagated through the heat affected zone into the plate.
- Propagated through metal with hardness values significantly below 250 HV.
- Were filled with oxides.
- Were found in longitudinal and circ seams.
Cracking likely initiated due to carbonate stress corrosion cracking. Once the cracks reached the heat affected zone, they propagated due to stress oriented hydrogen induced cracking.
The vessel was decommissioned.
The shell side of the austenitic stainless steel heat exchanger tubes was exposed to steam. The tube side fluids contained chlorides and other corrosive elements.
Cracking originated from the shell side and it was the result of exposure to steam from untreated makeup water. Further makeup water was treated and the failures ended.